Withania somnifera, commonly known as Ashwagandha, is an important medicinal plant that has been used in Ayurvedic and indigenous medicine for over 3,000 years. In view of its varied therapeutic potential, it has also been the subject of considerable modern scientific attention. The major chemical constituents of the Withania genus, the withanolides, are a group of naturally occurring C28-steroidal lactone triterpenoids built on an intact or rearranged ergostane framework, in which C-22 and C-26 are appropriately oxidized to form a six-membered lactone ring. In recent years, numerous pharmacological investigations have been carried out into the components of W. somnifera extracts. We present here an overview of the chemical structures of triterpenoid components and their biological activity, focusing on two novel activities, tumor inhibition and antiangiogenic properties of withaferin A and the effects of withanolide A on Alzheimer's disease. The most recent attempts in biotechnological production of withanolides are also discussed.

/pdf/steroidal-lactones-from-withania-somnifera-an-ancient-plant-1jii9ajyat.pdf

Steroidal lactones from Withania somnifera, an ancient plant for novel medicine.

High levels of metals impede plant growth by affecting physiological processes. Siderophores are microbial Fe-chelators that, however, bind other metals. This study evaluated plant growth in a soil containing elevated levels of metals, including Al, Cu, Fe, Mn, Ni, and U, using Streptomyces-derived cell-free supernatant containing siderophores and auxins. Cowpea plants in the soil were treated with the culture filtrate. Growth was measured and biochemical analyses such as chlorophyll contents, RNA and protein quantification, lipid membrane peroxidation, and anti-oxidative responses were conducted to evaluate oxidative stress in the plants. Liquid chromatography–mass spectrometry was used to simulate competition for siderophore binding, and metal content of plants was determined spectroscopically. Whereas the metals inhibited plant growth, addition of siderophores improved growth. There was evidence of lipid peroxidation, an enhanced superoxide dismutase activity, and lowered chlorophyll, RNA, protein, carotenoid and residual indole acetic acid contents, especially in control plants. Siderophore competition assays between Al and Fe, and Fe and Cu suggested that trivalent metals are more competitive for siderophore binding than divalent ones. Compared to control plants, higher amounts of metals were obtained in siderophore-treated plants. Siderophores were able to supply plants with Fe in the presence of levels of metals, mainly Al, Cu, Mn, Ni and U that otherwise inhibit Fe acquisition. This led to enhanced chlorophyll content, circumventing lipid peroxidation effects on leaves. Siderophores lowered the formation of free radicals, thereby protecting microbial auxins from degradation and enabling them to enhance plant growth which in turn resulted in augmented metal uptake.

Metal-induced oxidative stress impacting plant growth in contaminated soil is alleviated by microbial siderophores

/pdf/ashwagandha-withania-somnifera-role-in-safeguarding-health-3mb6dw2nhf.pdf

Ashwagandha (Withania somnifera): Role in Safeguarding Health, Immunomodulatory Effects, Combating Infections and Therapeutic Applications: A Review

Enzymatic synthesis of banana flavour (isoamyl acetate) by Bacillus licheniformis S-86 esterase

Among the vast microbial genomic resources now available, most microbes are unculturable in the laboratory. A culture-independent metagenomic approach is a novel technique that circumvents this culture limitation. For the screening of novel lipolytic enzymes, a metagenomic library was constructed from compost, and the clone of estCS2 was selected for lipolytic properties on a tributyrin-containing medium. The estCS2 sequence encodes a protein of 570 amino acid residues, with a predicted molecular mass of 63 kDa, and based on amino acid identity it most closely matches (45%) the carboxylesterase from Haliangium ochraceum DSM 14365. EstCS2 belong to family VII, according to the lipolytic enzyme classification proposed by Arpigny and Jaeger, and it retains the catalytic triad Ser245-Glu363-His466 that is typical of an α/β hydrolase. The Ser245 residue in the catalytic triad of EstCS2 is located in the consensus active site motif GXSXG. The EstCS2 exhibits strong activity toward p-nitrophenyl caproate (C6), and it is stable up to 60°C with an optimal enzymatic activity at 55°C. The maximal activity is observed at pH 9, and it remains active between pH 6-10. EstCS2 shows remarkable stability in up to 50% (v/v) dimethyl sulfoxide (DMSO) or dimethylformamide (DMF). The enzyme has the ability to cleave sterically hindered esters of tertiary alcohol, as well as to degrade polyurethanes, which are widely used in various industries. The high stability of EstCS2 in organic solvents and its activity towards esters of ketoprofen and tertiary alcohols, and in polyurethane suggests that it has potential uses for many applications in biotransformation and bioremediation.

/pdf/a-novel-family-vii-esterase-with-industrial-potential-from-4m1krqp4ux.pdf

A novel family VII esterase with industrial potential from compost metagenomic library

The genome sequence of Streptomyces coelicolor A3(2) contains 51 putative lipase and esterase genes mostly of unknown function. The gene estB (locus SCO 6966) was expressed as a His-tagged protein in E. coli. Esterase B was active at low temperatures exerting its maximum activity at 30 degrees C and retaining more than 25% of its activity at 4 degrees C. The optimum pH was 8-8.5. The enzyme was active against short synthetic p-nitrophenylesters (C2-C10) with maximum activity towards the acetate ester (C2). The esterase was tested on 13 series of racemic esters of potential interest for the synthesis of chiral pharmaceutical compounds. 4 of the series were substrates and a modest degree of enantioselectivity was observed (enantiomeric ratios of 1.1-1.9).

A cold-active esterase of Streptomyces coelicolor A3(2): from genome sequence to enzyme activity

A gene from Bacillus pumilus expressed under its native promoter was cloned in Escherichia coli . Recombinant B. pumilus esterase (BPE) affects the kinetic resolution of racemic mixtures such as unsubstituted and substituted 1-(phenyl)ethanols ( E  ∼ 33–103), ethyl 3-hydroxy-3-phenylpropanoate ( E  ∼ 45–71), trans -4-fluorophenyl-3-hydroxymethyl- N -methylpiperidine ( E  ∼ 10–13) and ethyl 2-hydroxy-4-phenylbutyrate ( E  ∼ 7). The enzyme is composed of a 34-amino acid signal peptide and a 181-amino acid mature protein corresponding to a molecular weight of ∼19.2 kD and pI ∼ 9.4. 3-D the structural model of the enzyme built by homology modelling using the atomic coordinates from the crystal structure of B. subtilis lipase (LipA) showed a compact minimal α/β hydrolase fold.

Molecular cloning of enantioselective ester hydrolase from Bacillus pumilus DBRL-191.

A novel peroxidase from Withania somnifera.

Purification and characterization of peroxidases from Withania somnifera (AGB 002) and their ability to oxidize IAA.

Molecular cloning of carboxylesterase gene and biochemical characterization of encoded protein from Bacillus subtilis (RRL BB1)

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