Withanolides from Physalis minima and their inhibitory effects on nitric oxide production

Six new withanolides (1-6), including two uncommon 1,10-seco withanolides (1 and 2), together with five known withanolides (7-11), were isolated from the whole plants of Physalis minima Linn.. The structures of new compounds were elucidated through spectroscopic methods, including (1)H, (13)C NMR, 2D-NMR, HRESIMS and circular dichroism (CD). Inhibitory effects of the isolates on nitric oxide (NO) production in lipopolysaccaride-activated RAW264.7 macrophages were evaluated. Compounds 2 and 5 showed strong inhibitory activities with IC50 values of 8.04 and 10.01 μM, respectively. Compounds 1, 9 and 10 exhibited moderate inhibitory activities with IC50 values from 25.54 to 43.58 μM.

A withanolide coagulin-L inhibits adipogenesis modulating Wnt/β-catenin pathway and cell cycle in mitotic clonal expansion

Obesity is a result of adipocyte hypertrophy followed by hyperplasia. It is a risk factor for several metabolic disorders such as dyslipidemia, type-2 diabetes, hypertension, and cardiovascular diseases. Coagulanolides, particularly coagulin-L isolated from W. coagulan has earlier been reported for anti-hyperglycemic activity. In this study, we investigated the effect of coagulin-L on in vitro models of adipocyte differentiation including 3T3-L1 pre-adipocyte, mouse stromal mesenchymal C3H10T1/2 cells and bone marrow derived human mesenchymal stem cells (hMSCs). Our results showed that, coagulin-L reduces the expressions of peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα), the major transcription factors orchestrating adipocyte differentiation. Detailed analysis further proved that early exposure of coagulin-L is sufficient to cause significant inhibition during adipogenesis. Coagulin-L inhibited mitotic clonal expansion (MCE) by delayed entry in G1 to S phase transition and S-phase arrest. This MCE blockade was caused apparently by decreased phosphorylation of C/EBPβ, modulation in expression of cell cycle regulatory proteins, and upregulation of Wnt/β-catenin pathway, the early stage regulatory proteins of adipogenic induction. Taken together all evidences, a known anti-hyperglycemic agent coagulin-L has shown potential to inhibit adipogenesis significantly, which can be therapeutically exploited for treatment of obesity and metabolic syndrome.

Pharmacological levels of Withaferin A (Withania somnifera) trigger clinically relevant anticancer effects specific to triple negative breast cancer cells

Withaferin A (WA) isolated from Withania somnifera (Ashwagandha) has recently become an attractive phytochemical under investigation in various preclinical studies for treatment of different cancer types. In the present study, a comparative pathway-based transcriptome analysis was applied in epithelial-like MCF-7 and triple negative mesenchymal MDA-MB-231 breast cancer cells exposed to different concentrations of WA which can be detected systemically in in vivo experiments. Whereas WA treatment demonstrated attenuation of multiple cancer hallmarks, the withanolide analogue Withanone (WN) did not exert any of the described effects at comparable concentrations. Pathway enrichment analysis revealed that WA targets specific cancer processes related to cell death, cell cycle and proliferation, which could be functionally validated by flow cytometry and real-time cell proliferation assays. WA also strongly decreased MDA-MB-231 invasion as determined by single-cell collagen invasion assay. This was further supported by decreased gene expression of extracellular matrix-degrading proteases (uPA, PLAT, ADAM8), cell adhesion molecules (integrins, laminins), pro-inflammatory mediators of the metastasis-promoting tumor microenvironment (TNFSF12, IL6, ANGPTL2, CSF1R) and concomitant increased expression of the validated breast cancer metastasis suppressor gene (BRMS1). In line with the transcriptional changes, nanomolar concentrations of WA significantly decreased protein levels and corresponding activity of uPA in MDA-MB-231 cell supernatant, further supporting its anti-metastatic properties. Finally, hierarchical clustering analysis of 84 chromatin writer-reader-eraser enzymes revealed that WA treatment of invasive mesenchymal MDA-MB-231 cells reprogrammed their transcription levels more similarly towards the pattern observed in non-invasive MCF-7 cells. In conclusion, taking into account that sub-cytotoxic concentrations of WA target multiple metastatic effectors in therapy-resistant triple negative breast cancer, WA-based therapeutic strategies targeting the uPA pathway hold promise for further (pre)clinical development to defeat aggressive metastatic breast cancer.

