Highest Α-glucosidase Inhibitory Activity Research Articles

In Vitro Hypoglycemic Activities of Lactobacilli and Bifidobacterium Strains from Healthy Children's Sources and Their Effect on Stimulating GLP-1 Secretion in STC-1 Cells.

A long-term use of chemical drugs cannot cure type II diabetes mellitus (T2DM) and their numerous toxic side effects can be harmful to human health. In recent years, probiotics have emerged as a natural resource to replace chemical drugs in alleviating many human ailments. Healthy children's intestines have a lot of colonized Lactobacilli and Bifidobacterium, and these beneficial bacteria can help promote overall health. The objective of this study was to isolate potential antidiabetic probiotic strains from healthy children and evaluate their application prospects. Firstly, Lactobacillus and Bifidobacterium strains were isolated from healthy children's feces and identified by the pheS or clpC genes with their respective 16S rRNA genes. Then, hydrophobicity, artificial gastrointestinal fluid tolerance, α-Glucosidase and Dipeptidyl peptidase IV (DPP-IV) inhibitory activities of isolated strains were determined, and antioxidant activities and promoting secretion of GLP-1 in STC-1 cells of candidate strains were tested. Results showed that 6 strains of Lactobacillus and Bifidobacterium were obtained from the feces of healthy children aged 3 years, respectively, including Lacticaseibacillus paracasei L-21 and L-25, Levilactobacillus brevis L-16, Lentilactobacillus buchneri L-9, Lactiplantibacillus plantarum L-8 and L-3, Bifidobacterium bifidum 11-1 and B-84, Bifidobacterium longum subsp. longum 6-1, 6-2, B42 and B53. The hydrophobicity and auto-aggregation levels of all these strains were higher than 30% and 50%, respectively, and the decrease in the number of colonies of all strains in the artificial gastrointestinal fluid was less than 2 log CFU/mL. Strains L-3, L-8, L-9, L-21, 6-1, 11-1, B53 and B84 were selected based on their high α-glucosidase inhibitory activity and DPP-IV inhibitory activity, and results of the antioxidant capacity assay showed that the remaining strains all had intense comprehensive antioxidant activity. Additionally, Lacticaseibacillus paracasei L-21 and Bifidobacterium longum subsp. longum B-53 had the most substantial prompting effect on GLP-1 secretion in the STC-1 cell line. These results indicated that Lacticaseibacillus paracasei L-21 and Bifidobacterium longum subsp. longum B-53 could be used as a potential antidiabetic strain; thus, its application as a food supplement and drug ingredient could be recommended after in vivo mitigation of type II diabetes test.

Investigation of Phytochemical, Antioxidant and Antidiabetic Potentials of Scabiosa L. (Caprifoliaceae) Species with Chemometric Methods.

In this research, the total phenolic and flavonoid amounts, phenolic compositions, in vitro antioxidant, antibacterial and antidiabetic properties of the methanol extracts obtained from Scabiosa L. (Caprifoliaceae) species distributed in the flora of Türkiye were investigated using chemometric methods. For this purpose, principal component (PCA) and agglomerative hierarchical clustering analysis were performed as chemometric methods. Chlorogenic acid, quinic acid and cyranoside were determined in the extracts. According to chemometric analysis, S. columbaria subsp. ochroleuca var. ochroleuca and S. triniifolia species were found to be valuable in terms of methanol extract yields, total phenolic and flavonoid contents, antioxidant and antidiabetic activities while S. columbaria subsp. ochroleuca var. webbiana species were found to be valuable in terms of phenolic composition. The methanol extracts of Scabiosa species showed high antioxidant activity, with high phenolic and flavonoid contents. Among the tested 13 bacteria, Scabiosa extracts showed only low activity against Klebsiella pneumoniae, Streptococcus pneumoniae and Pseudomonas aeruginosa. The extracts showed high α-amylase and α-glucosidase inhibitory activity. The results show that Scabiosa methanol extracts may be a source of alternative antioxidants that may be beneficial in slowing or preventing the progression of various oxidative stress-related diseases.

