ABSTRACT
Eleven alkaloids including four previously undescribed oxoisoaporphine alkaloids, menisoxoisoaporphines A-D (1-4), four known analogues (5-8), and three aporphine alkaloids (9-11), were isolated and identified from the rhizomes of Menispermum dauricum. Their structures were elucidated by extensive spectroscopic data and single-crystal X-ray diffraction analyses. Among them, compounds 1 and 4 were the first samples of oxoisoaporphine with C-6 isopentylamino moiety, and 2 was a rare C-4 methylation product of oxoisoaporphine alkaloid. The in vitro anti-inflammatory activity of compounds 1-11 was performed by evaluating the inhibition of NO level in LPS-induced RAW264.7 macrophages. Among them, compound 4 exhibited the most potent NO inhibition activity with an IC50 value of 1.95 ± 0.33 µM. The key structure-activity relationships of those oxoisoaporphine alkaloids for anti-inflammatory effects have been summarized.
ABSTRACT
Four previously unreported tirucallane-type triterpenoids (1-4), together with four known analogues (5-8), were isolated from the fruits of Melia toosendan Sieb. et Zucc. Their planar structures were comprehensively elucidated by detailed analyses of HRESIMS, 1D and 2D NMR spectra data. The relative configurations of 1-4 were determined by NOESY experiments. The comparison of experimental and calculated electronic circular dichroism (ECD) spectra led to the establishment of the absolute configurations of new compounds. All isolated triterpenoids were evaluated for their α-glucosidase inhibitory activities in vitro. Compounds 4 and 5 showed moderate α-glucosidase inhibitory activities with IC50 values of 120.3 ± 5.8 and 104.9 ± 7.1 µM, respectively.
