Catharnthus alkaloids XXXI: Isolation of ajmalicine, pericalline, tetrahydroalstonine, vindolinine, and ursolic acid from Catharanthus trichophyllus roots

✍ Scribed by Alvin B. Segelman; Norman R. Farnsworth

• Publisher: John Wiley and Sons
• Year: 1974
• Tongue: English
• Weight: 415 KB
• Volume: 63
• Category: Article
• ISSN: 0022-3549
• DOI: 10.1002/jps.2600630918

✦ Synopsis

Certain active cytotoxic alkaloid fractions prepared from Catharanthus trichophyllus roots were investigated. This work resulted in the isolation of ajmalicine, pericalline, tetrahydroalstonine, vindolinine, and ursolic acid. These compounds were not responsible for the observed cytotoxic activity. Ajmalicine, tetrahydroalstonine, and ursolic acid were previously isolated from this plant, whereas vindolinine and pericalline are now reported for the first time from C. trichophyllus.

Keyphrases Catharanthus alkaloids-isolation of ajmalicine, pericalline, tetrahydroalstonine, vindolinine, and ursolic acid from C. trichophyllus roots, cytotoxic activity 0 Vindolinine-isolation and identification from C. trichophyllus roots, cytotoxic activity Pericalline-isolation and identification from C. trichophyllus roots, cytotoxic activity It has been reported that certain alkaloid fractions prepared from Catharanthus trichophyllus exhibit a significant inhibitory activity against the P-1534 leukemia in DBA/2 mice, as well as a cytotoxic activity against Eagle's 9KB carcinoma of the nasopharynx in cell culture (1). Prior to the present study, phytochemical investigations were limited to the aboveground parts of this plant and led to the isolation of ajmalicine (2), tetrahydroalstonine (l), vindorosine (l), and ursolic acid (1). The present phytochemical study dealt with the roots of C. trichophyllus and resulted in the isolation of ajmalicine, tetrahydroalstonine, vindolinine, pericalline, and ursolic acid. EXPERIMENTAL' Plant Material-The coarsely milled and air-dried roots2 of C. trichophyllus (Bak.) Pich. (Apocynaceae) used in this study were collected in Madagascar during 1969. Melting points were determined in open capillary tubes using a Thomas-Hoover apparatus and are uncorrected. Specific rotations were measured using a Rudolph model 70 precision polarimeter. UV spectra were taken in ethanol or methanol using a Perkin-Elmer model 202 spectrophotometer. IR spectra were measured in KBr pellets uersus air with a Beckman model IR-8 spectrophotometer. Mass spectra were recorded at 70 ev using a LKB-9000 mass spectrometer (LKB Produkter, Stockholm, Sweden), operated in the direct probe mode. NMR spectra were determined in deuterochloroform, containing tetramethylsilane as the interior standard, using a Varian model A-60 spectrometer or HR-100 spectrometer. All concentrations and evaporations were carried out with water pump vacuum at less than 40°. Routine TLC was carried out using silica gel C (Merck) plates. The solvent systems used were: A. ethyl acetate-absolute ethanol (3:l); B, 1-butanol-acetic aciddistilled water (4:l:l); C, anhydrous methanol (100%); D, chlorofom-acetone (54); E, benzeneethyl acetate (72); and F, benzene-ethyl acetate-diethylamine (7:21). Nonalkaloid substances were detected on TLC plates by spraying with sulfuric acid followed by charring at 120°. Ceric ammonium sulfate reagent (3) and modified Dragendorff (4) reagent were used as spray reagents to visualize resolved alkaloids on TLC plates. Preparative thicklayer chromatography was carried out on silica gel P F ~M (Merck) I-mm layers, resolved components being detected by quenching under 254-nm UV light. Appropriate zones were scraped from the plates and pure components were recovered from the removed zones by elution with ethanol, followed by filtration and removal of the solvent.