High-performance thin-layer chromatography HPTLC-direct bioautography as a method of choice for alpha-amylase and antioxidant activity evaluation in marine algae

Application of effect-directed analysis using TLC-bioautography for rapid isolation and identification of antidiabetic compounds from the leaves of Annona cherimola Mill

INTRODUCTION

Type 2 diabetes mellitus is a globally prevalent chronic disease characterised by hyperglycaemia and oxidative stress. The search for new natural bioactive compounds that contribute to controlling this condition and the application of analytical methodologies that facilitate rapid detection and identification are important challenges for science. Annona cherimola Mill. is an important source of aporphine alkaloids with many bioactivities.

OBJECTIVE

The aim of this study is to isolate and identify antidiabetic compounds from alkaloid extracts with α-glucosidase and α-amylase inhibitory activity from A. cherimola Mill. leaves using an effect-directed analysis by thin-layer chromatography (TLC)-bioautography.

METHODOLOGY

Guided fractionation for α-glucosidase and α-amylase inhibitors in leaf extracts was done using TLC-bioassays. The micro-preparative TLC was used to isolate the active compounds, and the identification was performed by mass spectrometry associated with web-based molecular networks. Additionally, in vitro estimation of the inhibitory activity and antioxidant capacity was performed in the isolated compounds.

RESULTS

Five alkaloids (liriodenine, dicentrinone, N-methylnuciferine, anonaine, and moupinamide) and two non-alkaloid compounds (3-methoxybenzenepropanoic acid and methylferulate) with inhibitory activity were isolated and identified using a combination of simple methodologies. Anonaine, moupinamide, and methylferulate showed promising results with an outstanding inhibitory activity against both enzymes and antioxidant capacity that could contribute to controlling redox imbalance.

CONCLUSIONS

These high-throughput methodologies enabled a rapid isolation and identification of seven compounds with potential antidiabetic activity. To our knowledge, the estimated inhibitory activity of dicentrinone, N-methylnuciferine, and anonaine against α-glucosidase and α-amylase is reported here for the first time.

Intra-Species Variations of Bioactive Compounds of Two Dictyota Species from the Adriatic Sea: Antioxidant, Antimicrobial, Dermatological, Dietary, and Neuroprotective Potential

The marine environment has a significant impact on life on Earth. Organisms residing in it are vital for the ecosystem but also serve as an inexhaustible source of biologically active compounds. Herein, the biodiversity of two brown seaweeds, Dictyota dichotoma and Dictyota fasciola from the Adriatic Sea, was evaluated. The aim of the study was the determination of differences in compound composition while comparing their activities, including antioxidant, antimicrobial, and enzyme inhibition, in connection to human digestion, dermatology, and neurological disorders. Chemical analysis revealed several terpenoids and steroids as dominant molecules, while fucoxanthin was the main identified pigment in both algae. D. dichotoma had higher protein, carbohydrate, and pigment content. Omega-6 and omega-3 fatty acids were identified, with the highest amount of dihomo-γ-linolenic acid and α-linolenic acid in D. dichotoma. Antimicrobial testing revealed a dose-dependent inhibitory activity of methanolic fraction against Escherichia coli and Staphylococcus aureus. Moderate antioxidant activity was observed for both algae fractions, while the dietary potential was high, especially for the D. fasciola dichloromethane fraction, with inhibition percentages of around 92% for α-amylase and 57% for pancreatic lipase at 0.25 mg/mL. These results suggest that Dictyota species might be a potent source of naturally derived agents for obesity and diabetes.

