Cyanidin and cyanidin-3-glucoside derived from Vigna unguiculata act as noncompetitive inhibitors of pancreatic lipase.

The consumption of legumes positively correlated with the reduction of body weight. In the present study, we identified and evaluated pancreatic lipase inhibitors from Vigna unguiculata and unraveled their mode of inhibition. The highly sensitive fluorometric method was adopted to access the pancreatic lipase activity and the ethanolic extract of Vigna unguiculata showed the maximum inhibition (IC50 of 15.2 µg/ml). Cyanidin and cyanidin-3-glucoside are the major anthocyanins observed in Vigna unguiculata. The IC50 value of cyanidin was 28.29 µM which was 6.5-fold higher than the cyanidin-3-glucoside (188.28 µM). We determined an apparent Ki of 27.28 µM for cyanidin and cyanidin-3-glucoside (88.97 µM) with noncompetitive inhibition. Collectively, these results suggest that the glycosylation of the anthocyanidins significantly reduces lipase inhibition. The noncompetitive inhibition of pancreatic lipase by Vigna unguiculata anthocyanins may exert significant pharmacological activities toward obesity complications by calorie restriction. PRACTICAL APPLICATIONS: The results of this study emphasize the importance of legumes in our diet to combat obesity-related complications. Consumption of legumes minimizes fat absorption by inhibiting the action of the fat-digesting enzyme.

Tea polyphenols as novel and potent inhibitory substances against renin activity.

Renin inhibitory activities of three tea products were investigated for the first time in this work. Water extracts from fermented oolong and black tea showed strong renin inhibitory activities. By the means of ultrafiltration, gradient high performance liquid chromatography and spectroscopic analysis, four active compounds were separated from aqueous black tea extract and identified as theasinensin B, theasinensin C, strictinin, and a hexose sulfate with a galloyl moiety, which had IC50 values of 19.33, 40.21, 311.09, and 50.16 µM against renin activity, respectively. Further detection indicated that the potent inhibitor theasinensin B was present only in black tea, and that monomeric catechins did not contribute significantly to the renin inhibitory activities of tea products. These results revealed novel and potent tea-derived renin inhibitors and suggested another potential pathway for tea consumption to control hypertension.

Inhibitory effect of catechin-related compounds on renin activity.

Renin is a crucial enzyme in the renin-angiotensin system, and the inhibition of its activity is considered as a useful approach to the treatment of hypertension. The inhibitory effect of catechin-related compounds on renin was investigated in this work. It was found that epigallocatechin gallate (EGCg) possessed the strongest activity with an IC50 value of 44.53 µM and acted in an uncompetitive manner. Gallated catechins exerted higher inhibition than the ungallated forms, and gallic acid exhibited an inhibitory potency close to that of epicatechin gallate (ECg). Results indicated that the galloyl moiety and ortho-trihydroxy phenyl structures might be favorable for the renin-inhibitory activity of these compounds.

Phenolic antioxidants in some Vigna species of legumes and their distinct inhibitory effects on α-glucosidase and pancreatic lipase activities.

Phenolic extracts of 4 Vigna species of legumes (mung bean, moth bean, and black and red varieties of adzuki beans) were evaluated for phenolic contents, antioxidant activities, and inhibitory properties against α-glucosidase and pancreatic lipase. Results showed that adzuki bean varieties contain higher phenolic indexes than mung bean and moth beans. Adzuki bean (black) variety was found to be the most active 2,2'-diphenyl-1-picrylhydrazyl and superoxide anion scavenger. However, the hydrogen peroxide scavenging and metal chelating abilities were significantly higher in adzuki bean (red) variety. Mung bean exhibited least antioxidant activities in all the methods tested. Phenolic extracts from these legumes also showed distinct variations in the inhibition of enzymes associated with hyperglycemia and hyperlipidemia. Inhibitory activities of all the extracts against lipase were found to be more potent than α-glucosidase. Although, α-glucosidase inhibitory activity was superior in the black variety of adzuki bean (IC(50,) 26.28 mg/mL), both adzuki bean varieties (black and red) along with moth bean showed strong inhibitory activities on lipase with no significant difference in their IC(50) values (7.32 to 9.85 mg/mL). These results suggest that Vigna species of legumes are potential source of antioxidant phenolics and also great sources of strong natural inhibitors for α-glucosidase and lipase activities. This information may help for effective utilization of these legumes as functional food ingredients for promoting health. Practical Application: Vigna species of legumes are good sources of phenolic antioxidants and strong natural inhibitors of enzymes associated with diabetes and obesity. Therefore, utilization of these legumes in the development of functional foods with increased therapeutic value would be a significant step toward health promotion and wellness.

