Effects of extraction methods on the physicochemical characteristics and biological activities of polysaccharides from okra (Abelmoschus esculentus).

Fruit, vegetables, and mushrooms for the preparation of extracts with α-amylase and α-glucosidase inhibition properties: A review.

The digestive enzymes–polyphenolic compounds (PCs) interactions behind the inhibition of these enzymes have not been completely studied. The existing studies have mainly analyzed polyphenolic extracts and reported inhibition percentages of catalytic activities determined by UV-Vis spectroscopy techniques. Recently, pure PCs and new methods such as isothermal titration calorimetry and circular dichroism have been applied to describe these interactions. The present review focuses on PCs structural characteristics behind the inhibition of digestive enzymes, and progress of the used methods. Some characteristics such as molecular weight, number and position of substitution, and glycosylation of flavonoids seem to be related to the inhibitory effect of PCs; also, this effect seems to be different for carbohydrate-hydrolyzing enzymes and proteases. The digestive enzyme–PCs molecular interactions have shown that non-covalent binding, mostly by van der Waals forces, hydrogen binding, hydrophobic binding, and other electrostatic forces regulate them. These interactions were mainly associated to non-competitive type inhibitions of the enzymatic activities. The present review emphasizes on the digestive enzymes such as α-glycosidase (AG), α-amylase (PA), lipase (PL), pepsin (PE), trypsin (TP), and chymotrypsin (CT). Existing studies conducted in vitro allow one to elucidate the characteristics of the structure–function relationships, where differences between the structures of PCs might be the reason for different in vivo effects.

https://www.mdpi.com/1420-3049/22/4/669/pdf

Polyphenolic Compounds and Digestive Enzymes: In Vitro Non-Covalent Interactions

In this work we report the green synthesis of silver nanoparticles (AgNPs) using the aqueous leaf extract of Lonicera japonica. A color change from pale yellow to brown was observed during the synthesis process. Ultraviolet-visible (UV-vis) studies show an absorption band at 435 nm due to surface plasmon resonance of the AgNPs, further characterized using the average size and stability of the AgNPs, which were 53 nm and −35.6 mV as determined by a zeta sizer. The spherical, hexagonal shape and the face centered cubic crystalline structure of metallic silver were confirmed by high resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD). The functional group of biomolecules present in the AgNPs was characterized by Fourier transform infrared spectra (FTIR). The synthesized AgNPs exhibited strong antioxidant activity. The antidiabetic ability of AgNPs was shown by the effective inhibition against carbohydrate digestive enzymes such as α-amylase and α-glucosidase with IC50 values of 54.56 and 37.86 μg mL−1, respectively. The inhibition of the kinetic mechanism was analyzed with LB and Dixon plots. AgNPs were identified to be reversible noncompetitive inhibitors and Ki values of 25.9 and 24.6 μg were found for key enzymes of diabetes (α-amylase and α-glucosidase). We conclude that the results suggest that the AgNPs were found to show remarkable potential antidiabetic activity against the key enzymes of diabetes and were found to be an appropriate nanomedicine for nanobiomedical applications.

Antidiabetic activity of silver nanoparticles from green synthesis using Lonicera japonica leaf extract

Characterization and identification of novel antidiabetic and anti-obesity peptides from camel milk protein hydrolysates.

Dietary inhibitors of fats and carbohydrates degrading enzymes can reduce obesity and type 2 diabetes. In this study, we screened crude extracts from 30 commonly consumed fruits to test their in vitro inhibitory effect against key enzymes relevant for obesity (pancreatic lipase) and type 2 diabetes (α-glucosidase and α-amylase), total phenolic content (Folin–Ciocalteu method), and antioxidant capacity (ABTS and FRAP). The IC50 values of the fruits tested varied from 39.91 to >400 mg/mL, from 1.04 to >80 mg/mL, and from 0.72 to 135.07 mg/mL against α-glucosidase, α-amylase, and pancreatic lipase, respectively. Antioxidant capacity ranged from 0.66 to 124.66 μmol of TE/g of fruit and strongly correlated with phenolic content, while the enzyme inhibition was poorly correlated with total phenolic and antioxidant capacity. Among fruits tested, blue honeysuckle and red gooseberry exhibited the highest inhibitory activity with respect to the carbohydrate degrading enzymes, while lingonberry had the strongest ant...

