Α-glucosidase Inhibitory Activity Research Articles

Undescribed Cyclohexene and Benzofuran Alkenyl Derivatives from Choerospondias axillaris, a Potential Hypoglycemic Fruit

The fruit of Choerospondias axillaris (Anacardiaceae), known as south wild jujube in China, has been consumed widely in several regions of the world to produce fruit pastille and leathers, juice, jam, and candy. A comprehensive chemical study on the fresh fruits led to the isolation and identification of 18 compounds, including 7 new (1–7) and 11 known (8–18) comprised of 5 alkenyl (cyclohexenols and cyclohexenones) derivatives (1–5), 3 benzofuran derivatives (6–8), 6 flavonoids (9–14) and 4 lignans (15–18). Their structures were elucidated by extensive spectroscopic analysis. The known lignans 15–18 were isolated from the genus Choerospondias for the first time. Most of the isolates exhibited significant inhibitory activity on α-glucosidase with IC50 values from 2.26 ± 0.06 to 43.9 ± 0.96 μM. Molecular docking experiments strongly supported the potent α-glucosidase inhibitory activity. The results indicated that C. axillaris fruits could be an excellent source of functional foods that acquire potential hypoglycemic bioactive components.

Antidiabetic, antioxidant, and phytochemical profile of Pennisetum glaucum cultivated in central-southern Morocco and imported from India

Alternative methods of producing food sustainably are being considered due to rapid expanding population, increasing food needs, declining agricultural soils fertility, and ongoing drought. To achieve that, we examined the pharmacological, functional, and nutritional characteristics of two cultivars of pearl millet (Pennisetum glaucum), which are distinguished by their ability to tolerate a variety of climates compared to other cereal grains. In this study, we evaluated the antioxidant and antidiabetic effects of two seeds cultivars: one cultivated in Morocco and the other grown in India. In addition to having a higher energy value (403.91 Kcal), higher protein (9.13 %) and lipid content (7.11 %), and a lower capacity for self-oxidation than the Indian variety due to its fatty acid composition, the content of phenolic compounds of Moroccan millet is well concentrated in its seeds, making it more powerful as an antioxidant and hypoglycemic plant. The ethanolic extract of Moroccan pearl millet showed the greatest total phenolic content (36.278 mg GAE/g extract), DPPH and ABTS radical scavenging activity (IC50 = 152.286 and 252.480 μg/mL respectively), α-amylase and α-glucosidase inhibitory activity (IC50 = 84.439 μg/mL and 224.103 μg/mL respectively). The evidence gathered in this study indicates that P.glaucum possesses characteristics that qualify it as a food, medicinal, and productive plant.

Free radical scavenging, α-amylase, α-glucosidase, and lipase inhibitory activities of metabolites from strawberry kombucha: Molecular docking and in vitro studies

Obesity, a global issue, is linked to cardiometabolic syndrome. Dietary modification is one of the recommended modes for managing cardiometabolic syndrome. Strawberries, a functional food, and kombucha, a fermented tea beverage, have gained attention for their health benefits. This study investigated the bioactive components of strawberry kombucha drink (SKD) and their effects on antioxidant activities and improving metabolic disorder markers. An in vitro experiment was performed to determine the effect of SKD on enzymatic parameters: lipase, α-glucosidase, and α-amylase activities. In addition, antioxidant activity using the DPPH method and quantification of the radical scavenging activity were also measured. Furthermore, untargeted metabolomic profiling of SKD and molecular docking simulation were conducted. The findings suggest that SKD, rich in secondary metabolites, can inhibit lipase, α-glucosidase, and α-amylase activities. It demonstrated in vitro anti-obesity, anti-diabetic, and antioxidant properties, potentially reducing metabolic and inflammatory issues. Thus, SKD could be a therapeutic beverage to alter metabolic issues associated with obesity. Nevertheless, further preclinical study is warranted to determine SKD’s potential in vivo.

