1H-NMR-based metabolomics approach to understanding the drying effects on the phytochemicals in Cosmos caudatus

1H-NMR-based metabolomic profiling and proteomic analysis of soybean (Glycine max L.) in response to dicarboxylic acids (photon) application as a stress priming agent

Soybean (Glycine max L.) serves not only as food for humans, animals, and industrial purposes, but is also a plant that can be used to comprehend molecular mechanisms occurring in stress response to various development techniques. To reveal the effect of applying dicarboxylic acids as stress priming agents on a metabolic level in soybean leaf extracts, the chemical profile of methanolic extracts were collected at different time points (1 h, 2 h, 12 h, 24 h, 1 week, 2 weeks and 3 weeks) after spraying were analyzed using 1H-NMR based metabolomics by way of PCA and OPLS-DA. The OPLS-DA revealed several metabolites, including organic acids (fumarate, citrate and malate) and amino acids (asparagine, alanine and GABA), which accumulated in higher amounts, with fumarate accumulating the highest in Glycine max L. leaf extracts compared to untreated leaves. Denaturing 1DE gels were prepared for MS-based protein analysis and the presence of fatty acids (linolenic, oleic and α-linolenic acid) were confirmed by gas chromatography coupled with mass spectrometry (GC-MS), which served as jasmonic acid precursors. The MS-based profiling of proteins on the denaturing 1DE gels revealed several proteins that were differentiated between the treated and untreated leaf extracts. These proteins included ferritins, CaM, ferredoxin-thioredoxin reductase and chalcone-flavanone isomerase 1A. Following the treatment, fumarate was significantly elevated at 12 h to 3 weeks, compared to other compounds. It is, therefore, proposed that elevated quantities of fumarate could be related to the KEAP1-NRF2 metabolic pathway. This study represents the initial investigation of the effect of dicarboxylic acid application as a stress priming agent on Glycine max L. using 1H-NMR metabolomic analysis, GC-MS and proteomic analysis.

Characterization of flours from the aroeira leaf (Schinus terebinthifolius Raddi), obtained by different drying methods

The present work aimed at the development and characterization of aroeira leaf flour (Schinus terebinthifolius Raddi), obtained by lyophilization and drying in an air circulation oven. The technological, physical, physico-chemical, morphological, functional, and microbiological aspects were analyzed. Physico-chemical analysis identified the following properties with values provided respectively for fresh leaves (FOin) and flours (FES and FLIO): low water activity (0.984, 0.370, 0.387 g/100 g), moisture (64.52, 5.37, 7.97 g /100 g), ash (2.69, 6.51, and 6.89 g/100 g), pH (0.89, 4.45, 4.48 g/100 g), lipids (0.84, 1.67, 5.23 g/100 g), protein (3.29, 8.23, 14.12 g/100 g), carbohydrates (17.02, 53.12, 33.02 g/100 g), ascorbic acid (19.70, 34.20, 36.90 mg/100 g). Sources of fiber from plant leaves and flours (11.64, 25.1, 32.89 g/100 g) showed increased levels of luminosity. For NMR, the presence of aliphatic and aromatic compounds with olefinic hydrogens and a derivative of gallic acid were detected. The most abundant minerals detected were potassium and calcium. Micrographs identified the presence of irregular, non-uniform, and sponge-like particles. The main sugars detected were: fructose, glucose, and maltose. Malic, succinic, citric, lactic, and formic acids were found. Fifteen phenolic compounds were identified in the samples, highlighting: kaempferol, catechin, and caffeic acid. The values ​​found for phenolics were (447, 716.66, 493.31 mg EAG/100 g), flavonoids (267.60, 267.60, 286.26 EC/100 g). Antioxidant activity was higher using the ABTS method rather than FRAP for analysis of FOin, FES, and FLIO. Since the flours of the aroeira leaf have an abundant matrix of nutrients with bioactive properties and antioxidant activity, they have a potential for technological and functional use when added to food.

Assessment of the effect of drying on Brassica greens via a multiplex approach based on LC-QTOF-MS/MS, molecular networking, and chemometrics along with their antioxidant and anticancer activities

Turnip (Brassica rapa var rapa L.) leaves are a rich source of versatile bioactive phytochemicals with great potential in the food and herbal industries. However, the effect of drying on its constituents has never been studied before. Hereto, three drying techniques were compared, namely, lyophilization (LY), vacuum oven (VO), and shade drying (SD). Chemical profiling utilizing liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (LC-QTOF-MS/MS) combined with chemometrics showed the different impacts of the drying methods on the phytochemical composition of the alcoholic leaf extracts. Unsupervised principal component analysis (PCA) and supervised partial least squares-discriminant analysis (PLS-DA) of the LC-QTOF-MS/MS data showed distinct distant clustering across the three drying techniques. Loading plots and VIP scores demonstrated that sinapic acid, isorhamnetin glycosides, and sinapoyl malate were key markers for LY samples. Meanwhile, oxygenated and polyunsaturated fatty acids were characteristic for SD samples and oxygenated polyunsaturated fatty acids and verbascoside were characteristic for VO samples. LY resulted in the highest total phenolics (TP) and total flavonoid (TF) contents followed by SD and VO. LY and SD samples had much higher antioxidant activity than VO measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH), oxygen radical absorbance capacity (ORAC), and iron metal chelation assays. According to the anticancer activity, the drying methods were ranked in descending order as SD > LY ≫ VO when tested against colon, breast, liver, and lung cancer cell lines. Among the identified compounds, flavonoids and omega-3 fatty acids were key metabolites responsible for the anticancer activity as revealed by partial least squares (PLS) regression and correlation analyses. In conclusion, compared to LY, SD projected out as a cost-effective drying method without compromising the phytochemical and biological activities of Brassica greens. The current findings lay the foundation for further studies concerned with the valorization of Brassica greens.

1H NMR-Based Metabolomics Profile of Green and Red Amaranthus Grown in Open Field versus Greenhouse Cultivation System

Traditionally, indigenous African leafy vegetables such as Amaranthus, blackjack, jute mallow, cleome monophyla, and spider plants have been conventionally and organically grown as weeds in open fields. However, the lack of land space due to the increase in population has resulted in unconventional, modern, and advanced agricultural farming. The introduction of a greenhouse has recently become the second most popular growing system alongside shade net and glasshouse to increase productivity and meet consumers' demand. Several studies on Amaranthus species have solely focused on physiological parameters and nutritional composition, leaving a huge gap on their metabolomic profile of the leaves which is crucial to comprehend when growing Amaranthus species in different cropping systems. Therefore, the study aimed to determine the influence of different cropping systems on the release of metabolites of two commonly consumed Amaranthus species in South Africa. H1 -Nuclear Magnetic Resonance (NMR) tool was used to profile the untargeted metabolites of green (Amaranthus graecizans L.) and red (Amaranthus cruentus L.) species. A total of 12 metabolites-trehalose, betaine, glutamine, choline, sucrose, caprate, adenosine, asparagine, carnitine, caffeine, aspartate, and alanine-were detected in green amaranth grown in open fields. Except for caffeine, aspartate, and caprate, which were found in the green amaranth grown in open fields, all the other metabolites were detected in the greenhouse grown once. Interestingly, allantoin, which serves as an allelochemical, was the sole distinct metabolite detected in greenhouse cultivated green amaranth. On the contrary, seven similar metabolites were quantified in red amaranth grown in both open fields and greenhouses, apart from caffeine, which was only detected in greenhouse-cultivated red amaranth.

Protective effect of Clinacanthus nutans in cisplatin-induced nephrotoxicity on human kidney cell (PCS-400-010) elucidated by an LCMS-based metabolomics approach

Cisplatin-induced nephrotoxicity has been widely reported in numerous studies. The objective of this study is to assess the potential nephroprotective effects of Clinacanthus nutans (Burm. f.) Lindau (Acanthaceae) leaf extracts on human kidney cells (PCS-400-010) in vitro using an LCMS-based metabolomics approach. Orthogonal partial least square-discriminant analysis identified 16 significantly altered metabolites when comparing the control and pre-treated C. nutans cisplatin-induced groups. These metabolites were found to be associated with glycerophospholipid, purine, and amino acid metabolism, as well as the glycolysis pathway. Pre-treatment with C. nutans aqueous extract (125 μg/mL) for 24 h, followed by 48 h of cisplatin induction in PCS-400-010 cells, demonstrated a nephroprotective effect, particularly involving the regulation of amino acid metabolism.

