Evaluation of the Best Procurement Time for Ashwagandha [Withania somnifera (L.) Dunal] Root by Liquid Chromatographic and Pharmacognostical Studies

Abstract

Aim: The present study was undertaken to establish the best procurement time for collection of Ashwagandha [Withania somnifera (L.) Dunal] root by analyzing the variation in bioactive secondary metabolite during six seasons by quantitative high performance liquid chromatography (HPLC) and comparative pharmacognosy by taking into consideration the Ayurvedic literature. In Ayurveda, Sharad ritu has been prescribed for procurement of crude drugs. But the description for procurement of useful part of individual plants is not mentioned anywhere in the literature. Therefore, to establish the best time for collection, the present study has been taken up. Materials and methods: To establish the best time for collection, Ashwagandha root was collected from the same habitat in all six seasons described in Ayurveda: i.e., Shishir (January-February), Vasant (March-April), Grishm (May-June), Varsha (July-August), Sharad (September-October), and Hemant (November-December). Authentication of the source of collected plant was carried out in the herbarium NVARI, Jhansi. Identification and authentication of the collected plant material through macro-, micro-, and powder microscopic studies were carried out besides extraction and its quantitative HPLC evaluation for the best procurement time for all six seasons. Results: The present study showed that internal microscopical features remain the same throughout the year, although a variation was observed in extractive values and selective marker compound. Withanolide A was taken as a selected marker compound and was quantified in samples collected in each season by HPLC. An extractive value was found to be maximum at 0.77 g in the sample collected in Sharad ritu for methanol extract. HPLC estimation showed that the abundance of Withanolide A is more up to 0.183% in the Hemant ritu sample among all seasons.