Dauresorcinols A and B, two pairs of merosesquiterpenoid enantiomers with new carbon skeletons from Rhododendron dauricum

Five pairs of new merosesquiterpenoid enantiomers, named dauresorcinols A−E (1−5), were isolated from the leaves of Rhododendron dauricum. Their structures were elucidated by comprehensive spectroscopic data analysis, quantum chemical calculations, Rh2(OCOCF3)4-induced ECD, and single-crystal X-ray diffraction analysis. Dauresorcinols A (1) and B (2) possess two new merosesquiterpene skeletons bearing an unprecedented 2,6,7,10,14-pentamethyl-11-oxatetracyclo[8.8.0.02,7.012,17]octadecane and a caged 15-isohexyl-1,5,15-trimethyl-2,10-dioxatetracyclo[7.4.1.111,14.03,8]pentadecane motif, respectively. Plausible biosynthetic pathways of 1−5 are proposed involving key oxa-electrocyclization and Wagner−Meerwein rearrangement reactions. (+)/(−)-1 and 3−5 showed potent α-glucosidase inhibitory activity, 3 to 22 times stronger than acarbose, an antidiabetic drug targeting α-glucosidase. Docking results provide a basis to design and develop merosesquiterpenoids as potent α-glycosidase inhibitors.

Effect of Phenol and Alkylamide Interaction on α-Glucosidase Inhibition and Cellular Antioxidant Activity during In Vitro Digestion: Using Szechuan Pepper (Zanthoxylum genus) as a Model.

Although recent evidence indicated significant phenol and alkylamide interaction in aqueous solutions, the gastrointestinal digestion influence of the combination remains unclear. This study aims to investigate phenol and alkylamide interaction during in vitro digestion, focusing on bioaccessibility and bioactivity, including α-glucosidase inhibition and cellular antioxidant activity. Additionally, the structural mechanism of phenol and alkylamide interaction during in vitro digestion was explored. The results indicated that the presence of phenols and alkylamides significantly increased or decreased their respective bioaccessibility, depending on the Zanthoxylum varieties. Furthermore, although antagonistic phenol/alkylamide interaction was evident during α-glucosidase inhibition, cellular oxidative stress alleviation, and antioxidant gene transcription upregulation, this effect weakened gradually as digestion progressed. Glycoside bond cleavage and the methylation of phenols as well as alkylamide isomerization and addition were observed during digestion, modifying the hydrogen bonding sites and interaction behavior. This study provided insights into the phenol/alkylamide interaction in the gastrointestinal tract.

Investigation of novel benzimidazole-based indole/thiazole hybrids derivatives as effective anti-diabetics and anti-alzheimer's agents: Structure-activity relationship insight, in vitro and in silico approaches

Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM) are common in developed countries and their incidence is increasing. The research is mostly concentrated on the exploration of novel therapies to remedy or avert these ailments. AD and T2DM have several molecular pathways in common that contributes to their degenerative development.A novel series of ten hybrid analogues (1-10) based on benzimidazole bearing indole analogues were synthesized and these scaffolds were characterized by spectroscopic techniques like HR-EIMS, 13CNMR and 1HNMR. Furthermore,the synthesized moieties were screened for α-amylase and α-glucosidase inhibitory activities. All these synthesized analogues showed good to moderate α-amylase and α-glucosidase inhibition potency ranging (4.90 ± 0.10 to 15.30 ± 0.60 µM) and (5.30 ± 0.10 to 16.10 ± 0.60 µM) while acarbose was used as a reference standard (IC50 = 10 .30 ±0.20µM), (IC50 = 9.80 ± 0.20 µM). Another series of ten hybrid analogues (11-20) based on benzimidazole bearing thiazole moieties were synthesized and were evaluated for AChE and BuChE inhibition activities. All these newly afforded analogues showed good to moderate AChE and BuChE inhibitory potential ranging of (IC50 = 0.20 ± 0.01 µM), (IC50 = 0.15 ± 0.01 µM) to (IC50 = 3.90 ± 0.20 µM), (IC50 = 3.80 ± 0.10 µM) while Donepezil was taken as a reference standard with (IC50 = 0.016 ± 0.01 µM), (IC50 = 0.30 ± 0.010 µM).The scaffolds were also characterized using spectroscopic techniques such as HR-EIMS, 13CNMR and 1HNMR for a better understanding of their structure. SAR was done for all synthesized analogues for substituents.In addition, docking research was conducted to determine the binding mode of interaction between the active site of analogues and targeted enzymes. This work aims to estimate the potential of the synthesized scaffolds as competitors to existing drugs. Incorporating molecular docking analysis with in vitro activities improves the accuracy of predictions and validates the possibility of these compounds as options for treating type-2 diabetes and Alzheimer's disease.

