Pharmacognosy and Chemotypes of Passionflower (Passiflora incarnata L.)

Passionflower (Passiflora incarnata L.) is used in phytotherapy as a mild sedative and anxiolytic agent. In the literature it is clear this plant shows considerable qualitative and quantitative variability with respect to its content of C-glycosyl flavones, some of which are used as marker compounds for extracts. Analysis of plant material cultivated in Australia revealed two chemically distinct groups; hence an investigation was carried out to determine whether distinct intraspecific chemotypes exist in this species. Eleven P incarnata samples were analysed by HPLC, LC-MS and two different TLC methods. The samples fell into two distinct groups with respect to their C-glycosyl flavone profile, with little within-group variation. One chemotype was dominated by isovitexin and schaftoside/isoschaftoside, as is most widely reported in the literature for this species. The other chemotype was characterized by a high level of swertisin, with low levels of schaftoside/isoschaftoside. The two chemotypes are readily identified by both HPLC and TLC. Although the compounds responsible for the therapeutic activity of P incarnata are yet to be identified, phytomedicines should be made with the accepted isovitexin chemotype until the pharmacological implications of chemotypical differences are understood.