Thin-Layer Chromatography (TLC) in the Screening of Botanicals-Its Versatile Potential and Selected Applications

The aim of this paper is to present a comprehensive overview of the main aims and scopes in screening of botanicals, a task of which thin-layer chromatography (TLC) is, on an everyday basis, confronted with and engaged in. Stunning omnipresence of this modest analytical technique (both in its standard format (TLC) and the high-performance one (HPTLC), either hyphenated or not) for many analysts might at a first glance appear chaotic and random, with an auxiliary rather than leading role in research, and not capable of issuing meaningful final statements. Based on these reflections, our purpose is not to present a general review paper on TLC in screening of botanicals, but a blueprint rather (illustrated with a selection of practical examples), which highlights a sovereign and important role of TLC in accomplishing the following analytical tasks: (i) solving puzzles related to chemotaxonomy of plants, (ii) screening a wide spectrum of biological properties of plants, (iii) providing quality control of herbal medicines and alimentary and cosmetic products of biological origin, and (iv) tracing psychoactive plants under forensic surveillance.

Effect-directed analysis in food by thin-layer chromatography assays

Thin-layer chromatography (TLC) is widely used for food analysis and quality control. As an open chromatographic system, TLC is compatible with microbial-, biochemical-, and chemical-based derivatization methods. This compatibility makes it possible to run in situ bioassays directly on the plate to obtain activity-profile chromatograms, i.e., the effect-directed analysis of the sample. Many of the properties that can be currently measured using this assay format are related to either desired or undesired features for food related products. The TLC assays can detect compounds related to the stability of foods (antioxidant, antimicrobial, antibrowning, etc.), contaminants (antibiotics, pesticides, estrogenic compounds, etc.), and compounds that affect the absorption, metabolism or excretion of nutrients and metabolites or could improve the consumers health (enzyme inhibitors). In this article, different food related TLC-assays are reviewed. The different detection systems used, the way in which they are applied as well as selected examples are discussed.

High-performance thin-layer chromatography coupled attenuated total reflectance-Fourier-transform infrared and NMR spectroscopy-based identification of α-amylase inhibitor from the aerial part of Asparagus racemosus Willd

INTRODUCTION

α-Amylase inhibitors from natural sources are of interest for new drug development for the treatment of diabetes mellitus (DM). High-performance thin-layer chromatography (HPTLC) coupled bioassay guided isolation of bioactive compounds has been improved within last few years.

OBJECTIVE

A microchemical derivatised HPTLC-coupled attenuated total reflectance-Fourier-transform infrared (ATR-FTIR) and nuclear magnetic resonance (NMR) spectroscopy was employed for profiling α-amylase inhibitor from the aerial part of Asparagus racemosus Willd.

METHODOLOGY

Asparagus racemosus Willd. aerial part extracted with different solvents (n-hexane, chloroform, ethyl acetate, and methanol) and assayed to detect free radical scavengers and α-amylase inhibitor by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and starch-iodine assay method, respectively. HPTLC-coupled ATR-FTIR and NMR spectroscopy was used to identify the α-amylase inhibitor.

RESULTS

Methanolic extract of A. racemosus showed highest antioxidant activity (21.99 μg GAE/μL) where n-hexane extract showed lowest antioxidant activity (5.87 μg GAE/μL). The α-amylase inhibition was recorded as highest and lowest in ethyl acetate extract (13.13 AE/μL) and n-hexane extract (3.92 AE/μL), respectively. The deep blue zone of α-amylase sprayed TLC plate of extracts with hR_F  = 72 analysed for ATR-FTIR and NMR spectroscopy which revealed the presence of stigmasterol is responsible for α-amylase inhibition.

CONCLUSION

The present work establishes the α-amylase inhibiting properties of A. racemosus maintaining its use for the treatment of DM as a traditional medicine. Bioassay guided isolation through HPTLC-coupled ATR-FTIR and NMR spectroscopy offers an effective method for the exploration of bioactive compounds such as α-amylase inhibitor from complex plant extracts.