Ultrasound-assisted preparation of protein–polyphenol conjugates and their structural and functional characteristics

Herein, ultrasound-assisted conventional covalent binding methods (alkali treatment, free radical mediation, and an enzymatic method) were used to prepare soybean protein isolate (SPI)-(−)-epigallocatechin gallate (EGCG) conjugates to investigate the enhancement effect of the ultrasound synergistic treatment. In addition, the influence of EGCG grafting on the structure and properties of SPI was evaluated via reactive group analysis, spectral analysis, surface hydrophobicity measurements, emulsification property assessment, and α-glucosidase inhibition analysis. The obtained results revealed that the enzymatic method produced the highest polyphenol grafting content among the conventional techniques. Meanwhile, ultrasound treatment increased the amount of grafted polyphenol species during the alkali treatment and free radical mediation procedure, decreased the grafting efficiency in the enzymatic method, and maximized the grafting efficiency during the alkali treatment. In addition, reactive group and spectral analyses demonstrated that EGCG formed C–N and C–S bonds with SPI and decreased the α-helix content in the protein structure, thereby increasing the molecular flexibility of SPI. It also produced hydrogen bonds and hydrophobic interactions, as demonstrated by the results of molecular docking. Furthermore, the EGCG grafting of SPI conducted under the ultrasound-assisted conditions endowed SPI with unique functional characteristics, including good emulsification and antioxidant properties and high α-glucosidase inhibitory activity, while the ultrasound-assisted alkali treatment resulted in the optimal functional properties. The results of this study provide new insights into the effective preparation of SPI–EGCG complexes with multiple functionalities, thereby expanding the scope of high-value SPI utilization.

Necessity of Different Lignocellulose on Exopolysaccharide Synthesis and Its Hypoglycemic Activity In Vitro of Inonotus obliquus.

Current work proposes elm sawdust, poplar sawdust, pine sawdust, and cotton straw with different lignocellulose compositions and structures as the research objects to investigate the relationship between the hypoglycemic activity of mycelium polysaccharides from Inonotus obliquus and lignocellulose biodegradation. Four kinds of lignocellulosic materials could significantly increase the exopolysaccharide content and α-glucosidase inhibition rate and advance the occurrence time of α-glucosidase inhibition activity. Among all groups, the polysaccharide synthesis promotion effect of the cotton straw group was the best, which exopolysaccharide yield was 92.05% higher than that of the control group after 11-day fermentation. Meanwhile, the highest α-glucosidase inhibitory activity was found in the elm sawdust group on the 11th day (30.99%, which was 137.47% higher than control), and the exopolysaccharide in the elm sawdust group showed its effectiveness on glucose consumption of insulin resistant HepG2 cells at the concentration of 20 µg/mL, significantly higher than that of the metformin group (P < 0.05). The cellulose in the non-crystalline region of elm and pine and the hemicellulose of poplar were mainly used in the fermentation of I. obliquus, while the cellulose in the crystalline zone and amorphous zone of cotton straw was degraded to improve the exopolysaccharide content of I. obliquus. This paper revealed the necessity of different kinds of lignocellulose for the synthesis of active polysaccharide from I. obliquus and provided a new idea for the regulation of polysaccharide synthesis pathway.

Oral administration of Bifidobacterium longum WHH2270 ameliorates type 2 diabetes in rats.

