Identification of Potential Leishmania N-Myristoyltransferase Inhibitors from Withania somnifera (L.) Dunal: A Molecular Docking and Molecular Dynamics Investigation

Leishmaniasis is a group of infectious diseases caused by Leishmania protozoa. The ineffectiveness, high toxicity, and/or parasite resistance of the currently available antileishmanial drugs has created an urgent need for safe and effective leishmaniasis treatment. Currently, the molecular-docking technique is used to predict the proper conformations of small-molecule ligands and the strength of the contact between a protein and a ligand, and the majority of research for the development of new drugs is centered on this type of prediction. Leishmania N-myristoyltransferase (NMT) has been shown to be a reliable therapeutic target for investigating new anti-leishmanial molecules through this kind of virtual screening. Natural products provide an incredible source of affordable chemical scaffolds that serve in the development of effective drugs. Withania somnifera leaves, roots, and fruits have been shown to contain withanolide and other phytomolecules that are efficient anti-protozoal agents against Malaria, Trypanosoma, and Leishmania spp. Through a review of previously reported compounds from W. somnifera-afforded 35 alkaloid, phenolic, and steroid compounds and 132 withanolides/derivatives, typical of the Withania genus. These compounds were subjected to molecular docking screening and molecular dynamics against L. major NMT. Calycopteretin-3-rutinoside and withanoside IX showed the highest affinity and binding stability to L. major NMT, implying that these compounds could be used as antileishmanial drugs and/or as a scaffold for the design of related parasite NMT inhibitors with markedly enhanced binding affinity.

Withania somnifera (L.) Dunal (Ashwagandha) for the possible therapeutics and clinical management of SARS-CoV-2 infection: Plant-based drug discovery and targeted therapy

Coronavirus disease 2019 (COVID-19) pandemic has killed huge populations throughout the world and acts as a high-risk factor for elderly and young immune-suppressed patients. There is a critical need to build up secure, reliable, and efficient drugs against to the infection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. Bioactive compounds of Ashwagandha [Withania somnifera (L.) Dunal] may implicate as herbal medicine for the management and treatment of patients infected by SARS-CoV-2 infection. The aim of the current work is to update the knowledge of SARS-CoV-2 infection and information about the implication of various compounds of medicinal plant Withania somnifera with minimum side effects on the patients' organs. The herbal medicine Withania somnifera has an excellent antiviral activity that could be implicated in the management and treatment of flu and flu-like diseases connected with SARS-CoV-2. The analysis was performed by systematically re-evaluating the published articles related to the infection of SARS-CoV-2 and the herbal medicine Withania somnifera. In the current review, we have provided the important information and data of various bioactive compounds of Withania somnifera such as Withanoside V, Withanone, Somniferine, and some other compounds, which can possibly help in the management and treatment of SARS-CoV-2 infection. Withania somnifera has proved its potential for maintaining immune homeostasis of the body, inflammation regulation, pro-inflammatory cytokines suppression, protection of multiple organs, anti-viral, anti-stress, and anti-hypertensive properties. Withanoside V has the potential to inhibit the main proteases (Mpro) of SARS-CoV-2. At present, synthetic adjuvant vaccines are used against COVID-19. Available information showed the antiviral activity in Withanoside V of Withania somnifera, which may explore as herbal medicine against to SARS-CoV-2 infection after standardization of parameters of drug development and formulation in near future.

Withanolides from the genus Exodeconus (Solanaceae). Chemotaxonomical considerations

Five Exodeconus species were phytochemically analyzed. From the aerial parts of E. pusillus, the 7α,27-dihydroxy-1-oxo-22R-witha-2,5,24-trienolide and three other previously unreported normal-type withanolides were isolated. All the studied species had normal type and/or ring-D aromatic withanolides, and some had already been isolated from other Solanaceae genera, and therefore, these compounds are not chemotaxonomic markers at the generic level. The chemical composition of an undescribed Exodeconus species analyzed here supports the designation of this taxon as a new entity. The integral chemical profile of Exodeconus can be evaluated for its taxonomic implication when a more robust phylogeny of Solanaceae is available that allows the phylogenetic relationships with its closest genera to be clarified.