Major lipophilic pigments in Atlantic seaweeds as valuable food ingredients: Analysis and assessment of quantification methods

Current trends towards the use of ingredients from natural origin in food, cosmetic and pharmaceutical industry, place macroalgae as a good reservoir of novel compounds. Among them, lipophilic major pigments such as chlorophylls and fucoxanthin, are of great interest because of their multiple applications as bioactive compounds and dyes. In this work, a mid-polarity medium was used to extract pigments from twenty-four species from North coast of Spain, including brown (Phaeophyceae) and red macroalgae (Rhodophyta). The fucoxanthin and chlorophyll a content was assessed by means of two different methods, spectrophotometric and high-performance liquid chromatography coupled to diode array detection (HPLC-DAD). The effect of dried processing on the pigment content of selected species was also evaluated. A linear relationship between the extractability of fucoxanthin and chlorophyll a was observed, being the highest content recorded among members belonging to the order Fucales and Undaria pinnatifida. This work provides good insights about the content on pigments in Spanish North Atlantic macroalgae with future commercial value in different industrial fields, as well as a critical overview of the suitability of the quantification methods and challenges related to their effect in results evaluation.

Biological properties and potential of compounds extracted from red seaweeds

Macroalgae have been recently used for different applications in the food, cosmetic and pharmaceutical industry since they do not compete for land and freshwater against other resources. Moreover, they have been highlighted as a potential source of bioactive compounds. Red algae (Rhodophyta) are the largest group of seaweeds, including around 6000 different species, thus it can be hypothesized that they are a potential source of bioactive compounds. Sulfated polysaccharides, mainly agar and carrageenans, are the most relevant and exploited compounds of red algae. Other potential molecules are essential fatty acids, phycobiliproteins, vitamins, minerals, and other secondary metabolites. All these compounds have been demonstrated to exert several biological activities, among which antioxidant, anti-inflammatory, antitumor, and antimicrobial properties can be highlighted. Nevertheless, these properties need to be further tested on in vivo experiments and go in-depth in the study of the mechanism of action of the specific molecules and the understanding of the structure-activity relation. At last, the extraction technologies are essential for the correct isolation of the molecules, in a cost-effective way, to facilitate the scale-up of the processes and their further application by the industry. This manuscript is aimed at describing the fundamental composition of red algae and their most studied biological properties to pave the way to the utilization of this underused resource.

Development of a validated HPTLC-bioautographic method for evaluation of aromatase inhibitory activity of plant extracts and their constituents

INTRODUCTION

Aromatase is a CYP450 enzyme that catalyses the conversion of androgens into oestrogens, where the decrease in the production of oestrogens aided by aromatase inhibitors is considered a target in post-menopausal breast cancer therapy. TLC-bioautography is a technique employed for combining chromatographic separations on TLC plates with bioassays. This is the first report to evaluate aromatase inhibitory activity using this technique.

OBJECTIVES

The aim of this study is to develop and validate a new TLC-bioautographic method for determination of aromatase inhibitory activity in 14 plant extracts. Two quantitation methods, the peak area method and reciprocal iso-inhibition volume (RIV) method, were compared and investigated to attain reliable results. Factors affecting the enzymatic reaction (temperature, pH, enzyme and substrate concentrations … etc.) were also investigated to attain the optimum parameters.

METHODOLOGY

TLC assisted by digital image processing was implemented for quantitative estimation of the aromatase inhibition of 14 plant extracts using chrysin as positive control. The fluorometric substrate dibenzyl fluorescein (DBF) was utilised for the assay, where inhibitory compounds were visualised as dark spots against a blue fluorescent background. Two software programs, Sorbfil® videodensitometer (in the peak area method) and ImageJ® (in the RIV method), were thoroughly validated using the International Council on Harmonisation (ICH) guideline and used for quantitation.

RESULTS

The RIV method showed superiority over the peak area method in the quantitation results of the tracks with non-homogenous background with %RSD values of 0.98 and 1.49 compared with 2.86 and 3.58, respectively. Further, the methods allow the comparison of the activity of different unknown inhibitory compounds without the need for a reference or a positive control.

CONCLUSION

Using the TLC-bioautographic method by image processing combined with the RIV quantitation method, simultaneous separation and quantitation of aromatase inhibitory components could be applied to estimate the relative activity of various plant extracts.

