RESUMEN
Isodon amethystoides (Benth.) Hara (IA) tea is a commonly used dietetic Chinese herb and employed for the treatments of tumor and lung abscess. To assess chemical composition and antioxidant capacity of IA leaves extract, a UPLC-LTQ-Orbitrap-MS method and antioxidant tests were used, respectively. 17 compounds were identified including Vinyl caffeate (1), 3,4-dimethoxyphenyl-ß-D-glucopyranoside (2), Rutin (3), Quercetin (4), Loliolide (5), Caffeic acid (6), Rubesanolide D (7), Isorhamnetin (8), Lambertic acid (9), 6, 7-Dehydroroyleanone (10), Dihydrorabdokunmin C (11), Nervosin (12), Quercitrin (13), Vitexin (14), ß-sitosterol (15), Wangzaozin A (16), Amethystonoic acid (17). Among these, 1-14 compounds were novel and have not been reported ever before in IA while component 10 was a novel finding within this genus. Flavonoid components showed better free radical scavenging ability and profound correlation was observed between diterpenoid compounds content and flavonoids activity. Our results provide experimental basis for extraction and separation of chemical constituents of IA which are antioxidant in nature.