Coupling G2/M arrest to the Wnt/β-catenin pathway restrains pancreatic adenocarcinoma

β-catenin plays a pivotal role in organogenesis and oncogenesis. Alterations in β-catenin expression are common in pancreatic cancer, which is an extremely aggressive malignancy with a notably poor prognosis. In this report, we analyzed the apoptotic activity of withanolide-D (witha-D), a steroidal lactone that was purified from an Indian medicinal plant, Withania somnifera, and its underlying mechanism of action. Witha-D induced apoptosis in pancreatic ductal adenocarcinoma cells by prompting cell-cycle arrest at the G2/M phase. This lactone abrogated β-catenin signaling in these cells regardless of disease grade, mutational status, and gemcitabine sensitivity. Witha-D also upregulated E-cadherin in most cells, thereby supporting the inversion of the epithelial-mesenchymal transition. Furthermore, the Akt/Gsk3β kinase cascade was identified as a critical mediator of G2/M regulation and β-catenin signaling. Witha-D deactivated Akt, which failed to promote Gsk3β deactivation phosphorylation. Consequently, activated Gsk3β facilitated β-catenin destruction in pancreatic carcinoma cells. The knockdown of Chk1 and Chk2 further activated Akt and reversed the molecular signal. Taken together, the results of the current study represent the first evidence of β-catenin signal crosstalk during the G2/M phase by functionally inactivating Akt via witha-D treatment in pancreatic cancer cells. In conclusion, this finding suggests the potential identification of a new lead molecule in the treatment of pancreatic adenocarcinoma.

Structure-activity relationship (SAR) of withanolides to inhibit Hsp90 for its activity in pancreatic cancer cells

Withaferin A (WA), a naturally occurring steroidal lactone, directly binds to Hsp90 and leads to the degradation of Hsp90 client protein. The purpose of this study is to investigate the structure activity relationship (SAR) of withanolides for their inhibition of Hsp90 and anti-proliferative activities in pancreatic cancer cells. In pancreatic cancer Panc-1 cells, withaferin A (WA) and its four analogues withanolide E (WE), 4-hydroxywithanolide E (HWE), 3-aziridinylwithaferin A (AzWA) inhibited cell proliferation with IC50 ranged from 1.0 to 2.8 μM. WA, WE, HWE, and AzWA also induced caspase-3 activity by 21-, 6-, 11- and 15-fold, respectively, in Panc-1 cells, while withaperuvin (WP) did not show any activity. Our data showed that WA, WE, HWE, and AzWA, but not WP, all directly bound to Hsp90 and induced Hsp90 aggregation,hence inhibited Hsp90 chaperone activity to induce degradation of Hsp90 client proteins Akt and Cdk4 through proteasome-dependent pathway in pancreatic cancer cells. However, only WA, HWE and AzWA disrupted Hsp90-Cdc37 complexes but not WE and WP. SAR study suggested that the C-5(6)-epoxy functional group contributes considerably for withanolide to bind to Hsp90, inhibit Hsp90 chaperone activity, and result in Hsp90 client protein depletion. Meanwhile, the hydroxyl group at C-4 of ring A may enhance withanolide to inhibit Hsp90 activity and disrupt Hsp90-Cdc37 interaction. These SAR data provide possible mechanisms of anti-proliferative action of withanolides.

Epoxide group relationship with cytotoxicity in withanolide derivatives from Withania somnifera

Withania somnifera is one of the highly reputed medicinal plants of India. Its steroidal constituents exist in the form of two major substitution patterns, viz. withaferin A (1) and withanone (5). Withaferin A with oxidation at carbons 4, 5, and 6 is considered as an active type, especially as anticancer, whereas the withanones with oxidation at carbons 5, 6, and 7 rarely show any activity. We prepared a series of derivatives with modifications at carbons 5, 6, and 7 in ring B of these withanolides to study the role of the epoxide group towards the cytotoxic property of these bioactive steroids. We have converted withanolides into the respective thiiranes, amino alcohols and alcohols by selective reactions at the epoxide ring and were evaluated for in vitro anticancer activity against four cancer cell lines to study the structure activity relationships. The transformations of the epoxide group in withanolides of the withaferin A type showed moderate reduction in their cytotoxicity whereas the almost inactive withanones have shown some improvements in their alcohol derivatives.

