Left, Right, or Both? On the Configuration of the Phenanthroindolizidine Alkaloid Tylophorine from Tylophora indica

The alkaloid (−)-tylophorine was isolated from a sample of Tylophora indica, and the crude extract was analyzed by HPLC/MSⁿ and chiral HPLC/MS. While the literature states that the naturally occurring form of this alkaloid is the R-enantiomer and that its S-antipode is usually not found in nature, we confirmed the hypothesis of Govindachari and Nagarajan that natural levorotatory tylophorine is indeed a nearly racemic mixture with a slight excess of the R-enantiomer.