Withasteroids are a group of naturally occurring C28-steroidal lactones built on an intact or rearranged ergostane framework. Withaferin A (64), the first member of this group of compounds, was isolated (1) from the well-known Indian medicinal plant, Withania somnifera (Sanskrit: Aswagandha) and its structure was fully elucidated by Lavie and coworkers in 1965 (2). The structural novelty and interesting biological activities (3) elicited by this compound led to a thorough chemical investigation of the plant and numerous compounds having similar structural features were isolated. These C28-steroidal lactones characterised by a nine carbon side chain with a six membered ring lactone were designated as ‘withanolides’after the name of the plant genus (4). The withanolide skeleton may therefore, be defined as 22-hydroxyergostan-26-oic acid 26,22-lactone (I) and using this trivial name, withaferin A (64) may be designated as 4β, 27-dihydroxy-5β, 6β-epoxy-l-oxowitha-2,24-dienolide, the nomenclature that has been most widely adopted. However, many structurally related C28-steroidal lactones which do not conform to the above definition have also been referred to as with-anolides (5), a practice giving rise to confusion. Also, there are many novel structural variants of withanolides with modifications either of the carbocyclic skeleton or of the side chain and these have often been described as modified withanolides or ergostane-type steroids related to withanolides.

Withasteroids, a Growing Group of Naturally Occurring Steroidal Lactones

This study involves a detailed investigation about the effect of three elicitors, such as chitosan, jasmonic acid and salicylic acid (SA) on withaferin A and withanolide A contents of Withania somnifera (L.) Dunal (Poshita variety). Moreover, the different environmental regimes were also studied to assess and optimise the accumulation of withaferin A and Withanolide A contents. In an open environment, the total withaferin A content was found to be increased 6.3 and 5.8 times when sprayed with chitosan, 10 ppm and 50 ppm, respectively, as compared to control. Similarly, the total withanolide A content was found to be increased 4.5 and 3.6 times when sprayed with jasmonic acid (400 ppm and 200 ppm, respectively) with respect to control. In a controlled condition, the total withaferin A content was found to be increased 6 and 4.5 times when sprayed with jasmonic acid (400 ppm and 200 ppm, respectively) as compared to control. On the other hand, the total withanolide A content was found to be enhanced by 7 and 4.3 times when sprayed with jasmonic acid (400 ppm) and SA (1 ppm), respectively, as compared to control. Therefore, this study was focussed on the optimisation of enhanced accumulation of withaferin A and withanolide A contents in the aerial parts of the plant in open and controlled environment by foliar application of elicitors in minimal concentrations.

Foliar application of elicitors enhanced the yield of withanolide contents in Withania somnifera (L.) Dunal (variety, Poshita)

Withania somnifera (L.) Dunal is a valuable medicinal plant in the Solanaceae family. It is commonly known as Ashwagandha and is widely distributed around the globe. It has multiple pharmacological properties owing to the existence of diverse secondary metabolites viz., withanolide A, withanolide D, withaferin A, and withanone. It is in great demand in the herbal industry because of its extensive use. In this background, the major challenge lies in the rapid multiplication of elite cultivars of W. somnifera in order to produce genetically and phytoconstituents uniform plant material for pharmaceutical industries. Thus it is necessary to explore various biotechnological approaches for the clonal mass propagation and synthesis of pharmaceutically important constituents in W. somnifera. Though there are several studies on in vitro propagation on W. somnifera, yet many factors that critically influence the in vitro response and withanolides production need to be fine-tuned in the pretext of the existing knowledge. The current review focuses on the advancements and prospects in biotechnological interventions to meet the worldwide demands for W. somnifera and its bioactive compounds. This update on in vitro studies on W. somnifera will be useful to many researchers, entrepreneurs, and herbal industries looking for its in vitro mass multiplication and scientific utilization. 

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Critical factors influencing in vitro propagation and modulation of important secondary metabolites in Withania somnifera (L.) dunal

Bioinoculants in agriculture are employed to promote crop growth and development mainly by mobilizing soil nutrients and tolerance to abiotic stresses. As the population is increasing, the demand for agricultural products also increases which can be achieved by manipulating or introducing enhance agricultural methods. In recent years, the application of chemical growth regulators, fertilizers, and pesticides has increased that has imposed serious threats to humankind. Therefore, bioinoculants are being targeted for achieving an environment-friendly and economic alternative for sustainable farming. The plant–microbiome associations play a critical part in plant’s growth and development by changing over inaccessible nutritional components into an accessible form. In conclusion, bioinoculants based sustainable agricultural frameworks must be essential to address food security, biosafety, and soil management.

Bioinoculants for Agricultural Sustainability

An overview of biotechnological interventions and abiotic elicitors on biomass and withanolide biosynthesis in Withania somnifera (L.) Dunal

Five varieties of Ashwagandha (Withania somnifera L. (Dunal) i.e. Chetak, Pratap, Nimithli, Poshita and Jawahar-20 were analyzed for withanolide A and withaferin A. These components were evaluated from leaf, stem, root and seeds using HPLC. These components were present in all these tissues. However, their content varies from tissues to tissue and variety to variety viz (Chetak, Pratap, Nimithli, Poshita and Jawahar-20). Withaferin A and withanolide A contents were found to be highest in Poshita followed by Jawahar-20. Withaferin A and withanolide A contents were also evaluated and compared in field-grown and in-vitro grown plants of Poshita and Jawahar-20. Callus derived from Poshita root showed the highest withaferin A content however, withanolide A was found to be highest in callus derived from Jawahar-20 leaf. Thus this study indicated that promoting an elite variety through tissue culture with consistency in the withanolide contents can be a promising approach to meet the growing demand of Ashwagandha. Key-words: Withania somnifera, Withaferin A, Withanolide A, HPLC, Field grown, In-vitro grown, Ashwagandha INTRODUCTION Withania somnifera (L.) Dunal, popularly known as Ashwagandha, is a high valued medicinal plant of India. It is a priority medicinal plant which is identified by National Medicinal Plant Board of India. The roots and leaves of Ashwagandha contain various alkaloids viz withanolides [1] and withaferin A . Among withanolides, withaferin A and withanolide A have been reported to be dominant metabolite distributed among various tissues of this plant in varying concentrations . How to cite this article Singh M, Shah P, Punetha H, Agrawal S. Varietal Comparison of Withanolide

Pallavi Shah

Papers

Varietal Comparison of Withanolide Contents in Different Tissues of Withania somnifera (L.) Dunal (Ashwagandha)