Five new indole alkaloids from the leaves of Rauvolfia yunnanensis.

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.

https://www.mdpi.com/1420-3049/24/24/4574/pdf

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

Rauvolfia yunnanensis Tsiang are commonly used as a folklore herb to treat hypertension, snake bites, and insanity in the southwest of China, and an important industrial raw material of reserpine. The phytochemical constituents of the rhizome of it have been investigated intensively. Reserpine and yohimbine are two effective biological activities compounds isolated from the rhizome of Rauvolfia yunnanensis. But the wild resources of it reduced gradually in recent years, thus we have introduced and cultivated it to the arid hot valley region of Yunnan. China, and investigated the chemical constituents variety of it for the sustainable utilization. In the present work, the chemical-constituents of the flowers of R. yunnanensis have been investigated for extending the utilizable efficiency of resources. The dried flowers powder(1.0 kg) of R. yunnanensis was extracted with 95% EtOH(10 L x 6, 48 h each) at room temperature, and then extracted successively with EtOAc(1 L x 6). The EtOAc portion(50 g) led to the isolation of nine compounds by column chromatography (silica, alumina and Sephadex LH-20 gel) methods. Their structures were identified as(18Z)-11-methoxypicrinine(1), caberoline(2), 11-methoxystrictamine(3), strictamine(4), russulamide(5), ursolic acid (6), urs-12 (13)-en-3 alpha-yl acetate(7), beta-amyryl nonanoate(8) and beta-sitosterol (9) by spectral analysis(UV, IR, MS and ID, 2D NMR), respectively. Among them, compound 1 is a new indole alkaloids, compounds 5, 7 and 8 are firstly isolated from it. But reserpine and yohimbine haven't been isolated.

Wang Hai-Bo

Papers

Novel Indole Alkaloid from the Flowers of Rauvolfia yunnanensis