Fourteen alkaloids were isolated from the stem bark of MELODINUS TENUICAUDATUS Tsiang et P. T. Li. Eleven of them were identified as known alkaloids, namely, scandine ( 2), Delta (14)-eburnamine ( 4), vindolinine N(b)-oxide ( 5), 11-methoxytabersonine ( 6), vindolinine ( 7), EPI-vindolinine N(b)-oxide ( 8), hazuntine ( 9), compactinervine ( 10), 11-hydroxytabersonine ( 11), Delta (14)-vincine ( 12), and normacusine B ( 14). Two alkaloids were new: 10-hydroxyscandine ( 1), and the dimer, tenuicausine ( 3); their structures were elucidated by spectroscopic and chemical methods. One alkaloid ( 13) occurring in trace amounts, could not be identified.

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Hispidanins A-D (1-4), four unprecedented asymmetric dimeric diterpenoids, were obtained from the rhizomes of Isodon hispida. Their structures were elucidated by extensive spectroscopic analysis (1D and 2D NMR, MS, UV, IR), as well as single-crystal X-ray diffraction analysis. Hispidanin B showed significant cytotoxicities against tumor cell lines SGC7901, SMMC7721, and K562, with IC50 values of 10.7, 9.8, and 13.7 μM, respectively.