Jasmonate responsive transcription factor WsMYC2 regulates the biosynthesis of triterpenoid withanolides and phytosterol via key pathway genes in Withania somnifera (L.) Dunal

Functional characterization of WsMYC2 via artificial microRNA mediated silencing and transient over-expression displayed significant regulatory role vis-à-vis withanolides and stigmasterol biosyntheses in Withania somnifera. Further, metabolic intensification corroborated well with higher expression levels of putative pathway genes. Additionally, copious expression of WsMYC2 in response to exogenous elicitors resulted in enhanced withanolides production. Withania somnifera, a high value multipurpose medicinal plant, is a rich reservoir of structurally diverse and biologically active triterpenoids known as withanolides. W. somnifera has been extensively pursued vis-à-vis pharmacological and chemical studies. Nonetheless, there exists fragmentary knowledge regarding the metabolic pathway and the regulatory aspects of withanolides biosynthesis. Against this backdrop, a jasmonate-responsive MYC2 transcription factor was identified and functionally characterized from W. somnifera. In planta transient over-expression of WsMYC2 showed significant enhancement of mRNA transcript levels which corroborated well with the enhanced content of withanolides and stigmasterol. Further, a comparative analysis of expression levels of some of the genes of triterpenoid pathway viz. WsCAS, WsCYP85A, WsCYP90B and WsCYP710A in corroboration with the over-expression and silencing of WsMYC2 suggested its positive influence on their regulation. These corroboratory approaches suggest that WsMYC2 has cascading effect on over-expression of multiple pathway genes leading to the increased triterpenoid biosynthesis in infiltered plants. Further, the functional validation of WsMYC2 was carried out by artificial micro-RNA mediated silencing. It resulted in significant reduction of withanolides and stigmasterol levels, indicative of crucial role of WsMYC2 in the regulation of their biosyntheses. Taken together, these non-complementary approaches provided unambiguous understanding of the regulatory role of WsMYC2 in context to withanolides and stigmasterol biosyntheses. Furthermore, the upstream promoter of WsMYC2 presented several cis-regulatory elements primarily related to phytohormone responsiveness. WsMYC2 displayed inducible nature in response to MeJA. It had substantial influence on the higher expression of WsMYC2 which was in consonance with enhanced accumulation of withanolides.

Cytotoxic Withanolides from the Roots of Indian Ginseng ( Withania somnifera)

Withania somnifera, commonly known as "Indian ginseng" or "ashwagandha", is popular as a functional food because of its diverse purported therapeutic efficacies including invigorating, improvement of cognitive ability, and stress release activities. Chemical investigation of the MeOH extract of W. somnifera roots combined with LC/MS-based analysis resulted in the identification of six new withanolides, withasilolides A-F (1-6), as well as seven known compounds (7-13). The structures of the new compounds were established by application of spectroscopic methods, including 1D and 2D NMR, HRMS, and ECD measurements. The cytotoxicity of the isolated compounds was evaluated against four human cancer cell lines (A549, SK-OV-3, SK-MEL-2, and HCT-15). Compounds 1, 2, 4, 6, and withanone (11) each showed cytotoxicity for one or more of the four cancer cell lines used.

A Decade of Molecular Understanding of Withanolide Biosynthesis and In vitro Studies in Withania somnifera (L.) Dunal: Prospects and Perspectives for Pathway Engineering

Withania somnifera, a multipurpose medicinal plant is a rich reservoir of pharmaceutically active triterpenoids that are steroidal lactones known as withanolides. Though the plant has been well-characterized in terms of phytochemical profiles as well as pharmaceutical activities, limited attempts have been made to decipher the biosynthetic route and identification of key regulatory genes involved in withanolide biosynthesis. This scenario limits biotechnological interventions for enhanced production of bioactive compounds. Nevertheless, recent emergent trends vis-à-vis, the exploration of genomic, transcriptomic, proteomic, metabolomics, and in vitro studies have opened new vistas regarding pathway engineering of withanolide production. During recent years, various strategic pathway genes have been characterized with significant amount of regulatory studies which allude toward development of molecular circuitries for production of key intermediates or end products in heterologous hosts. Another pivotal aspect covering redirection of metabolic flux for channelizing the precursor pool toward enhanced withanolide production has also been attained by deciphering decisive branch point(s) as robust targets for pathway modulation. With these perspectives, the current review provides a detailed overview of various studies undertaken by the authors and collated literature related to molecular and in vitro approaches employed in W. somnifera for understanding various molecular network interactions in entirety.

