In vitro antiglycation and hypoglycaemic effects of Syzygium cumini leaf extracts

Abstract

Glycation is a prime mechanism responsible for chronic diabetic complications, a process which is enhanced under hyperglycaemia. Natural inhibitors of protein glycation and those which can lower postprandial blood glucose elevation are of utmost importance in minimising the damage caused by diabetes. One objective of this study was to assess the in vitro inhibitory effects of Syzygium cumini (SC) leaf extracts on protein glycation and α-glucosidase activity. The other objective was to identify the type of inhibition on α-amylase activity. SC leaf powder was sequentially extracted with hexane (H), ethyl acetate (E), methanol (M) and water (W). In vitro inhibitory effects of extracts on protein glycation, α-amylase and α-glucosidase enzymes were measured. M and W were the major fractions recovered [50.74 and 27.94 % (w/w), respectively] while H was the smallest fraction [7.35 % (w/w)] out of total yield. All extracts inhibited fructosamine formation, protein glycation and protein crosslinking at 2 mgmL -1 . At 0.05 mgmL -1 , fructosamine formation was inhibited in the presence of E, M and W while there was no significant inhibition with H. At 0.1 mgmL -1 , antiglycation effect of the H extract was negligible while other extracts retained their effects. IC 50 values of H, E, M and W extracts against α-glucosidase were 7.89, 3.11, 0.86 and 0.69 µgmL -1 , respectively. A mixed type inhibitory effect was observed on α-amylase with E, M and W extracts. H extract did not inhibit α-amylase. In conclusion, the results provide evidence for antiglycation and hypoglycaemic effects of SC leaf extracts demonstrating better activities in E, M and W extracts.

Antidiabetic Activity of Widely Used Medicinal Plants in the Sri Lankan Traditional Healthcare System: New Insight to Medicinal Flora in Sri Lanka

“…A significant blood glucose reduction was observed in healthy mice treated with the methanol extract of S. cumini bark (0.25 mg/g) [ 54 ]. Hexane, ethyl acetate, methanol, and water extracts resulted from sequential extraction on leaf powder of S. cumini at a dose of 2 mg/mL showed an inhibition of fructosamine formation, protein glycation, and protein cross-linking [ 55 ]. Moreover, the same study revealed that the water extract exerts the highest α -glucosidase inhibitory activity with an IC 50 value of 0.69 µ g/mL.…”

The α-glucosidase inhibitory activity of avicularin and 4-O-methyl gallic acid isolated from Syzygium myrtifolium leaves

“…A previous in vitro study of multiple Syzygium revealed their potential as α-glucosidase inhibitors. Other species include Syzygium aqueum ( Manaharan et al, 2012 ), Syzygium aromaticum ( Adefegha and Oboh, 2012 , Oboh et al, 2015 ), Syzygium cumini ( Ajiboye et al, 2020 , Franco et al, 2020 , Perera et al, 2018 , Liu et al, 2018 , Omar et al, 2012 , Priya et al, 2018 , Trinh et al, 2016 ), Syzygium malaccence ( Arumugam et al, 2014 , Arumugam et al, 2016 ); Syzygium polyanthum ( Abdulrahman et al, 2019 , Dewijanti et al, 2020 , Elya et al, 2015 , Rahayu et al, 2019 ).…”