Rapid screening of potential α-glucosidase inhibitors from the waste leaves of Rheum tanguticum by activity-oriented extraction and enrichment optimization, UPLC-QTOF-MS/MS, molecular docking and in vitro validation

In the present study, an efficient strategy has been established for rapid screening of potential α-glucosidase inhibitors from the waste leaves of Rheum tanguticum by activity-oriented extraction and enrichment optimization, UPLC-QTOF-MS/MS, molecular docking, and in vitro validation. With α-glucosidase inhibitory activity as the evaluation index, the extraction process was optimized by response surface methodology and the enrichment process by macroporous resins was optimized by adsorption and desorption experiments. The active flavonoids yield was 8.85 mg/g under the optimized extraction conditions. After AB-8 macroporous resins enrichment, the active flavonoids purity increased from 2.89 % to 47.6 %, a 17-fold increase, while the IC50 of α-glucosidase reduced from 13.97 mg/mL to 412 μg/mL, a 33.9-fold reduction. Thirty-six flavonoids in the active flavonoids fraction were identified by UPLC-QTOF-MS/MS. Molecular docking screening, in vitro activity assay and multispectral approaches verification confirmed the potential of six flavonoids as novel α-glucosidase inhibitors.

Compositional, structural, and functional characterization of fucoidan extracted from Sargassum polycystum collected from Saint Martin's Island, Bangladesh

Fucoidan is a sulphated polysaccharide with diversified biological activities commonly found in brown seaweeds. In our present study, fucoidan was extracted from Sargassum polycystum collected from Saint Martin's Island in three different extraction methods. The composition of the fucoidans was determined by measuring the total carbohydrate, sulfate, uronic acid, fucose, and protein contents. Fourier-transform infrared spectroscopy (FT-IR) and Proton nuclear magnetic resonance (1H NMR) were studied to determine the structural groups of extracted fucoidans. Functional activities were analyzed by antioxidant activity and anti-diabetic activity assay. Fucoidan yield was obtained highest in the acid extraction method (0.061 ± 0.007 g/g), followed by the water extraction method (0.058 ± 0.005 g/g) and salt extraction method (0.041 ± 0.005 g/g). Water extracted fucoidan showed the highest carbohydrate content (62.97 %), uronic acid content (6.46 %), and protein content (2.62 %). Sulphate content (28.56 %) was highest in salt extracted fucoidan, whereas fucose content (24.0 %) was highest in water extracted fucoidan. FT-IR and 1H NMR analysis confirm several characteristic picks for the extracted fucoidans. Extracted fucoidans presented comparable antioxidant activity, but salt-extracted fucoidan presented the highest DPPH radical scavenging assay (86.85 ± 0.74 %, IC50 = 0.03 mg/mL), ABTS radical scavenging assay (65.13 ± 0.92 %, IC50 = 1.94 mg/mL), Phosphomolybdenum assay (4.356 ± 0.11) and Nitric Oxide (NO) radical scavenging assay (57.08 ± 0.52 %, IC50 = 3.73 mg/mL) in dose-dependency manner. Further anti-diabetic activity assay resulted in the highest α-amylase inhibition activity (62.82 ± 1.36 %, IC50 = 2.30 mg/mL) and α-glucosidase inhibition activity (55.73 ± 0.84 %, IC50 = 3.71 mg/mL) by salt-extracted fucoidan. These functional potentials of seaweed may add significant value to the development of functional food and pharmaceutical materials.

Phenolic constituents with potent α-glucosidase inhibitory and cytotoxic activities from Rumex nepalensis var. remotiflorus

Quantitative analysis of Rumex nepalensis var. remotiflorus revealed that its roots contain rich anthraquinones, which has emodin, chrysophanol, and physcion contents of up to 0.30, 0.67, and 0.98 mg/g, respectively. Further phytochemical study led to the isolation and purification of seven undescribed phenolic constituents, including one flavan derivative with a 13-membered ring, polygorumin A (1), two dianthrone glucosides, polygonumnolides F and G (2, 3), two diphenylmethanones, rumepalens A and B (4, 5), and a pair of epimeric oxanthrone C-glucosides, rumejaposides K and L (6a, 6b) from the roots of R. nepalensis var. remotiflorus. Furthermore, 1 undescribed natural product, 1-β-D-glucoside-6'-[(2E)-3-(4-hydroxy-3-methoxyphenyl)-2-propenoate]-3-hydroxy-5-methylphenyl (19), and 21 known phenolic compounds were obtained from the aforementioned plant for the first time. Their structures were elucidated through extensive spectroscopic data analysis. Notably, compounds 1, 4-5, and 7-9 exhibited inhibitory activity on α-glucosidase with IC50 values ranging from 1.61 ± 0.17 to 32.41 ± 0.87 μM. In addition, the isolated dianthrone, chrysophanol bianthrone (14), showed obvious cytotoxicity against four human cancer cell lines (HL-60, SMMC-7721, A-549, and MDA-MB-231) with IC50 values ranging from 3.81 ± 0.17 to 35.15 ± 2.24 μM. In silico target prediction and molecular docking studies demonstrated that the mechanism of the anticancer activity of 14 may be related to the interaction with protein kinase CK2.

