Optimization of Extraction of Hypoglycemic Ingredients from Grape Seeds and Evaluation of α-Glucosidase and α-Amylase Inhibitory Effects In Vitro

Exploring the biomedical potential of a novel modified glass ionomer cement against the pandrug-resistant oral pathogen Candida albicans SYN-01

Dental caries is an infectious disease that is a major concern for dentists. Streptococci and Lactobacilli were long thought to be the primary etiology responsible for caries. Candida albicans with acidogenic and aciduric characteristics has recently been implicated in the onset and progression of cariogenic lesions. Moreover, due to the increased resistance to common antimicrobials, the discovery of innovative candidates is in high demand. Therefore, our study might be the first report that explores the efficacy of glass ionomer cement (GIC) incorporated with a newly modified carboxylated chitosan derivative (CS-MC) against multidrug-resistant (MDR) and/or pandrug resistant (PDR) C. albicans isolated from the oral cavity. In this work, four CS-MC-GIC groups with different concentrations were formulated. Group four (CS-MC-GIC-4) gave a significant performance as an anticandidal agent against selected PDR Candida strain, with an obvious decrease in its cell viability and high antibiofilm activity. It also, enhanced all the mechanical properties and supports cell viability of Vero cells as a nontoxic compound. Moreover, CS-MC-GIC-4 inhibited neuraminidases completely, which might provide a novel mechanism to prevent dental/oral infections. Thus, findings in this study open up new prospect of the utilization of CS-MC-GIC as a novel dental filling material against oral drug-resistant Candida.

Dual Regulation of Sulfonated Lignin to Prevent and Treat Type 2 Diabetes Mellitus

With the rapid increase of diabetes cases in the world, there is an increasing demand for slowing down and managing diabetes and its effects. It is considered that a viable prophylactic treatment for type 2 diabetes mellitus (T2DM) is to reduce carbohydrate digestibility by controlling the activities of α-amylase and α-glucosidase to control postprandial hyperglycemia and promote the growth of intestinal beneficial bacteria. In this work, the effects of sulfonated lignin with different sulfonation degrees (0.8 mmol/g, SL₁; 2.9 mmol/g, SL₂) on the inhibition of α-amylase and α-glucosidase and the proliferation of intestinal beneficial bacteria in vitro were investigated. The results showed that both SL₁ and SL₂ can inhibit the activity of α-amylase and α-glucosidase. The inhibition capacity (IC₅₀, 32.35 μg/mL) of SL₂ with a low concentration (0-0.5 mg/mL) to α-amylase was close to that of acarbose to α-amylase (IC₅₀, 27.33 μg/mL). Compared with the control groups, the bacterial cell concentrations of Bifidobacteria adolescentis and Lactobacillus acidophilus cultured with SL₁ and SL₂ increased in varying degrees (8-36%), and the produced short-chain fatty acids were about 1.2 times higher. This work demonstrates the prospect of sulfonated lignin as a prebiotic for the prevention and treatment of T2DM, which provides new insights for opening up a brand new field of lignin.

Role and mechanism of fruit waste polyphenols in diabetes management

Among various diseases in humans, diabetes is one of the most complicated disorders resulting either from the malfunctioning of β cells, causing a poor discharge of insulin from them, or poor functioning of the liberated insulin. A wide array of chemical compounds so-called secondary metabolites are present in plants. These phytochemicals are produced as by-products of metabolism and play a key role in plant protection. However, in humans, they offer several beneficial functions. Polyphenols are an important class of phytochemicals and apart from fruits, they are also found in their major wastes mainly including the peel, pomace, and seed. The current review is aimed to focus on the potential sources, distribution, and extraction/isolation of polyphenols from major fruit wastes along with highlighting their medicinal and therapeutic benefits, especially in the management of diabetes.

