<i>In Vitro</i> <i>α</i>-Glucosidase and <i>α</i>-Amylase Inhibitory Activities of Free and Bound Phenolic Extracts from the Bran and Kernel Fractions of Five Sorghum Grain Genotypes
Yun Xiong,
Ken Ng,
Pangzhen Zhang,
Robyn Dorothy Warner,
Shuibao Shen,
Hsi-Yang Tang,
Zijian Liang,
Zhongxiang Fang
Affiliations
Yun Xiong
Faculty of Veterinary and Agricultural Sciences, School of Agriculture and Food, University of Melbourne, Parkville VIC 3010, Australia
Ken Ng
Faculty of Veterinary and Agricultural Sciences, School of Agriculture and Food, University of Melbourne, Parkville VIC 3010, Australia
Pangzhen Zhang
Faculty of Veterinary and Agricultural Sciences, School of Agriculture and Food, University of Melbourne, Parkville VIC 3010, Australia
Robyn Dorothy Warner
Faculty of Veterinary and Agricultural Sciences, School of Agriculture and Food, University of Melbourne, Parkville VIC 3010, Australia
Shuibao Shen
College of Animal Science and Technology, Guangxi University, Nanning 530004, China
Hsi-Yang Tang
Faculty of Veterinary and Agricultural Sciences, School of Agriculture and Food, University of Melbourne, Parkville VIC 3010, Australia
Zijian Liang
Faculty of Veterinary and Agricultural Sciences, School of Agriculture and Food, University of Melbourne, Parkville VIC 3010, Australia
Zhongxiang Fang
Faculty of Veterinary and Agricultural Sciences, School of Agriculture and Food, University of Melbourne, Parkville VIC 3010, Australia
Diabetes is a global health challenge. Currently, an effective treatment for diabetes is to reduce the postprandial hyperglycaemia by inhibiting the carbohydrate hydrolysing enzymes in the digestive system. In this study, we investigated the in vitro α-glucosidase and α-amylase inhibitory effects of free and bound phenolic extracts, from the bran and kernel fractions of five sorghum grain genotypes. The results showed that the inhibitory effect of sorghum phenolic extracts depended on the phenolic concentration and composition. Sorghum with higher phenolic contents generally had higher inhibitory activity. Among the tested extracts, the brown sorghum (IS131C)-bran-free extract (BR-bran-free, half-maximal inhibitory concentration (IC50) = 18 ± 11 mg sorghum/mL) showed the strongest inhibition against α-glucosidase which was comparable to that of acarbose (IC50 = 1.39 ± 0.23 mg acarbose/mL). The red sorghum (Mr-Buster)-kernel-bound extract (RM-kernel-bound, IC50 = 160 ± 12 mg sorghum/mL) was the most potent in inhibiting α-amylase but was much weaker compared to acarbose (IC50 = 0.50 ± 0.03 mg acarbose/mL).