Optimization of Composite Enzymatic Extraction, Structural Characterization and Biological Activity of Soluble Dietary Fiber from Akebia trifoliata Peel.

In order to reduce the waste of Akebia trifoliata peel and maximize its utilization, in this study, on the basis of a single-factor experiment and the response surface method, the optimum technological conditions for the extraction of soluble dietary fiber from Akebia trifoliata peel with the compound enzyme method were obtained. The chemical composition, physical and chemical properties, structural characterization and biological activity of the purified soluble dietary fiber (AP-SDF) from the Akebia trifoliata peel were analyzed. We discovered that that the optimum yield was 20.87% under the conditions of cellulase addition 600 U/g, enzymolysis time 100 min, solid-liquid ratio 1:24 g/mL and enzymolysis temperature 51 °C. At the same time, AP-SDF was a porous network structure cellulose type I acidic polysaccharose mainly composed of arabinoxylan (36.03%), galacturonic acid (27.40%) and glucose (19.00%), which possessed the structural characteristic peaks of the infrared spectra of polysaccharides and the average molecular weight (Mw) was 95.52 kDa with good uniformity. In addition, the AP-SDF exhibited high oil-holding capacity (15.11 g/g), good water-holding capacity and swelling capacity, a certain antioxidant capacity in vitro, hypoglycemic activity in vitro for α-glucosidase inhibition and hypolipidemic activity in vitro for the binding ability of bile acids and cholesterol. These results will provide a theoretical basis for the development of functional products with antioxidant, hypoglycemic and hypolipidemic effects, which have certain application value in related industries.

Nutritional composition, bioactive compounds, and pharmacological activities of tossa jute sprout (Corchorus olitorius L.): A potential functional food

This study investigated the food properties, phytochemical profiles, and pharmacological activities of tossa jute sprout, underscoring the exploration of its potential as a functional food. Tossa jute sprout is rich in protein, carbohydrate, fiber, total soluble solids, color content, total energy, vitamins, and minerals, with a lower fat and sugar content. Bioactive compound profiling found that it contains a significant quantity of total phenolics and flavonoids. The HPLC-DAD polyphenol profile detected ten compounds, with 3,4 dihydroxybenzoic acid being the most abundant compound, followed by (-) epicatechin, rosmarinic acid, kaempferol, catechin hydrate, caffeic acid, myricetin, catechol, trans-ferulic acid, and rutin hydrate. It has strong radical scavenging, reducing power, metal chelating power, and total antioxidant power, suggesting this sprout's ability to repair cellular oxidative damage or restore impaired cellular oxidative homeostasis. It also possesses strong α-glucosidase and pancreatic lipase inhibition activities, but mild α-amylase, acetylcholinesterase (AChE), and butyrylcholinesterase (BChE) inhibition activities support the sprout’s ability to lower blood sugar, suppress postprandial hyperglycemia, downregulate fat metabolism, and maintain or restore acetylcholine. Overall findings established tossa jute sprout’s high potential as a functional food in eliminating malnutrition, maintaining quality health, and eradicating or moderating ailments, including diabetes, obesity, and Alzheimer’s.

Anti-Obesity and Anti-Diabetic Effects of Ostericum koreanum (Ganghwal) Extract.