Bioactive Compounds, Health Benefits and Food Applications of Grape

Grape (Vitis vinifera L.) is one of the most popular fruits worldwide. It contains various bioactive compounds, such as proanthocyanidins, anthocyanins, flavonols, phenolic acids and stilbenes, the contents of which could vary considerably in grape skin, pulp and seed. Many studies have revealed that grape possesses a variety of health benefits, such as antioxidant, anti-inflammatory, gut-microbiota-modulating, anticancer and cardioprotective effects. Grape is eaten as fresh fruit and is also used as raw material to produce various products, such as wine, grape juice and raisins. Moreover, the byproducts of grape, such as grape pomace and grape seed, have many applications in the food industry. In this paper, the bioactive compounds in grape are briefly summarized based on literature published in recent years. In addition, the health benefits of grape and its bioactive components are discussed, with special attention paid to the underlying mechanisms. Furthermore, the applications of grape in the food industry are elucidated, especially the applications of grape pomace and grape seed. This paper can contribute to understanding the health benefits and mechanisms of grape and its bioactive compounds, as well as the promotion of the use of grape in the food industry.

Inhibition of Three Diabetes-Related Enzymes by Procyanidins from Lotus (Nelumbo nucifera Gaertn.) Seedpods

The inhibitory effects of procyanidins from lotus (Nelumbo nucifera Gaertn.) seedpods on the activities of α-amylase, α-glucosidase and protein tyrosine phosphatase 1B (PTP1B), were studied and compared with those of (+)-catechin, (-)-epicatechin, epigallocatechin gallate (EGCG), procyanidin dimer B2 and trimer C1. The results showed that Lotus procyanidin extract (LPE) significantly inhibited α-amylase, α-glucosidase and PTP1B with IC₅₀ values of 5.5, 1.0, and 0.33 μg/mL, respectively. The inhibition increased with the degree of polymerization and the existence of galloyl or gallocatechin units. Kinetic analysis showed that LPE inhibited α-glucosidase activity in a mixed competitive and noncompetitive mode. Fluorescence quenching revealed that α-glucosidase interacted with LPE or EGCG in an apparent static mode, or the model of "sphere of action". The apparent static (K) and bimolecular (k_q) constants were 4375 M^-1 and 4.375 × 10¹¹ M^-1 s^-1, respectively, for LPE and 1195 M^-1 and 1.195 × 10¹¹ M^-1 s^-1, respectively, for EGCG. Molecular docking analysis provided further information on the interactions of (+)-catechin, (-)-epicatechin, EGCG, B2 and C1 with α-glucosidase. It is hypothesized that LPE may bind to multiple sites of the enzyme through hydrogen bonding and hydrophobic interactions, leading to conformational changes in the enzyme and thus inhibiting its activity. These findings first elucidate the inhibitory effect of LPE on diabetes-related enzymes and highlight the usefulness of LPE as a dietary supplement for the prophylaxis of diabetes.

Inhibitory activities of grape bioactive compounds against enzymes linked with human diseases

A quest for identification of novel, safe and efficient natural compounds, as additives in the modern food and cosmetic industries, has been prompted by concerns about toxicity and side effects of synthetic products. Plant phenolic compounds are one of the most documented natural products due to their multifarious biological applications. Grape (Vitis vinifera) is an important source of phenolic compounds such as phenolic acids, tannins, quinones, coumarins and, most importantly, flavonoids/flavones. This review crisply encapsulates enzyme inhibitory activities of various grape polyphenols towards different key human-ailment-associated enzymes: xanthine oxidase (gout), tyrosinase (hyperpigmentation), α-amylase and α-glucosidase (diabetes mellitus), pancreatic lipase (obesity), cholinesterase (Alzheimer's disease), angiotensin i-converting enzymes (hypertension), α-synuclein (Parkinson's disease) and histone deacetylase (various diseases). The review also depicts the enzyme inhibitory mechanism of various grape polyphenols and briefly discusses their stature as potential therapeutic and drug development candidates. KEY POINTS: • Nineteen major bioactive polyphenols from the grape/grape products and their disease targets are presented • Sixty-two important polyphenols as enzyme inhibitors from grape/grape products are presented • A thorough description and graphical presentation of biological significance of polyphenols against various diseases.