Withanolides with phytotoxic activity from two species of the genus Salpichroa: S. origanifolia and S. tristis var. lehmannii

Seven new withanolides, salpichrolides O-U (1-7), the known 2,3-dihydrosalpichrolide B (9), a substance not previously isolated from a natural source, and three known compounds, salpichrolide D (8), salpichrolide A (10), and salpichrolide C (11), were isolated and characterized from the aerial parts of Salpichroa origanifolia and S. tristis var. lehmannii. Compounds 1-4 and 8 have an oxygenated D ring, while compounds 5-7 and 9-11 possess a six-membered aromatic D ring. The structures of the isolated compounds were identified by analysis of their spectroscopic data including NMR and MS. Withanolides 1, 3, 8, 10, and 11 exhibited selective radicle growth inhibition toward Lactuca sativa (lettuce) at 150 and 400 ppm.

Myeloid-derived suppressor cell function is reduced by Withaferin A, a potent and abundant component of Withania somnifera root extract

Myeloid cells play a crucial role in tumor progression. The most common tumor-infiltrating myeloid cells are myeloid-derived suppressor cells (MDSC) and tumor-associated macrophages (TAMs). These cells promote tumor growth by their inherent immune suppressive activity which is enhanced by their cross-talk. The root extract of the plant Withania somnifera (Ashwagandha) (WRE) has been reported to reduce tumor growth. HPLC analysis identified Withaferin A (WA) as the most abundant constituent of WRE and led us to determine whether the anti-tumor effects of WRE and WA involve modulating MDSC and TAM activity. A prominent effect of MDSC is their production of IL-10 which increases upon cross-talk with macrophages, thus polarizing immunity to a pro-tumor type 2 phenotype. In vitro treatment with WA decreased MDSC production of IL-10 and prevented additional MDSC production of IL-10 generated by MDSC-macrophage cross-talk. Macrophage secretion of IL-6 and TNFα, cytokines that increase MDSC accumulation and function, was also reduced by in vitro treatment with WA. Much of the T-cell suppressive activity of MDSC is due to MDSC production of reactive oxygen species (ROS), and WA significantly reduced MDSC production of ROS through a STAT3-dependent mechanism. In vivo treatment of tumor-bearing mice with WA decreased tumor weight, reduced the quantity of granulocytic MDSC, and reduced the ability of MDSC to suppress antigen-driven activation of CD4+ and CD8+ T cells. Thus, adjunctive treatment with WA reduced myeloid cell-mediated immune suppression, polarized immunity toward a tumor-rejecting type 1 phenotype, and may facilitate the development of anti-tumor immunity.

Withaferin A, a steroidal lactone from Withania somnifera, induces mitotic catastrophe and growth arrest in prostate cancer cells

Cell cycle deregulation is strongly associated with the pathogenesis of prostate cancer. Clinical trials of cell cycle regulators that target either the G0/G1 or G2/M phase to inhibit the growth of cancers including prostate cancer are increasing. The present study focused on the cell cycle regulatory potential of the withanolide withaferin A (1) on prostate cancer cells. Compound 1 induced G2/M arrest in both prostate cancer cell lines (PC-3 and DU-145) when treated for 48 h. The G2/M arrest was accompanied by upregulation of phosphorylated Wee-1, phosphorylated histone H3, p21, and Aurora B. On the other hand, downregulation of cyclins (A2, B1, and E2) and a reduction in phosphorylated Cdc2 (Tyr15) were observed in 1-treated prostate cancer cells. In addition, decreased levels of phosphorylated Chk1 (Ser345) and Chk2 (Thr68) were evident in prostate cancer cells on treatment with 1. These results suggest that activation of Cdc2 leads to arrest in the M phase, with abnormal duplication, and initiation of mitotic catastrophe that results in cell death. In conclusion, these results show clearly the potential of 1 as a regulator of the G2/M phase of the cell cycle and as a therapeutic agent for prostate cancer.