"Ganghwal" is a widely used herbal medicine in Republic of Korea, but it has not been reported as a treatment strategy for obesity and diabetes within adipocytes. In this study, we determined that Ostericum koreanum extract (OKE) exerts an anti-obesity effect by inhibiting adipogenesis and an anti-diabetic effect by increasing the expression of genes related to glucose uptake in adipocytes and inhibiting α-glucosidase activity. 3T3-L1 preadipocytes were differentiated for 8 days in methylisobutylxanthine, dexamethasone, and insulin medium, and the effect of OKE was confirmed by the addition of 50 and 100 µg/mL of OKE during the differentiation process. This resulted in a reduction in lipid accumulation and the expression of PPARγ (Peroxisome proliferator-activated receptor γ) and C/EBPα (CCAAT enhancer binding protein α). Significant activation of AMPK (AMP-activated protein kinase), increased expression of GLUT4 (Glucose Transporter Type 4), and inhibition of α-glucosidase activity were also observed. These findings provide the basis for the anti-obesity and anti-diabetic effects of OKE. In addition, OKE has a significant antioxidant effect. This study presents OKE as a potential natural product-derived material for the treatment of patients with metabolic diseases such as obesity- and obesity-induced diabetes.

Phytochemical profiling, antidiabetic, antiobesity, and antibacterial activities of Cometes abyssinica

This study aims to complete my chemical and biological studies on Cometes abyssinica (CA). The chemical profile was reported by LC-ESI-TOF-MS and GC-MS analyses. Antidiabetic (α-Glucosidase and a-amylase inhibitory activity assay), antiobesity (Lipase inhibitory activity assay), and antibacterial activity (agar well diffusion assay) were determined. The GC-MS analysis led to the identification of 27 hydrocarbons representing 93.4% of the total hydrocarbon content in hexane extract. 11-Octadecenoic acid, methyl ester (28.07%), citronellol (9.31%), hexadecanoic acid, methyl ester (7.64%), phytol (5.93%), and 10-epi-γ-eudesmol (4.91%) were the major components. The LC-ESI-TOF-MS analyses of aqueous-methanolic extract led to the identification of 99 secondary metabolites including phenolics, flavonoids, alkaloids, and vitamins. The percentages of inhibition of the n-hexane, chloroform, ethyl acetate, and methanol extracts of CA were evaluated against α-glucosidase, α-amylase, and pancreatic lipase enzymes at different concentrations. Hexane extract showed the most powerful α-glucosidase and α-amylase inhibitory activity with IC50 value of 0.22 and 0.27 mg/ml comparing with acarbose (IC50 0.43 and 0.38), respectively. Among all CA extracts, only ethyl acetate extract revealed potent antiobesity as a lipase inhibitory activity with IC50 value of 0.079 mg/ml comparing with orlistat (IC50 0.11 mg/ml). CA extracts showed mild-weak antibacterial effect against Pseudomonas aeruginosa and Bacillus cereus. KEY WORDS: Cometes abyssinica, Chemical constituents, α-Amylase inhibitors, α-Glucosidase inhibitors, Lipase inhibitors Bull. Chem. Soc. Ethiop. 2024, 38(4), 1051-1067.                                                           DOI: https://dx.doi.org/10.4314/bcse.v38i4.19

Peptidomics-based identification of antihypertensive and antidiabetic peptides from sheep milk fermented using Limosilactobacillus fermentum KGL4 MTCC 25515 with anti-inflammatory activity: in silico, in vitro, and molecular docking studies.

This study investigated the synthesis of bioactive peptides from sheep milk through fermentation with Limosilactobacillus fermentum KGL4 MTCC 25515 strain and assessed lipase inhibition, ACE inhibition, α-glucosidase inhibition, and α-amylase inhibition activities during the fermentation process. The study observed the highest activities, reaching 74.82%, 70.02%, 72.19%, and 67.08% (lipase inhibition, ACE inhibition, α-glucosidase inhibition, and α-amylase inhibition) after 48h at 37°C, respectively. Growth optimization experiments revealed that a 2.5% inoculation rate after 48h of fermentation time resulted in the highest proteolytic activity at 9.88mg/mL. Additionally, fractions with less than 3kDa of molecular weight exhibited superior ACE-inhibition and anti-diabetic activities compared to other fractions. Fermentation of sheep milk with KGL4 led to a significant reduction in the excessive production of NO, TNF-α, IL-6, and IL-1β produced in RAW 267.4 cells upon treatment with LPS. Peptides were purified utilizing SDS-PAGE and electrophoresis on 2D gels, identifying a maximum number of proteins bands ranging 10-70kDa. Peptide sequences were cross-referenced with AHTPDB and BIOPEP databases, confirming potential antihypertensive and antidiabetic properties. Notably, the peptide (GPFPILV) exhibited the highest HPEPDOCK score against both α-amylase and ACE.