Accumulating evidence suggests that specific probiotic strains exert hypoglycemic effects on type 2 diabetes mellitus (T2DM), and probiotic strains within Bifidobacterium exhibit potential beneficial effects on T2DM. In this study, α-glucosidase inhibitory activities of 14 Bifidobacterium strains were assessed in vitro. The hypoglycemic effects of Bifidobacterium longum WHH2270 with high α-glucosidase inhibitory activity (42.03%) were then investigated in a high-fat diet/streptozotocin-induced T2DM rat model. Oral administration of WHH2270 (4 × 109 CFU/kg/day) for 8weeks significantly reversed the reduced body weight and ameliorated the levels of fasting blood glucose, serum triglyceride, serum total cholesterol, glucose tolerance, and insulin resistance in T2DM rats. Using 16S rRNA high-throughput sequencing of feces, WHH2270 was revealed to reshape the gut microbiome composition by increasing the abundances of Lactobacillus and Bifidobacterium and decreasing the abundances of UCG_005, Clostridium, and Faecalibacterium in T2DM rats. Besides, the fecal levels of short-chain fatty acids (SCFAs) including acetate, propionate, and butyrate were also elevated after WHH2270 administration. Moreover, the gene expressions of SCFA receptors FFAR2 and FFAR3 in the colon and pancreas of T2DM rats were restored by WHH2270 administration, accompanied by increased levels of serum acetate. In summary, these results provide evidence that WHH2270 has the potential to improve T2DM symptoms by alleviating hyperglycemia, which was associated with changes in the gut microbiome composition and SCFA production. PRACTICAL APPLICATION: Bifidobacterium longum WHH2270 with high α-glucosidase inhibitory activity may serve as a promising hypoglycemic agent for the treatment of T2DM.

Nutritional Composition and Pharmacological Activity of Musa balbisiana Colla Seed: An Insight into Phytochemical and Cellular Bioenergetic Profiling.

Musa balbisiana Colla belongs to the family Musaceae which is well-known for its nutritional and pharmacological properties. Here, we have analysed the phytochemical content and evaluated the nutritional, antioxidant, anti-glycation, α-amylase, and α-glucosidase inhibition potential. Moreover, for the first time, we have studied the bioenergetic profiles of the bioactive fractions of M. balbisiana seeds extract against oxidative stress-related mitochondrial and cellular dysfunction using XFe24 extracellular flux analyzer. M. balbisiana seeds have high nutritional values with significant levels of carbohydrates, starch, protein, and minerals (Ca, Na, Mg, Cu, Fe, and Zn). Bioactivity-guided fractionation of the methanolic extract of M. balbisiana seeds revealed that the ethyl acetate fraction (EAF) showed the highest antioxidant, anti-glycation, and phytochemical content as compared to other fractions. Moreover, the EAF showed a lower α-amylase inhibition and a higher α-glucosidase inhibitory activity. Most importantly, our GC-MS analyses of EAF revealed the presence of unique and previously unreported 14 phytochemical compounds. A strong correlation between the biological activities and total phenolic/tannin content was observed. In addition, the bioactive fraction of M. balbisiana seeds (EAF) improved the bioenergetic profiles of free fatty acid-induced oxidative stress with a concomitant increase in ATP production, and respiratory and glycolytic capacity. Altogether, our findings suggest that M. balbisiana seeds can be used as a natural supplement to boost antioxidant levels and combat oxidative stress and non-enzymatic glycation.

Optimization of microwave assisted extraction and biological activities of total flavonoids from grape seed using response surface methodology

Aiming to reduce the environmental contamination and resource wastage generated by discarded grape seed, the management of discarded grape seed should be carried out and their potential bioactivities and pharmacological properties ought to be exploited to the fullest extent possible. A Box–Behnken design of response surface methodology was employed to further optimize microwave-assisted extraction setting for grape seed total flavonoids (GSFE). In addition, the extract (GSFE) of total flavonoids obtained were refined through AB-8 macroporous resin for obtaining more pure flavonoid (GSFP) with determination of their in vitro hypoglycemic activity and antioxidant activity. The results indicated that following optimized extraction conditions were achieved: ethanol concentration 50% liquid-solid ratio 21:1 mL/g, microwave power 540 W, microwave time 126 s. Below mentioned conditions, the extraction yield reached an average experimental value (1.979 mg/g), representing 1.69 times higher than that of water extraction (1.17 mg/g). In contrast to GSFE, the purity of GSFE after purification (GSFP) exhibited a high degree of purity at 13.753 mg/g, representing nearly 2.50 times that of GSFE (3.926 mg/g). GSFP possessed high α-glucosidase and α-amylase inhibitory activities as well as DPPH and ABTS+ free radical scavenging activities with an IC50 value of 0.00641, 0.0257, 0.0669 and 0.0708 mg/mL, inferior to that of GSFE (0.0514, 0.186, 0.129 and 0.223 mg/g). Within present work, the microwave technique for extraction of total flavonoids from grape seeds was investigated with an efficient and cost-effective extraction method. Total flavonoids of grape seeds have certain in vitro blood glucose and antioxidant activity, and the purified total flavonoid biological activity has improved, laying the foundation for further study of its pharmacological activity.

