Antioxidant constituents in the dayflower (Commelina communis L.) and their α-glucosidase-inhibitory activity

Abstract

The dayflower, Commelina communis L., contains 1-deoxynojirimycin (DNJ) and (2R,3R,4R,5R)2,5-bis(hydroxymethyl)-3,4-dihydroxypyrrolidine (DMDP), potent alpha-glucosidase inhibitors. The extracts and powder of this herb are important food materials for prophylaxis against type 2 diabetes. Eleven flavonoid glycosides as antioxidants, isoquercitrin, isorhamnetin-3-O-rutinoside, isorhamnetin-3-O-beta-D-glucoside, glucoluteolin, chrysoriol-7-O-beta-D-glucoside, orientin, vitexin, isoorientin, isovitexin, swertisin, and flavocommelin, were identified from the aerial parts of C. communis. Their antioxidant activities were measured using in vitro assays employing the 1,1-diphenyl-2-picrylhydrazyl radical- and superoxide radical-scavenging assays. The results showed that glucoluteolin, orientin, isoorientin, and isoquercitrin are the predominant antioxidants in this herb. Moreover, isoquercitrin, isorhamnetine-3-O-rutinoside, vitexin, and swertisin inhibited the activity of alpha-glucosidase from rat intestine.

α-Glucosidase inhibition, 15-lipoxygenase inhibition, and brine shrimp toxicity of extracts and isolated compounds fromTerminalia macropteraleaves

“…Narcissin, however, was reported to be inactive (Robak et al, 1988). Of the flavonoids, only rutin showed high activity as a-glucosidase inhibitor, in accordance with previous investigations (De Souza Schmidt Goncalves et al, 2010;Shibano et al, 2008). Due to the lack of material, the highest measured concentration for narcissin was 6.3 mM, so it may be that narcissin may have activity toward a-glucosidase at higher concentrations.…”

“…Due to the lack of material, the highest measured concentration for narcissin was 6.3 mM, so it may be that narcissin may have activity toward a-glucosidase at higher concentrations. A previous investigation (Shibano et al, 2008) reported an IC 50 value for narcissin of 510 mM. Chebulic acid trimethyl ester, a novel compound previously isolated by us (Pham et al, 2011b), was found to have good 15-LO inhibitory activity, but was inactive as a-glucosidase inhibitor at the highest measured concentration (50 mM).…”

In vitro antioxidant activity and potential inhibitory action against α-glucosidase of polysaccharides from fruit peel of tea (Camellia sinensis L.)

“…Previous reports have shown that polysaccharides from a wide range of food or medical plant sources could be effective α-glucosidase inhibitors (Kwon et al, 2008;Shibano et al, 2008;Kim et al, 2010). In this study, the inhibitory effects of TFPPs on α-glucosidase were investigated.…”

Anti-Diabetic Effects of Actinidia arguta Polyphenols on Rats and KK-Ay Mice

“…Extracts from various plants such guava leaves (Deguchi and Miyazaki, 2010), Salacia reticulate (Yoshino et al, 2009), and mulberry leaves (Asano et al, 2001;Park et al, 2009) have been shown to inhibit α-glucosidase activity, often with the involvement of polyphenols. Isoquercitrin, which was isolated from dayflower (Commelina communis L.), was found to be a component that inhibits α-glucosidases with potency close to that of 1-deoxynojirimycin, a potent α-glucosidase inhibitor (Shibano et al, 2008). In rats with alloxan-induced type 1 diabetes mellitus, isoquercitrin is known to decrease fasting blood glucose levels and to improve diabetes mellitus by reducing insulin synthesis and/or secretion, and/or by suppressing G6Pase activity (Panda and Kar, 2007).…”