Iridoid glycosides from the flowers of Gardenia jasminoides: Isolation, characterization, and antioxidant potential.

Four new iridoids elucidated as jasmigeniposide C (1), jasmigeniposide D (2), jasmigeniposide E (3), and jasmigeniposide F (4), along with six known iridoids (5-10) were isolated from the flowers of Gardenia jasminoides. Their structures were determined on the basis of spectroscopic analyses and chemical reactions. The antioxidant activities of these compounds were preliminarily evaluated by DPPH radical scavenging assay. The results revealed that compounds 1-5 exhibited some antioxidant activity. Notably, compound 2 displayed the most potent antioxidant activity among the tested compounds.