Hypoglycemic effects of space-induced Lactobacillus plantarum SS18-5 on type 2 diabetes in a rat model

Probiotics can improve dyslipidemia and promote metabolic control as a therapeutic approach for type 2 diabetes mellitus (T2DM). The hypoglycemic effects of space-induced Lactobacillus plantarum SS18-5 on T2DM were explored in 4-week-old male Sprague Dawley rats. The normal (N) group was fed a basal diet, while the other groups received a high glucose fat diet. T2DM was established by streptozotocin injection and the T2DM rats were randomly divided into three groups, a diabetic (D) group (T2DM rats treated with saline only), GS18 group (T2DM rats treated with 10⁹  CFU/ml of L. plantarum GS18), and SS18-5 group (T2DM rats treated with 10⁹  CFU/ml of L. plantarum SS18-5). After continuous gavage for 6 weeks, blood biochemical indices were measured and livers were collected for histopathological examination. The colon contents were collected for counting of Escherichia coli, Clostridium perfringens, and Lactobacillus sp. The results showed that L. plantarum SS18-5 effectively controlled the weight of rats, reduced levels of fasting blood glucose, glycosylated hemoglobin, and insulin, increased liver glycogen levels, improved abnormal metabolism of blood lipids, enhanced the effect of anti-lipid peroxidation, alleviated chronic inflammation and fatty liver disease, and regulated the intestinal microbiota by reducing the numbers of E. coli and C. perfringens, and increasing the numbers of Lactobacillus sp. From these results, we conclude that space-induced L. plantarum SS18-5 has the potential to improve T2DM by alleviating hypoglycemia and regulating the intestinal microbiota. PRACTICAL APPLICATIONS: With the exploration of the universe, a large number of studies have observed the changes of microorganisms in space flight, which provided a new method for high-quality microbial pharmaceuticals in the space environment. In this study, the space environment mutated. Lactobacillus plantarum SS18-5 can effectively improve the blood glucose of rats with type 2 diabetes, relieve oxidative stress, reduce blood lipid content, enhance immune capacity, and regulate intestinal microflora, which has potential use in the treatment of type 2 diabetes.

Chemical Properties of Vitis Vinifera Carménère Pomace Extracts Obtained by Hot Pressurized Liquid Extraction, and Their Inhibitory Effect on Type 2 Diabetes Mellitus Related Enzymes

Grape pomace polyphenols inhibit Type 2 Diabetes Mellitus (T2DM)-related enzymes, reinforcing their sustainable recovery to be used as an alternative to the synthetic drug acarbose. Protic co-solvents (ethanol 15% and glycerol 15%) were evaluated in the hot pressurized liquid extraction (HPLE) of Carménère pomace at 90, 120, and 150 °C in order to obtain extracts rich in monomers and oligomers of procyanidins with high antioxidant capacities and inhibitory effects on α-amylase and α-glucosidase. The higher the HPLE temperature (from 90 °C to 150 °C) the higher the total polyphenol content (~79%, ~83%, and ~143% for water-ethanol, water-glycerol and pure water, respectively) and antioxidant capacity of the extracts (Oxygen Radical Absorbance Capacity, ORAC), increased by ~26%, 27% and 13%, while the half maximal inhibitory concentration (IC₅₀) decreased by ~65%, 67%, and 59% for water-ethanol, water-glycerol, and pure water extracts, respectively). Water-glycerol HPLE at 150 and 120 °C recovered the highest amounts of monomers (99, 421, and 112 µg/g dw of phenolic acids, flavanols, and flavonols, respectively) and dimers of procyanidins (65 and 87 µg/g dw of B1 and B2, respectively). At 90 °C, the water-ethanol mixture extracted the highest amounts of procyanidin trimers (13 and 49 µg/g dw of C1 and B2, respectively) and procyanidin tetramers of B2 di-O-gallate (13 µg/g dw). Among the Carménère pomace extracts analyzed in this study, 1000 µg/mL of the water-ethanol extract obtained, at 90 °C, reduced differentially the α-amylase (56%) and α-glucosidase (98%) activities. At the same concentration, acarbose inhibited 56% of α-amylase and 73% of α-glucosidase activities; thus, our grape HPLE extracts can be considered a good inhibitor compared to the synthetic drug.

