Phenylpropanoids from the leaves and twigs of Croton mangelong and their biological activities.

Three previously undescribed phenylpropanoids, (7R)-crotomanin O (1a), (7S)-crotomanin O (1b), and crotomanin P (2), along with five known compounds (3a, 3b, 4-6) were isolated from the leaves and twigs of Croton mangelong. Compounds 1a and 1b, as well as 3a and 3b, were successfully resolved by Chiral HPLC analysis. Their structures were elucidated through extensive spectroscopic analysis, including HRESIMS, 1D and 2D, NMR. Among them, known compounds 3a, 3b, 4, and 6 were isolated from C. mangelong for the first time. The inhibitory activities of compounds 1a, 1b, 2, and the racemic mixture 1 against α-glucosidase, protein tyrosine phosphatase 1B (PTP1B) and nitric oxide (NO) production were evaluated. In addition, the known compounds 3, 3a, 3b, and 4 were also evaluated for their NO inhibitory activity. At a concentration of 50 μM, the racemate 1 showed significant inhibitory effects on NO production with percent inhibition rate of 54.58 ± 3.14%. Unexpectedly, 1a and 1b showed lower inhibitory rate of 31.01 ± 0.31% and 24.78 ± 1.57%, respectively, against NO production at the same concentration.