To comprehensively examine the antioxidant capacity of Perilla frutescens leaves extract, eight assays including hydroxyl radical, hydrogen peroxide, ferrous ionchelating, total antioxidant capacity, nitric oxide, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), 2,2′-diphenyl-1-picrylhydrazyl, and ferrous reducing antioxidant assays were employed. The results indicated that the ethyl acetatesoluble fraction of P. frutescens leaves extract displayed the highest antioxidant activities. The antioxidant constituents from ethyl acetate-soluble fraction of P. frutescens leaves extract were screened by 2,2′-diphenyl-1-picrylhydrazyl highperformance liquid chromatography, and 11 compounds were identified after isolation using step-wise high-speed countercurrent chromatography. Protocatechuic acid, chlorogenic acid, caffeic acid, rosmarinic acid, luteolin, methyl-rosmarinic acid, apigenin, and 4′,5,7-trimethoxyflavone are the major antioxidant constituents in ethyl acetate-soluble fraction of P. frutescens leaves extract. ARTICLE HISTORY

Stauntonia hexaphylla (Thunb.) Decne. (Lardizabalaceae) leaves (SHL) have been used traditionally as analgesics, sedatives, diuretics, and so on, in China. To date, no data have been reported on the inhibitory effect of SHL and its constituents on rat lens aldose reductase (RLAR) and advanced glycation end products (AGEs). Therefore, the inhibitory effect of compounds isolated from SHL extract on RLAR and AGEs was investigated to evaluate potential treatments of diabetic complications. The ethyl acetate (EtOAC) fraction of SHL extract showed strong inhibitory activity on RLAR and AGEs; therefore, EtOAc fraction (3.0 g) was subjected to Sephadex LH-20 column chromatography, for further fractionation, with 100% MeOH solvent system to investigate its effect on RLAR and AGEs. Phytochemical investigation of SHL led to the isolation of seven compounds. Among the isolated compounds, chlorogenic acid, calceolarioside B, luteolin-3′-O-β-D-glucopyranoside, quercetin-3-O-β-D-glucopyranoside, and luteolin-7-O-β-D-glucopyranoside exhibited significant inhibitory activity against RLAR with IC50 in the range of 7.34–23.99 μM. In addition, 3-(3,4-dihydroxyphenyl) propionic acid, neochlorogenic acid, and luteolin-3′-O-β-D-glucopyranoside exhibited the most potent inhibitory activity against formation of AGEs, with an IC50 value of 115.07–184.06 μM, compared to the positive control aminoguanidine (820.44 μM). Based on these findings, SHL dietary supplements could be considered for the prevention and/or treatment of diabetes complication.

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BackgroundProtein tyrosine phosphatase expressed in insulin-sensitive tissues (such as liver, muscle, and adipose tissue) has a key role in the regulation of insulin signaling and pathway activation, making protein tyrosine phosphatase a promising target for the treatment of type 2 diabetes mellitus and obesity and response surface methodology (RSM) is an effective statistical technique for optimizing complex processes using a multi-variant approach.MethodsIn this study, Zea mays L. (Purple corn kernel, PCK) and its constituents were investigated for protein tyrosine phosphatase 1β (PTP1β) inhibitory activity including enzyme kinetic study and to improve total yields of anthocyanins and polyphenols, four extraction parameters, including temperature, time, solid-liquid ratio, and solvent volume, were optimized by RSM.ResultsIsolation of seven polyphenols and five anthocyanins was achieved by PTP1β assay. Among them, cyanidin-3-(6”malonylglucoside) and 3′-methoxyhirsutrin showed the highest PTP1β inhibition with IC50 values of 54.06 and 64.04 μM, respectively and 4.52 mg gallic acid equivalent/g (GAE/g) of total polyphenol content (TPC) and 43.02 mg cyanidin-3-glucoside equivalent/100 g (C3GE/100g) of total anthocyanin content (TAC) were extracted at 40 °C for 8 h with a 33 % solid-liquid ratio and a 1:15 solvent volume. Yields were similar to predictions of 4.58 mg GAE/g of TPC and 42.28 mg C3GE/100 g of TAC.ConclusionThese results indicated that PCK and 3′-methoxyhirsutrin and cyanidin-3-(6”malonylglucoside) might be active natural compounds and could be apply by optimizing of extraction process using response surface methodology.

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