Chemical composition and biological activities of essential oils and extract of Eucalyptus citriodora Hook

In this study, the leaves of Eucalyptus citriodora Hook (Lemon-Scented Eucalyptus) were harvested and collected from Üzümlü neighborhood of Fethiye district of Muğla in 2021. Chemical content analysis of steam distillation and hydrodistillation of essential oils were determined by GC-MS, while phenolic content of methanol extract was determined by HPLC-DAD. Antioxidant activities of essential oils and methanol extracts were determined by DPPH radical removal, ABTS cation removal, β-carotene linoleic acid, and CUPRAC activity methods; Anticholinesterase activity against AChE and BChE enzymes was determined by Ellman method; and tyrosinase inhibition associated with melanin hyperpigmentation, α-amylase inhibition, and α-glucosidase inhibition activities associated with diabetes were determined as an in vitro. The bioactivities and chemical contents of E. citriodora species, a great value of, Türkiye, were determined, bringing new natural products to organic chemistry. As a result of the study, new bioactive extracts would be obtained and thus, they can effectively reveal the potential of new business opportunities. Since methanol extract is effective against incurable diseases such as Alzheimer's and diabetes, it will also be possible to develop therapeutics of such diseases by investigating the advanced chemistry and in vivo activities of the extracts with new projects.

Tannin-Tolerant Saccharomyces cerevisiae Isolated from Traditional Fermented Tea Leaf (Miang) and Application in Fruit Wine Fermentation Using Longan Juice Mixed with Seed Extract as Substrate.

This study focused on isolating tannin-tolerant yeasts from Miang, a fermented tea leaf product collected from northern Laos PDR, and investigating related food applications. From 43 Miang samples, six yeast isolates capable of ethanol production were obtained, with five isolates showing growth on YPD agar containing 4% (w/v) tannic acid. Molecular identification revealed three isolates as Saccharomyces cerevisiae (B5-1, B5-2, and C6-3), along with Candida tropicalis and Kazachstania humilis. Due to safety considerations, only Saccharomyces spp. were selected for further tannic acid tolerance study to advance food applications. Tannic acid at 1% (w/v) significantly influenced ethanol fermentation in all S. cerevisiae isolates. Notably, B5-2 and C6-3 showed high ethanol fermentation efficiency (2.5% w/v), while others were strongly inhibited. The application of tannin-tolerant yeasts in longan fruit wine (LFW) fermentation with longan seed extract (LSE) supplementation as a source of tannin revealed that C6-3 had the best efficacy for LFW fermentation. C6-3 showed promising efficacy, particularly with LSE supplementation, enhancing phenolic compounds, antioxidant activity, and inhibiting α-glucosidase activity, indicating potential antidiabetic properties. These findings underscore the potential of tannin-tolerant S. cerevisiae C6-3 for fermenting beverages from tannin-rich substrates like LSE, with implications for functional foods and nutraceuticals promoting health benefits.

Flavonoids glycosides from Camellia phanii

By combining chromatography methods, three new flavonoid glycosides, kaempferol 3-O-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranosyl-(1→2)-α-L-rhamnopyranoside (1), kaempferol 3-O-(4-acetyl)-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranosyl-(1→2)-α-L-rhamnopyranoside (2), and (2 R,3 S) 5,7,4′-tetrahydroxyflavanonol 3-O-(4-acetyl)-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranosyl-(1→2)-α-L-rhamnopyranoside (3) as well as three known compounds, chrysandroside A (4), p-hydroxybenzaldehyde (5), and p-hydroxybenzoic acid (6) were isolated from the leaves of Camellia phanii Hakoda & Ninh. Their structure was elucidated by 1D and 2D-NMR spectra and compared to previously published in literature. In addition, all compounds were evaluated for their ability to inhibit α-glucosidase activity. As the results, flavonoid glycosides 1-3 inhibited α-glucosidase activity with IC50 values of 276.8 ± 19.4, 258.9 ± 24.3, and 341.4 ± 25.6 µM; phenolics (5 and 6) inhibited α-glucosidase activity with IC50 values of 295.5 ± 15.1 and 217.4 ± 23.6 µM, respectively.