Development of lentil peptides with potent antioxidant, antihypertensive, and antidiabetic activities along with umami taste.

Lentil peptides have shown promising bioactive properties regarding the antioxidant activity and also inhibitory activity of angiotensin-I-converting enzyme (ACE). Sequential hydrolysis of proteins has shown a higher degree of hydrolysis with enhanced antioxidant and ACE-inhibitory activities. The lentil protein concentrate (LPC) was sequentially hydrolyzed using Alcalase and Flavourzyme at 2% w/w. The hydrolysate (LPH) was cross-linked (LPHC) or sonicated (LPHUS) and sequentially cross-linked (LPHUSC). Amino acid profile, molecular weight (MW) distribution, DPPH and ABTS radical scavenging activities (RSA; 7mg/mL), ACE (0.1-2mg/mL), α-glucosidase, and α-amylase inhibitory activities (10-500 μg/mL), and umami taste were determined. The highest DPPH RSA was obtained for LPH (68.75%), followed by LPHUSC (67.60%), and LPHUS (67.49%) while the highest ABTS RSA values were obtained for LPHC (97.28%) and LPHUSC (97.20%). Cross-linking and sonication led to the improvement of the ACE-inhibitory activity so that LPHUSC and LPHC had IC50 values of 0.23 and 0.27 mg/mL, respectively. LPHC and LPHUSC also indicated higher α-glucosidase inhibitory activity (IC50 of1.2 and 1.23 mg/mL) compared to LPH (IC50 of1.74 mg/mL) and LPHUS (IC50 of1.75 mg/mL) whilethe IC50 value of acarbose indicated 0.51 mg/mL. Moreover, LPHC and LPHUSC exhibited higher α-amylase inhibitory activities (IC50 of 1.35 and 1.16 mg/mL) than LPHUS (IC50 of 1.95 mg/mL), and LPH (IC50 of 2.51 mg/mL) while acarbose had an IC50 value of 0.43 mg/mL. Umami taste analysis revealed that LPH and LPHC due to MW of 1.7 and 2.3kDa and also high umami amino acids could be well considered as representative of meaty and umami analog flavors while indicating stronger antioxidant, antihypertension, and antidiabetic attributes.

Optimization and Molecular Mechanism of Novel α-Glucosidase Inhibitory Peptides Derived from Camellia Seed Cake through Enzymatic Hydrolysis.

In recent years, food-derived hypoglycemic peptides have received a lot of attention in the study of active peptides, but their anti-diabetic mechanism of action is not yet clear. In this study, camellia seed cake protein (CSCP) was used to prepare active peptides with α-glucosidase inhibition. The optimization of the preparation of camellia seed cake protein hydrolyzed peptides (CSCPH) was conducted via response surface methodology (RSM) using a protamex with α-glucosidase inhibition as an indicator. The optimal hydrolysis conditions were pH 7.11, 4300 U/g enzyme concentration, 50 °C hydrolysis temperature, and 3.95 h hydrolysis time. Under these conditions, the α-glucosidase inhibition rate of CSCPH was 58.70% (IC50 8.442 ± 0.33 mg/mL). The peptides with high α-glucosidase inhibitory activity were isolated from CSCPH by ultrafiltration and Sephadex G25. Leu-Leu-Val-Leu-Tyr-Tyr-Glu-Tyr (LLVLYYEY) and Leu-Leu-Leu-Leu-Pro-Ser-Tyr-Ser-Glu-Phe (LLLLPSYSEF) were identified and synthesized for the first time by Liquid chromatography electrospray ionisation tandem mass spectrometry (LC-ESI-MS/MS) analysis and virtual screening with IC50 values of 0.33 and 1.11 mM, respectively. Lineweaver-Burk analysis and molecular docking demonstrated that LLVLYYEY was a non-competitive inhibitor of α-glucosidase, whereas LLLLPSYSEF inhibited α-glucosidase, which displayed a mixed inhibition mechanism. The study suggests the possibility of using peptides from Camellia seed cake as hypoglycaemic compounds for the prevention and treatment of diabetes.

