HPLC method for measurement of human salivary α-amylase inhibition by aqueous plant extracts

Abstract

Control of hyperglycemia is an important treatment in metabolic disorders such as type II diabetes and obesity. α-Amylase, as the first enzyme of glucose release from dietary polysaccharides, is a potential target to identify new sources of novel anti-obesity and anti-diabetic drugs. In this work, different herbal extracts as α-amylase inhibitors were studied by measuring the rate of the cleavage of a maltooligomer substrate 2-chloro-4-nitrophenyl-β-D-maltoheptoside. Measurement of chromophore containing products after reversed phase HPLC separation was used for α-amylase activity measurement. Rates of hydrolysis catalysed by human salivary α-amylase were determined in the presence and absence of lyophilised water extracts of eleven herbs. Remarkable bioactivities were found for extracts of Cinnamomum zeylanicum Blume (bark), Camellia sinensis L. (leaf), Ribes nigrum L. (leaf), Laurus nobilis L. (leaf), Vaccinium macrocarpon Aiton (fruit) and Syzygium aromaticum L. (bud). Determined IC values were in 0.017-41 μg/ml range for these six selected plant extracts. Our results confirm the applicability of this HPLC-based method for the quick and reliable comparison of plants as α-amylase inhibitors.

In vitro anti-diabetic effects and phytochemical profiling of novel varieties of Cinnamomum zeylanicum (L.) extracts

“…Another finding showed a 352 mg/g yield for the freeze dried aqueous extract of C . zeylanicum and that was higher than the yield obtained in the current study ( Takács et al, 2017 ) . Species of Cinnamon, climate, growth condition, cultivation site, age of the bark, thickness of the bark and the density of the oil cells are positively correlated with the yield of the Cinnamon essential oils ( Li, Kong & Wu, 2013 ) .…”

“…In the current study, the percent yields obtained for SW, SG, and CC extracts prepared using SD were comparable to the previously reported yield (2.6%) for the commercially available C. zeylanicum in Turkey (Sihoglu Tepe & Ozaslan, 2020). Another finding showed a 352 mg/g yield for the freeze dried aqueous extract of C. zeylanicum and that was higher than the yield obtained in the current study (Takács et al, 2017). Species of Cinnamon, climate, growth condition, cultivation site, age of the bark, thickness of the bark and the density of the oil cells are positively correlated with the yield of the Cinnamon essential oils (Li, Kong & Wu, 2013).…”

Peer Review #1 of "In vitro anti-diabetic effects and phytochemical profiling of novel varieties of Cinnamomum zeylanicum (L.) extracts (v0.1)"

“…In the current study, the percent yields obtained for SW, SG, and CC extracts prepared using SD were comparable to the previously reported yield (2.6%) for the commercially available C. zeylanicum in Turkey (Sihoglu Tepe & Ozaslan, 2020). Another finding showed a 352 mg/g yield for the freeze dried aqueous extract of C. zeylanicum and that was higher than the yield obtained in the current study (Takács et al, 2017). Manuscript to be reviewed essential oils (Li, Kong & Wu, 2013).…”

Inhibition studies on α-amylase using isothermal titration calorimetry

“…Some of the herbs tested in this project have been proven to be α-amylase inhibitors. Cinnamon extracts inhibited PPαA [29] and HSαA [30] during in vitro experiments. They were effective in rat starch tolerance test and also in human clinical trials as antidiabetic agent [31].…”