Molecular characterization of two A-type P450s, WsCYP98A and WsCYP76A from Withania somnifera (L.) Dunal: expression analysis and withanolide accumulation in response to exogenous elicitations

BACKGROUND

Pharmacological investigations position withanolides as important bioactive molecules demanding their enhanced production. Therefore, one of the pivotal aims has been to gain knowledge about complete biosynthesis of withanolides in terms of enzymatic and regulatory genes of the pathway. However, the pathway remains elusive at the molecular level. P450s monooxygenases play a crucial role in secondary metabolism and predominantly help in functionalizing molecule core structures including withanolides.

RESULTS

In an endeavor towards identification and characterization of different P450s, we here describe molecular cloning, characterization and expression analysis of two A-type P450s, WsCYP98A and WsCYP76A from Withania somnifera. Full length cDNAs of WsCYP98A and WsCYP76A have open reading frames of 1536 and 1545 bp encoding 511 (58.0 kDa) and 515 (58.7 kDa) amino acid residues, respectively. Entire coding sequences of WsCYP98A and WsCYP76A cDNAs were expressed in Escherichia coli BL21 (DE3) using pGEX4T-2 expression vector. Quantitative real-time PCR analysis indicated that both genes express widely in leaves, stalks, roots, flowers and berries with higher expression levels of WsCYP98A in stalks while WsCYP76A transcript levels were more obvious in roots. Further, transcript profiling after methyl jasmonate, salicylic acid, and gibberellic acid elicitations displayed differential transcriptional regulation of WsCYP98A and WsCYP76A. Copious transcript levels of both P450s correlated positively with the higher production of withanolides.

CONCLUSIONS

Two A-types P450 WsCYP98A and WsCYP76A were isolated, sequenced and heterologously expressed in E. coli. Both P450s are spatially regulated at transcript level showing differential tissue specificity. Exogenous elicitors acted as both positive and negative regulators of mRNA transcripts. Methyl jasmonate and salicylic acid resulted in copious expression of WsCYP98A and WsCYP76A. Enhanced mRNA levels also corroborated well with the increased accumulation of withanolides in response to elicitations. The empirical findings suggest that elicitors possibly incite defence or stress responses of the plant by triggering higher accumulation of withanolides.

Withaferin A-related steroids from Withania aristata exhibit potent antiproliferative activity by inducing apoptosis in human tumor cells

Six new withanolides (1-6) along with eleven known ones (7-17) were isolated from the leaves of Withania aristata. Their structures were elucidated on the basis of spectroscopic analysis, including 1D and 2D NMR techniques. Semisynthesis of the minority metabolites 7 and 15 from compounds 6 and 9, respectively, as starting material, was performed. The isolated compounds as well as three derivatives (7a, 9a and 9b) of withaferin A were evaluated for cytotoxicity against HeLa (carcinoma of the cervix), A-549 (lung carcinoma) and MCF-7 (breast adenocarcinoma) human cancer cell lines, and against normal Vero cells (African green monkey kidney). Five compounds from this series (8, 9a, 9b, 11 and 13) exhibited potent antiproliferative effects on the tumor cells, even higher than the well known anticancer agent, withaferin A (9). Phosphatidylserine externalization, chromatin condensation, and caspase-3 activation clearly indicated apoptosis as a mechanism of action. The structure-activity relationship revealed valuable information on the pharmacophore for withanolide-type compounds.

