Effect of Nitrogen Fertilizer on Yield and Amount of Alkaloids in Periwinkle and Determination of Vinblastine and Vincristine by HPLC and TLC

Periwinkle (Catharanthus roseus L.) is a most important medicinal plant which is a rich source of bioactive compounds such as alkaloids. The purpose of the present study was to investigate the effect of various concentrations of nitrogen on content and yield of alkaloids in periwinkle. This study showed that there were significant differences among various concentrations of nitrogen in all measured parameters except the fresh and dry weight of shoot tips. The results indicated that the fresh and dry weight of total foliage of periwinkle increased with increasing the amount of nitrogen fertilization from 0-100 kg N ha-1 and then decreased at 150 kg N ha-1. The alkaloids of vinblastine and vincristine were measured by HPLC and TLC assays. The highest content and yield of vinblastine was observed in 150 kg N ha-1 while the lowest content and yield of vincristine was found in 150 kg N ha-1 by both methods of assessment. The results also showed that the content and yield of vinblastine and vincristine quantified with HPLC assay was higher than the samples determined by TLC method. The results provided important information of nitrogen effect on yield and alkaloid content of plant for commercial production of periwinkle.