Withanolide-based steroids from the cultured soft coral Sinularia brassica

Seven novel withanolides, sinubrasolides A-G (1-7), have been isolated from the cultured soft coral Sinularia brassica. The structures of the new metabolites were determined by extensive spectroscopic analyses, and the absolute configuration of 1 was established by X-ray crystallographic analysis. The cytotoxicities of compounds 1-7 against a limited panel of cancer cell lines also were determined.

Chemical and pharmacological standardization of Ashwagandhadi lehyam: an ayurvedic formulation

Standardization is an important measurement for ensuring the quality control of herbal drugs. It has become essential to develop reliable, specific and sensitive quality control methods. One of the prime ingredients of Ashwagandhadi lehyam is Withania somnifera L. Dunal (Solanaceae) (ashwagandha). In the present study, Ashwagandhadi lehyam was formulated and the quality assessment of the formulation was based on phytochemical screening and physico-chemical evaluation. Ashwagandhadi lehyam was formulated according to a working formula and subjected to phytochemical screening by FTIR analysis and HPTLC fingerprinting, heavy metal determination by AAS, determination of alcohol content, tested for Escherichia coli, Staphylococcus aureus, aerobic bacteria, yeasts and mould, oral toxicity studies and anti-epileptic activity by MES method. The physico-chemical studies showed total ash content as 6.45%, extractive values and some trace elements such as lead, mercury, cadmium and arsenic with 3.2, 0.05, 0.18 and 0.48 ppm, respectively. FTIR and HPTLC studies revealed the presence of functional groups of withanolides in Ashwagandhadi lehyam, resulting in its chemical standardization. The formulation exhibited less epileptic seizures in various phases when compared with that of standard phenytoin and found to possess better anti-inflammatory activity, thus making it biologically standardized. The physico-chemical and pharmacological analysis to standardize Ashwagandhadi lehyam confirmed its use as a safe anti-inflammatory agent and for various seizure disorders.

Induction of quinone reductase (QR) by withanolides isolated from Physalis pubescens L. (Solanaceae)

In the present study, it was demonstrated that the dichloromethane extract of Physalis pubescens L. (DEPP) had weak potential quinone reductase (QR) inducing activity, but an UPLC-ESI-MS method with glutathione (GSH) as the substrate revealed that the DEPP had electrophiles (with an α,β-unsaturated ketone moiety). These electrophiles could induce quinone reductase (QR) activity, which might be attributed to the modification of the highly reactive cysteine residues in Keap1. Herein, four withanolides, including three new compounds physapubescin B (2), physapubescin C (3), physapubescin D (4), together with one known steroidal compound physapubescin (1) were isolated. Structures of these compounds were determined by spectroscopic analysis and that of physapubescin C (3) was confirmed by a combination of molecular modeling and quantum chemical DFT-GIAO calculations. Evaluation of the QR inducing activities of all withanolides indicated potent activities of compounds 1 and 2, which had a common α,β-unsaturated ketone moiety.

Cytotoxic withanolides from the leaves of Moroccan Withania frutescens

CONTEXT

Withania species are a rich source of interesting phytochemical substances (withanolides) which have shown several biological properties.

OBJECTIVE

To investigate the cytotoxic potential of Withania frutescens (L.) Pauquy (Solanaceae) leaf extracts and isolated active compounds against cultured tumor cell lines.

MATERIALS AND METHODS

The crude methanol extract of W. frutescens leaves was partitioned with dichloromethane, ethyl acetate and n-butanol. MeOH extract and its fractions were tested for their cytotoxic activity against cancer cell lines (HepG2 and HT29) using the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. Bioassay-guided fractionation was performed for the active CH₂Cl₂ fraction employing column chromatography and preparative high-performance liquid chromatography. Structural elucidation of the isolated active compounds was carried out mainly by 1D and 2D NMR and mass spectrometry. The compounds were then tested for their cytotoxic activity.

RESULTS

The CH₂Cl₂ fraction was the most active against HT29 cell line. The fractionation procedure resulted in the isolation of 4β,17α,27-trihydroxy-1-oxo-22-R-witha-2,5,24-trienolide (1), 5β,6β-epoxy-4β,17α,27-trihydroxy-1-oxowitha-2,24-dienolide (2) and 2,3-dihydroxywithaferin A-3β-O-sulfate (3). The latter exhibited the strongest cytotoxic activity against HT29 cancer cell lines (IC₅₀ of 1.78 ± 0.09 µM) which was comparable to that of 5-fluorouracil (5-FU) used as the positive antimitotic control.

