Investigation of the EtOAc fraction of Tagetes minuta L. (Asteraceae) aerial parts has afforded a
new flavonol glucoside, minutaside A (quercetagetin 6-O-(6-O-hexanoyl)-b-D-glucopyranoside)
(1), together with four known flavonoids: axillarin 7-O-b-D-glucopyranoside (2), quercetagetin
3,7-dimethoxy-6-O-b-D-glucopyranoside (3), quercetagetin 7-methoxy-6-O-b-D-glucopyranoside
(4), and quercetagetin 6-O-b-D-glucopyranoside (5). Their structures were established by
multiple spectroscopic methods in addition to HRESIMS (high-resolution electrospray
ionisation mass spectra) and comparison with literature data. The antioxidant and anti-diabetic
activities of the isolated flavonoids were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH)
and a-amylase inhibition assays. Compounds 1 and 5 showed significant antioxidant activity
(84.1 and 83.0% at a 20 mM dose, respectively). Compounds 1, 4, and 5 exhibited strong aamylase inhibitory activity compared with acarbose (a reference a-amylase inhibitor). However, 2
and 3 showed moderate activity. Molecular modeling studies of 1–5 that included docking,
flexible alignment, and surface mapping were performed to evaluate their recognition profile aamylase receptor. In docking simulations, 5 displayed a binding mode similar to that of acarbose
in the active site of a-amylase enzyme.