In vitro inhibitory effect on digestive enzymes and antioxidant potential of commonly consumed fruits.

Type 2 diabetes mellitus, which is usually a result of wrong dietary habits and reducedphysical activity, represents 85-95% of all diabetes cases and among other diet related diseases is themajor cause of deaths. The disease is characterized mainly by hyperglycemia, which is associated withattenuated insulin sensitivity or beta cells dysfunction caused by multiple stimuli, including oxidativestress and loss of insulin secretion. Since polyphenols possess multiple biological activities and constitutean important part of the human diet, they have recently emerged as critical phytochemicals in type2 diabetes prevention and treatment. Their hypoglycemic action results from their antioxidative effectinvolved in recovering of altered antioxidant defenses and restoring insulin secreting machinery in pancreatic cells, orabilities to inhibit the activity of carbohydrates hydrolyzing enzymes (α-amylase and α-glucosidase) or protein tyrosinephosphatase 1B (PTP1B), which is known as the major negative regulator in insulin signaling.This study investigates the total phenolic content (Folin−Ciocalteu and HPLC methods) and antioxidant capacity (ABTS)of 20 polyphenolic extracts obtained from selected edible plants, which were screened in terms of α -amylase, α -glucosidase and protein tyrosine phosphatase 1B inhibitors or protective agents against oxidative stress induced by tertbutylhydroperoxide(t-BOOH) in βTC3 pancreatic beta cells used as a model target for antidiabetes drugs. The study concludesthat Chaenomeles japonica, Oenothera paradoxa and Viburnum opulus may be promising natural sources for activecompounds with antidiabetic properties.

Antidiabetic Effect of Polyphenolic Extracts from Selected Edible Plants as α-Amylase, α -Glucosidase and PTP1B Inhibitors, and β Pancreatic Cells Cytoprotective Agents - A Comparative Study

Assays of the inhibitory potential against enzymes involved in carbohydrate and lipid digestion (α-amylase, α-glucosidase, and lipase) as well as the total contents of phenolics and anthocyanins, anthocyanin profile, and antioxidant capacity revealed significant differences (p < 0.05) between five varieties of red cabbage. Among the varieties, the highest inhibitory activity against α-glucosidase (IC50 = 3.87 ± 0.12 mg dry weight (DW) of cabbage/mL) and lipase (IC50 = 1.57 ± 0.06 mg DW/mL) was exhibited by the Koda variety, which showed the highest antioxidant capacity in ABTS (Trolox equivalent antioxidant capacity (TEAC) = 141 ± 4.71 μmol/g DW) and ferric-reducing antioxidant power (TEAC = 125 ± 1.94 μmol/g DW) assays and had the highest total phenolics level (19.6 ± 0.48 mg/g DW). The highest total anthocyanin content (12.0 ± 0.16 mg/g DW) and inhibitory activity against α-amylase (IC50 = 69.0 ± 3.65 mg DW of cabbage/mL) was shown by the Kissendrup variety. The anthocyanin profiles of these two varieti...

Iwona Majewska

Papers

In vitro inhibitory effect on digestive enzymes and antioxidant potential of commonly consumed fruits.

Antidiabetic Effect of Polyphenolic Extracts from Selected Edible Plants as α-Amylase, α -Glucosidase and PTP1B Inhibitors, and β Pancreatic Cells Cytoprotective Agents - A Comparative Study

Inhibitory Potential of Red Cabbage against Digestive Enzymes Linked to Obesity and Type 2 Diabetes.