Is Our Natural Food Our Homeostasis? Array of a Thousand Effect-Directed Profiles of 68 Herbs and Spices

The beneficial effects of plant-rich diets and traditional medicines are increasingly recognized in the treatment of civilization diseases due to the abundance and diversity of bioactive substances therein. However, the important active portion of natural food or plant-based medicine is presently not under control. Hence, a paradigm shift from quality control based on marker compounds to effect-directed profiling is postulated. We investigated 68 powdered plant extracts (botanicals) which are added to food products in food industry. Among them are many plants that are used as traditional medicines, herbs and spices. A generic strategy was developed to evaluate the bioactivity profile of each botanical as completely as possible and to straightforwardly assign the most potent bioactive compounds. It is an 8-dimensional hyphenation of normal-phase high-performance thin-layer chromatography with multi-imaging by ultraviolet, visible and fluorescence light detection as well as effect-directed assay and heart-cut of the bioactive zone to orthogonal reversed-phase high-performance liquid chromato-graphy-photodiode array detection-heated electrospray ionization mass spectrometry. In the non-target, effect-directed screening via 16 different on-surface assays, we tentatively assigned more than 60 important bioactive compounds in the studied botanicals. These were antibacterials, estrogens, antiestrogens, androgens, and antiandrogens, as well as acetylcholinesterase, butyrylcholinesterase, α-amylase, α-glucosidase, β-glucosidase, β-glucuronidase, and tyrosinase inhibitors, which were on-surface heart-cut eluted from the bioautogram or enzyme inhibition autogram to the next dimension for further targeted characterization. This biological-physicochemical hyphenation is able to detect and control active mechanisms of traditional medicines or botanicals as well as the essentials of plant-based food. The array of 1,292 profiles (68 samples × 19 detections) showed the versatile bioactivity potential of natural food. It reveals how efficiently and powerful our natural food contributes to our homeostasis.

UVB Radiation Protective Effect of Brown Alga Padina australis: A Potential Cosmeceutical Application of Malaysian Seaweed

Marine natural products are a good source of antioxidants due to the presence of a wide range of bioactive compounds. Accumulating evidence proves the potential use of seaweed-derived ingredients in skincare products. This study aims to evaluate the ultraviolet (UV) protective activity of the ethanol and water extracts of Padina australis. As the preliminary attempt for this discovery, the total phenolic content (TPC) and total flavonoid content (TFC) were measured, followed by the in vitro antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and reducing the power to shed light on its bioactivity. The UVB protective activity was examined on HaCaT human keratinocyte cells. The findings of this study reveal that the P. australis ethanol extract serves as a promising source of antioxidants, as it exhibits stronger antioxidant activities compared with the water extract in DPPH and the reducing power assays. The P. australis ethanol extract also demonstrated a higher level of total phenolic (76 mg GAE/g) and flavonoid contents (50 mg QE/g). Meanwhile, both the ethanol (400 µg/mL) and water extracts (400 µg/mL) protected the HaCaT cells from UVB-induced cell damage via promoting cell viability. Following that, LCMS analysis reveals that the P. australis ethanol extract consists of sugar alcohol, polysaccharide, carotenoid, terpenoid and fatty acid, whereas the water extract contains compounds from phenol, terpenoid, fatty acid, fatty alcohol and fatty acid amide. In summary, biometabolites derived from P. australis have diverse functional properties, and they could be applied to the developments of cosmeceutical and pharmaceutical products.

Characterisation of α-amylase inhibitors in marigold plants via bioassay-guided high-performance thin-layer chromatography and attenuated total reflectance-Fourier transform infrared spectroscopy

A high-performance thin-layer chromatography with microchemical derivatization and bioassay guided detection was used for bioanalytical profiling of selected marigold plant extracts. Anisaldehyde/sulfuric acid reagent and thymol/sulfuric acid reagent were used to visualize separated components on the chromatograms. Antioxidant activity and α-amylase inhibition were assessed with 2 bioassays, DPPH assay to detect free radical scavengers and starch-iodineassay method to detect compounds that inhibit α-amylase. The highest antioxidant activity of 10.12 μg of gallic acid equivalents (GAE) per 20 µL of extract was measured in extract from Tagetes flowers and the lowest in the extract from Calendula leaves with 5.10 μg of GAE. Multiple zones of α-amylase inhibition were detected. A detailed analysis of the ATR-FTIR spectra from the bands at RF = 0.24 suggest that faradiol esters and saturated fatty acids esters, palmitic acid, myristic acid, and lauric acid are responsible for α-amylase inhibition, unsaturated fatty acids for the band at RF = 0.51 and phytoecdysteroids for the band at RF = 0.53.

