Soluble and insoluble phenolic compounds and antioxidant activity of immature calamondin affected by solvents and heat treatment

Microbial succession and organic acid metabolism during spontaneous calamondin fermentation: The vital role of Pichia

Calamondin (Citrus microcarpa) is rich in bioactive components, indicating potential for fermented calamondin fruit (FCF) development with improved flavor and bioactivity. However, reports on this are limited. This study systematically analyzed changes in physicochemical properties, phenolic/flavor compounds, enzyme inhibition rates, and microbial community structure during FCF spontaneous fermentation. Results indicated significant changes in organic acid profiles during FCF spontaneous fermentation. The inhibition rate of digestion-related enzymes increased, correlating with phenolic compound composition changes. Additionally, the fermentation improved the flavor profile of FCF, including isoamyl acetate and ethyl acetate formation. The microbial community revealed succession patterns with Acetobacter and Pichia as core genera. Variations in organic acids influenced fungal community succession, particularly Pichia. Additionally, a Pichia terricola strain (QJJY1) was isolated; genomic analysis linked it to carbohydrate and amino acid metabolism. Simulated fermentation demonstrated P. terricola QJJY1's role in regulating organic acid profiles, shedding light on its impact on microbial and metabolite profiles during FCF fermentation. This study offers insights into the high-value utilization of calamondin resources and development of new fermented products.

Recovery, Bioactivity, and Utilization of Bioactive Phenolic Compounds in Citrus Peel

Citrus peels are rich in bioactive phenolic compounds with various health effects including antioxidant, antiobesity, antiinflammatory, antihypertensive, antihypercholesterolemic, antimicrobial, antidiabetic, and anticarcinogenic activities. Both extractable and nonextractable phenolics are present in significant amounts in Citrus peel with diverse bioactivities. While extractable phenolics can be recovered from the fruit peels by conventional extraction methods, nonextractable phenolics remaining in the residues must be released from the cell matrix first by hydrolysis with acid, alkali, or enzymes. Novel processing technologies can help in improvement of extraction efficiency. Extreme process or medium conditions degrade phenolics and their bioactivity where encapsulation can be applied to improve their stability, solubility, and bioactivity. Citrus peel powder including ascorbic acid and dietary fiber besides phenolics or extracts therefrom can be used as functional food ingredients to extend shelf life and provide health benefits. In addition, phenolic extracts can be used as antioxidant and antimicrobial agents in active food packaging applications. Phenolic extracts have also a potential to be used as nutraceuticals and pharmaceuticals. In this review, phenolic compounds in different forms in Citrus peels, their recovery, bioactivity and possible applications for upcycling in the industry are presented.

Effectively Enhancing the Physiological Activity and Sensory Quality of Whole Calamondin Puree via Yeast Fermentation

To explore the feasibility of pure yeast fermentation in whole Calamondin puree (FWCP) for the utilization of the whole fruit, yeasts were isolated from naturally fermented Calamondin, and their fermentation characteristics were evaluated. The results indicated that all yeasts were able to ferment FWCP, reducing the sour taste by degrading citric acid, increasing the contents of nutrients (such as phenols and limonins) and volatile compounds, and enhancing the antioxidant activity and inhibition of α-glucosidase activity (p < 0.05). Among them, P. terricola QJJY1 and H. opuntiae QJJY14 exhibited stronger abilities to degrade organic acids, with P. terricola QJJY1 enhancing the antioxidant capacity by releasing phenolic compounds such as phloretin-3',5'-di-c-β-glucoside, vitexin-2″-O-rhamnoside, and isomargaritene. Moreover, H. opuntiae QJJY15 improved the contents of characteristic volatile compounds such as terpene hydrocarbons and higher alcohols. In total, 70 components were identified as differential metabolites based on their fold change in the metabolites, with 42 differential metabolites involved in 29 metabolic pathways across four strains. The main pathways related to phenol and flavor enrichment were flavonoid, flavone, and flavonol biosynthesis, monoterpenoid biosynthesis, and glyoxylate and dicarboxylate metabolism. Therefore, yeast fermentation is an effective method for utilizing whole Calamondin.