Multivariate modelling analysis for prediction of glycidyl esters and 3-monochloropropane-1,2-diol (3-MCPD) formation in periodically heated palm oil

Palm oil is a vegetable oil that is widely used for cooking and deep-frying because of its affordability. However, repeatedly heated palm oil is also prone to oxidation due to its significant content of unsaturated fatty acids and other chemical toxicants such as glycidyl esters and 3-monochloropropane-1,2-diol (3-MCPD). Initially, the physicochemical properties such as colour, viscosity, peroxide, p-anisidine and total oxidation (TOTOX) of periodically heated palm oil were investigated. Chemical profiling and fingerprinting of six different brands of palm cooking oil during heating cycles between 90 and 360 min were conducted using Fourier transform infrared (FTIR) and 1H Nuclear Magnetic Resonance (NMR) metabolomics. In addition, the multivariate analysis was employed to evaluate the 1H NMR spectroscopic pattern of repeatedly heated palm oil with the corresponding physicochemical properties. The FTIR metabolomics showed significant different of the chemical fingerprinting subjected to heating duration, which in agreement with the result of 1H NMR metabolomics. Partial least squares (PLS) model revealed that most of the physicochemical properties of periodically heated palm oil are positively correlated (R2 values of 0.98-0.99) to their spectroscopic pattern. Based on the findings, the color of the oils darkened with increased heating time. The peroxide value (PV), p-anisidine value (p-AnV), and total oxidation (TOTOX) values increased significantly due to degradation of unsaturated compounds and oxidation products formed. We identified targeted metabolites (probable carcinogens) such as 3-monochloropropane-1,2-diol (3-MCPD) and glycidyl ester (GE), indicating the conversion of 3-MCPD to GE in repeatedly heated oils based on PCA and OPLSDA models. Our correlation analysis of NMR and physicochemical properties has shown that the conversion of 3-MCPD to GE was significantly increased from 180 to 360 min cooking time. The combination spectroscopic techniques with physicochemical properties are a reliable and robust methods to evaluate the characteristics, stability and chemical's structure changes of periodically heated palm oil, which may contribute to probable carcinogens development. This study has proven that combination of NMR and physicochemical analysis may predict the formation of the probable carcinogens of heated cooking oil over time which emphasizing the need to avoid certain heating cycles to mitigate formation of probable carcinogens during cooking process.

Effect of Different Climatic Regions and Seasonal Variation on the Antibacterial and Antifungal Activity, and Chemical Profile of Helichrysum aureonitens Sch. Bip

Native South Africans make use of Helichrysum aureonitens Sch. Bip. extracts for the treatment of a variety of infections and they are important in traditional medicinal preparations. This study investigated the effect of seasonal variation and geographical location on the antibacterial and antifungal activities of H. aureonitens. Material was collected in two different seasons: early spring, with high rainfall and high temperatures (October), and late autumn, with low rainfall and lower temperatures (May). Further analysis was carried out using ¹H-NMR based metabolomics to analyse and compare the chemical profiles of the plants in both seasons and locations. Plant materials were collected from two sites for each season, at Wakefield farm (KwaZulu-Natal), representing a colder, wetter environment, and Telperion (Mpumalanga), representing a drier and warmer environment. Leaves of H. aureonitens were tested against bacteria (Proteus vulgaris (P. vulgaris) and Bacillus subtilis (B. subtilis)) as well as fungi (Aspergillus flavus (A. flavus), Aspergillus nomius (A. nomius), Cladosporium cladosporioides (C. cladosporioides), Fusarium oxysporum (F. oxysporum) and Penicillum halotolerans (P. halotolerans)). Extracts from the October harvest showed significant activities against the Gram-negative bacterium P. vulgaris compared to the May harvest, with an MIC value of 62.5 µg/mL. Similar activity was observed between the extracts from the wet season across the two geographically different locations. There was generally very good antifungal activity observed for all the species, with the exception of A. nomius, which had MIC values ranging from 0.39–1.56 µg/mL. Extracts of plant materials harvested in the wetter region had a significantly higher activity against A. flavus and F. oxysporum in both seasons than those from plants harvested in the drier region. Telperion-harvested plants exhibited better activity against F. oxysporum in the autumn. Hydrogen-1 NMR metabolomic analysis confirmed the significant effects of the seasons and the peculiar climates of different localities on the secondary metabolite profile of H. aureonitens.

1H-NMR and LC-MS Based Metabolomics Analysis of Potato (Solanum tuberosum L.) Cultivars Irrigated with Fly Ash Treated Acid Mine Drainage

1H NMR and LC-MS, commonly used metabolomics analytical platforms, were used to annotate the metabolites found in potato (Solanum tuberosum L.) irrigated with four different treatments based on FA to AMD ratios, namely: control (0% AMD; tap water), 1:1 (50% AMD), 3:1 (75% AMD is 75% FA: AMD), and 100% AMD (untreated). The effects of stress on plants were illustrated by the primary metabolite shifts in the region from δH 0.0 to δH 4.0 and secondary metabolites peaks were prominent in the region ranging from δH 4.5 to δH 8.0. The 1:3 irrigation treatment enabled, in two potato cultivars, the production of significantly high concentrations of secondary metabolites due to the 75% FA: AMD content in the irrigation mixture, which induced stress. The findings suggested that 1:1 irrigation treatment induced production of lower amounts of secondary metabolites in all crops compared to crops irrigated with untreated acid mine drainage treatment and with other FA-treated AMD solutions.

A method establishment and comparison of in vivo lung cancer model development platforms for evaluation of tumour metabolism and pharmaceutical efficacy

BACKGROUND

Currently, the identification of accurate biomarkers for the diagnosis of patients with early-stage lung cancer remains difficult. Fortunately, metabolomics technology can be used to improve the detection of plasma metabolic biomarkers for lung cancer. In a previous study, we successfully utilised machine learning methods to identify significant metabolic markers for early-stage lung cancer diagnosis. However, a related research platform for the investigation of tumour metabolism and drug efficacy is still lacking.

HYPOTHESIS/PURPOSE

A novel methodology for the comprehensive evaluation of the internal tumour-metabolic profile and drug evaluation needs to be established.

METHODS

The optimal location for tumour cell inoculation was identified in mouse chest for the non-traumatic orthotopic lung cancer mouse model. Microcomputed tomography (micro-CT) was applied to monitor lung tumour growth. Proscillaridin A (P.A) and cisplatin (CDDP) were utilised to verify the anti-lung cancer efficacy of the platform. The top five clinically valid biomarkers, including proline, L-kynurenine, spermidine, taurine and palmitoyl-L-carnitine, were selected as the evaluation indices to obtain a suitable lung cancer mouse model for clinical metabolomics research by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS).

RESULTS

The platform was successfully established, achieving 100% tumour development rate and 0% surgery mortality. P.A and CDDP had significant anti-lung cancer efficacy in the platform. Compared with the control group, four biomarkers in the orthotopic model and two biomarkers in the metastatic model had significantly higher abundance. Principal component analysis (PCA) showed a significant separation between the orthotopic/metastatic model and the control/subcutaneous/KRAS transgenic model. The platform was mainly involved in arginine and proline metabolism, tryptophan metabolism, and taurine and hypotaurine metabolism.

CONCLUSION

This study is the first to simulate clinical metabolomics by comparing the metabolic phenotype of plasma in different lung cancer mouse models. We found that the orthotopic model was the most suitable for tumour metabolism. Furthermore, the anti-tumour drug efficacy was verified in the platform. The platform can very well match the clinical reality, providing better lung cancer diagnosis and securing more precise evidence for drug evaluation in the future.

In Vitro Anti-Diabetic Activities and UHPLC-ESI-MS/MS Profile of Muntingia calabura Leaves Extract

Anti-diabetic compounds from natural sources are now being preferred to prevent or treat diabetes due to adverse effects of synthetic drugs. The decoction of Muntingia calabura leaves was traditionally consumed for diabetes treatment. However, there has not been any published data currently available on the processing effects on this plant’s biological activity and phytochemical profile. Therefore, this study aims to evaluate the effect of three drying methods (freeze-drying (FD), air-drying (AD), and oven-drying (OD)) and ethanol:water ratios (0, 50, and 100%) on in vitro anti-diabetic activities of M. calabura leaves. In addition, an ultrahigh-performance-liquid chromatography–electrospray ionization tandem mass spectrometry (UHPLC-ESI-MS/MS) method was used to characterize the metabolites in the active extract. The FD M. calabura leaves, extracted with 50% ethanol, is the most active extract that exhibits a high α-glucosidase and α-amylase inhibitory activities with IC₅₀ values of 0.46 ± 0.05 and 26.39 ± 3.93 µg/mL, respectively. Sixty-one compounds were tentatively identified by using UHPLC-ESI-MS/MS from the most active extract. Quantitative analysis, by using UHPLC, revealed that geniposide, daidzein, quercitrin, 6-hydroxyflavanone, kaempferol, and formononetin were predominant compounds identified from the active extract. The results have laid down preliminary steps toward developing M. calabura leaves extract as a potential source of bioactive compounds for diabetic treatment.