Cytotoxicity, anti-diabeticity, and phytocomposition investigation of Vietnamese Euphorbia tithymaloides Linn. (Euphorbiaceae).

In this study, the aerial parts of mature Vietnamese Euphorbia tithymaloides plants were put through cytotoxic, anti-diabetic, and phytocompositional evaluations. Specifically, four extracts (petroleum ether (PE), ethyl acetate (EA), methanol (Me), and aqueous (W)) were prepared by maceration at room temperature. All extracts, together with some isolated compounds, were investigated for cytotoxicity against some human normal and cancer cell lines (fibroblasts, HeLa, NCI-H460, HepG2, MCF-7, and Jurkat) using the standardized modified sulforhodamine B (SRB) assay. Additionally, the anti-diabetic activity of extracts and compounds was evaluated via their α-glucosidase inhibitory capacity. The obtained results indicated that Vietnamese E. tithymaloides extracts exhibited moderate cytotoxic activity, among which the PE extract possessed the highest values, on the NCI-H460 cell line. Second, the aqueous extract was revealed to possess very high α-glucosidase inhibitory activity (IC50 = 113.75 ± 14.02 μg ml-1). From the PE extract, three new jatrophane diterpenoids (named tithymal A, tithymal B, and tithymal C) and two known ones were isolated and structurally elucidated using NMR and MS spectroscopies. Noticeably, tithymal A exhibited significantly high inhibitory activity against α-glucosidase (IC50 = 10.71 ± 0.52 μg ml-1). These observations have significantly highlighted the medicinal potential of Vietnamese E. tithymaloides and expanded its scientific fascination.

Identification, characterization and in vitro activity of hypoglycemic peptides in whey hydrolysates from rubing cheese by-product

The by-product of Chinese rubing cheese is rich in whey protein. Whey hydrolysates exhibit good hypoglycemic activity, but which specific peptide components are responsible for this effect have not yet been investigated. Herein, the α-glucosidase inhibitory activity of the ultrafiltered fraction (<3 kDa) of rubing cheese whey hydrolysates was evaluated with the inhibition rate of 37.89 %. In addition, peptide identification was conducted using LC-MS/MS, and three peptides YPVEPF, VPYPQ, and LPYPY were identified. Among these, YPVEPF had higher α-glucosidase inhibitory activity (IC50 = 3.52 mg/mL) and interacted with α-glucosidase via hydrogen bonding and hydrophobic forces. YPVEPF was characterized as an amphipathic peptide rich in antiparallel (50.50 %) and random coil (35.20 %) structures, as well as showed good tolerance to gastrointestinal digestion and incubation under the temperature range of 20–80 °C. Notably, YPVEPF activity increased in the presence of Al3+ and Fe3+, as well as within the pH range of 2.0–6.0. Furthermore, YPVEPF had negligible hemolytic activity at a concentration of 1.0 mg/mL, no toxicity at concentrations below 0.5 mg/mL, and significantly promoted glucose consumption in HepG2 cells (p < 0.0001). Collectively, these findings indicate the potential of YPVEPF to be used as a novel hypoglycemic peptide in functional foods.

