Menisperdaurines A-W, structurally diverse isoquinoline alkaloids from Menispermum dauricum and their dopamine D1 receptor activities.

A total of 33 structurally diverse isoquinoline alkaloids were isolated from the rhizomes of Menispermum dauricum, including seventeen benzylisoquinoline analogues (menisperdaurines A-Q, 1-17), five protoberberine analogues (menisperdaurines R-V, 18-22), a quaternary phenanthrene alkaloid (menisperdaurine W, 23) and ten known compounds (24-33). Compound structures, including absolute configurations, were determined by extensive spectroscopic methods, quantum chemical calculations of chemical shifts, and calculated and experimental electronic circular dichroism (ECD) data. Compounds 1-5 were glycosidic benzylisoquinolines with glucose moieties attached at the C-12 position. Compound 8 was the first example that was isolated from the rhizomes of Menispermum dauricum, benzylisoquinoline and an aromatic unit connected by a sugar bridge. Compounds were evaluated for their inhibitory effects on the dopamine D1 receptor. Compounds 1, 8, 21, 24 and 29 showed potent D1 antagonistic activities, with IC50 values ranging from 1.0 to 4.5 µM. Compound 1 exhibited the highest antagonistic activity with an IC50 value of 1.0 ± 0.2 µM.

Isoquinoline alkaloid dimers with dopamine D1 receptor activities from Menispermum dauricum DC.

A phytochemical investigation on chemical constituents from the rhizomes of Menispermum dauricum DC. identified eight undescribed dimeric alkaloids with structurally diverse monomeric isoquinoline. Alkaloid structures were elucidated by a combination of spectroscopic data analyses and time-dependent density functional theory (TDDFT) ECD calculation. The isolates were evaluated for inhibitory effect on dopamine D1 receptor and compound 1 exhibited potent D1 receptor antagonistic activity with an IC50 value of 8.4 ± 2.0 µM.

Anti-rheumatoid arthritis potential of diterpenoid fraction derived from Rhododendron molle fruits.

Rhododendron molle G. Don is first recorded in Shengnong's Herbal Classic, and its fruits, which are termed as Liuzhouzi, are often used to treat rheumatoid arthritis in Chinese folk. During our ongoing investigation to develop a safer and potential new arthritis therapy, a process for the preparation of diterpenoid fraction from Rhododendron mollefruits was established. In order to evaluate the main components and the anti-rheumatoid arthritis effect of the diterpenoid fraction, phytochemical and pharmacological experiments were used. As the result, the main components of diterpenoid fraction were identified as rhodojaponin III (1), rhodojaponin VI (2), 2-O-methylrhodojaponin (3), and 5'-ß-D-glucopyranosy-loxyjasmonic acid (4). These four components constitute greater than 95% of diterpenoid fraction using area normalization method of HPLC-ELSD. The results of CIA rat experiment showed that high dose of diterpenoid fraction (0.6 mg·kg-1·d-1) significantly alleviated the symptoms of rheumatoid arthritis, similar to tripterygium polyglycosides, an effective RA therapy. Preliminary mechanism studies indicated that diterpenoid fraction significantly inhibited the abnormal proliferation of T and B lymphocytes, and remarkably reduced the levels of pro-inflammatory cytokines IL-6, IL-1ß and TNF-α. Overall, our findings may provide a more effective and safe alternative treatment for RA using common clinical Chinese medicines like tripterygium polyglycosides.