Yeast α-Glucosidase Inhibitory Phenolic Compounds Isolated from Gynura medica Leaf

Abstract

Gynura medica leaf extract contains significant amounts of flavonols and phenolic acids and exhibits powerful hypoglycemic activity against diabetic rats in vivo. However, the hypoglycemic active constituents that exist in the plant have not been fully elaborated. The purpose of this study is to isolate and elaborate the hypoglycemic activity compounds against inhibition the yeast α-glucosidase in vitro. Seven phenolic compounds including five flavonols and two phenolic acids were isolated from the leaf of G. medica. Their structures were identified by the extensive NMR and mass spectral analyses as: kaempferol (1), quercetin (2), kaempferol-3-O-β-D-glucopyranoside (3), kaempferol-3-O-rutinoside (4), rutin (5), chlorogenic acid (6) and 3,5-dicaffeoylquinic acid methyl ester (7). All of the compounds except 1 and 3 were isolated for the first time from G. medica. Compounds 1–7 were also assayed for their hypoglycemic activity against yeast α-glucosidase in vitro. All of the compounds except 1 and 6 showed good yeast α-glucosidase inhibitory activity with the IC50 values of 1.67 mg/mL, 1.46 mg/mL, 0.38 mg/mL, 0.10 mg/mL and 0.53 mg/mL, respectively.

Phenolic constituents from <i>Sarcopyramis nepalensis</i> and their α-Glucosidase inhibitory activity

“…Ten phenolic constituents that include seven flavonols and three phenolic acids were isolated. Flavonol and its glycosides (1-7) showed good activity, which was in good agreement with our previous reports that many flavonoids from plants have been reported as α-glucosidase inhibitors (Tan et al 2013). …”

“…medica previously (Tan et al 2013). In continuation of our studies on α-glucosidase inhibitory phenolic constituents from natural medicinal plants,…”

Dietary solutions to dyslipidemia: Milk protein–polysaccharide conjugates as liver biochemical enhancers

“…In a similar mechanism as the Colocasia esculenta 's and the Abelmoschus esculentus ' mucilage (Chukwuma, Islam, & Amonsou, ) Cymodocea nodosa 's mucilage (Zhang, Yang, Liang, Jiao, & Zhao, ) and related Ziziphus mauritana (Deshpande et al, ) and Ziziphus jujuba 's mucilage (Ganachari, Kumar, & Alagawadi, ), Nabq mucilage (Table ) diminished lipid absorption at the intestinal level by inhibiting the activity of pancreatic lipase (Elbashir et al, ), scoring as the second best inhibitor among 18 dietetic plants. Dechakhamphu and Wongchum (), as Tan et al () went deeper to arraign plant phenolics (within identical mucilages) as potent inhibitors of carbohydrate digesting enzymes, namely phenolic acids like ferulic acid (and other phenolic acids like p‐coumarin, p‐hydroxybenzoic acid, and syringic acid or phenolic esters like chlorogenic acid); Ghafoor, Qadir, and Fakhri () found ferulic acid in the NabM as well as phenolic compounds like rutin, apigenin, and quercetin. High phenolic diet also plays a role in stabilizing and modulating antioxidants from milk protein, improving their prophylactic effect against the oxidative stress (Xing et al, ).…”

α-Glucosidase inhibiting activity and bioactive compounds of six red wine grape pomace extracts

“…The comparison of the α-glucosidase inhibitory potential of several crude grape pomace extracts allows the identification of the grape variety that is potentially rich in the inhibiting compounds. Although yeast α-glucosidase is readily available in pure form and widely used for nutraceutical investigations (Tan et al, 2013; Zhao et al, 2013), α-glucosidase from mammalian source is more biologically relevant. The mammalian enzyme complex was hence extracted and purified from rat intestinal powder.…”