α-Glucosidase Inhibitory Activity of Tannat Grape Phenolic Extracts in Relation to Their Ripening Stages

The present study aimed to screen grape extracts as novel α-glucosidase inhibitors to prevent type-2 diabetes and hyperglycemia. The total polyphenol content (TPC) was measured by Folin-Ciocalteu assay and the stilbene, anthocyanin and flavan-3-ol compounds were measured by Ultra High-Performance Liquid Chromatography coupled to Mass Spectrometry (UHPLC-MS). The α-glucosidase inhibitory of seed and skin Tannat grape extracts at four ripening stages were investigated. The highest TPC values were measured in seeds at the “veraison stage” (65.29 ± 5.33 g of Gallic Acid Equivalent (GAE) per kilogram of Fresh Weight (FW)). This was in accordance with the high flavan-3-ol contents measured for these two extracts (43.22 ± 2.59 and 45.45 ± 6.48 g/kg of seeds FW, respectively). The skin and seed extracts at the first stage of ripening exerted strong α-glucosidase inhibition, exceeding 95% (p < 0.05). A high linear correlation (R = 0.723, p ≤ 0.05) was observed between flavan-3-ol contents and the α-glucosidase inhibitory activity. The stilbene contents and this activity were moderately to strongly anti-correlated (R = –0.828, p ≤ 0.05 for trans-resveratrol). The enzyme kinetic studies revealed a mixed type of inhibition. This study brings promising results for the therapeutic potential of seed and skin Tannat grape extracts as a functional food product with anti-diabetic activity.

In vitro inhibitory effects of Chinese bayberry (Myrica rubra Sieb. et Zucc.) leaves proanthocyanidins on pancreatic α-amylase and their interaction

Chinese bayberry leaves proanthocyanidins (BLPs) belongs to the prodelphinidin category with potent EGCG unit, whose inhibition effect on α-amylase and their interaction were investigated by in vitro digestion and enzyme kinetic analysis, multi fluorescence spectroscopies (fluorescence quenching, synchronous fluorescence, and three-dimensional fluorescence), circular dichroism spectra, Fourier transform infrared spectroscopy and in silico modelling. The results revealed that BLPs was a mixed inhibitor to α-amylase with the IC₅₀ value of 3.075 ± 0.073 μg/mL. BLPs could lead to a static fluorescence quenching of α-amylase, mainly by means of interacting with amino acids (mainly Try and Tyr residues) in one site on α-amylase molecule under the action of hydrogen bonding and/or Van der Waals force. This interaction further induced the change of secondary conformational structure, functional group structure and hydrophobicity of α-amylase, thus resulting in lowering activity. Molecular docking simulated that this binding occurred in a cavity on the surface of the α-amylase molecule, and BLPs trimer showed a relatively high binding energy. The present study provided a new insight of BLPs as an α-amylase inhibitor, which could be considered in anti-diabetic therapy.

Hypoglycemic effects and modulation of gut microbiota of diabetic mice by saponin fromPolygonatum sibiricum

Polygonatum sibiricumis a medicinal and homologous plant grown in China. The saponin inPolygonatum sibiricumhas shown its good hypoglycemic performance, and it can be developed as functional foods and drugs with hypoglycemic effect.