Review of the recent developments in metabolomics-based phytochemical research

Phytochemicals are important bioactive components present in natural products. Although the health benefits of many food products are well-known and accepted as a common knowledge, the identity of the main bioactive molecules and the mechanism by which they interact in the body of human are often unknown. It was only in the last 30 years when the field of metabolomics had matured that the identification of such molecules with bioactivity has been made possible through the development of instruments to separate and computational techniques to characterize complex samples. This in turn has enabled in vitro studies to quantify the biological activity of the respective phytochemical either in mice models or in humans. In this review, the importance of key dietary phytochemicals such as phenolic acids, flavonoids, carotenoids, resveratrol, curcumin, and capsaicinoids are discussed together with their potential functions for human health. Untargeted metabolomics, in particular, liquid chromatography mass spectrometry, is the most used method to isolate, identify and profile bioactive compounds in the study of phytochemicals in foods. The application of metabolomics in drug discovery is a common practice nowadays and has boosted the drug and/or supplement manufacturing sector.HighlightsPhytochemicals are beneficial compounds for human healthPhytochemicals are plant-based bioactive and obtainable from natural productsUntargeted metabolomics has boosted the discovery of phytochemicals from foodTargeted metabolomics is key in the authentication and screening of phytochemicalsMetabolomics of phytochemicals is reshaping the road to drug and supplement manufacture.

1 H-NMR analysis, antioxidant activity, and α-amylase and α-glucosidase inhibitory potential of ten common Thai edible flowers

BACKGROUND

Edible flowers have been used in cooking as foods as well as medicine alternatives. The objectives were to identify a major class of organic compounds in edible flowers by applying proton nuclear magnetic resonance (¹ H-NMR) metabolite fingerprinting and to evaluate bioactivity including antioxidant and α-amylase and α-glucosidase inhibitory activities.

RESULTS

A total of 32 metabolites including five organic acids, eight sugars, 11 amino acids and eight phenolic compounds were identified by using ¹ H-NMR at 600 MHz. The aromatic proton of phenolic compounds was observed at the low-field region ranged between δ 5.5 ppm and 10.0 ppm. Total phenolic content (TPC) of the extracts of edible flowers ranged from 6.0 mg GAE g^-1 dry weight (DW) to 47.97 mg GAE g^-1 DW. Antioxidant activity varied from 140.5 mmol L^-1 TE g^-1 DW to 985.2 mmol L^-1 TE g^-1 DW. The extracts from edible flowers showed dose-dependent inhibition against enzyme. The extract of African marigold (Tagetes erecta L.) had the highest half maximal inhibitory concentration (IC₅₀ ) against α-amylase at 0.13 mg mL^-1 while the extract of flower of Sesban agasta (Sesbania grandiflora Desv.) had the lowest IC₅₀ against α-amylase at 0.63 mg mL^-1 . Moderate correlation was found between IC₅₀ values against α-glucosidase and antioxidant activity values (R²  = 0.66) (P < 0.05).

CONCLUSION

¹ H-NMR application provided metabolomic fingerprinting of edible flowers and the in vitro inhibitory potential activity against key enzymes related to diabetes indicated that specific edible flowers have a potential use for dietary management during the early stages of hyperglycaemia. © 2021 Society of Chemical Industry.

Effect of post-harvest drying process on chlorogenic acids, antioxidant activities and CIE-Lab color of Thai Arabica green coffee beans

Drying process affected the qualitative indicators of green coffees; chlorogenic acid (CGAs), total phenolic content (TPC), antioxidant activities and CIE-lab color to varying degrees. Sun drying and heat pump drying resulted in comparable levels of CGAs and antioxidant activities in green coffees; however, color parameters, especially lightness (L*), differed. Correlation analyses indicated a relationship between specific CGAs, antioxidant activities and color parameters among coffees. PLS analysis revealed that the high contents of 5-caffeoylquinic acid in green coffees did not correlate with antioxidant activities. Results from CGAs contents and PCA analysis provided a linkage to previous research relating important components and quality indices of both green and roasted coffees as affected by postharvest drying. Results indicated that heat pump drying at 50 °C is a viable alternative and possibly superior to sun drying for preserving certain desirable chemical and physical characteristics of green coffee.

The In Vitro α-Glucosidase Inhibition Activity of Various Solvent Fractions of Tamarix dioica and 1H-NMR Based Metabolite Identification and Molecular Docking Analysis

The Tamarix dioica (T. dioica) is widely used medicinal plant to cure many chronic ailments. T. dioica is being used to manage diabetes mellitus in traditional medicinal system; however, very little scientific evidence is available on this plant in this context. The current study involves the fractionation of crude methanolic extract of T. dioica using n-hexane, ethyl acetate, chloroform, and n-butanol. The screening for antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay was carried out. The in vitro antidiabetic potential was assessed by measuring α-glucosidase inhibition. Total phenolic and flavonoid contents were also determined for each fraction. The metabolites were identified using highly sensitive and emerging ¹H-NMR technique. The results revealed the ethyl acetate fraction as the most potent with DPPH scavenging activity of 84.44 ± 0.21% and α-glucosidase inhibition with IC₅₀ value of 122.81 ± 2.05 µg/mL. The total phenolic and flavonoid content values of 205.45 ± 1.36 mg gallic acid equivalent per gram dried extract and 156.85 ± 1.33 mg quercetin equivalent per gram dried extract were obtained for ethyl acetate fraction. The bucketing of ¹H-NMR spectra identified 22 metabolites including some pharmacologically important like tamarixetin, tamaridone, quercetin, rutin, apigenin, catechin, kaempferol, myricetin and isorhamnetin. Leucine, lysine, glutamic acid, aspartic acid, serine, and tyrosine were the major amino acids identified in ethyl acetate fraction. The molecular docking analysis provided significant information on the binding affinity among secondary metabolites and α-glucosidase. These metabolites were most probably responsible for the antioxidant activity and α-glucosidase inhibitory potential of ethyl acetate fraction. The study ascertained the ethnomedicinal use of T. dioica to manage diabetes mellitus and may be a helpful lead towards naturopathic mode for anti-hyperglycemia.

NMR-Based Metabolomic Analyses to Identify the Effect of Harvesting Frequencies on the Leaf Metabolite Profile of a Moringa oleifera Cultivar Grown in an Open Hydroponic System

Moringa oleifera Lam. is one of the world’s most useful medicinal plants. Different parts of the M. oleifera tree contain a rich profile of important minerals, proteins, vitamins, and various important bioactive compounds. However, there are differences in the phytochemical composition of the medicinal plant’s raw materials due to seasonal variation, cultivation practices, and post-harvest processing. The main objective of this study was therefore to determine the effect of harvesting frequencies on selected bioactive compounds of a M. oleifera cultivar (PKM1) grown in a hydroponic system under a shade net structure. Three harvesting frequency treatments were applied in the study, with the plants harvested at every 30 days (high frequency), 60 days (intermediate frequency), and 90 days (low frequency) respectively. ¹H-NMR was used for data acquisition, and multivariate data analysis by means of principal component analysis (PCA), partial least square discriminatory analysis (PLS-DA), and orthogonal partial least square discriminatory analysis (OPLS-DA) were applied to determine the changes in the leaf metabolite profile, and also to identify the spectral features contributing to the separation of samples. Targeted metabolite analysis was used to match the NMR peaks of the compounds with the NMR chemical shifts of the contribution plot. The contribution plot showed that the increase in concentration of some compounds in aliphatic, sugar and aromatic regions contributed to the separation of the samples. The results revealed that intermediate and low harvesting frequencies resulted in a change in the leaf metabolite profile. Compounds such as chlorogenic acid, ferulic acid, vanillic acid, wogonin, esculetin, niazirin, and gamma-aminobutyric acid (GABA) showed an increase under intermediate and low harvesting frequencies. These results provide insight into the effect of harvesting frequencies on the metabolite profile and associated medicinal activity of M. oleifera.

Immunomodulatory and Antioxidant Activities of Select Indonesian Vegetables, Herbs, and Spices on Human Lymphocytes

Edible plants have attracted increasing attention as functional foods as they are rich in bioactive compounds with health benefits, including antioxidant and immunomodulatory activities. However, scientific evidence of these health effects is limited. This study is aimed at determining antioxidant and immunomodulatory activities of 25 select vegetables, herbs, and spices commonly consumed in Indonesia. Phytochemical profiles were determined by measuring total flavonoid content and 1H-NMR. Human blood lymphocyte cells were used to probe the immunomodulatory potency and treated with the methanol extract of these vegetables, herbs, and spices. The results showed the enhanced propensity for all tested plant extracts to stimulate lymphocyte proliferation, except Pandanus amaryllifolius. Etlingera elatior, Ocimum xcitriodorum, Kaempferia galanga, and Apium graveolens had the highest lymphocyte cell proliferation stimulation index (SI) at concentrations of 41.67, 16.67, 4.17, and 2.5 mg/mL culture, respectively (SI 2.21 ± 0.05, 2.62 ± 0.12, 3 ± 0.05, and 2.64 ± 0.07, respectively). The NMR spectra of these four most potent plants showed low peaks in the aromatic/phenolic area and several other peaks indicating the presence of terpenoid, steroid, amino acid, and sugar compounds. The results demonstrate the immunomodulatory potential of all vegetables, herbs, and spices, except P. amaryllifolius, although this potential did not necessarily correlate with flavonoid content and antioxidant activity. Nevertheless, this research showed promising health effect, particularly immunomodulation, of the various local plants. Further elaboration on the specific immunomodulatory activity will be interesting.