Water-soluble phenolics from Phoenix dactylifera fruits as potential reno-protective agent against cisplatin-induced toxicity: pre- and post-treatment strategies

Nephrotoxicity is the major side effect of cisplatin, an effective platinum-based chemotherapeutic drug that is applicable in the treatment of several solid-tissue cancers. Studies have indicated that certain water-soluble phenolics offer renal protection. Thus, this study investigates the role of pre and post-treatment of rats with water-soluble phenolics from Phoenix dactylifera (PdP) against nephrotoxicity induced by cisplatin. Rats were either orally pretreated or post-treated with 200 mg/kg body weight of PdP before or after exposure to a single therapeutic dose of cisplatin (5 mg/kg body weight) for 7 successive days intraperitoneally. The protective effects of PdP against Cisplatin-induced nephrotoxicity was based on the evaluation of various biochemical and redox biomarkers, together with histopathological examination of kidney tissues. The composition, structural features, and antioxidative influence of PdP were determined based on chromatographic, spectroscopic, and in vitro antioxidative models. Cisplatin single exposure led to a substantial increase in the tested renal function biomarkers (uric acid, creatinine, and urea levels), associated with an increase in malondialdehyde indicating lipid peroxidation and a significant decline (p < 0.05) in reduced glutathione (GSH) levels in the renal tissue when compared with the control group. A marked decline exists in the kidney antioxidant enzymes (catalase, SOD, and GPx). Nevertheless, treatment with PdP significantly suppressed the heightened renal function markers, lipid peroxidation, and oxidative stress. Spectroscopic analysis revealed significant medicinal phenolics, and in vitro tests demonstrated antioxidative properties. Taken together, results from this study indicate that pre- and/or post-treatment strategies of PdP could serve therapeutic purposes in cisplatin-induced renal damage.

The Self-Assembly Soluplus Nanomicelles of Nobiletin in Aqueous Medium Based on Solid Dispersion and Their Increased Hepatoprotective Effect on APAP-Induced Acute Liver Injury

Purpose

APAP-induced liver injury (AILI) is a common cause of acute liver failure (ALF). Nobiletin (NOB) is a potential hepatoprotective agent for the treatment of APAP-induced liver injury. However, the poor solubility and low bioavailability of NOB hinders its application. In this study, a novel self-assembly nano-drug delivery system of nobiletin (solid dispersion of NOB, termed as NOB/SD) was developed based on solid dispersion technology to improve the bioavailability and hepatoprotective ability of NOB for APAP-induced liver injury therapy.

Methods

The optimized NOB/SD system was constructed using the amphiphilic copolymers of Soluplus and PVP/VA 64 via hot melt extrusion technology (HME). NOB/SD was characterized by solubility, physical interaction, drug release behavior, and stability. The bioavailability and hepatoprotective effects of NOB/SD were evaluated in vitro and in vivo.

Results

NOB/SD maintained NOB in matrix carriers in a stable amorphous state, and self-assembled NOB-loaded nanomicelles in water. Nanostructures based on solid dispersion technology exhibited enhanced solubility, improved release behavior, and promoted cellular uptake and anti-apoptosis in vitro. NOB/SD displayed significantly improved bioavailability in healthy Sprague Dawley (SD) rats in vivo. Furthermore, NOB/SD alleviated the APAP-induced liver injury by improving anti-oxidative stress with reactive oxygen species (ROS) scavenging and nuclear factor erythroid 2-related factor 2 (Nrf2) activation.

Conclusion

These results suggested that NOB/SD could be considered as a promising hepatoprotective nano-drug delivery system for attenuating APAP-induced acute liver injury with superior bioavailability and efficient hepatoprotection, which might provide an effective strategy for APAP-induced acute liver injury prevention and treatment.

Elucidation of flavanones, phenols and antioxidant capacity influenced by drying methods from physiologically dropped underutilized Citrus grandis fruits

Introduction

Nutritional content in citrus fruit is enormous. Citrus grandis (L.) Osbeck is underutilised citrus crop that receives little attention due to the lack of knowledge regarding its nutritional value. Citrus waste disposal poses a problem due to economic and environmental factors.

Methods

The metabolites flavonoids, phenols and antioxidant capacity in the dropped fruits of the underutilised citrus species pomelo (Citrus grandis (L.) Osbeck) were examined.

