Two new degraded diterpenoids, trigohowilols A (1) and B (2), four new heterodimers, trigohowilols C–F (3–6), one new homodimer, trigohowilol G (7), and three known degraded diterpenoids (8–10) were isolated from the methanol extract of the stems of Trigonostemon howii. Compounds 1–7 were evaluated for their cytotoxic activity against five human tumor cell lines by an MTT assay, and trigohowilols E (5) and F (6) exhibited inhibitory activity with IC50 values ranging from 2.33 to 12.57 μM. Moreover, compounds 1–6 showed weak antimicrobial activities (MIC values: 6.25–25 μg/mL) against Staphylococcus aureus, Pseudomonas aeruginosa, MRSA 92#, and MRSA 98# using a 2-fold dilution method.
Gui-Hua Tang, Yu Zhang, Chun-Mao Yuan, Yan Li, Yu-Cheng Gu, Ying-Tong Di, Yue-Hu Wang, Guo-Ying Zuo, Shi-Fei Li, Shun-Lin Li, Hong-Ping He, and Xiao-Jiang Hao
J. Nat. Prod., Article ASAP
Publication Date (Web): November 13, 2012