UHPLC-UV/PDA Method Validation for Simultaneous Quantification of Luteolin and Apigenin Derivatives from Elaeis guineensis Leaf Extracts: An Application for Antioxidant Herbal Preparation

Luteolin and apigenin derivatives present in oil palm (Elaeis guineensis) leaves (OPL) are reported to possess excellent antioxidant properties relating to numerous health benefits. To meet the global demand for flavonoids, OPL, which is plentifully generated as an agricultural by-product from oil palm plantations, can be further exploited as a new source of natural antioxidant compounds. However, to produce a standardized herbal preparation, validation of the quantification method for these compounds is required. Therefore, in this investigation, we developed and validated an improved and rapid analytical method, ultra-high-performance liquid chromatography equipped with ultraviolet/photodiode array (UHPLC-UV/PDA) for the quantification of 12 luteolin and apigenin derivatives, particularly focusing on flavonoid isomeric pairs: orientin/isoorientin and vitexin/isovitexin, present in various OPL extracts. Several validation parameters were assessed, resulting in the UHPLC-UV/PDA technique offering good specificity, linearity, accuracy, precision, and robustness, where the values were within acceptable limits. Subsequently, the validated method was employed to quantify luteolin and apigenin derivatives from OPL subjected to different drying treatments and extraction with various solvent systems, giving total luteolin (TLC) and apigenin content (TAC) in the range of 2.04-56.30 and 1.84-160.38 µg/mg extract, respectively. Additionally, partial least square (PLS) analysis disclosed the combination of freeze dry-aqueous methanol yielded OPL extracts with high TLC and TAC, which are strongly correlated with antioxidant activity. Therefore, we provide the first validation report of the UHPLC-UV/PDA method for quantification of luteolin and apigenin derivatives present in various OPL extracts, suggesting that this approach could be employed in standardized herbal preparations by adopting orientin, isoorientin, vitexin, and isovitexin as chemical markers.

1H-NMR and LC-MS Based Metabolomics Analysis of Wild and Cultivated Amaranthus spp

Amaranthus crops are important for their use as food and nutritional sources, as well as for their medicinal properties. They are mostly harvested from the wild, and cultivation of Amaranthus species is still rare, and therefore, attempts are being made to commercialize and market this important crop. This research investigated the effect of cultivation and environment on the chemical profile of both cultivated and wild A. cruentus and A. hybridus by multivariate statistical analysis of spectral data deduced by Nuclear Magnetic Resonance (NMR). Furthermore, wild samples of A. cruentus and A. hybridus were subjected to Liquid Chromatography-Mass Spectrometry (LC-MS) for further analysis. Through NMR analysis, it was found that maltose and sucrose increased in both cultivated A. cruentus and A. hybridus. Moreover, the amino acid, proline was present in cultivated A. cruentus in high quantity whereas, proline and leucine were prominent in A. hybridus. Other compounds that were found in both wild and cultivated A. cruentus and A. hybridus are trehalose, trigonelline, lactulose, betaine, valine, alanine, fumarate, formate and kynurenine. LC-MS analysis revealed the presence of rutin, 2-phenylethenamine and amaranthussaponin I in both wild A. cruentus and A. hybridus, while chlorogenic acid was identified only in cultivated A. hybridus. On the contrary, L-tryptophan, kaempferol, phenylalanine and quercetin were detected only in wild A. cruentus. Amaranth is not only rich in macro and micronutrients, but the leaves also contain phytochemicals that vary between species and cultivated plants, and might, therefore, affect the medicinal properties of the material.

NMR-based metabolomics for elucidating the bioactive compounds from Mangifera caesia Jack and Ficus auriculata lour

Mangifera caesia and Ficus auriculata are neglected fruits found in Malaysia and are locally known as "buah binjai" and "buah ara", respectively. To profile the metabolites for both fruits, we conducted a robust ¹ H-nuclear magnetic resonance (NMR)-based metabolomics approach. Principal component analysis (PCA) and partial least square (PLS) analyses were applied to distinguish the metabolites variations of M. caesia and F. auriculata fruits extracted with different ethanol ratios (0, 70, and 100%). In total, 34 metabolites were identified in M. caesia and F. auriculata fruits. The 70% ethanol extracts of both fruits displayed the highest antioxidant and α-glucosidase inhibitory activities, as well as notable with the highest phenolic content, compared with the other samples. The present metabolomics study shows that the polarities of solvent extractions play a crucial role in the assessment and recovery of the metabolites for the high value of natural antioxidants and α-glucosidase inhibitors in M. caesia and F. auriculata fruits. PRACTICAL APPLICATIONS: Antioxidant and antidiabetic agents from fruit sources are increasingly becoming popular due to its potential contributions to human health, by protecting against infections and degenerative diseases. However, some of these fruits were neglected where the scientific data on their potential benefits and biochemical contents are lacking. The information gained from this study provides valuable knowledge on M. caesia and F. auriculata fruits as natural antioxidant and α-glucosidase inhibitors agents that might be beneficial to consumers, further promote the usage of neglected fruits as functional food and natural supplements.

Metabolite variations and antioxidant activity of Muntingia calabura leaves in response to different drying methods and ethanol ratios elucidated by NMR-based metabolomics

INTRODUCTION

Muntingia calabura from the Muntingiaceae family has been documented for several medicinal uses. The combinations of drying treatment and extracting solvents for a plant species need to be determined and optimised to ensure that the extracts contain adequate amounts of the bioactive metabolites.

OBJECTIVE

Evaluate the metabolite variations and antioxidant activity among M. calabura leaves subjected to different drying methods and extracted with different ethanol ratios using proton nuclear magnetic resonance (¹ H-NMR)-based metabolomics. Methodology The antioxidant activity of M. calabura leaves dried with three different drying methods and extracted with three different ethanol ratios was determined by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and nitric oxide (NO) scavenging assays. The metabolites variation among the extracts and correlation with antioxidant activity were analysed by ¹ H-NMR-based metabolomics.

RESULTS

Muntingia calabura leaves extracted with 50% and 100% ethanol from air-drying and freeze-drying methods had the highest total phenolic content and the lowest IC₅₀ value for the DPPH scavenging activity. Meanwhile, oven-dried leaves extracted with 100% ethanol had the lowest IC₅₀ value for the NO scavenging activity. A total of 43 metabolites, including sugars, organic acids, amino acids, phytosterols, phenolics and terpene glycoside were tentatively identified. A noticeable discrimination was observed in the different ethanol ratios by the principal component analysis. The partial least-squares analysis suggested that 32 compounds out of 43 compounds identified were the contributors to the bioactivities.

CONCLUSION

The results established set the preliminary steps towards developing this plant into a high value product for phytomedicinal preparations.

Metabolite Characterization and Correlations with Antioxidant and Wound Healing Properties of Oil Palm (Elaeis guineensis Jacq.) Leaflets via 1H-NMR-Based Metabolomics Approach

Oil palm (Elaeis guineensis Jacq.) leaflets (OPLs) are one of the major agricultural by-products generated from the massive cultivation of Malaysian palm oil. This biomass is also reported to be of potential value based on its health-improving effects. By employing proton nuclear magnetic resonance (1H-NMR) spectroscopy combined with multivariate data analysis (MVDA), the metabolite profile of OPLs was characterized and correlated with their antioxidant and wound healing properties. Principal component analysis (PCA) classified four varieties of extracts, prepared using solvents ranging from polar to medium polarity, into three distinct clusters. Cumulatively, six flavonoids, eight organic acids, four carbohydrates, and an amine were identified from the solvent extracts. The more polar extracts, such as, the ethyl acetate-methanol, absolute methanol, and methanol-water, were richer in phytochemicals. Based on partial least square (PLS) analysis, the constituents in these extracts, such as (+)-catechin, (-)-epicatechin, orientin, isoorientin, vitexin, and isovitexin, were strongly correlated with the measured antioxidant activities, comprising ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and nitric oxide (NO) free radical scavenging activities, as well as with cell proliferation and migration activities. This study has provided crucial evidence on the importance of these natural antioxidant compounds on the wound healing properties of OPL.