Results and discussion

Hesperidin varied from 1.22 to 2.83% and 1.08 to 1.16% from 10 mm to 14 mm whereas naringin dominates in fruits measuring 10 mm and 12mm with 60.61%, 60.77%, and 47.76%, 45.87% in freeze dried (FD) and hot air oven dried (HAOD) samples. According to the results of the antioxidant assays, the highest concentrations of ABTS azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) and DPPH (2, 2-diphenyl-1-picrylhydrazyl radical) were found in freeze dried samples, ranging from 9.679 to 10.416 mmol L^-1 Trolox and 14.825 to 16.432 mmol L^-1 Trolox, respectively. However, the Ferric Reducing Antioxidant Power (FRAP) assay revealed higher content in samples of both FD and HAOD that were 10mm in size (4.578 mmol L^-1 Trolox and 3.730 mmol L^-1 Trolox). Total phenol content was measured, and the highest concentrations were found in fruits with a diameter between 10 mm and 18 mm. It ranged from 48.479 to 54.498 mg GAE L^-1 in FD samples and from 45.757 to 51.159 mg GAE L^-1 in HAOD samples. The smallest fruits, or those that were still in the immature stage, had the highest content. It was found that when the immature dropped fruits were dried by HAOD, the content decreased. At p<0.01 and p<0.05, there was a significant positive correlation between the flavonoids, antioxidants, and total phenols. The results showed that the immature dropped immature fruits of lesser known underutilised citrus sp. Citrus grandis can act as potential source of flavonoids, total phenol concentration, and antioxidant potential. Freeze drying can be recommended to recover the most bioactive substances from physiologically dropped fruits of Citrus grandis for use in the pharmaceutical and nutraceutical sectors. This study will help in reducing the environmental impact caused due to citrus dropped fruits and its responsible management.

Bioactive Compounds of Underground Valerian Extracts and Their Effect on Inhibiting Metabolic Syndrome-Related Enzymes Activities

Extractions of the underground parts of valerian were prepared with water and ethanol (25-95%) at 25-75 °C. Extraction yields, bioactive compounds, and the 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability of lyophilized extracts were determined. The inhibitory effects of the extracts, valerenic acid derivatives and phenolic acids, on metabolic syndrome (MS)-related enzymes activities were further examined. Both roots and rhizomes extracted with 95% ethanol at 75 °C had the highest levels of bioactive compounds. The antioxidant capacity and inhibition of MS-related enzymes of the roots extract were better than those of the rhizomes. The roots extract more strongly inhibited pancreatic lipase (inhibition of 50% of enzyme activity (IC₅₀), 17.59 mg/mL), angiotensin-converting enzyme (ACE, IC₅₀, 3.75 mg/mL), α-amylase (IC₅₀, 12.53 mg/mL), and α-glucosidase (IC₅₀, 15.40 mg/mL). These four phenolic acids inhibited the activity of MS-related enzymes. Valerenic acid demonstrated more of an inhibitory ability for ACE (IC₅₀, 0.225 mg/mL, except for caffeic acid) and α-glucosidase (IC₅₀, 0.617 mg/mL) than phenolic acids. Valerian extract inhibited key enzyme activities that were associated with obesity (lipase), hypertension (ACE), and type 2 diabetes (α-amylase and α-glucosidase), suggesting that it is a potential candidate for the development of functional supplements.

Fruit pomaces-their nutrient and bioactive components, effects on growth and health of poultry species, and possible optimization techniques

The ever-growing human population, coupled with the exigent need to meet the increasing demand for poultry meat and egg, has put the onus on poultry nutritionists and farmers to identify alternative feed ingredients that could assure the least-cost feed formulation. In addition, the public desire for non-antibiotic-treated poultry products has also necessitated the ultimate search for potent antibiotic alternatives for use in poultry production. While some identified alternatives are promising, their cost implications and technical know-how requirements may discourage their ease of adoption in poultry. The use of plants and/or their by-products, like fruit pomaces, present a pocket-friendly advantage and as a result, are gaining much interest. This is traceable to their rich phytochemical profile, nutritional composition, ready availability, and relatively cheap cost. The fruit juice and wine pressing industries generate a plethora of fruit wastes annually. Interestingly, fruit pomaces contain appreciable dietary fibre, protein, and phenolic compounds, and thus, their adoption could serve the poultry industry in dual capacities including as substitutes to antibiotics and some conventional feedstuff. Thus, there is a possibility to reduce fruit wastes produced and feed-cost in poultry farming from environmental and economical standpoints, respectively. This review seeks to provide reinforcing evidence on the applicability and impact of fruit pomaces in poultry nutrition.