Simple, selective, and rapid quantification of 1-deoxynojirimycin in mulberry leaf products by high-performance anion-exchange chromatography with pulsed amperometric detection.

1-Deoxynojirimycin (DNJ) occurs in mulberry and other plants and is a highly potent glycosidase inhibitor reported to suppress blood glucose levels, thus preventing diabetes. Derivatization is required for quantification of DNJ upon use of spectral detection methods. Because of this difficulty, the DNJ contents of mulberry-based food products are rarely stated, even if DNJ is their active component. A simple, selective, and rapid method of high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) to quantify DNJ in mulberry-based food products was developed. Stability testing of DNJ under heat treatment was also performed. A water extract of mulberry tea sample was subjected to HPAEC-PAD in a CarboPac MA1 column with a sodium hydroxide gradient. DNJ was clearly separated at a retention time of 7.26 min without interference and was selectively detected in the water extract. The detection limit was 5 ng. Heat stability studies suggested that DNJ was heat stable. HPAEC-PAD was not subject to interference, was highly selective for DNJ, and was superior to other high-performance liquid chromatography (HPLC) techniques in terms of sample preparation, resolution, and sensitivity. The method allowed simple, selective, and rapid analysis of DNJ in food matrices and might be useful for development of mulberry-based food products. Heat treatment could be an option for sterilizing mulberry-based products.

Continuous orally administered coffee enhanced the antigen-specific Th1 response and reduced allergic development in a TCR-transgenic mice model.

Coffee is a globally consumed beverage. Although recent studies have suggested that coffee reduced the risk of lifestyle-related diseases, there are few studies regarding allergic response. This study investigates the effects of orally administered coffee (91 ml/kg/d) on allergic responses using a T cell receptor (TCR)-transgenic DO11.10 mouse allergic model. Splenocytes from coffee-administered naïve mice increased antigen (Ag)-specific interleukin (IL)-12p40 secretion. When Ag sensitization and coffee administration were concurrently performed, the splenocytes from coffee-administered mice showed a decrease of IL-2 and an increase of IL-12p40 secretion. The Ag-specific cutaneous response and serum IgE level were reduced in coffee-administered mice, although, after establishing the allergy, coffee administration did not suppress the allergic reaction. These results suggest that coffee could induce a Th1-type response of the immune system and prevent an allergy developing. Further studies on the optimum dose, cultivar differences, and roasted degree need to be undertaken.

Inhibitory effects of several flavonoids on E-selectin expression on human umbilical vein endothelial cells stimulated by tumor necrosis factor-alpha.

The present study investigates the suppressive effect of flavonoids on TNF-alpha-stimulated E-selectin expression on HUVECs by carrying out a comparative examination of the 37 flavonoids. Several flavonoids: fisetin, luteolin and apigenin (subclass of flavone), kaempferol and quercetin (flavonols), eriodictyol (flavanones), genistein (isoflavones) and butein (chalcone) exhibit the inhibitory effects. Considerations to the structure of flavonoids, the C2-C3 double bond of C-ring and 4-oxo functional group are essential for their inhibition activities. These results help to explain the pharmacological efficacy of flavonoids as anti-inflammatory compounds.

Inhibitory effect of some flavonoids on tumor necrosis factor-alpha production in lipopolysaccharide-stimulated mouse macrophage cell line J774.1.

Certain naturally occurring flavonoids affect immunoregulatory activities in vitro and in vivo against cytokine production. Since tumor necrosis factor (TNF)-alpha is one of the major inflammatory cytokines, the effects of various dietary flavonoids on TNF-alpha production in lipopolysaccharide (LPS)-stimulated J774.1 cells were evaluated in vitro. Flavones, flavonols, and chalcone are the most potent inhibitors of production of TNF-alpha. Flavanone, naringenin, anthocyanidin, pelargodinin, and cyanidin exhibit moderate inhibitory activity. In contrast, genistein isoflavone displays weak inhibition, while eriodictyol flavanone is inactive. It is clear that the double bond between carbons 2 and 3 and the ketone group at position 4 of flavonoids are necessary for potent inhibitory effect. The difference in inhibitory action appears to depend on the categorized subclass of flavonoids.