Ultrasound-Assisted Extraction of Polyphenolic Contents and Acid Hydrolysis of Flavonoid Glycosides from Oil Palm (Elaeis guineensis Jacq.) Leaf: Optimization and Correlation with Free Radical Scavenging Activity

Malaysia is ranked as the second largest oil palm producer in the world after Indonesia. This leads to the generation of large quantities of oil palm (Elaeis guineensis Jacq.) leaves (OPLs) annually, considered an underutilized oil palm biomass with low economical value. The present study aimed to study the effects of several parameters of ultrasound-assisted extraction (UAE) and the acid hydrolysis of phenolic compounds from OPLs using the single factor experimental approach. The effects of different solvents (hexane, ethyl acetate, 1:1 methanol–ethyl acetate, absolute methanol, and 4:1 methanol–water), solid–liquid ratios (1:20, 1:40, 1:50, 1:60, and 1:70), times (0.5, 1, 2, 3, and 5 h), and temperatures (25, 30, 40, 60, and 70 °C) were investigated for UAE. Moreover, the effects of acid concentration (0.2, 1, 2, 4, 6, and 12 M), incubation time (10, 30, 45, 60, and 90 min), and incubation temperature (65, 75, 85, 90, and 95 °C) on the acid hydrolysis of flavonoid glycosides were also determined. The results revealed that some of the tested parameters had prominent effects on the total phenolic (TPC) and total flavonoid (TFC) contents, as well as the DPPH free radical scavenging activity recovered from the OPLs. The optimal UAE conditions were determined to be 0.5 h at 25 °C using 4:1 methanol–water and 1:50 solid–liquid ratio, producing OPL extracts with TPC and TFC at 335.30 and 60.67 milligrams quercetin equivalents per gram of extract (mg QCE/g extract), respectively, and DPPH free radical scavenging activity at 94.06%. The phenolics present in OPLs were optimally hydrolysed using 6 M hydrochloric acid with an incubation period of 45 min at 95 °C with TPC, TFC, and DPPH free radical scavenging activity at 126.33 milligrams gallic acid equivalents per gram of extract (mg GAE/g extract), 36.08 mg QCE/g, and 54.88%, respectively. Moreover, acid hydrolysis managed to optimally recover the total apigenin content (TAC), total luteolin content (TLC), and total flavonoid C-glycoside content (TFCGC) with values of 79.12 micrograms vitexin equivalents per milligram of extract (µg VE/mg extract), 20.97 micrograms orientin equivalents per milligram of extract (µg OE/mg extract), and 100.09 µg/mg, respectively. Additionally, there were significant correlations between the polyphenolic compounds, flavonoid C-glycosides, and antioxidant activity for all parameters based on the Pearson correlation analysis. This indicates that OPLs have potential as a natural source of phenolic compounds, especially flavonoid C-glycosides, with beneficial free radical scavenging activity that can be incorporated in food and pharmaceutical products.

NMR-Based Metabolomic Analysis and Microbial Composition of Soil Supporting Burkea africana Growth

Burkea africana is a leguminous tree used for medicinal purposes, growing in clusters, on soils impoverished from most nutrients. The study aimed to determine the factors responsible for successful reproduction and establishment of the B. africana trees in nature, as all efforts for commercial production has been proven unsuccessful. An investigation was carried out to determine the metabolomic profile, chemical composition, and microbial composition of the soils where B. africana grows (Burkea soil) versus the soil where it does not grow (non-Burkea soil). 1H-NMR metabolomic analysis showed different metabolites in the respective soils. Trehalose and betaine, as well as a choline-like and carnitine-like compound, were found to be in higher concentration in Burkea soils, whereas, acetate, lactate, and formate were concentrated in non-Burkea soils. Liquid Chromatography-Mass Spectrometry analysis revealed the presence of numerous amino acids such as aspartic acid and glutamine to be higher in Burkea soils. Since it was previously suggested that the soil microbial diversity is the major driver for establishment and survival of seedlings in nature, Deoxyribonucleic acid (DNA) was extracted and a BLAST analysis conducted for species identification. Penicillium species was found to be highly prevalent and discriminant between the two soils, associated with the Burkea soils. No differences in the bacterial composition of Burkea and non-Burkea soils were observed. The variances in fungal composition suggests that species supremacy play a role in development of B. africana trees and is responsible for creating a supporting environment for natural establishment and survival of seedlings.

1H NMR-Based Metabolomics Approach in Investigating the Chemical Profile, Antioxidant and Anti-Inflammatory Activities of Gynura procumbens and Cleome gynandra

Gynura procumbens and Cleome gynandra are two herbs commonly used in Malaysia to treat various ailments and are also consumed as salads (ulam) and vegetables. The present study aims to evaluate the relationship between the chemical compositions of both herbs and their antioxidant and anti-inflammatory properties using nuclear magnetic resonance (NMR) metabolomics approach, which is being reported for the first time. Different ethanolic extracts of both herbs were tested for DPPH scavenging and inhibition of nitric oxide (NO) via RAW 264.7 macrophage cell induction. Principal component analysis (PCA) revealed a good separation between the extracts and the corresponding metabolites identified via ¹H NMR spectroscopy. The 100% ethanolic extract from both herbs and 20% ethanolic extract of C. gynandra were found to have the best antioxidant and anti-inflammatory activities. Kaempferol, quercetin, caffeoylquinic, dicaffeoylquinic acids, gallic acid, mallic acid, citric acid, phenylalanine, and choline are among the metabolites that contributed to bioactivities. The partial least square (PLS) model for both herbs have an overall acceptable goodness of fit and predictive power, which further strengthens the validity of this study. The present study provides a preliminary reference for the selection of optimum extract and will shed some light on the potential use of G. procumbens and C. gynandra as a phytomedicinal preparation.

Yield and Metabolite Production of Pelargonium sidoides DC. in Response to Irrigation and Nitrogen Management

Competition for water between agricultural and non-agricultural economic sectors hampers agricultural production, especially in water-scarce regions. Understanding crop responses in terms of yield and quality to irrigation is an important factor in designing appropriate irrigation management for optimal crop production and quality. Pelargonium sidoides DC., often harvested from the wild, is in high demand in the informal market and for commercial formulations. Agricultural production of high-quality materials through cultivation can help reduce pressure on its wild populations. This study aimed at determining the effects of water and nitrogen on P. sidoides yield and metabolite production. The irrigation treatments applied were 30%, 50%, and 70% of an allowable depletion level (ADL), while the nitrogen (N) levels were 0 (control), 50, 100, and 150 kg ha⁻¹. The 30% ADL resulted in a significantly higher biomass and root yield. Nitrogen at 50 and 100 kg ha⁻¹ resulted in a significantly higher biomass yield, compared to the N control. An increase in sugars and citrate cycle components was observed for the well-watered 30% ADL treatment, whereas water-stressed (50% and 70% ADL) treatments increased alanine, aspartate, and glutamate metabolism, increasing levels of asparagine, 4-aminobutyrate, and arginine. The treatments had no significant effect on the root content of esculin, scopoletin, and umckalin. Water stress induced metabolite synthesis to mitigate the stress condition, whereas under no water stress primary metabolites were synthesized. Moreover, cultivation of P. sidoides as a conservation strategy can increase yield without affecting its bioactivity, while providing sustenance for the rural communities.

Antibacterial Activity and Metabolomics Profiling of Torch Ginger (Etlingera elatior Jack) Flower Oil Extracted Using Subcritical Carbon Dioxide (CO2)

The aim of this study was to identify the bioactive compound and evaluate the antibacterial activity of torch ginger flower oil extracted using subcritical carbon dioxide. The antibacterial activity was evaluated in agar diffusion assay, while MIC and MBC were determined using the microdilution broth assay. The essential oil was subjected to metabolomics profiling using GC-MS and 1H-NMR techniques. The results demonstrated strong antibacterial activity towards Salmonella typhimurium, Staphylococcus aureus, and Escherichia coli. The MIC values were 0.0625, 0.25, and 0.25 mg/mL, and the MBC values were 0.25, 0.5, and 1 mg/mL towards S. typhimurium, S. aureus, and E. coli, respectively. A total of 33 compounds were identified using GC-MS including 15 compounds (45%) known for their antimicrobial activity. In addition, sixteen metabolites were identified using NMR analysis and 8 out of the sixteen metabolites (50%) have antibacterial activity. The extracted oil demonstrated broad range for antibacterial activity and has high potential for applications in pharmaceutical and food industries. Practical Applications. The oil extracted from the torch ginger flower was found very stable and has promising applications as antibacterial agent for food and pharmaceutical industries.

NMR-Based Plant Metabolomics in Nutraceutical Research: An Overview

Few topics are able to channel the interest of researchers, the public, and industries, like nutraceuticals. The ever-increasing demand of new compounds or new sources of known active compounds, along with the need of a better knowledge about their effectiveness, mode of action, safety, etc., led to a significant effort towards the development of analytical approaches able to answer the many questions related to this topic. Therefore, the application of cutting edges approaches to this area has been observed. Among these approaches, metabolomics is a key player. Herewith, the applications of NMR-based metabolomics to nutraceutical research are discussed: after a brief overview of the analytical workflow, the use of NMR-based metabolomics to the search for new compounds or new sources of known nutraceuticals are reviewed. Then, possible applications for quality control and nutraceutical optimization are suggested. Finally, the use of NMR-based metabolomics to study the impact of nutraceuticals on human metabolism is discussed.