Phenolic compounds as antidiabetic, anti-inflammatory, and anticancer agents and improvement of their bioavailability by liposomes

Phenolic compounds, widespread in plants, are a necessary part of the human regimen due to their antioxidant and pro-oxidative properties. Naturally, phenolics structurally range from a very simple phenolic molecule moiety to an intricate polymer. For decades, phenolic compounds have gained pronounced attention because of their protective effects against degenerative disorders such as inflammation, diabetes and cancer. Physico-chemical properties (eg, solubility) restricted their bioactivity and also limited their usage as nutraceutical ingredients. However, encapsulation technology like liposomal formulations has been developed for the delivery of phenolic compounds without affecting their original aesthetic and organoleptic property. Hence, this review outlines the antioxidant and pro-oxidative properties of phenolic compounds and focuses on biological activity reports of flavonoids and phenolic acids as antidiabetic, anti-inflammatory and anticancer agents. Also, the delivery applications of phenolic compounds as liposomes are discussed with few examples.

Physiochemical and nutritional evaluation of whole kumquat fruits powder and its protective effect on thyroid hormones and blood sugar levels in diabetic rats

The present study was conducted to evaluate the chemical composition, antioxidant activity and hypoglycemic effects of whole kumquat (Ku) powder in diabetic rats fed a high-fat-high-cholesterol (HFHC) diet. The antioxidant activities were evaluated using stable 1,1-diphenyl 2-picrylhydrazyl (DPPH) free radical scavenging method, 2,2´-azinobis (3-ethyl benzo thiazoline-6-sulphonic acid) radical cation (ABTS) and Ferric reducing antioxidant power (FRAP). Total phenolic content was (51.85 mg GAE/g) and total flavonoid content was (0.24 mg Cateachin Equivalent, CE/g). DPPH and ABTS values were 3.32 and 3.98 mg Trolox equivalent (TE)/g where FRAP value was 3.00 mM Fe2+/kg dry material. A total of 90 albino rats were used in the present study. Rats group were as follows: normal diet; normal treated (2, 4, and 6% Ku.), diabetic rats (non-treated), diabetic + HFHC diet (non-treated), HFHC (non-treated), Diabetic (treated), HFHC (treated) and Diabetic + HFHC (treated). The diets were followed for 8 weeks. Blood samples were collected at the end of the experiment. Serum glucose was recorded and thyroid hormones (T4, Thyroxine and T3, Triiodothyronine) were conducted. Diet supplemented with Kumquat at different concentrations have a hypoglycemic effect and improve the thyroid hormones of both diabetic rats and HFHC diabetic rats.

Widely Targeted UHPLC-MS/MS Metabolomic Analysis on the Chemical Variation in Blueberry-Filled Pastries During Processing

The majority of components in fruits are sensitive to heat-processing. Nevertheless, fruits are becoming popular ingredients in processed foods, like bakery foods. Therefore, the fate of the components in the fruit-involved food during thermal processing is important for the assessment of their nutritional values and sensory properties. Unfortunately, comprehensive knowledge of the compositional alteration in real food products during processing is limited. In the current study, a popular bakery food, blueberry-filled pastry, was taken as the object, and a widely targeted metabolomic approach was applied to investigate the holistic compositional variation of blueberry filling during pastry preparation. Amongst the total of 630 chemicals identified, 288 chemicals were screened as differential compounds between samples collected at different processing stages. The most variation of the chemicals was observed during the process of stir-frying. A total of 197 chemicals varied significantly in concentrations during stir-frying, while only 75 chemicals altered significantly in contents during baking. Amongst 288 differential compounds, 117 belonged to the group of phenolic compounds, with the others found to be sugars and organic acids, amino acids, lipids, nucleotides, etc. The possible mechanisms of the chemical alterations during thermal processing were also discussed in the current study. The data provide comprehensive information on the compositional changes in berry-containing fillings during thermal processing, and hints and emphasis for further investigation of the underlying mechanisms.

Chemistry and Antioxidant Potential of Phytoconstituents from Aegle Marmelos Fruit-Shell

BACKGROUND

Oxidative stress is among the main causes of metabolic disorders. Hence, there is a need to discover potent antioxidants for therapeutic applications.

OBJECTIVE

The objective of this study has been to investigate the phytoconstituents of the methanolic extract of the hard shell of Aegle marmelos fruit and their antioxidant potential.

METHODS

Methanolic extract was fractionated using different solvents by liquid-liquid extraction. Characterization of the phytoconstituents was done by using phytochemical tests and GC-MS analysis. The free radical scavenging activity, total reducing power, lipid peroxidation inhibition and cell protection assays against oxidative stress were performed with methanolic extract and its fractions.

