New thiophene and flavonoid from Tagetes minuta leaves growing in Saudi Arabia

Phytochemical investigation of the methanolic extract of Tagetes minuta L. (Asteraceae) leaves resulted in the isolation and identification of two new compounds: 5-methyl-2,2',5',2'',5'',2''',5''',2''''-quinquethiophene (1) and quercetagetin-6-O-(6-O-caffeoyl-β-D-glucopyranoside) (9), in addition to seven known compounds: quercetin-3,6-dimethyl ether (2), quercetin-3-methyl ether (3), quercetin (4), axillarin-7-O-β-D-glucopyranoside (5), quercetagetin-3,7-dimethoxy-6-O-β-D-glucopyranoside (6), quercetagetin-7-methoxy-6-O-β-D-glucopyranoside (7), and quercetagetin-6-O-β-D-glucopyranoside (8). The compounds were identified by UV, IR, 1D, 2D NMR, and HRESIMS spectral data. They showed significant antioxidant activity, comparable with that of propyl gallate. Compounds 8 and 3 showed weak to moderate antileishmanial and antimalarial activities, with IC₅₀ values of 31.0 μg/mL and 4.37 μg/mL, respectively.