1H-NMR Metabolomics and LC-MS Analysis to Determine Seasonal Variation in a Cosmeceutical Plant Leucosidea sericea

Leucosidea sericea is an evergreen shrub belonging to the Rosaceae family with previous studies that indicated that L. sericea extracts exhibited strong anti-bacterial properties against Propionibacterium acnes, showing potential as a cosmeceutical. The plant is traditionally used as a vermifuge, as an astringent and to treat conjunctivitis. Commercial production is, however, not possible as no information is available on cultivation and the effect of external environmental factors such as seasonal variation on the medicinal properties of the plant. Seasonal variation was investigated and it was found that significant differences were observed between the anti-acne (P. acnes) activity of plant material collected in different seasons. The best activity was found in winter with a mean minimum inhibitory concentration (MIC) of 5.20 μg mL^–1 compared to spring at 26.04 μg mL^–1. A ¹H NMR-based untargeted metabolomic analysis was used to determine the differences in the chemical profiles of plant samples collected in different seasons. Principal component analysis (PCA) showed clear separation of the seasons and a supervised orthogonal partial least square discriminant analysis (OPLS-DA) was used to determine the compounds that differentiated the spring from the winter samples. The contribution plot indicated a strong positive association with the NMR regions from δ 1.2–1.6, 3.3–4.1, and 6.8–8.0 ppm indicative of a compound with an aromatic ring. Different LC-MS analyses were used in conjunction with a compound database, MAGMa and CSIFingerID, which led to the identification of the compound 2-(4-ethoxyphenyl)-5,6,7,8-tetramethoxy-4H-1-benzopyran-4-one and also confirmed the presence of tangeritin, rutin, quercetin glucoside, and kaempferol glucosides as well as several other compounds previously identified from the plant. This compound similar in structure to the anti-microbial flavonoid tangeritin, was only present in the winter samples. It is therefore recommended that seasonal variation be closely monitored during cultivation and commercial harvesting, and that winter is the preferred harvesting season to obtain the best anti-acne activity.

Variation in the metabolites and α-glucosidase inhibitory activity of Cosmos caudatus at different growth stages

BACKGROUND

Cosmos caudatus is an annual plant known for its medicinal value in treating several health conditions, such as high blood pressure, arthritis, and diabetes mellitus. The α-glucosidase inhibitory activity and total phenolic content of the leaf aqueous ethanolic extracts of the plant at different growth stages (6, 8. 10, 12 and 14 weeks) were determined in an effort to ascertain the best time to harvest the plant for maximum medicinal quality with respect to its glucose-lowering effects.

METHODS

The aqueous ethanolic leaf extracts of C. caudatus were characterized by NMR and LC-MS/MS. The total phenolic content and α-glucosidase inhibitory activity were evaluated by the Folin-Ciocalteu method and α-glucosidase inhibitory assay, respectively. The statistical significance of the results was evaluated using one-way ANOVA with Duncan's post hoc test, and correlation among the different activities was performed by Pearson's correlation test. NMR spectroscopy along with multivariate data analysis was used to identify the metabolites correlated with total phenolic content and α-glucosidase inhibitory activity of the C. caudatus leaf extracts.

RESULTS

It was found that the α-glucosidase inhibitory activity and total phenolic content of the optimized ethanol:water (80:20) leaf extract of the plant increased significantly as the plant matured, reaching a maximum at the 10th week. The IC50 value for α-glucosidase inhibitory activity (39.18 μg mL- 1) at the 10th week showed greater potency than the positive standard, quercetin (110.50 μg mL- 1). Through an 1H NMR-based metabolomics approach, the 10-week-old samples were shown to be correlated with a high total phenolic content and α-glucosidase inhibitory activity. From the partial least squares biplot, rutin and flavonoid glycosides, consisting of quercetin 3-O-arabinofuranoside, quercetin 3-O-rhamnoside, quercetin 3-O-glucoside, and quercetin 3-O-xyloside, were identified as the major bioactive metabolites. The metabolites were identified by NMR spectroscopy (J-resolve, HSQC and HMBC experiments) and further supported by dereplication via LC-MS/MS.

CONCLUSION

For high phytomedicinal quality, the 10th week is recommended as the best time to harvest C. caudatus leaves with respect to its glucose lowering potential.

NMR-Based Metabolomics Profiling for Radical Scavenging and Anti-Aging Properties of Selected Herbs

Herbs that are usually recognized as medicinal plants are well known for their therapeutic effects and are traditionally used to treat numerous diseases, including aging. This study aimed to evaluate the metabolite variations among six selected herbs namely Curcurma longa, Oenanthe javanica, Vitex negundo, Pluchea indica, Cosmos caudatus and Persicaria minus using proton nuclear magnetic resonance (¹H-NMR) coupled with multivariate data analysis (MVDA). The free radical scavenging activity of the extract was measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azinobis(3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) and oxygen radical absorbance capacity (ORAC) assay. The anti-aging property was characterized by anti-elastase and anti-collagenase inhibitory activities. The results revealed that P. minus showed the highest radical scavenging activities and anti-aging properties. The partial least squares (PLS) biplot indicated the presence of potent metabolites in P. minus such as quercetin, quercetin-3-O-rhamnoside (quercitrin), myricetin derivatives, catechin, isorhamnetin, astragalin and apigenin. It can be concluded that P. minus can be considered as a potential source for an anti-aging ingredient and also a good free radical eradicator. Therefore, P. minus could be used in future development in anti-aging researches and medicinal ingredient preparations.

Antioxidants and α-glucosidase inhibitors from Neptunia oleracea fractions using 1H NMR-based metabolomics approach and UHPLC-MS/MS analysis

Background

Neptunia oleracea is a plant cultivated as vegetable in Southeast Asia. Previous works have revealed the potential of this plant as a source of natural antioxidants and α-glucosidase inhibitors. Continuing our interest on this plant, the present work is focused in identification of the bioactive compounds from different polarity fractions of N. oleracea, namely hexane (HF), chloroform (CF), ethyl acetate (EF) and methanol (MF).

Methods

The N. oleracea fractions were obtained using solid phase extraction (SPE). A metabolomics approach that coupled the use of proton nuclear magnetic resonance (¹H NMR) with multivariate data analysis (MVDA) was applied to distinguish the metabolite variations among the N. oleracea fractions, as well as to assess the correlation between metabolite variation and the studied bioactivities (DPPH free radical scavenging and α-glucosidase inhibitory activities). The bioactive fractions were then subjected to ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC–MS/MS) analysis to profile and identify the potential bioactive constituents.

Results

The principal component analysis (PCA) discriminated EF and MF from the other fractions with the higher distributions of phenolics. Partial least squares (PLS) analysis revealed a strong correlation between the phenolics and the studied bioactivities in the EF and the MF. The UHPLC-MS/MS profiling of EF and MF had tentatively identified the phenolics present. Together with some non-phenolic metabolites, a total of 37 metabolites were tentatively assigned.

Conclusions

The findings of this work supported that N. oleracea is a rich source of phenolics that can be potential antioxidants and α-glucosidase inhibitors for the management of diabetes. To our knowledge, this study is the first report on the metabolite-bioactivity correlation and UHPLC–MS/MS analysis of N. oleracea fractions.

1 H-NMR metabolomics for evaluating the protective effect of Clinacanthus nutans (Burm. f) Lindau water extract against nitric oxide production in LPS-IFN-γ activated RAW 264.7 macrophages

INTRODUCTION

Clinacanthus nutans, a small shrub that is native to Southeast Asia, is commonly used in traditional herbal medicine and as a food source. Its anti-inflammation properties is influenced by the metabolites composition, which can be determined by different binary extraction solvent ratio and extraction methods used during plant post-harvesting stage.

OBJECTIVE

Evaluate the relationship between the chemical composition of C. nutans and its anti-inflammatory properties using nuclear magnetic resonance (NMR) metabolomics approach.

METHODOLOGY

The anti-inflammatory effect of C. nutans air-dried leaves extracted using five different binary extraction solvent ratio and two extraction methods was determined based on their nitric oxide (NO) inhibition effect in lipopolysaccharide-interferon-gamma (LPS-IFN-γ) activated RAW 264.7 macrophages. The relationship between extract bioactivity and metabolite profiles and quantifications were established using ¹ H-NMR metabolomics and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The possible metabolite biosynthesis pathway was constructed to further strengthen the findings.

RESULTS

Water and sonication prepared air-dried leaves possessed the highest NO inhibition activity (IC₅₀  = 190.43 ± 12.26 μg/mL, P < 0.05). A total of 56 metabolites were tentatively identified using ¹ H-NMR metabolomics. A partial least square (PLS) biplot suggested that sulphur containing glucoside, sulphur containing compounds, phytosterols, triterpenoids, flavones and some organic and amino acids were among the potential NO inhibitors. LC-MS/MS targeted quantification further supported sonicated water extract was among the extract that possessed the most abundant C-glycosyl flavones.