RESULTS

Therapeutically significant class of compounds, for example, polyphenols, glycosides and sterols were revealed in the hard-shell extract. Differential separation of compounds was achieved by liquid-liquid extraction using different solvents. Six compounds: 4-Hydroxybenzeneacetic acid; 5-Oxo-pyrrolidine-2-carboxylic acid methyl ester; 1-[3-Methyl-3-Butenyl] Pyrrolidine; Trans-sinapyl alcohol; 5-[Hydroxymethyl]-2-furaldehyde and 2,4- Dihydroxy-2,5-dimethyl-3[2H]-furan-3-one, identified in the fruit-shell extract, are being reported for the first time from this plant. Strong antioxidant potential of the extract was evident from efficient scavenging of free radicals. The extract also conferred protection to yeast cells against oxidative damage.

CONCLUSION

Results showed that the hard shell of the Aegle marmelos fruit was a potent source for antioxidant compounds, which can be developed for therapeutic applications in the control and management of metabolic diseases.

Extraction of Nobiletin and Tangeretin From Peels of Shekwasha and Ponkan Using [C2mim][(MeO)(H)PO2] and Centrifugation

The polymethoxyflavonoids nobiletin and tangeretin are isolated from peels of shekwasha ( Citrus depressa Hayata) and ponkan ( Citrus reticulata Blanco). These natural products possess biological activities, including anticancer and anti-inflammation properties. This report describes an efficient method for the extraction and isolation of nobiletin and tangeretin from citrus peels using 1-ethyl-3-methylimidazolium methylphosphonate ([C2mim][(MeO)(H)PO2]) and centrifugation/decantation. The results showed that the extraction yield of nobiletin and tangeretin using [C2mim][(MeO)(H)PO2]/organic solvent (1:1 w/w) was 1.4 to 1.6 times higher than that using organic solvent. This extraction method is expected to be applicable for obtaining other organic compounds from natural sources.

Quality Characteristics and Antioxidant Activities of Rice/Adzuki Bean Mixtures Cooked Using Two Different Methods

This study explored the optimal preparation and the antioxidant levels of rice/adzuki bean mixtures. We compared the quality and physicochemical characteristics of cooked mixtures of rice and adzuki beans prepared using normal and high-pressure rice cookers, with and without the addition of alcohol (15%, v/v). The water-binding capacity and swelling power decreased upon addition of adzuki beans, but water solubility increased. The peak, trough, final, and setback viscosities decreased, but the breakdown viscosity increased. The total polyphenol and flavonoid contents increased after addition of adzuki beans. Total polyphenol contents in cooked rice/20% (w/w) Arari and Geomguseul bean mixtures in a normal cooker with addition of alcohol were 3.00 and 3.09 times higher than plain rice. The flavonoid contents were 10.33 and 8.90 times higher than plain rice. The predominant phenolic acids in cooked rice/Arari bean mixtures were p-coumaric acid and trans-3-hydroxycinnamic acid, and in cooked rice/Geomguseul bean mixtures, they were syringic acid and trans-3-hydroxycinnamic acid. Overall, phenolic acid levels were higher in mixtures cooked in plain water. The DPPH- and ABTS-radical-scavenging activities increased upon addition of adzuki beans. DPPH radical-scavenging activities in cooked rice/20% (w/w) Arari and Geomguseul bean mixtures in a normal cooker with addition of alcohol were 9.09 and 9.22 times higher than plain rice. ABTS radical-scavenging activities were 8.74 and 9.01 times higher than plain rice. Moreover, rice/adzuki bean mixtures prepared in a normal cooker, with addition of alcohol, exhibited higher antioxidant levels than other samples. We present the antioxidative properties of rice/adzuki bean mixtures prepared in different ways; these data will aid manufacturers.

Changes in the functional components and radical scavenging activity of maize under various roasting conditions

The phenolic compounds and radical scavenging activity of ethanolic extracts from maize at various roasting conditions were evaluated in this research. The free sugar contents in roasted maize significantly decreased with higher roasting temperature and longer roasting time. The total polyphenol and total flavonoid contents in roasted maize significantly increased with higher roasting temperature and longer roasting time. The predominant phenolic acid in the roasted maize was homogentisic acid. The contents of homogentisic acid and myricetin in roasted maize significantly increased with higher roasting temperature and longer roasting time. The DPPH and ABTS radical scavenging activities of roasted maize significantly increased with higher roasting temperature and longer roasting time. DPPH and ABTS radical scavenging activities were positively correlated with phenolic compounds. The activities of these components increased following heat treatments because of the low molecularization effects of the heating process, which resulted in active, low-molecular-weight components that were readily extracted.