Screening of strains with potential hypoglycemic effect and its application in fermented garlic production

Microbial fermentation could produce many active substances in green and pollution-free ways. In recent years, studies on the hypoglycemic ability of microorganisms had become a trending topic in the prevention and treatment of diabetes. Garlic is a food containing a variety of biologically active substances and physiological functions, but it is not accepted by the general public because of its strong pungent smell. In our study, the microorganisms with potential hypoglycemic effect were screened from strains resistant to garlic juice. As a result, 41 strains of Bacillus, 157 strains of lactic acid bacteria, and 23 strains of yeast with tolerance of garlic juice were screened from the selected 568 strains. After primary screening of α-amylase inhibitor, it was found that 15 Bacillus and 9 lactic acid bacteria had high α-amylase inhibitory activity. Besides, after α-glucosidase inhibitor re-screening, Pediococcus acidilactici Z1 with high α-amylase inhibitory activity and α-glucosidase inhibitory activity was screened out. The results of fermented garlic showed that the inhibition rate of α-amylase and α-glucosidase of garlic from different origins were significantly increased from 59.09 to 63.99% (p < 0.01) and from 52.71 to 71.93% (p < 0.01) after Z1 fermentation, respectively. The improvement rates of α-amylase and α-glucosidase were 107.69 to 287.32%, and 197.74 to 239.86%, respectively. In a word, this study provides a theoretical and experimental basis for the development of new functional garlic products.

Red and brown seaweeds extracts: A source of biologically active compounds

The biological activities of Porphyra sp., Gracilaria gracilis, Alaria esculenta and Saccharina latissima extracts prepared by enzymatic and ball milling-assisted methods and hot water were evaluated. Enzyme-assisted methods allowed the highest extraction yields. Alcalase-assisted extraction (EAA) was the most effective in the recovery of polyphenolic compounds and Porphyra sp. had the highest content. The efficiency of flavonoids extraction was highly dependent on the used method. Globally, Porphyra sp. and EAA extracts exhibited the highest antioxidant and chelating activities. The highest α-amylase inhibitory activity was determined in HW Porphyra sp. extract while EAA A. esculenta extract had the highest α-glucosidase inhibitory activity. The highest ACE inhibitory activity was obtained in EAA from S. latissima. None of the extracts showed antimicrobial activity against the tested bacteria. The results showed that Porphyra sp. and S. latissima are potentially useful as ingredient in functional foods and nutraceuticals.

In vitro α-glucosidase inhibitory activity of Tamarix nilotica shoot extracts and fractions.

α-glucosidase inhibitors represent an important class of type 2 antidiabetic drugs and they act by lowering postprandial hyperglycemia. Today, only three synthetic inhibitors exist on the market, and there is a need for novel, natural and more efficient molecules exhibiting this activity. In this study, we investigated the ability of Tamarix nilotica ethanolic and aqueous shoot extracts, as well as methanolic fractions prepared from aqueous crude extracts to inhibit α-glucosidase. Both, 50% ethanol and aqueous extracts inhibited α-glucosidase in a concentration-dependent manner, with IC50 values of 12.5 μg/mL and 24.8 μg/mL, respectively. Importantly, α-glucosidase inhibitory activity observed in the T. nilotica crude extracts was considerably higher than pure acarbose (IC50 = 151.1 μg/mL), the most highly prescribed α-glucosidase inhibitor on the market. When T. nilotica crude extracts were fractionated using methanol, enhanced α-glucosidase inhibitory activity was observed in general, with the highest observed α-glucosidase inhibitory activity in the 30% methanol fraction (IC50 = 5.21 μg/mL). Kinetic studies further revealed a competitive reversible mechanism of inhibition by the plant extract. The phytochemical profiles of 50% ethanol extracts, aqueous extracts, and the methanolic fractions were investigated and compared using a metabolomics approach. Statistical analysis revealed significant differences in the contents of the crude extracts and fractions and potentially identified the molecules that were most responsible for these observed variations. Higher α-glucosidase inhibitory activity was associated with an enrichment of terpenoids, fatty acids, and flavonoids. Among the identified molecules, active compounds with known α-glucosidase inhibitory activity were detected, including unsaturated fatty acids, triterpenoids, and flavonoid glycosides. These results put forward T. nilotica as a therapeutic plant for type 2 diabetes and a source of α-glucosidase inhibitors.