Grape Seeds: Chromatographic Profile of Fatty Acids and Phenolic Compounds and Qualitative Analysis by FTIR-ATR Spectroscopy

The primary product of the oenological sector is wine. Nonetheless, the grape processing produces large amounts of by-products and wastes, e.g., the grape seeds. In the context of a sustainable production, there is a strong push towards reutilizing these by-products and waste for making useful derivatives since they are rich of bioactive substances with high additional value. As it is true for the wine itself, bringing these by-products derivatives to the market calls for quality measures and analytical tools to assess quality itself. One of the main objectives is to collect analytical data regarding bioactive compounds using potentially green techniques. In the present work, the profile of fatty acids and the main phenolic compounds were investigated by conventional methods. The qualitative analysis of the main functional groups was carried out by Fourier Transform Infrared (FTIR) spectroscopy. Moreover, the successful use of FTIR technique in combination with chemometric data analysis is shown to be a suitable analytical tool for discriminating the grape seeds. Grape seeds of different origin have different content of bioactive substances, making this technique useful when planning to recover a certain substance with specific potential application in health area as food supplement or nutraceutical. For example, Cesanese d’Affile seeds were found to have a rather high fat content with a significant fraction of unsaturated fatty acids. On the other hand, the seeds of Nero d’Avola exhibit the highest amount of phenolic compounds.

Interaction mechanism between α-glucosidase and A-type trimer procyanidin revealed by integrated spectroscopic analysis techniques

α-Glucosidase is an important enzyme in human intestine, and inhibition of its activity can lower blood sugar levels to effectively prevent hyperglycaemia induced tissue damage. Here, we investigated the inhibitory activities of procyanidins with different structures on α-glucosidase and the underlying mechanism. The results showed that the IC₅₀ of catechin and compounds 2-7 on α-glucosidase was lower than that of acarbose. A-type procyanidins might have better inhibitory activity than B-type procyanidins. In addition, there was no positive correlation between the polymerization degree of A-type procyanidin oligomer and its inhibitory effect on α-glucosidase. Compound 7 (A-type trimer) with the best inhibitory effect reversibly inhibited the activity of α-glucosidase in a mixed-type manner. Fluorescence data confirmed that the intrinsic fluorescence of α-glucosidase was quenched by compound 7 through static-dynamic quenching. The calculated thermodynamic parameters indicated that their binding was spontaneous and driven by hydrophobic interaction, which was also confirmed by the UV spectrum experiment. Besides, circular dichroism analysis displayed that their binding resulted in conformational changes of α-glucosidase characterized by a decrease in α-helix and an increase in β-sheet. The results demonstrate the ability of procyanidins to intervene in the progression of type 2 diabetes by inhibiting α-glucosidase.

The Antidiabetic Potential of Black Mulberry Extract-Enriched Pasta through Inhibition of Enzymes and Glycemic Index

In the present work, pasta enriched in different formulations by black mulberry extract in order to inhibit enzymes related to starch hydrolyzation. Total phenol content (TPC), antioxidant activity and anthocyanin components of ethanol/water black mulberry extract were investigated. TPC of the black mulberry extract was found 65.61 ± 0.07 mg GAE/g. Black mulberry extract could scavenge the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals more effectively than tertiary butylhydroquinone (TBHQ) also vitamin C due to its detected polyphenolic compounds (cyanidin-3-glucoside, cyanidin-3-rutinoside, and cyanidin-3-xyloside). The IC₅₀ value of the black mulberry extract was obtained 8.31 μg/mL while it was measured 59.62 and 62.64 μg/mL for TBHQ and vitamin C, respectively. The pasta-enriched with freeze-dried black mulberry extract showed effective inhibition against applied α-amylases (α-amylase from porcine pancreas, Bacillus sp, and human saliva) and α-glucosidase originated from Saccharomyces cerevisiae. The IC₅₀ values of tested enzymes exhibited that black mulberry effectively act as an inhibitory agent comparing with acarbose because of its antioxidant activity. Results revealed that starch hydrolysis index (HI) and predicted glycemic index (GI_predicted) of cooked pasta-enriched with various concentration levels of black mulberry extract were significantly decreased especially when 1.5% of the extract was incorporated. In addition, The IC₅₀ value of the black mulberry extract obtained from cooked pasta was increased against α-amylase and α-glucosidase. The results obviously presented that diabetes mellitus type 2 could be resolved by enrichment of polyphenolic compounds into the pasta.