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.

Hardy kiwifruit leaves (Actinidia arguta): An extraordinary source of value-added compounds for food industry

The present study reports for the first time the identification and quantification of phenolic compounds, the antioxidant and antimicrobial activities as well as the in vitro radical scavenging activity and intestinal cell effects of A. arguta leaves extracts. Extractions were carried out under water, water:ethanol (50:50) and ethanol. The highest antioxidant activity were obtained in alcoholic extract (IC₅₀ = 53.95 ± 3.09 μg/mL for DPPH; 6628.42 ± 382.49 µmol/mg dry weight basis for FRAP) while the phenolic profile confirmed by HPLC analysis revealed highest amounts of phenolic acids (hydroxycinnamic acid derivatives) and flavonoids (flavan-3-ol and flavonols derivatives). An excellent scavenging activity against reactive oxygen and nitrogen species were determined for all extracts as well as no adverse effects on Caco-2 and HT29-MTX cells in concentrations below 100 μg/mL and 1000 μg/mL, respectively. These results highlight the potentialities of hardy kiwi leaves valorization.

Comparative Evaluation of Soluble and Insoluble-Bound Phenolics and Antioxidant Activity of Two Chinese Mistletoes

Mistletoes are used medicinally in order to treat various human illnesses. Few studies have reported on the phenolic content and antioxidant properties of Chinese mistletoes (CMs). In this work, the total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activities of soluble and insoluble-bound phenolic extracts from CMs hosted by Camellia assamica (Mast.) Chang (CMC) and Pyrus, i, f. (CMP) were compared. Phenolic compounds in CMC and CMP were identified and quantified using high-performance liquid chromatography (HPLC). The results indicated that the TPC of soluble phenolic extracts was higher than insoluble-bound phenolic counterparts in both CMC and CMP. In addition, the TPC of soluble, insoluble-bound and total phenolic fractions (9.91 ± 0.23, 4.59 ± 0.27 and 14.50 ± 0.35 μmol ferulic acid equivalents per gram (FAE/g) dry sample) extracted from CMP were higher than those extracted from CMC. The soluble phenolic extracts in CMP showed higher antioxidant activities than those in CMC. Eighteen phenolic compounds from soluble and insoluble-bound phenolic extracts from the CMs were identified and quantified by HPLC. This study indicates that CMC and CMP, especially the latter, could be sources of antioxidants in human health care.

Effect of drying temperature on the sugars, organic acids, limonoids, phenolics, and antioxidant capacities of lemon slices

Changes in contents of sugars, organic acids, limonoids, phenolics contents, and antioxidant capacities of lemon slices dried at different temperatures were evaluated. Air drying (AD) promoted losses of sugars, citric acid, ascorbic acid, extractable phenolics (EPs), and non-extractable phenolics (NEPs), while it introduced an increase in limonoids. Phenolics of lemon were mainly presented in their extractable form. Hesperidin and eriocitrin were the main EPs; protocatechuic acid and poncirin were the predominant NEPs. The decrease in extractable phenolic acid, EP, and NEP content in lemon is lower at low drying temperatures, while the increase in non-extractable phenolic acid content is higher at high drying temperatures. The antioxidant capacity of EP was higher than that of NEP. Phenolics contributed to antioxidant capacities of lemon slices, and flavonoids were the main contributors among phenolics. Considering limonoids contents and the high levels of EP, NEP, and antioxidant capacities, AD at 60 °C could be an appreciate treatment for dehydrating lemon slices.

Seasonal, gender and regional variations in total phenolic, flavonoid, and condensed tannins contents and in antioxidant properties from Pistacia atlantica ssp. leaves

CONTEXT

The widespread use of Pistacia atlantica Desf. ssp. (Anacardiaceae) in traditional medicine can be partly attributed to the content of its secondary metabolites, in particular, the phenolic compounds.

OBJECTIVE

The effects of harvest period, growing region and gender on the phenolic compounds, flavonoids and condensed tannins contents were studied, as well as on the antioxidant activities of P. atlantica leaves in order to provide a scientific basis for optimal collection.

MATERIALS AND METHODS

Leaves were collected monthly from April to October 2010 in two Algerian sites. The powdered leaves were used for preparing the ethyl acetate extract. Contents of total phenolics (TPC), flavonoids (FC) and condensed tannins (CTC) were determined spectrophotometrically. Antioxidant activity was evaluated through radical scavenging activity (RSA) of 2,2-diphenyl-1-picrylhydrazyl (250 μM) and the reducing power capacity (RPC) determination by K3Fe(CN)6 (1%).