DISCUSSION AND CONCLUSION

Compounds 2 and 3 were isolated from W. frutescens for the first time. Data obtained suggest that the sulfated steroidal lactone (3) can be considered as a compound with potential application in the new anticancer drugs development field.

Physalin A induces apoptosis via p53-Noxa-mediated ROS generation, and autophagy plays a protective role against apoptosis through p38-NF-κB survival pathway in A375-S2 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Physalin A is a bioactive withanolide isolated from natural plant Physalis alkekengi L. var. franchetii (Mast.) Makino, a traditional Chinese herbal medicine named Jindenglong which has long been used for the treatment of cough, sore throat, hepatitis, eczema, dysuria and tumors in China.

AIM OF THE STUDY

Based on the previous study that physalin A induced cytotoxic effect in human melanoma A375-S2 cells, this study was designed to further illustrate the molecular mechanisms underlying.

MATERIALS AND METHODS

Cell viability was evaluated in A375-S2 cells by MTT assay, and the mechanisms involved in physalin A-induced A375-S2 cell death were investigated by phase contrast microscopy and fluorescence microscopy, siRNA transfection, flow cytometry and western blot analysis.

RESULTS

We demonstrated that physalin A decreased the proportion of viable A375-S2 cells in a time- and dose-dependent manner, and exposure of A375-S2 cells to physalin A led to both apoptosis and autophagy. Moreover, physalin A-induced apoptosis was triggered by activation of p53-Noxa pathway and intracellular reactive oxygen species (ROS) generation. The administration of ROS scavengers NAC and GSH resulted in the complete inhibition of physalin A-induced ROS generation and apoptosis. Application of p53 inhibitor PFT-α or transfection with Noxa-siRNA could also lead to the same results. Autophagy, demonstrated by the punctuate distribution of monodansylcadaverine staining, as well as the change of LC3-II/LC3-I proportion and Beclin 1 activation, played a protective role against apoptosis via up-regulation of the p38-NF-κB survival pathway in A375-S2 cells. Additionally, inhibition of autophagy by the specific autophagic inhibitor 3MA or blocking the p38-NF-κB pathway with p38 inhibitor SB203580 or NF-κB inhibitor PDTC obviously promoted physalin A-induced apoptosis.

CONCLUSIONS

Physalin A induced apoptotic cell death via p53-Noxa-mediated ROS generation, and autophagy played a protective role against apoptosis through up-regulating the p38-NF-κB survival pathway in A375-S2 cells. These results stated the possibility that physalin A would be a potential agent for the treatment of melanoma in the future.

Physalin A induces apoptotic cell death and protective autophagy in HT1080 human fibrosarcoma cells

Physalin A (1) is a withanolide isolated from Physalis alkekengi var. franchetii. In this study, the selective growth inhibitory effects on tumor cells induced by 1 were screened, and the mechanism was investigated on 1-induced growth inhibition, including apoptosis and autophagy, in human fibrosarcoma HT1080 cells. Apoptosis induced by 1 in HT1080 cells was associated with up-regulation of caspase-3 and caspase-8 expression. However, there were no significant changes in caspase-9, Bid, Bax, and Bcl-2 expression, indicating that 1-induced apoptosis in HT1080 cells occurs mainly through activation of the death receptor-associated extrinsic apoptotic pathways. Autophagy induced by 1 was found to antagonize apoptosis in HT1080 cells. This effect was enhanced by rapamycin and suppressed by the autophagy inhibitor 3-methyladenine (3MA). Loss of beclin 1 (as an autophagic regulator) function led to similar results to 3MA. However, 1 did not show inhibitory effects on normal human cells (human peripheral blood mononuclear cells). Taken together, these results suggest that 1 may be a promising agent for the treatment of cancer.