Oleanane-Type Triterpene Glycosides from Camellia phanii and Their α-Glucosidase Inhibitory Activity.

Three new oleanane-type triterpene saponins, named camphanosides A-C (1-3), along with five known compounds, chikusetsusaponin IVa (4), spinasaponin A 28-O-glucoside (5), (-)-epicatechin (6), (--)-epicatechin 3-O-gallate (7), and (-)-epigallocatechin 3-O-gallate (8) were isolated from the leaves Camellia phanii Hakoda & Ninh. Their structures were established by 1D and 2D-NMR and mass spectral analysis and chemical methods. Moreover, compounds 1-5 were also evaluated for α-glucosidase inhibitory activity. Compounds 1-3 exhibited moderate α-glucosidase inhibitory activity with IC50 values of 230.7±18.0, 251.4±22.7, and 421.4±25.6 μM, respectively.

Yellow pigment fraction from Monascus-fermented durian seed: thermal stability and bioactivities

Angkak is a functional product made by fermenting rice with Monascus purpureus. Studies have shown that agro-industrial by-products such as durian seeds are able to support Monascus growth, thus the potential of producing Monascus-fermented products with similar functional activities as angkak. Utilization of durian seeds to produce Monascus-fermented durian seed (MFDS) would improve durian production sustainability. Monascus yellow pigment (MYP) fraction was separated from MFDS and evaluated for its thermal stability by time (30 and 60 mins) and temperature treatments (40℃, 60℃, 80℃ and 100℃), antioxidant activity with 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity assay, and anti-diabetes activities by measuring α-glucosidase inhibition activity. MYP showed increasing stability when treated with increasing incubation temperature, ranging from 90.87±0.35% to 96.33±0.00% (p < 0.05). MYP reached the highest stability when incubated at 100℃ for 60 mins. The antioxidant activity of MYP was detected to be 51.84±0.17%. MYP showed anti-diabetes activity ranging from -0.72±0.27% (10 μg/mL) to 29.40±4.27% (100 μg/mL). There was an increase in α-glucosidase inhibition activity along with increasing MYP concentration. Monascus yellow pigments extracted from Monascus-fermented durian seed have the potential to be used as a functional ingredient in the food industry.

Characterization of kombucha prepared from black tea and coffee leaves: A comparative analysis of physiochemical properties, bioactive components, and bioactivities.

The utilization of coffee leaves in kombucha production has intrigued researchers; however, the lack of understanding regarding the characteristics of coffee leaf kombucha (CK) and its differentiation from black tea kombucha (BK) has impeded its application in the beverage industry. Therefore, this study aimed to characterize and compare the physiochemical properties, phytochemical compositions, antioxidant activity, and α-glucosidase inhibitory ability of kombucha prepared from the leaves of Coffea arabica (CK) and black tea (Camellia sinensis, BK) and their extracts (CT and BT). After fermentation, pH and the contents of total sugars, reducing sugars, and free amino acids of BK and CK were decreased, whereas the levels of total acids and organic acids, such as gluconic, lactic, and acetic acid were increased. Notably, the concentration of vitamin C in CK was 48.9% higher than that in BK. HPLC analysis exhibited that 5-caffeoylquinic acid in CT was significantly decreased by 48.0% in CK, whereas the levels of 3-caffeoylquinic acid and 4-caffeoylquinic acid were significantly increased after fermentation. The content of caffeine was significantly (p<0.05) reduced by 9.5% and 22.0% in BK and CK, respectively, whereas thetheobromine level was significantly increased in CK. Notably, CK has superior total phenolic and flavonoid contents and antioxidant activity than BK, whereas BK possesses higher α-glucosidase inhibitory capacity. Electronic nose analysis demonstrated that sulfur-containing organics were the main volatiles in both kombuchas, and fermentation significantly increased their levels. Our study indicates that coffee leaves are a promising resource for preparing kombucha. PRACTICAL APPLICATION: This article investigates the differences in physicochemical properties, bioactive constituents, antioxidant activity, and α-glucosidase inhibitory activity of kombucha preparation from black tea and coffee leaves. We have found that after fermentation BK had brighter soup color and higher α-glucosidase inhibitory capacity, whereas CK had higher levels of total phenols, flavonoids, vitamin C, and antioxidants and lower contents of sugars. This study provides valuable information for the preparation of CK with high-quality attributes and antioxidant activity.