Withania somnifera prevents morphine withdrawal-induced decrease in spine density in nucleus accumbens shell of rats: a confocal laser scanning microscopy study

Opiate withdrawal is associated with morphological changes of dopamine neurons in the ventral tegmental area and with reduction of spine density of second-order dendrites of medium size spiny neurons in the nucleus accumbens shell but not core. Withania somnifera has long been used in the Middle East, Africa, and India as a remedy for different conditions and diseases and a growing body of evidence points to its beneficial effects on a number of experimental models of neurological disorders. Recently, many studies focused on the potential neuritic regeneration and synaptic reconstruction properties of its methanolic extract and its constituents (withanolides). This study investigates whether morphine withdrawal-induced spine reduction in the nucleus accumbens is affected by the administration of a Withania somnifera extract. To this end, rats were chronically treated with Withania somnifera extract along with morphine or saline and, upon spontaneous (1 and 3 days) or pharmacologically precipitated withdrawal, their brains were fixed in Golgi-Cox stain for confocal microscopic examination. In a separate group of animals, Withania somnifera extract was administered during three days of spontaneous withdrawal. Withania somnifera extract treatment reduced the severity of the withdrawal syndrome when given during chronic morphine but not during withdrawal. In addition, treatment with Withania somnifera extract during chronic morphine, but not during withdrawal, fully prevented the reduction of spine density in the nucleus accumbens shell in spontaneous and pharmacologically precipitated morphine withdrawal. These results indicate that pretreatment with Withania somnifera extract protects from the structural changes induced by morphine withdrawal potentially providing beneficial effects on the consequences related to this condition.

Selective killing of cancer cells by leaf extract of Ashwagandha: identification of a tumor-inhibitory factor and the first molecular insights to its effect

PURPOSE

Ashwagandha is regarded as a wonder shrub of India and is commonly used in Ayurvedic medicine and health tonics that claim its variety of health-promoting effects. Surprisingly, these claims are not well supported by adequate studies, and the molecular mechanisms of its action remain largely unexplored to date. We undertook a study to identify and characterize the antitumor activity of the leaf extract of ashwagandha.

EXPERIMENTAL DESIGN

Selective tumor-inhibitory activity of the leaf extract (i-Extract) was identified by in vivo tumor formation assays in nude mice and by in vitro growth assays of normal and human transformed cells. To investigate the cellular targets of i-Extract, we adopted a gene silencing approach using a selected small hairpin RNA library and found that p53 is required for the killing activity of i-Extract.

RESULTS

By molecular analysis of p53 function in normal and a variety of tumor cells, we found that it is selectively activated in tumor cells, causing either their growth arrest or apoptosis. By fractionation, purification, and structural analysis of the i-Extract constituents, we have identified its p53-activating tumor-inhibiting factor as with a none.

CONCLUSION

We provide the first molecular evidence that the leaf extract of ashwagandha selectively kills tumor cells and, thus, is a natural source for safe anticancer medicine.

Changes in morphological phenotypes and withanolide composition of Ri-transformed roots of Withania somnifera

Developmental variability was introduced into Withania somnifera using genetic transformation by Agrobacterium rhizogenes, with the aim of changing withasteroid production. Inoculation of W. somnifera with A. rhizogenes strains LBA 9402 and A4 produced typical transformed root lines, transformed callus lines, and rooty callus lines with simultaneous root dedifferentiation and redifferentiation. These morphologically distinct transformed lines varied in T-DNA content, growth rates, and withasteroid accumulation. All of the lines with the typical transformed root morphology contained the T(L) T-DNA, and 90% of them carried the T(R) T-DNA, irrespective of the strain used for infection. Accumulation of withaferin A was maximum (0.44% dry weight) in the transformed root line WSKHRL-1. This is the first detection of withaferin A in the roots of W. somnifera. All of the rooty callus lines induced by strain A4 contained both the T(L) and the T(R)-DNAs. In contrast, 50% of the rooty-callus lines obtained with strain LBA 9402 contained only the T(R) T-DNA. All the rooty callus lines accumulated both withaferin A and withanolide D. The callusing lines induced by LBA 9402 lacked the T(L) T-DNA genes, while all the callusing lines induced by strain A4 contained the T(L) DNA. Four of these callus lines produced both withaferin A (0.15-0.21% dry weight) and withanolide D (0.08-0.11% dry weight), and they grew faster than the transformed root lines. This is the first report of the presence of withasteroids in undifferentiated callus cultures of W. somnifera.

Antileishmanial Physalins fromPhysalis minima

Three new physalins (1-3) and a new withanolide 7 have been isolated from the whole plant of Physalis minima, along with three known physalins: physalin H (4), isophysalin B (5), and 5beta,6beta-epoxyphysalin B (6). Their structures were deduced on the basis of in-depth spectroscopic analyses. Compounds 1-6 showed significant in vitro leishmanicidal activities (0.92-19.4 microg/ml) against promastigotes of Leishmania major.