Rapid analytical approach for bioprofiling compounds with radical scavenging and antimicrobial activities from seaweeds

Brown seaweeds are traditionally used as food in Asian countries, and they are a valuable source of bioactive compounds. Herein, a novel high-throughput methodological approach was developed for the tracing of compounds with radical scavenging and antimicrobial activities in Saccharina japonica and Undaria pinnatifida methanol extracts. The seaweed metabolites were separated by a novel high-performance thin-layer chromatography method, the bioactive bands were identified by bioautography assays. The bioactive compounds were characterized with ultra-high-performance liquid chromatography coupled with linear trap quadrupole tandem mass spectrometry. Stearidonic, eicosapentaenoic, and arachidonic acids were identified as major components having radical scavenging and antimicrobial activities. The suggested method provides a fast identification and quantification of bioactive compounds in multicomponent biological samples.

Chemical profiling and anti-psoriatic activity of marine sponge (Dysidea avara) in induced imiquimod-psoriasis-skin model

Since Marine sponge Dysidea avara is regarded as a source of anti-inflammatory compounds, we decided to evaluate its potential anti-psoriatic activity in a psoriasis Imiquimod-induced in the mouse model. Psoriatic mice were treated with three different methanolic extracts of Dysidea avara compared with betamethasone-treated mice in in- vivo studies. Clinical skin severity was assessed with the psoriasis area index (PASI), whilst ELISA detected the expression of TNF-α, IL-17A, and IL-22. Dysidea avara activity was studied by employing GC-MS (to distinguish compounds), HPTLC (for skin permeation and accumulation), and SEA DOCK to predict single compound potential anti-inflammatory activity. After 7 days of treatment, mice treated with Dysidea avara displayed a dose-dependent, statistically significant improvement compared to controls (p< 0.001). In line with the clinical results, ELISA revealed a statistically significant decrease in IL-22, IL-17A, and TNF-α after treatment; the same SEA DOCK analysis suggests a possible anti-psoriatic activity of the extracts.

High-performance thin layer chromatography-based phytochemical and bioactivity characterisation of anticancer endophytic fungal extracts derived from marine plants

Bioactive compounds from endophytic fungi exhibit diverse biological activities which include anticancer effect. Capitalising on the abundance of unexplored endophytes that reside within marine plants, this study assessed the anticancer potential of ethyl acetate endophytic fungal extracts (i.e. MBFT Tip 2.1, MBL 1.2, MBS 3.2, MKS 3 and MKS 3.1) derived from leaves, stem and fruits of marine plants that grow along Morib Beach, Malaysia. For identification of endophytic fungi, EF 4/ EF 3 and ITS 1/ ITS 4 PCR primer pairs were used to amplify the fungal 18S rDNA sequence and ITS region sequence, respectively. The resultant sequences were subjected to similarity search via the NCBI GenBank database. High-performance thin layer chromatography (HPTLC) hyphenated with bioassays was used to characterise the extracts in terms of their phytochemical profiles and bioactivity. Microchemical derivatisation was used to assess polyphenolic and phytosterol/ terpenoid content whereas biochemical derivatisation was used to establish antioxidant activities and α-amylase enzyme inhibition. The sulforhodamine B (SRB) assay was used to assess the anticancer effect of the extracts against HCT116 (a human colorectal cancer cell line). The present results indicated MBS 3.2 (Penicillium decumbens) as the most potent extract against HCT116 (IC₅₀ = 0.16 μg/mL), approximately 3-times more potent than 5-flurouracil (IC₅₀ = 0.46 μg/mL). Stepwise multiple regression method suggests that the anticancer effect of MBS 3.2 could be associated with high polyphenolic content and antioxidant potential. Nonlinear regression analysis confirmed that low to moderate α-amylase inhibition exhibits maximum anticancer activity. Current findings warrant further in-depth mechanistic studies.

