Altitudinal and Seasonal Variation in Bioactive Compound Aconitine in Aconitum violaceum, a Threatened Medicinal Plant of Indian Himalayan Region

Aconitum violaceum Jacq. (Ranunculaceae) is an important medicinal plant of the Indian Himalayan Region shares its position with threatened plant species. The present study was carried out to investigate the altitudinal and seasonal variation in content of bioactive compound aconitine in different plant parts of Aconitum violaceum Jacq. Plants were collected in three seasons from five populations across the altitudinal gradients. Morphological features were, in general, negatively correlated with an increase in the altitude. Maximum plant height (26.9 ± 3.1 cm) was observed in populations from lower altitude (Hemkund I, 3650 m asl), whereas, the minimum value (14.2 ± 2.9 cm) was recorded from the relatively higher altitude (Hemkund V, 4400 m asl). Maximum vegetative growth was observed in month of September. The aconitine content of the plant ranged between 0.081 to 0.99% (on dry wt. basis, in different parts of the plant). The result indicated that the aconitine content was found to be significantly higher in tubers as compared to other parts of the plant e.g. stem, leaves, buds, at every altitude. The biosynthesis of aconitine in tubers was found to be highest in the month of October (0.99% on dry wt. basis). The maximum aconitine content reported in the leaves was highest in the month of August, which is the pre-flowering season of the plant, however, aconitine content decreases significantly during month of October. Effect of altitude on aconitine content was also analyzed. A positive correlation was observed between the aconitine content and the altitude of growing sites.