Green tea flavonols inhibit glucosidase II

Anti-hyperglycaemic effects of the Japanese red maple Acer pycnanthum and its constituents the ginnalins B and C

“…In addition, the galloyl part may inhibit enzymes through a high affinity for proteins [24]. And these tannins inhibit α-glucosidase in an uncompetitive manner [21,25]. It is also conceivable that the 1-deoxyglucose part of 1 or 2 may imitate glucose and mimic a disaccharide.…”

“…With regard to 1 and 2, it has been reported that some galloyl derivatives have shown α-glucosidase-inhibitory activity, such as epigallocatechingallate from tea (Camellia sinensis) [21] and ellagitannins from clove (Syzgium aromaticum) [22]. Gallotannins show high affinity for sugars [23], and gallotannin and sugars may form hydrogen bonds through the galloyl part of these compounds in the small intestine, and this may prevent their absorption.…”

Simultaneous Quantification of Bergenin, (+)-Catechin, Gallicin and Gallic acid; and Quantification of β-Sitosterol using HPTLC from Bergenia ciliata (Haw.) Sternb. Forma ligulata Yeo (Pasanbheda)

“…Bergenin is reported to have hepatoprotective [40], and immunomodulatory [41] activity. (+)-Catechin has been shown to have antioxidant [42], glucosidase-II [43] and matrix metalloproteinase inhibitory activity [44] and renoprotective effect [45]. It has also been reported to induce cancer preventive activity mediated through a chaperone like property [46].…”

Studying the interactions between tea polyphenols and α-amylase

“…Interestingly, the observed inhibitory effect was not dependent on the total phenolic content levels of the apple juice varieties, which is not in agreement with a positive correlation between α-amylase inhibitory activity and total phenolic content (Barbosa, Pinto, Sarkar, Ankolekar, Greene, & Shetty, 2010). This may result from the variances of some single phenolic compounds which have inhibitory effect on α-amylase, such as chlorogenic acid (Narita & Inouye, 2011), caffeic acid (Narita & Inouye, 2011), and flavan-3-ols (Gamberucci, Konta, Colucci, Giunti, Magyar, Mandl, et al, 2006). Hence, identifying the significance of individual phenolic compound accounting for the inhibitory effect of juice on α-amylase is necessary.…”

“…It has been reported that some plant extracts can perform bioactivity potentially beneficial to human health by inhibiting the activities of carbohydrate hydrolyzing enzymes, and the main active constituents in these plant extracts are phenolic compounds such as flavonoids that have several hydroxyl groups (Barrett, et al, 2013;Gamberucci, et al, 2006;Kamiyama, Sanae, Ikeda, Higashi, Minami, Asano, et al, 2010). The inhibitory activities of flavonoids have been reported to depend on not only the substitution of hydroxyl groups that can form hydrogen bonds with the catalytic residues of enzyme, but also the unsaturated C-ring with keto-group that is speculated to be responsible for the formation of a conjugated π-system that is proposed to stabilize the interactions with the active site of enzyme (Lo Piparo, Scheib, Frei, Williamson, Grigorov, & Chou, 2008).…”