Scientific Approaches on Extraction, Purification and Stability for the Commercialization of Fucoxanthin Recovered from Brown Algae

The scientific community has corroborated the numerous beneficial activities of fucoxanthin, such as its antioxidant, anti-inflammatory, anticancer or neuroprotective effects, among others. These properties have attracted the attention of nutraceutical, cosmetic and pharmacological industries, giving rise to various possible applications. Fucoxanthin may be chemically produced, but the extraction from natural sources is considered more cost-effective, efficient and eco-friendly. Thus, identifying suitable sources of this compound and giving a general overview of efficient extraction, quantification, purification and stabilization studies is of great importance for the future production and commercialization of fucoxanthin. The scientific research showed that most of the studies are performed using conventional techniques, but non-conventional techniques begin to gain popularity in the recovery of this compound. High Performance Liquid Chromatography (HPLC), Nuclear Magnetic Resonance (NMR) and spectroscopy techniques have been employed in the quantification and identification of fucoxanthin. The further purification of extracts has been mainly accomplished using purification columns. Finally, the stability of fucoxanthin has been assessed as a free molecule, in an emulsion, or encapsulated to identify the variables that might affect its further industrial application.

The TLC-Bioautography as a Tool for Rapid Enzyme Inhibitors detection - A Review

Microorganisms and plants can be important sources of many compounds with potential pharmaceutical applications. Extraction of these matrices is one of the ways of identifying the presence of inhibitory active substances against enzymes whose high activity leads to serious human diseases including cancer, Parkinson's or Crohn's diseases. The isolation and purification of inhibitors are time-consuming and expensive steps in the analysis of the crude extract and therefore, it is necessary to find a fast, efficient, and inexpensive method for screening extracts of interest. TLC-Bioautography combines the separation of the extract on a thin layer with its subsequent biological analysis. TLC-Bioautography methods have been developed for several classes of enzymes including oxidoreductases, hydrolases and isomerases, and there is a potential for developing functional methods for other classes of enzymes. This review summarizes known TLC-Bioautography methods and their applications for determining the presence of enzyme inhibitors in extracts and compares the effectiveness of different methodological approaches. It also indicates the current state and perspective of the development of TLC-Bioautography and its possible future applications.

High-performance thin-layer chromatography linked with (bio)assays and FTIR-ATR spectroscopy as a method for discovery and quantification of bioactive components in native Australian plants

Many native Australian plants have a long history of use as medicinal and culinary herbs and some are considered to be equivalents to the Mediterranean herbs. However, while therapeutic properties of Mediterranean herbs are well documented, there is limited information on the medicinal use of the Australian native herbs. Extracts of five native Australian plants were characterised with FTIR-ATR spectroscopy in the fingerprint region and screened for enzyme inhibitory and antioxidant activities via effect-directed analysis (EDA) based on bioautography. High-performance thin-layer chromatography (HPTLC) coupled with microchemical and biochemical derivatization assays was used for EDA screening. Detected compounds with biological activities were identified via FTIR-ATR spectroscopy. All herbs showed antioxidant activity with lemon myrtle being the most active. The α-amylase inhibition, observed in native thyme, sea parsley and native bush was associated with the presence of phenolic acids, chlorogenic acid and caffeic acid. The investigation of botanicals by a fast, hyphenated HPTLC method, has allowed an effect-directed high-throughput screening, fast characterization of complex mixtures and detection of biologically active phytochemicals (bioprofiling).

