Bilal Ahmad Mir

Natural products as lead compounds in drug discovery

This review surveys the diversity of natural products (NPs) derived from terrestrial plants, micro-organisms, marine organisms and fungi used in the treatment of various diseases. A wide spectrum of compounds derived from these sources has been found to have many applications in the fields of medicine, pharmacy, and general biology. The enormous structural diversity of NPs and their medicinal significance has led researchers to predict that screening natural resources will generate new ‘lead’ compounds. It is well established that structural analogs with greater pharmacological activity and fewer side effects can be generated by molecular modification of the functional groups of such lead compounds. The compounds derived from various NP sources have been a basis for the development of clinically important agents active against various diseases, including taxol, vinblastine, vincristine, and topotecan, which are important anticancer agents in widespread clinical use. A number of other promising agents such as flavopiridol, combretastatin, betulinic acid, and silvesterol are in clinical or preclinical development. A large number of anti-infective agents in clinical use are also derived from NPs.

Recombinant hyperthermophilic enzyme expression in plants: a novel approach for lignocellulose digestion

Plant biomass, as an abundant renewable carbon source, is a promising alternative to fossil fuels. However, the enzymes most commonly used for depolymerization of lignocellulosic biomass are expensive, and the development of cost-effective alternative conversion technologies would be desirable. One possible option is the heterologous expression of genes encoding lignocellulose-digesting enzymes in plant tissues. To overcome simultaneously issues of toxicity and incompatibility with high-temperature steam explosion processes, the use of heterologous genes encoding hyperthermophilic enzymes may be an attractive alternative. This approach could reduce the need for exogenous enzyme additions prior to fermentation, reducing the cost of the complete processing operation. This review highlights recent advances and future prospects for using hyperthermophilic enzymes in the biofuels industry.

Assessment and characterization of genetic diversity in Withania somnifera (L.) Dunal using RAPD and AFLP markers

Genetic diversity of 23 accessions of Withania somnifera collected from different geographical regions of India was estimated by employing Random Amplification of Polymorphic DNA (RAPD) and Amplified Fragment Length Polymorphism (AFLP) markers. Eighteen RAPD primers and six AFLP primer combinations revealed 37.82 and 43.94% polymorphism, respectively, among 163 and 286 genetic loci amplified. The AFLP assay revealed higher levels of polymorphism among the tested W. somnifera accessions compared to the RAPD. Mean genetic diversity based on Shannon index ranged from 1.33 (RAPD) to 5.13 (AFLP). Unweighted pair group method based on arithmetic average (UPGMA) analysis was performed on Jaccard’s similarity coefficient matrix. The matrix reveals, two main clusters, wild accessions formed one cluster and the cultivated accessions formed the other. The cultivated accessions are well separated from the wild ones at a low similarity value of 0.3, indicating that cultivated and wild accessions are highly distinct. Morphologically cultivated accessions were also quite distinct from the wild ones and the cluster analysis of RAPD and AFLP fingerprints clearly discriminated the five cultivated accessions of W. somnifera . A strong correlation was observed between morphology and molecular marker systems. Identification of specific markers to wild as well as cultivated accessions is yet another important finding in the present study. Such genetic diversity is useful in facilitating the development of large number of new varieties through hybridization, transfer of useful genes, thus maximizing the use of such available germplasms as genetic resource materials for breeders. The present input, first of its kind in Ashwagandha, will thus assist the marker assisted crop improvement programme. Key words: Withania somnifera, genetic diversity, RAPD, AFLP, polymorphism, Shannon index.

Production dynamics of Withaferin A in Withania somnifera (L.) Dunal complex

Withaferin A (WA) is an important withanolide holding promise in cancer treatment and as a relatively safe radiosensitive/chemotherapeutic agent, which is present in traces in all parts of Withania somnifera except the leaves, where as it is reported to be present in only two non-Indian chemotypes (South African chemotype/Israel chemotype 1). The present studies have marked its presence in all Indian populations (wild/cultivated), as well as two identified Indian chemotypes (AGB002 and AGB025). The quantitative dynamics of WA production in Indian populations and interchemotypic hybrids developed at our institute have been studied, and the results were compared with five previously reported chemotypes from Israel, South Africa and India. An analysis on inheritance characteristics based on presence/absence of WA in hybrid plants and their respective parents is given for future studies on the chemogenetics of this complex species in greater detail. Further, the production potential of WA in vitro propagated plants of elite varieties developed at our institute is discussed, in view of maintaining chemotypic fidelity and stability from a production point of view. Also, evidence-based clues suggesting the leaves as the site of the synthesis of WA is provided.