CONCLUSION

The present study may serve as a preliminary reference for the selection of optimum extract in further C. nutans in vivo anti-inflammatory study.

Identification of α-glucosidase inhibitors from Clinacanthus nutans leaf extract using liquid chromatography-mass spectrometry-based metabolomics and protein-ligand interaction with molecular docking

The present study used in vitro and in silico techniques, as well as the metabolomics approach to characterise α-glucosidase inhibitors from different fractions of Clinacanthus nutans. C. nutans is a medicinal plant belonging to the Acanthaceae family, and is traditionally used to treat diabetes in Malaysia. n-Hexane, n-hexane: ethyl acetate (1:1, v/v), ethyl acetate, ethyl acetate: methanol (1:1, v/v), and methanol fractions were obtained via partitioning of the 80% methanolic crude extract. The in vitro α-glucosidase inhibitory activity was analyzed using all the fractions collected, followed by profiling of the metabolites using liquid chromatography combined with mass spectrometry. The partial least square (PLS) statistical model was developed using the SIMCA P⁺14.0 software and the following four inhibitors were obtained: (1) 4,6,8-Megastigmatrien-3-one; (2) N-Isobutyl-2-nonen-6,8-diynamide; (3) 1′,2′-bis(acetyloxy)-3′,4′-didehydro-2′-hydro-β, ψ-carotene; and (4) 22-acetate-3-hydroxy-21-(6-methyl-2,4-octadienoate)-olean-12-en-28-oic acid. The in silico study performed via molecular docking with the crystal structure of yeast isomaltase (PDB code: 3A4A) involved a hydrogen bond and some hydrophobic interactions between the inhibitors and protein. The residues that interacted include ASN259, HID295, LYS156, ARG335, and GLY209 with a hydrogen bond, while TRP15, TYR158, VAL232, HIE280, ALA292, PRO312, LEU313, VAL313, PHE314, ARG315, TYR316, VAL319, and TRP343 with other forms of bonding.

•

The antidiabetic potential of various extracts of C. nutans leaf has been evaluated.

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Multivariate data analysis identified 4 α-glucosidase inhibiting compounds.

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In silico study predicted the protein-inhibitors interaction.

Identifying anti-HSV compounds from unrelated plants using NMR and LC-MS metabolomic analysis

INTRODUCTION

Plants have been used to treat various ailments and diseases, including viral infections. Often activity is reported after screening plants traditionally used, without identifying the active principles.

OBJECTIVES

This study investigated the use of metabolomics to identify common compound groups or compounds from unrelated plants, but with similar reported biological activity. Plants with anti-viral activities against Herpes Simplex Virus (HSV), Cytomegalovirus (CMV) and Human Immunodeficiency Virus (HIV) were collected and analysed. A few non-active plants, with no reported anti-viral activity were included as control samples.

METHODS

1H-NMR and LC-MS metabolomic analysis were conducted, to determine the chemical similarity between plants with similar activity using SIMCA and XCMS online.

RESULTS

Plants with anti-HSV, anti-HIV and anti-CMV activity, presented specific clusters, with the non-active samples separating from the active samples. The anti-HSV group presented a clear contribution plot and chlorogenic acid was identified by NMR. LC-MS metabolomic analysis confirmed the NMR results and furthermore identified several chlorogenic acid isomers including the main substructures of chlorogenic acids.

CONCLUSION

Metabolomic analysis on unrelated plants with similar activity can be used to identify the active compound groups or compounds, thereby eliminating the need for screening of plants to determine biological activity, additionally providing information on possible active principles. The two analytical methods identified chlorogenic acids and its building blocks as common and important compounds within plants with anti-HSV activity. Intensified research on plants containing chlorogenic acids should be the focus of future research for development of accessible anti-HSV treatments.

Solvent Extraction and Identification of Active Anticariogenic Metabolites in Piper cubeba L. through ¹H-NMR-Based Metabolomics Approach

The aim of this study was to determine the effects of different solvents for extraction, liquid⁻liquid partition, and concentrations of extracts and fractions of Piper cubeba L. on anticariogenic; antibacterial and anti-inflammatory activity against oral bacteria. Furthermore, ¹H-Nuclear Magnetic Resonance (NMR) coupled with multivariate data analysis (MVDA) was applied to discriminate between the extracts and fractions and examine the metabolites that correlate to the bioactivities. All tested bacteria were susceptible to Piper cubeba L. extracts and fractions. Different solvents extraction, liquid⁻liquid partition and concentrations of extracts and fractions have partially influenced the antibacterial activity. MTT assay showed that P. cubeba L. extracts and fractions were not toxic to RAW 264.7 cells at selected concentrations. Anti-inflammatory activity evaluated by nitric oxide (NO) production in lipopolysaccharide (LPS) stimulated cells showed a reduction in NO production in cells treated with P. cubeba L. extracts and fractions, compared to those without treatment. Twelve putative metabolites have been identified, which are (1) cubebin, (2) yatein, (3) hinokinin, (4) dihydrocubebin, (5) dihydroclusin, (6) cubebinin, (7) magnosalin, (8) p-cymene, (9) piperidine, (10) cubebol, (11) d-germacrene and (12) ledol. Different extraction and liquid⁻liquid partition solvents caused separation in principal component analysis (PCA) models. The partial least squares (PLS) models showed that higher anticariogenic activity was related more to the polar solvents, despite some of the active metabolites also present in the non-polar solvents. Hence, P. cubeba L. extracts and fractions exhibited antibacterial and anti-inflammatory activity and have potential to be developed as the anticariogenic agent.

Antioxidant Activity and Spectroscopic Characteristics of Extractable and Non-Extractable Phenolics from Terminalia sericea Burch. ex DC

The aim of this study was to determine the antioxidant activity of the extractable and non-extractable phenolics of Terminalia. Sericea Burch. Ex DC. Free, ester bound, ether or glycoside bound and insoluble phenolics were extracted from the fruit, leaves, stem, and root samples. Follin Ciocalteu was used to estimate the phenolic content while DPPH (2,2-diphenyl-1-picrylhydrazyl) assay was used to determine the antioxidant activity. The data obtained were subjected to multivariate analysis for relationships. The result indicated that the highest average total phenolic contents and antioxidant activities were found in the free (14.8 mgGAE/g; IC50 6.8 μg/mL) and ester bound (15.1 mgGAE/g; IC50 6.4 μg/mL) extractable phenolics. There was a strong negative correlation between TPC and DPPH (r = -0.828). Agglomerative hierarchical clustering revealed three clusters. Cluster one contained the insoluble and glycoside phenolics while cluster 2 contained only free phenolic acid of the root. The third cluster was predominantly free and ester bound phenolic extracts. The principal component analysis score plot indicated two major clusters with factor 1 (F1) explaining 61% of the variation. The nuclear magnetic resonance spectroscopy spectra indicated that gallic acid and resveratrol are the major phenolic compounds present in the root. This study has demonstrated that extractable phenolics contributed more to the antioxidant activities compared to the non-extractables.

Metabolite characterization of different palm date varieties and the correlation with their NO inhibitory activity, texture and sweetness

The aim of this study was to examine the variation in metabolite constituents of five commercial varieties of date fruits; Ajwa, Safawi and Ambar which originated from Madinah, the Iranian Bam and Tunisian Deglet Noor. The differences of metabolome were investigated using proton nuclear magnetic resonance (1H NMR) spectroscopy combined with multivariate data analysis (MVDA). Principal Component Analysis (PCA) revealed clear separation between the date varieties. The Tunisian Deglet Noor demonstrated distinct cluster from the rest of the palm date samples based on the metabolite composition as shown by the pattern observed in Hierarchical Clustering Analysis (HCA) and PCA. Deglet Noor exhibited a significant higher level of sucrose (δ 5.40) and fructose (δ 4.16) in comparison with the other four varieties which can be associated with the distinctive sweet taste of this variety. Dates originated from Madinah and Tunisia exhibited a contrast manner in the amount of xylose and moisture content. These two aspects may contribute towards the soft texture of Tunisian dates. All Madinah dates were found to contain phenolic compounds which were well established as great antioxidant and anti-inflammatory agent. Ajwa dates exerted greater effect in inhibiting the generation of nitric oxide (NO) from the stimulated RAW264.7 cells at 95.37% inhibition. Succinic acid was suggested to have the most significant correlation with the trend of NO inhibitory shown by the selected date palm varieties.

Comparison of partial least squares and random forests for evaluating relationship between phenolics and bioactivities of Neptunia oleracea

BACKGROUND

Neptunia oleracea is a plant consumed as a vegetable and which has been used as a folk remedy for several diseases. Herein, two regression models (partial least squares, PLS; and random forest, RF) in a metabolomics approach were compared and applied to the evaluation of the relationship between phenolics and bioactivities of N. oleracea. In addition, the effects of different extraction conditions on the phenolic constituents were assessed by pattern recognition analysis.