Bioassay-guided identification of α-amylase inhibitors in herbal extracts

This study focuses on the health benefits of several fresh herbs that are commonly used in the Mediterranean diet. Antioxidant activity, phytosterol content and α-amylase inhibitory activity of fresh basil, lavender, oregano, rosemary, sage, and thyme are analyzed and compared. High-performance thin-layer chromatography (HPTLC) combined with effect directed analysis was used to detect and quantify biological active compounds on chromatograms. The highest antioxidant activity was measured in the extract from oregano leaf, while the highest terpenoid content was in basil leaf extract. All extracts except lavender leaf and lavender flower extracts showed α-amylase inhibition. The same compound at hR_F = 68 in basil, oregano, rosemary, sage, and thyme extracts was responsible for α-amylase inhibition. Combined with effect-directed assays and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, hyphenated HPTLC allowed a fast characterization of the active compound. ATR spectral analysis of this band tentatively identified oleanolic acid (or its derivative) to be responsible for the α-amylase inhibition.

Hyphenated TLC as a Tool in the Effect-Directed Discovery of Bioactive Natural Products

Complex samples such as botanical extracts contain hundreds of compounds. Since we can only identify compounds that are stable, extractable, separable and detectable from complex botanical extracts, minimal sample treatment and different detection methods are essential. A combination of high-performance thin-layer chromatography (HPTLC) with non-targeted screening via bioassays (enzymes), microchemical and biological (microorganisms) detection allows for the fast and quantitative bioprofiling of complex samples. Further hyphenation of HPTLC with spectroscopic methods of identification enables targeted identification of bioactive natural products via Effect Directed Analysis (EDA).

HPTLC based approach for bioassay-guided evaluation of antidiabetic and neuroprotective effects of eight essential oils of the Lamiaceae family plants

A high-performance thin-layer chromatography (HPTLC) method combined with effect-directed-analysis (EDA) was developed to screen the antioxidant, neuroprotective and antidiabetic effects in essential oils derived from lavender flower, lemon myrtle, oregano, peppermint, sage, and rosemary leaves (Lamiaceae family). HPTLC hyphenated with microchemical (DPPH•, p-anisaldehyde, and ferric chloride) derivatizations, was used to evaluate antioxidant activity, presence of phytosterols and terpenoids, and polyphenolic content, while the combination with biochemical (α-amylase and acetylcholine esterase (AChE) enzymatic) derivatizations was used to asses α-amylase and AChE inhibitory activities. The superior antioxidant activity of oregano leaf extract is attributed to the presence of high levels of aromatic compounds, like polyphenolic acids. The strongest α-amylase inhibition was observed in lemon myrtle and rosemary plus extracts due to the presence of monoterpenes. Rosemary and sage extracts exhibit the highest AChE inhibition activity, with 1 μL essential oils being more potent than the recommended daily dose of donepezil. This superior neuroprotection was attributed to the presences of di- and triterpenes that displayed strong AChE inhibition and antioxidant potential in DPPH• free radical assay. Antioxidant activity was related to phenolic content (R = 0.49), while α-amylase inhibitory activity was positively related to antioxidant activity (R = 0.20) and terpenoid/sterol content (R = 0.31). AChE inhibitory activity was correlated (R = 0.80) to the combined effect of phenolics and terpenoids. Thus, the superior AChE inhibitory and neuroprotection potential of rosemary and sage essential oils could be attributed to joint effects of main phenolic and terpene constituents. The hyphenated HPTLC method provided rapid bioanalytical profiling of highly complex essential oil samples.

High-Performance Thin-Layer Chromatography Hyphenated with Microchemical and Biochemical Derivatizations in Bioactivity Profiling of Marine Species

Marine organisms produce an array of biologically active natural products, many of which have unique structures that have not been found in terrestrial organisms. Hence, marine algae provide a unique source of bioactive compounds. The present study investigated 19 marine algae and one seagrass collected from Torquay beach, Victoria, Australia. High-performance thin-layer chromatography (HPTLC) hyphenated with microchemical (DPPH•, p-anisaldehyde, and Fast Blue B) and biochemical (α-amylase and acetylcholine esterase (AChE) enzymatic) derivatizations was used to evaluate antioxidant activity, presence of phytosterols and phenolic lipids, α-amylase and AChE inhibitory activities of extract components. Significant α-amylase and AChE inhibitory activities were observed in samples 2, 6, 8 and 10. Antioxidant activities in the samples were found to be correlated to phytosterol content (R² = 0.78), but was not found to be related to either α-amylase or AChE inhibitory activities. α-Amylase inhibitory activities were correlated to AChE inhibition (R² = 0.77) and attributed to the phytosterol content, based on the similar peak position in the chromatograms with the β-sitosterol chromatogram. Samples 1, 8, and especially sample 20, were found to contain phenolic lipids (alkyl resorcinol derivatives) with significant antioxidant activities. The results suggest that these marine species have a significant number of bioactive compounds that warrant further investigation.

