Podophyllotoxin content in leaves and stems of Podophyllum hexandrum Royle from Indian Himalayan region

Abstract

The rhizomes of Podophyllum hexandrum Royle, a perennial herb found in restricted areas of the Himalayan region, is a commercial source of podophyllotoxin, a highly valued aryltetralin used as precursor of some widely used anticancer drugs. This detailed investigation highlights an alternative source of podophyllotoxin from leaves and stems of three morphological variants of P. hexandrum with one leaf (1 L), two leaves (2 L) and three leaves (3 L), collected from seven populations (2800 to 3600 m) of Uttarakhand state in Indian central Himalaya. In general, podophyllotoxin content (on % dry wt.) varied significantly (p < 0.05) between the morphological variants, in both leaf and stems. The content of leaf ranged from 0.001 to 0.599%; maximum (0.599%) podophyllotoxin in 3 L (Dodital), and minimum (0.001%) in 1 L and 3 L (Kedarnath) plants were detected. The mean podophyllotoxin content (population wise) was significantly (p < 0.05) higher in Dodital population, with maximum value (0.229%) in Dodital and minimum (0.003%) in Kedarnath. The levels in stem samples were found in the range of 0.001 to 0.596%, similar to those found in the leaves. While maximum amount (0.596%) was estimated in 3 L plants from Dodital, the minimum (0.001%) level was found in 1 L (Kedarnath), 2 L (Garur Chatti) and 3 L (Kedarnath) plants. The mean podophyllotoxin content (population wise) was significantly (p < 0.05) higher in Dodital, Dayara and Bharnala populations, with maximum value (0.234%) in Dodital. Both the leaves and stems of 3 L plants (from Dodital) contained maximum levels of podophyllotoxin. The observed variation in content emphasizes the need for the selection of ‘elites’ based on higher toxin content; use of stem and leaves should be seen as a renewable source of podophyllotoxin. Key words: Conservation, leaf, podophyllotoxin, renewable, medicinal herb.