3-N,N-Dimethylamino-3-deoxy lincomycin: A structure-based hybrid between lincomycin and the desosamine unit of erythromycin

The observation that the desosamine sugar unit in erythromycin and the methyl thiolincosaminide portion of lincomycin occupy virtually identical sites on the 23S rRNA according to X-ray crystallograpaic data, instigated the synthesis of 3-N,N-dimethylamino-3-deoxy lincomycin as a hybrid structure. The synthesis in eight steps from lincomycin, involving a trans-diequatorial opening of an intermediate epoxide as the key step, is described.

Cholinesterase inhibiting withanolides from Withania somnifera

A total of two new (1, 2) and four known (3-6) withanolides were isolated from the whole plant of Withania somnifera. Their structures were elucidated on the basis of spectroscopic techniques and were characterized as 6alpha,7alpha-epoxy-3beta,5alpha,20beta-trihydroxy-1-oxowitha-24-enolide (1), 5beta,6beta-epoxy-4beta,17alpha,27-trihydroxy-1-oxowitha-2,24-dienolide (2), withaferin-A (3), 2,3-dihydrowithaferin-A (4), 6alpha,7alpha-epoxy-5alpha,20beta-dihydroxy-1-oxowitha-2,24-dienolide (5), and 5beta,6beta-epoxy-4beta-hydroxy-1-oxowitha-2,14,24-trienolide (6), respectively. Compounds 2, 3, 5, and 6 displayed inhibitory potential against butyrylcholinesterase, but only compounds 3, 4, and 6 were found to be active against acetylcholinesterase.

The in vitro antibacterial/synergistic activities of Withania somnifera extracts

The methanol, hexane and diethyl ether extracts from both leaves and roots of Withania somnifera were evaluated for the antibacterial/synergistic activity by agar plate disc-diffusion assay against Salmonella typhimurium and Escherichia coli. Different concentrations of Tibrim, a combination of rifampicin and isoniazid, were tested to find out the minimum inhibitory concentration (MIC), which came out to be 0.1 mg/ml for S. typhimurium and E. coli. From the six extracts tested, only methanol and hexane extracts of both leaves and roots were found to have potent antibacterial activity. A synergistic increase in the antibacterial effect of Tibrim was noticed when MIC of Tibrim was supplemented with these extracts.

Structures of withanosides I, II, III, IV, V, VI, and VII, new withanolide glycosides, from the roots of Indian Withania somnifera DUNAL. and inhibitory activity for tachyphylaxis to clonidine in isolated guinea-pig ileum

Seven new withanolide glycosides called withanosides I, II, III, IV, V, VI, and VII were isolated from an Indian natural medicine, Ashwagandha, the roots of Indian Withania somnifera DUNAL. (Solanaceae), together with four known compounds, withaferin A, 5 alpha,20 alpha(F)(R)-dihydroxy-6 alpha,7 alpha-epoxy-1-oxowitha-2,24-dienolide, physagulin D, and coagulin Q. The structures of withanosides I, II, III, IV, V, VI, and VII were determined based on chemical and physicochemical evidence. Principal constituents, withanoside VI (10 and 30 microM) and withaferin A (10 microM), attenuated the tachyphylaxis to clonidine on electrically stimulated guinea-pig ileum in vitro.

Withanolide production by root cultures of Withania somnifera transformed with Agrobacterium rhizogenes

Transformed root cultures of Withania somnifera Dunal (Solanaceae) were obtained by infecting shoots cultured in vitro with Agrobacterium rhizogenes LBA 9402. They grew axenically in the absence of exogenous plant growth regulators in Murashige and Skoog's medium containing 3% (w/v) sucrose. The root cultures synthesized several withanolides of which withanolide D was isolated and identified. Transformed root (clone HR (1)) showed a growth index of 20.07 and a withanolide D yield of 0.30 mg g(-1) DW. The productivity of withanolide D in transformed roots (0.181 mg 1(-1) d(-1)) was higher than in untransformed root cultures (0.026 mg 1(-1) d(-1)).