Rapid microwave-assisted distillation–precipitation polymerization for the synthesis of magnetic molecular imprinted polymers coupled to HPTLC determination of perphenazine in human urine

Microwave-assisted distillation–precipitation polymerization (MWDPP) for the synthesis of magnetic molecularly imprinted polymers (MMIPs) under atmospheric pressure is reported.

Essential oils and functional herbs for healthy aging

As total life expectancy increases, the prevalence of age-related diseases such as diabetes and Alzheimer’s disease is also increasing. Many hypotheses about Alzheimer’s disease have been developed, including cholinergic neuron damage, oxidative stress, and inflammation. Acetylcholine is a major neurotransmitter in the brain and cholinergic deficits leads to cognitive dysfunction and decline. Recent studies have linked diabetes as a risk factor in developing Alzheimer’s disease and other types of dementia. The incidence of patients with type II diabetes and increased levels and activity of α-amylase is higher in patients with dementia. It has been shown that aromatherapy with essential oils from the mint family can improve cognitive performance in Alzheimer’s disease patients. Selected monoterpenoids from these essential oils are reported to inhibit acetylcholinesterase, both in vitro and in vivo. Terpenoids are small, fat-soluble organic molecules that can transfer across nasal mucosa if inhaled, or penetrate through the skin after topical application, enter into the blood and cross the blood-brain barrier. Recent evidence supports the idea that the common constituents of essential oils also inhibit α-amylase, a starch digestive enzyme that plays an important role in the control of diabetes. The mint family is a fragrant plant family that contains most of the culinary herbs found in the Mediterranean diet. The Mediterranean diet is considered to be one of the healthiest diets in the world, and is found to be beneficial not only for the heart but also for the brain. Herbs used in this diet are rich in antioxidants that can prevent oxidative damage caused by free radicals. However, our study shows that they also contain biologically active compounds with potent α-amylase and acetylcholinesterase inhibitory activities. Consumption of fresh herbs can help boost memory and reduce sugar levels in the body. The use of herbs as a functional food could lead to significant improvements in health. Cognitive stimulation with medical food and medical herbs could delay development of cognitive decline, and improve the quality of life of Alzheimer’s disease patients. This effect can be enhanced if combined with aromatherapy, topically or by inhalation, and/or by ingestion. Terpenes and terpenoids, the primary constituents of these essential oils are small, lipid soluble organic molecules that can be absorbed through the skin or across nasal mucosa into the systemic blood circulation. Many terpenes can also cross the blood-brain barrier. Therefore, topical application or inhalation of essential oils will also produce a systemic effect.

A screening method for cardiovascular active compounds in marine algae

The interaction of bioactive compounds from ethanolic extracts of selected marine algae samples, separated on chromatographic plates, with nitric/nitrous acid was investigated. The nature of bioactive compounds in the marine algae extracts was characterised using UV absorption spectra before and after reaction with diluted nitric acid, and from the characteristic colour reaction after derivatization with anisaldehyde. It was found that diterpenes from Dictyota dichotoma, an edible brown algae, and sterols from green algae Caulerpa brachypus, bind nitric oxide and may act as a nitric oxide carrier. Although the carotenoid fucoxanthin, found in all brown marine algae also binds nitric oxide, the bonds between nitrogen and the fucoxanthin molecule are much stronger. Further studies are required to evaluate the effects of diterpenes from Dictyota dichotoma and sterols from green algae Caulerpa brachypus to see if they have beneficial cardiovascular effects. The method reported here should prove useful in screening large numbers of algae species for compounds with cardiovascular activity.