The basic chemical substances of three medicinal parts from Rhododendron molle G. Don.

Rhododendron Molle G. Don belongs to Ericaceae family. As a toxic traditional Chinese medicine, its roots, flowers, and fruit are often mixed and substituted arbitrarily to treat rheumatoid arthritis in clinic. To clarify the main chemical basis of each medicinal part, and provide sufficient scientific basis for clinical application, analysis using HPLC-ELSD of the roots, flowers, and fruit from R. molle was established, and characteristic chemical constituents of them were separated by tracking. The structures were determined by NMR methods. Finally, 16, 21, and 18 compounds were obtained from the roots, flowers, and fruit, respectively. Overall, 49 compounds were obtained, of which 25 were identified for the first time in R. molle. Meanwhile, among the obtained compounds, 12, 11, and 6 characteristic peaks were identified from the roots, flowers, and fruit, respectively. Thus, the basic chemical substances of the medicinal parts of R. molle were determined initially.

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.