In planta expression of hyperthermophilic enzymes as a strategy for accelerated lignocellulosic digestion

Conversion of lignocellulosic biomass to biofuels and biomaterials suffers from high production costs associated with biomass pretreatment and enzymatic hydrolysis. In-planta expression of lignocellulose-digesting enzymes is a promising approach to reduce these cost elements. However, this approach faces a number of challenges, including auto-hydrolysis of developing cell walls, plant growth and yield penalties, low expression levels and the limited stability of expressed enzymes at the high temperatures generally used for biomass processing to release fermentable sugars. To overcome these challenges we expressed codon-optimized recombinant hyperthermophilic endoglucanase (EG) and xylanase (Xyn) genes in A. thaliana. Transgenic Arabidopsis lines expressing EG and Xyn enzymes at high levels without any obvious plant growth or yield penalties were selected for further analysis. The highest enzyme activities were observed in the dry stems of transgenic lines, indicating that the enzymes were not degraded during stem senescence and storage. Biomass from transgenic lines exhibited improved saccharification efficiency relative to WT control plants. We conclude that the expression of hyperthermophilic enzymes in plants is a promising approach for combining pretreatment and enzymatic hydrolysis processes in lignocellulosic digestion. This study provides a valid foundation for further studies involving in planta co-expression of core and accessory lignocellulose-digesting enzymes.

Design and synthesis of ring C opened analogues of α-santonin as potential anticancer agents

Here we describe ring opening reaction of a novel halo triene derivative viz., (3S, 5aS)-8-chloro-3a, 4, 5, 5a-tetrahydro-3, 5a, 9-trimethylnaphtho [1, 2-b] furan-2(3H)-one of α-santonin upon nucleophillic attack with alcohols. Halo-triene was synthesized from α-santonin upon reaction with vilsmeier reagent. The synthesized compounds from ring opening reaction were evaluated for anticancer activity against a panel of four human cancer cell lines (A-549, THP-1, HCT-15, and IMR-13). Most of the compounds exhibited promising anticancer activity against all cancer cells in vitro; however compound. 3d with benzyl substitution showed most potent anticancer activity with an IC50 value of 0.3, 0.51, 0.6 and 0.23 μM against A-549, THP-1, HCT-116 and IMR-13 cell lines respectively.

Metabolomic and Biotechnological approaches to determine therapeutic potential of Withania somnifera (L.) Dunal: A Review

BACKGROUND Withania somnifera, a high value medicinal plant is a major source of pharmaceutically important active compounds withanolides. Withania somnifera has been used in ayurveda as health restorative and anabolic agent besides having anti-arthritic, antidepressant, anti-microbial, anti-inflammatory, anti-diabetic, anti-stress, neuroprotective and cardio-protective activities. HYPOTHESIS/PURPOSE The mining of the compound(s) of interest offers opportunity to identify desired attributes in the therapeutic area of interest. Metabolomic has become an important tool in the field of pharmacological and functional genomics of medicinal plants. The analysis supports the information regarding differential outline of the gene expression for increasing important withanolides viz. withanolide A and withaferin A in W. somnifera. STUDY DESIGN The bioinformatics and biotechnological approaches viz. tissue culture, genetic transformation, genomic, transcriptomic, proteomic, gene mining and metabolomic studies have opened new windows about engineering of withanolide production. METHODS Target and network analysis for maximum therapeutic potential of Withania somnifera have been determined by employing Genemania software for finding interactions among various human genes that are being affected by active constituents. RESULTS Some of the major bioactive compounds of Withania somnifera have been discussed on protein-protein, protein-DNA and genetic interactions with respect to gene and protein expression data, protein domains, metabolic profiling, root organ culture, genetic transformation and phenotypic screening profiles CONCLUSION: The implementation of latest bioinformatic tools in combination with biotechnological techniques for breeding platforms are important in conservation of medicinal plant species in danger. The current review is based on molecular and in vitro methodologies employed in W. somnifera for accepting their importance in the improvement of this valuable medicinal species.