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Nine new monoterpenoid indole alkaloids, uncarialins A-I ( 1 - 9 ), were isolated from Uncaria rhynchophylla as well as 14 known analogues ( 10 - 23 ). Their structures were determined by HRESIMS, 1D and 2D NMR, and experimental and calculated electronic circular dichroism data. Compounds 5 , 7 , 15 , and 22 displayed significant agonistic effects against the 5-HT 1A receptor with EC 50 values of 2.2 ± 0.1, 0.1 ± 0.1, 1.6 ± 0.3, and 2.0 ± 0.5 μM, respectively. The mechanisms of action of these four compounds with the 5-HT 1A receptor were investigated by molecular docking, and the results suggested that amino acid residues Asp116, Thr196, Asn386, and Tyr390 played critical roles in the observed activity of the above-mentioned compounds.

An investigation on the bioactive chemical constituents of the roots of Euphorbia fischeriana has been conducted, with 21 diterpenoids obtained using various chromatographic techniques. On the basis of spectroscopic data analysis, the new compounds were elucidated as four ent-abietane-type diterpenoids (1-4) and four tigliane-type diterpenoids (13-16). Also obtained were eight known ent-abietane (5-12) and five known tigliane (17-21) diterpenoids. The potential antituberculosis effects of these diterpenoids were evaluated using a Mycobacterium smegmatis model. The most potent compound according to the in vitro bioassay used was 17-hydroxyjolkinolide B (12) (MIC 1.5 μg/mL).