Chemical Diversity and Bioactivities of Monoterpene Indole Alkaloids (MIAs) from Six Apocynaceae Genera

By the end of the twentieth century, the interest in natural compounds as probable sources of drugs has declined and was replaced by other strategies such as molecular target-based drug discovery. However, in the recent times, natural compounds regained their position as extremely important source drug leads. Indole-containing compounds are under clinical use which includes vinblastine and vincristine (anticancer), atevirdine (anti-HIV), yohimbine (erectile dysfunction), reserpine (antihypertension), ajmalicine (vascular disorders), ajmaline (anti-arrhythmic), vincamine (vasodilator), etc. Monoterpene Indole Alkaloids (MIAs) deserve the curiosity and attention of researchers due to their chemical diversity and biological activities. These compounds were considered as an impending source of drug-lead. In this review 444 compounds, were identified from six genera belonging to the family Apocynaceae, will be discussed. These genera (Alstonia, Rauvolfia, Kopsia, Ervatamia, and Tabernaemontana, and Rhazya) consist of 400 members and represent 20% of Apocynaceae species. Only 30 (7.5%) species were investigated, whereas the rest are promising to be investigated. Eleven bioactivities, including antibacterial, antifungal, anti-inflammatory and immunosuppressant activities, were reported. Whereas cytotoxic effect represents 47% of the reported activities. Convincingly, the genera selected in this review are a wealthy source for future anticancer drug lead.

Bioactivity-Guided Isolation and Identification of New and Immunosuppressive Monoterpenoid Indole Alkaloids from Rauvolfia yunnanensis Tsiang

Three new 11-hydroxyburnamine (1) and rauvoyunnanines A-B (2-3), and fourteen known (4-17) monoterpenoid indole alkaloids were isolated from the total alkaloids extract of Rauvolfia yunnanensis, which exhibited promising immunosuppressive activity on T cell proliferation in preliminary screening. Their structures were determined by analysis of high-resolution electrospray ionization mass (HRESIMS), ultraviolet (UV) and nuclear magnetic resonance (NMR) data, and by comparison with the literature. All the alkaloids were evaluated for inhibitory activity on T cell proliferation. Among them, one new compound (1) and reserpine (6) exhibited moderate immunosuppressive activity, with IC50 values of 5.9 μM and 5.0 μM, respectively.