RESULTS

Comparison of the PLS and RF showed that RF exhibited poorer generalization and hence poorer predictive performance. Both the regression coefficient of PLS and the variable importance of RF revealed that quercetin and kaempferol derivatives, caffeic acid and vitexin-2-O-rhamnoside were significant towards the tested bioactivities. Furthermore, principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) results showed that sonication and absolute ethanol are the preferable extraction method and ethanol ratio, respectively, to produce N. oleracea extracts with high phenolic levels and therefore high DPPH scavenging and α-glucosidase inhibitory activities.

CONCLUSION

Both PLS and RF are useful regression models in metabolomics studies. This work provides insight into the performance of different multivariate data analysis tools and the effects of different extraction conditions on the extraction of desired phenolics from plants. © 2017 Society of Chemical Industry.

Metabolite profiling, antioxidant, and α-glucosidase inhibitory activities of germinated rice: nuclear-magnetic-resonance-based metabolomics study

In an attempt to profile the metabolites of three different varieties of germinated rice, specifically black (GBR), red, and white rice, a ¹H-nuclear-magnetic-resonance-based metabolomics approach was conducted. Multivariate data analysis was applied to discriminate between the three different varieties using a partial least squares discriminant analysis (PLS-DA) model. The PLS model was used to evaluate the relationship between chemicals and biological activities of germinated rice. The PLS-DA score plot exhibited a noticeable separation between the three rice varieties into three clusters by PC1 and PC2. The PLS model indicated that α-linolenic acid, γ-oryzanol, α-tocopherol, γ-aminobutyric acid, 3-hydroxybutyric acid, fumaric acid, fatty acids, threonine, tryptophan, and vanillic acid were significantly correlated with the higher bioactivities demonstrated by GBR that was extracted in 100% ethanol. Subsequently, the proposed biosynthetic pathway analysis revealed that the increased quantities of secondary metabolites found in GBR may contribute to its nutritional value and health benefits.

Characterization of Metabolite Profile in Phyllanthus niruri and Correlation with Bioactivity Elucidated by Nuclear Magnetic Resonance Based Metabolomics

Phyllanthus niruri is an important medicinal plant. To standardize the extract and guarantee its maximum benefit, processing methods optimization ought to be amenable and beneficial. Herein, three dried P. niruri samples, air (AD), freeze (FD) and oven (OD), extracted with various ethanol to water ratios (0%, 50%, 70%, 80% and 100%) were evaluated for their metabolite changes using proton nuclear magnetic resonance (¹H-NMR)-based metabolomics approach. The amino acids analysis showed that FD P. niruri exhibited higher content of most amino acids compared to the other dried samples. Based on principal component analysis (PCA), the FD P. niruri extracted with 80% ethanol contained higher amounts of hypophyllanthin and phenolic compounds based on the loading plot. The partial least-square (PLS) results showed that the phytochemicals, including hypophyllanthin, catechin, epicatechin, rutin, quercetin and chlorogenic, caffeic, malic and gallic acids were correlated with antioxidant and α-glucosidase inhibitory activities, which were higher in the FD material extracted with 80% ethanol. This report optimized the effect of drying and ethanol ratios and these findings demonstrate that NMR-based metabolomics was an applicable approach. The FD P. niruri extracted with 80% ethanol can be used as afunctional food ingredient for nutraceutical or in medicinal preparation.

Anti-obesity effect of ethanolic extract from Cosmos caudatus Kunth leaf in lean rats fed a high fat diet

Background

Obesity is a major health concern both in developed and developing countries. The use of herbal medicines became the subject of interest for the management of obesity due to its natural origin, cost effectiveness and minimal side effects. The present study aimed at investigating anti-obesity potential of ethanolic extract from Cosmos caudatus Kunth leaf (EECCL).

Methods

In this study, the rats were randomly divided into six groups i.e., (1) Normal Diet (ND); (2) Normal Diet and 175 mg/kgBW of EECCL (ND + 175 mg/kgBW); (3) Normal Diet and 350 mg/kgBW of EECCL (ND + 350 mg/kgBW); (4) High Fat Diet (HFD); (5) High Fat Diet and 175 mg/kgBW of EECCL (HFD + 175 mg/kgBW); (6) High Fat Diet and 350 mg/kgBW of EECCL (HFD + 350 mg/kgBW). The anti-obesity potential was evaluated through analyses of changes in body weight, visceral fat weight, and blood biochemicals including total cholesterol, triglycerides, high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), leptin, insulin, adiponectin, ghrelin and fecal fat content. In addition, metabolite profiling of EECCL was carried out using NMR spectroscopy.

Results

Rats receiving EECCL together with HFD showed significant (p < 0.05) reduction in body weight gain compared to rats receiving HFD only. At the end of study, the body weight gain of EECCL treated rats was not significantly (p > 0.05) different with those of ND rats. Other related obesity biomarkers including plasma lipid profiles, insulin, leptin, ghrelin and adiponectin levels also showed significant improvement (p < 0.05). Administration of EECCL caused significant (p < 0.05) increase in fecal fat excretion, which validates the hypothesis of lipase inhibition, an anti-obesity mechanism similar to standard drug of Orlistat. The ¹H-NMR spectra of EECCL ascertained the presence of catechin, quercetin, rutin, kaempherol and chlorogenic acid in the extract.

Conclusion

Conclusively, EECCL showed anti-obesity properties by inhibition of intestinal lipid absorption and modulation of adipocytes markers.

Characterization of metabolites in different kiwifruit varieties by NMR and fluorescence spectroscopy

It is known from our previous studies that kiwifruits, which are used in common human diet, have preventive properties of coronary artery disease. This study describes a combination of ¹H NMR spectroscopy, multivariate data analyses and fluorescence measurements in differentiating of some kiwifruit varieties, their quenching and antioxidant properties. A total of 41 metabolites were identified by comparing with literature data Chenomx database and 2D NMR. The binding properties of the extracted polyphenols against HSA showed higher reactivity of studied two cultivars in comparison with the common Hayward. The results showed that the fluorescence of HSA was quenched by Bidan as much as twice than by other fruits. The correlation between the binding properties of polyphenols in the investigated fruits, their relative quantification and suggested metabolic pathway was established. These results can provide possible application of fruit extracts in pharmaceutical industry.

Rapid investigation of α-glucosidase inhibitory activity of Phaleria macrocarpa extracts using FTIR-ATR based fingerprinting

Phaleria macrocarpa, known as "Mahkota Dewa", is a widely used medicinal plant in Malaysia. This study focused on the characterization of α-glucosidase inhibitory activity of P. macrocarpa extracts using Fourier transform infrared spectroscopy (FTIR)-based metabolomics. P. macrocarpa and its extracts contain thousands of compounds having synergistic effect. Generally, their variability exists, and there are many active components in meager amounts. Thus, the conventional measurement methods of a single component for the quality control are time consuming, laborious, expensive, and unreliable. It is of great interest to develop a rapid prediction method for herbal quality control to investigate the α-glucosidase inhibitory activity of P. macrocarpa by multicomponent analyses. In this study, a rapid and simple analytical method was developed using FTIR spectroscopy-based fingerprinting. A total of 36 extracts of different ethanol concentrations were prepared and tested on inhibitory potential and fingerprinted using FTIR spectroscopy, coupled with chemometrics of orthogonal partial least square (OPLS) at the 4000-400 cm^-1 frequency region and resolution of 4 cm^-1. The OPLS model generated the highest regression coefficient with R²Y = 0.98 and Q²Y = 0.70, lowest root mean square error estimation = 17.17, and root mean square error of cross validation = 57.29. A five-component (1+4+0) predictive model was build up to correlate FTIR spectra with activity, and the responsible functional groups, such as -CH, -NH, -COOH, and -OH, were identified for the bioactivity. A successful multivariate model was constructed using FTIR-attenuated total reflection as a simple and rapid technique to predict the inhibitory activity.

Discrimination and Nitric Oxide Inhibitory Activity Correlation of Ajwa Dates from Different Grades and Origin

This study was aimed at examining the variations in the metabolite constituents of the different Ajwa grades and farm origins. It is also targeted at establishing the correlations between the metabolite contents and the grades and further to the nitric oxide (NO) inhibitory activity. Identification of the metabolites was generated using ¹H-NMR spectroscopy metabolomics analyses utilizing multivariate methods. The NO inhibitory activity was determined using a Griess assay. Multivariate data analysis, for both supervised and unsupervised approaches, showed clusters among different grades of Ajwa dates obtained from different farms. The compounds that contribute towards the observed separation between Ajwa samples were suggested to be phenolic compounds, ascorbic acid and phenylalanine. Ajwa dates were shown to have different metabolite compositions and exhibited a wide range of NO inhibitory activity. It is also revealed that Ajwa Grade 1 from the al-Aliah farm exhibited more than 90% NO inhibitory activity compared to the other grades and origins. Phenolic compounds were among the compounds that played a role towards the greater capacity of NO inhibitory activity shown by Ajwa Grade 1 from the al-Aliah farm.