Microwave-Assisted Synthesis of Andrographolide Analogues as Potent β-Glycosidase Inhibitors

Abstract

Andrographolide, a bioactive compound isolated from Andrographis paniculata exhibits multiple pharmacological activities, including anti-HIV, antiplatelet aggregation, hepatic lipid peroxidation protective, hepatoprotective, choleretic, and anticancer effects. Herein, we report the synthesis of diverse analogues of andrographolide along with their β-glucosidase inhibitory activity against sweet almond β-glucosidase. The parent compound, And-1, displayed moderate inhibitory activity against the sweet almond β-glucosidase with IC 50 of 142.5 μM. Among the synthesised analogues And-10 showed the best activity, with IC 50 of 92.4 μM, whereas the oxidised products (And-4 and And-5) were moderately active against the tested enzyme. Additionally, compounds And-6, And-7, And-8, and And-10 exhibited better β-glucosidase inhibitory activity than the positive control Castanospermine, with IC 50 of 100.2, 102.4, 106.5, and 92.4 μM, respectively. These results highlight the importance of an electron-withdrawing NO 2 group on the phenyl moiety in attaining the better β-glucosidase inhibition. It is noteworthy that the effect of a particular group plays a significant role in bioactivity. This study thus highlights an important aspect with regard to the most active compounds, which could extend the arsenal of compounds affecting the corresponding enzymes after further polishing and fine tuning.