RESULTS

The TPC was found to vary from 79 ± 13 to 259 ± 8 mg gallic acid equivalents/g of dry weight (DW) during the study period. The RSA and RPC varied between 262 ± 18 and 675 ± 21 mg Ascorbic Acid Equivalent (AAE)/g DW, and from 259 ± 16 to 983 ± 20 mg AAE/g DW, respectively. A seasonal pattern was observed consisting of a decrease in TPC content and RPC from spring to autumn. The FC, CTC and RSA did not show a seasonal pattern.

DISCUSSION AND CONCLUSION

Our findings showed that secondary metabolite content and antioxidant activities of P. atlantica leaves were more influenced by harvest time and growing region than by gender.

Traditional Small-Size Citrus from Taiwan: Essential Oils, Bioactive Compounds and Antioxidant Capacity

Background: The calamondin (Citrus microcarpa Bunge) and the kumquat (Fortunella crassifolia Swingle) are two small-size citrus fruits that have traditionally been consumed in Taiwan; however, there has been a lack of scientific research regarding the active compounds and functionalities of these fruits. Methods: Analysis of volatile composition of essential oil and phytosterol was carried out using Gas Chromatography–Mass Spectrometry (GC-MS). Flavonoid and limonoid were analyzed by High Performance Liquid Chromatography (HPLC). Moreover, antioxidant capacity from their essential oils and extracts were assessed in vitro. Results: The compositions of the essential oils of both fruits were identified, with the results showing that the calamondin and kumquat contain identified 43 and 44 volatile compounds, respectively. In addition, oxygenated compounds of volatiles accounted for 4.25% and 2.04%, respectively, consistent with the fact that oxygenated compounds are generally found in high content in citrus fruits. In terms of flavonoids, the calamondin exhibited higher content than the kumquat, with disomin-based flavonoids being predominant; on the other hand, phytosterol content of kumquat was higher than that of calamondin, with amyrin being the dominant phytosterol. Both of them contain high amounts of limonoids. The ethanol extracts and essential oils of small-sized citrus fruits have been shown to have antioxidant effects, with those effects being closely related to the flavonoid content of the fruit in question. Conclusions: The present study also reviewed antioxidant activity in terms of specific bioactive compounds in order to find the underlying biological activity of both fruits. The calamondin and kumquat have antioxidant effects, which are in turn very important for the prevention of chronic diseases.

Extraction of nobiletin from Citrus Unshiu peels by supercritical fluid and its CRE-mediated transcriptional activity

BACKGROUND

Polymethoxyflavone (PMF) is one of bioactive compounds in Citrus Unshiu and included mainly in the peels rather than the fruits, seeds and leaves.

HYPOTHESIS/PURPOSE

Supercritical CO₂ extraction is one candidate for selective extraction of polymethoxyflavone and in this study, supercritical CO₂ extraction with/without ethanol entrainer from Citrus Unshiu peels was examined at a temperature of 333K and a pressure of 30MPa.

METHODS

CRE (cyclic AMP response element)-mediated transcriptional assay was examined by using the extracts from supercritical fluid extraction.

RESULTS

The results showed that extracts including nobiletin increased with increasing ethanol concentration in supercritical CO₂ and the elapsed extraction time. Extracts at ethanol concentration of 5 mol% showed high CRE-mediated transcription activity. This can be caused by activity of the extract including nobiletin in addition to the other methoxylated flavonoid species such as tangeretin. Extracts at ethanol concentration of 50% showed the highest CRE-mediated transcription activity, which can be attributed to flavonoid glycoside such as hesperidin. From our investigations, flavonoid glycoside can be one of promoters of CRE-mediated transcription activity.

Thinned stone fruits are a source of polyphenols and antioxidant compounds

BACKGROUND

Thinned fruits are agricultural by-products that contain large quantities of interesting compounds due to their early maturity stage. In this work, the phenolic profile and the antioxidant activity of six thinned stone fruits (apricot, cherry, flat peach, peach, plum and nectarine) have been investigated, focussing on proanthocyanidins.