Phenolics-Linked Antioxidant and Anti-hyperglycemic Properties of Edible Roselle (Hibiscus sabdariffa Linn.) Calyces Targeting Type 2 Diabetes Nutraceutical Benefits in vitro

Phenolics- enriched plant food sources are excellent dietary and therapeutic targets to combat the increasing prevalence of diet and lifestyle-influenced non-communicable chronic diseases (NCDs), such as type 2 diabetes (T2D). Among plant sources, edible flowers rich in health protective phenolic compounds provide novel opportunities as ingredient and nutraceutical sources. Roselle (Hibiscus sabdariffa Linn.) is a popular edible flower and consumed as part of traditional cuisines and processed foods in several countries of Asia and Africa. Red calyces of Roselle are rich in phenolic compounds, which potentially have high antioxidant and anti-hyperglycemic properties. Therefore, there is merit in screening of dried Roselle calyces as sources for functional food ingredients or nutraceuticals to counter chronic oxidative stress and chronic hyperglycemia using in vitro assays. This has led to this study to investigate and compare phenolic compounds associated antioxidant and anti-hyperglycemic functions of different organic solvent-extracted fractions of dried Roselle calyces using rapid in vitro assays-based screening strategy. Total soluble phenolic content, profile of phenolic compounds, free radical scavenging assay-based total antioxidant activity, and anti-hyperglycemic function linked α-amylase and α-glucosidase inhibitory activities of four different organic solvents (chloroform, hexane, ethyl acetate, and initial crude extraction in 100% methanol) extracted fractions of calyces of Roselle were determined using in vitro assays. Studies indicated high phenolic-linked antioxidant and anti-hyperglycemic relevant properties in red Roselle calyces, specifically in ethyl acetate and methanol solvent-based extracted fractions. Major phenolic compounds in extracted fractions of Roselle calyces were chlorogenic acid, caffeic acid, gallic acid, catechin, rutin, benzoic acid, and cinnamic acid. Additionally, moderate α-amylase (30–92%) and very high α-glucosidase (81–98%) inhibitory activities were confirmed in undiluted samples of organic solvent-extracted fractions of Roselle calyces in the in vitro assays. Taken together these in vitro screening results indicated that calyces of Roselle are excellent sources of health protective phenolic compounds with high antioxidant and anti-hyperglycemic functions and organic solvent (ethyl acetate and methanol) extracted fractions of this edible flower can be strategically utilized to design functional food ingredients and nutraceuticals.

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.

Influence of Elicitation and Drying Methods on Anti-Metabolic Syndrome, and Antimicrobial Properties of Extracts and Hydrolysates Obtained from Elicited Lovage (Levisticum officinale Koch)

This research aims to investigate the influence of elicitation and drying methods (natural, convection, microwave, and freeze-drying), with jasmonic acid (JA) and yeast extract (YE) on the biological activity of extracts and hydrolysates from lovage (Levisticum officinale Koch) leaves. The results indicate that the highest TPC was determined for hydrolysates obtained from JA-elicited microwave-dried lovage (24.96 mg/gDW). The highest ACE and lipase inhibitory activity was noted for PBS extract obtained from JA-elicited lovage after microwave drying (EC50 = 0.16 and 0.12 mg/mL, respectively). Ethanolic extract from JA-elicited lovage after freeze-drying was characterized by the highest α-amylase inhibitory activity (EC50 = 3.92 mg/mL) and the highest α-glucosidase inhibitory activity (EC50 = 1.43 mg/mL) was noted for hydrolysates from control plants subjected to freeze-drying. The highest antimicrobial activity towards C. albicans yeasts was observed for microwave ethanolic extracts with minimal inhibition (MIC) and lethal (MLC) concentrations of 0.625 and 1.25 mg/mL, respectively.

