Swertisin chemotype of passionflower (Passiflora incarnata L.)

Passionflower (Passiflora incarnata) is a medicinal plant widely used for its sedative and anxiolytic properties. The botanical drug is included in the current European and British Pharmacopoeias and is characterised phytochemically by a number of flavonoids, including the C-glycosyl flavonoids vitexin, isovitexin, schaftoside and isoschaftoside [1]. Following the identification of P. incarnata raw material grown in Australia with an aberrant flavonoid profile, we undertook a survey of dried material originating in Italy (1 sample), India (1 sample) and Australia (8 samples). A commercial extract (Indena SpA) was also included. Five other Passiflora taxa, which are potential adulterants of the drug, were also analysed. Ethanolic (70%) extracts were analysed by HPLC and LC-MS. Methanolic extracts were used for TLC analysis. Samples were also examined macro- and microscopically. Other taxa were readily distinguishable from P. incarnata by both TLC and HPLC. The P. incarnata samples fell into two groups, each with a distinct flavonoid profile. Although both groups contained vitexin and isovitexin (albeit in different proportions), the samples from Italy and India, the commercial extract and two of the Australian samples all contained schaftoside/isoschaftoside, but no swertisin. In contrast, 6 other samples grown in Australia displayed a large swertisin peak and the absence of schaftoside/isoschaftoside. Although the flower colour was not known for all samples, the results suggest that the swertisin chemotype corresponds with the white-flowered phenotype P. incarnata 'Alba', while the normal chemotype corresponds with the typical purple-flowered phenotype. The existence of chemotypes may have implications for raw materials selection.

References: [1] Dhawan, K. et al. (2004) J Ethnopharmacol 94: 1–23.