RESULTS

Thinned nectarine had the highest content of total phenols [67.43 mg gallic acid equivalents (GAE) g^-1 dry weight (DW)] and total flavonoids (56.97 mg CE g^-1 DW) as well as the highest antioxidant activity measured by DPPH scavenging (133.30 mg [Trolox equivalents (TE) g^-1 DW] and FRAP assay (30.42 mg TE g^-1 DW). Proanthocyanidins were very abundant in these by-products, and the main phenolic group quantified in cherry (10.54 mg g^-1 DW), flat peach (33.47 mg g^-1 DW) and nectarine (59.89 mg g^-1 DW), while hydroxycinnamic acids predominate in apricot, peach and plum (6.67, 22.04 and 23.75 mg g^-1 DW, respectively). The low, mean degree of polymerisation of proanthocyanidins suggests that their bioavailability could be very high.

CONCLUSIONS

This study shows that thinned stone fruit extracts might be used as antioxidants in foods or as a source of compounds with health-related benefits that can be used in the pharmaceutical, cosmetic and food industries. © 2016 Society of Chemical Industry.

Phenolic compounds and biological activities of small-size citrus: Kumquat and calamondin

Kumquat and calamondin are two small-size citrus fruits. Owing to their health benefits, they are traditionally used as folk medicine in Asian countries. However, the research on flavonoids and biological activities of kumquat and calamondin have received less attention. This review summarizes the reported quantitative and qualitative data of phenolic compositions in these two fruits. Effects of maturity, harvest time, various solvent extractions and heat treatment of phenolic compositions, and bioactivities were discussed; distributions of the forms of phenolic compounds existing in kumquat and calamondin were also summarized. Furthermore, biological activities, including antioxidant, anti-tyrosinase, antimicrobial, antitumor, and antimetabolic disorder effects, have also been discussed. Effective phenolic components were proposed for a certain bioactivity. It was found that C-glycoside flavonoids are dominant phenolic compounds in kumquat and calamondin, unlike in other citrus fruits. Up to now, biological activities and chemical characteristics of C-glycoside flavonoids in kumquat and calamondin are largely unknown.

Metabolism of Flavonoids in Novel Banana Germplasm during Fruit Development

Banana is a commercially important fruit, but its flavonoid composition and characteristics has not been well studied in detail. In the present study, the metabolism of flavonoids was investigated in banana pulp during the entire developmental period of fruit. 'Xiangfen 1,' a novel flavonoid-rich banana germplasm, was studied with 'Brazil' serving as a control. In both varieties, flavonoids were found to exist mainly in free soluble form and quercetin was the predominant flavonoid. The most abundant free soluble flavonoid was cyanidin-3-O-glucoside chloride, and quercetin was the major conjugated soluble and bound flavonoid. Higher content of soluble flavonoids was associated with stronger antioxidant activity compared with the bound flavonoids. Strong correlation was observed between antioxidant activity and cyanidin-3-O-glucoside chloride content, suggesting that cyanidin-3-O-glucoside chloride is one of the major antioxidants in banana. In addition, compared with 'Brazil,' 'Xiangfen 1' fruit exhibited higher antioxidant activity and had more total flavonoids. These results indicate that soluble flavonoids play a key role in the antioxidant activity of banana, and 'Xiangfen 1' banana can be a rich source of natural antioxidants in human diets.

Drying effect on flavonoid composition and antioxidant activity of immature kumquat

A seven flavonoids in hot water extract of immature kumquat (Citrus japonica var. margarita) were identified and quantified (mg/100g fresh fruit): 3',5'-di-C-β-glucopyranosylphloretin (DGPP, 285.9 ± 2.9 mg/100g), acacetin 8-C-neohesperidoside (margaritene, 136.2 ± 2.6 mg/100g), acacetin 6-C-neohesperidoside (isomargaritene, 119.1 ± 1.8 mg/100g), fortunellin (acacetin 7-O-neohesperidoside, 28.5 ± 0.7 mg/100g), apigenin 8-C-neohesperidoside (16.9 ± 0.1mg/100g), poncirin (isosakuranetin 7-O-neohesperidoside, 5.1 ± 0.1mg/100g), and rhoifolin (apigenin 7-O-neohesperidoside, 2.0 ± 0.1mg/100g). When immature kumquat was dried at 110 and 130°C for 0.5h, the antioxidant activity, total phenolic content and identified flavonoids increased. The UV absorbance of browning products of immature kumquat dried at 130°C for 1.5h increased dramatically, while the identified flavonoids decreased. Therefore, it was concluded that drying below 130°C for 1.0 h, could release phenolic compounds, which resulted in the increasing antioxidant activity. Drying at 130°C for 1.5h, it might be due to the effect of formed browning products.