The effect of storage time on tea Polyphenols, catechin compounds, total flavones and the biological activity of Ya’an Tibetan tea ( Camellia sinensis )

The content of tea polyphenols (TPP), tea total flavones (TFS) and tea catechin compounds in Ya’an Tibetan tea after different storage times was investigated, and the α-glucosidase inhibition activity and antioxidative activity of tea were measured. Moreover, the correlation between the levels of tea catechins in Ya’an Tibetan tea with different storage years and their bioactivities were evaluated. During the period of storage, the content of Tibetan tea polyphenols decreased, and the content of Tibetan tea flavonoids increased significantly. Five catechins were identified in Ya’an Tibetan tea using UPLC-QqQ-MS/MS, and the Ya’an Tibetan tea had diverse antioxidant activities and α-glucosidase inhibitory activities over different storage years, due to the various tea catechin components. (-)-epigallocatechin gallate (EGCG), (-)-epicatechin gallate (ECG), and (-)-epicatechin (EC) were found to be responsible for its strong antioxidant activity and α-glucosidase inhibitory activity, indicating Ya’an Tibetan tea has potential as a functional food. Practical applications Ya’an Tibetan tea, also called as Kangzhuan brick tea, is a typical Chinese dark tea with a dark brown color. The change of the main active substances and its bioactivity in Ya’an Tibetan tea during a long-term storage was obtained in this study. These findings have provided important reference basis for people to have a better understanding of the chemical constituents and bioactivity of Ya’an Tibetan tea which store for a long time. Moreover, our study showed Ya’an Tibetan tea has high antioxidant activity and α-glucosidase inhibitory activity. These findings will improve product quality and upgrade Ya’an Tibetan tea industry, and promotes Tibetan tea economic development.

Effects of different extraction methods on the structure, antioxidant activity, α‐amylase, and α‐glucosidase inhibitory activity of polysaccharides from Potentilla discolor Bunge

Three different methods, namely hot water extraction (HWE), ultrasound-assisted extraction (UAE), and microwave-assisted extraction (MAE), were used to extract Potentilla discolor Bunge polysaccharides (PDBP). The effects of different extraction methods on the yield, chemical structure, antioxidant, α-amylase, and α-glucosidase activities of PDBP were investigated in this study. The results showed that MAE led to the highest PDBP yield (4.56%), the highest percentage of high molecular weight fraction, the highest galacturonic acid content, the highest antioxidant scavenging activity, and the highest α-glucosidase inhibitory activity. Besides, PDBP extracted by MAE have a unique surface morphology and better thermal stability. These findings suggest that MAE might be a potential technique that can be used in industry to extract PDBP with high bioactivities. Novelty impact statement Three different extraction methods were used to extract Potentilla discolor Bunge polysaccharides (PDBP). Different extraction methods affected the structure and activity of PDBP. PDBP by microwave-assisted extraction (MAE) has higher antioxidant ability and α-glucosidase inhibitory activity than other extraction methods.

Optimization of methodology for the extraction of polyphenolic compounds with antioxidant potential and α-glucosidase inhibitory activity from Jamun (Syzygium cumini L.) seeds

Jamun (Syzygium cumini L.) seed is one of the rich sources of polyphenolic compounds​ ​with antioxidant potential and α-glucosidase inhibitory activity. A study was conducted to​ ​optimize the methodology for the extraction of polyphenolic compounds (total phenolic​ ​and flavonoid contents) with antioxidant potential and α-glucosidase inhibitory activity​ ​from Jamun seed powder. The study showed that the nature of solvent and extraction​ ​conditions had a significant effect on total phenolic content (TPC), total flavonoid content​ ​(TFC), antioxidant potential, and α-glucosidase inhibitory activity. The TPC varied between​ ​6.0 (mg/g Jamun seed powder) for the acetone extract to 119.2 (mg/g) for 80% aqueous​ ​acetone extract and TFC varied between 1.06 mg/g for the acetone to 10.81 mg/g for the​ ​80% aqueous methanol. From the study, it was apparent that an aqueous form of acetone​ ​(acetone: water 80:20, v/v) is a better solvent system for extraction of polyphenolic​ ​compounds with high antioxidant potential and α-glucosidase inhibitory activity.​ ​Ultrasonication for 60 min increased the efficiency of phenolic extraction.