Withaferin A effectively targets soluble vimentin in the glaucoma filtration surgical model of fibrosis

Withaferin A (WFA) is a natural product that binds to soluble forms of the type III intermediate filament (IF) vimentin. Currently, it is unknown under what pathophysiological contexts vimentin is druggable, as cytoskeltal vimentin-IFs are abundantly expressed. To investigate druggability of vimentin, we exploited rabbit Tenon's capsule fibroblast (RbTCF) cell cultures and the rabbit glaucoma filtration surgical (GFS) model of fibrosis. WFA potently caused G₀/G₁ cell cycle inhibition (IC₅₀ 25 nM) in RbTCFs, downregulating ubiquitin E3 ligase skp2 and inducing p27(Kip1) expression. Transforming growth factor (TGF)-ß-induced myofibroblast transformation caused development of cell spheroids with numerous elongated invadopodia, which WFA blocked potently by downregulating soluble vimentin and α-smooth muscle actin (SMA) expression. In the pilot proof-of-concept study using the GFS model, subconjunctival injections of a low WFA dose reduced skp2 expression in Tenon's capsule and increased p27(Kip1) expression without significant alteration to vimentin-IFs. This treatment maintains significant nanomolar WFA concentrations in anterior segment tissues that correspond to WFA's cell cycle targeting activity. A ten-fold higher WFA dose caused potent downregulation of soluble vimentin and skp2 expression, but as found in cell cultures, no further increase in p27(Kip1) expression was observed. Instead, this high WFA dose potently induced vimentin-IF disruption and downregulated α-SMA expression that mimicked WFA activity in TGF-ß-treated RbTCFs that blocked cell contractile activity at submicromolar concentrations. These findings illuminate that localized WFA injection to ocular tissues exerts pharmacological control over the skp2-p27(Kip1) pathway by targeting of soluble vimentin in a model of surgical fibrosis.

Antiproliferative withanolides from Datura wrightii

A new withanolide, named withawrightolide (1), and four known withanolides (2-5) were isolated from the aerial parts of Datura wrightii. The structure of compound 1 was elucidated through 2D NMR and other spectroscopic techniques. In addition, the structure of withametelin L (2) was confirmed by X-ray crystallographic analysis. Using MTS viability assays, withanolides 1-5 showed antiproliferative activities against human glioblastoma (U251 and U87), head and neck squamous cell carcinoma (MDA-1986), and normal fetal lung fibroblast (MRC-5) cells with IC50 values in the range between 0.56 and 5.6 μM.

An in vitro study of apoptotic like death in Leishmania donovani promastigotes by withanolides

The aim of this study was to isolate and evaluate the withanolides in inducing apoptotic like death in Leishmania donovani in vitro. Withanolides were fractionated and isolated from the leaves of Withania somnifera and LC-MS/MS analysis of two fractions namely, F5 and F6 of ethanolic extracts, obtained through column chromatography with silica gel, was performed. The antileishmanial effect of withanolides on L. donovani promastigotes was assessed in vitro using PI dye exclusion test. The effect of withanolides on promastigote morphology was determined by scanning electron microscopy. To understand their mode of action against L. donovani, DNA fragmentation, quantification of parasites at sub G0/G1 phase, determination of phosphatidylserine externalization, measurement of reactive oxygen species (ROS) and mitochondrial membrane potential (Ψm) were done. Results showed that LC-MS/MS analysis confirmed the presence of withanolides in isolated fractions. Treatment with withanolides resulted in morphological alterations from spindle to round shape and loss of flagella/cell integrity in promastigotes. Moreover, it induced DNA nicks, cell cycle arrest at sub G0/G1 phase and externalization of phosphatidylserine in dose and time dependent manner via increase in ROS and decrease in Ψm. Results of this study indicate that withanolides induce apoptotic like death through the production of ROS from mitochondria and disruption of Ψm in promastigotes of L donovani.

Physangulidine A, a withanolide from Physalis angulata, perturbs the cell cycle and induces cell death by apoptosis in prostate cancer cells

Recently, our group reported the discovery of three new withanolides, physangulidines A-C, from Physalis angulata. In this study, the biological effects of physangulidine A (1), which was the most active and abundant of the three new constituents, are described. It was found that 1 significantly reduces survival in clonogenic assays for two hormone-independent prostate cancer cell lines. Flow cytometry and confocal microscopy studies in DU145 human prostate cancer cells indicated that 1 induces cell cycle arrest in the G(2)/M phase and causes defective mitosis. It was determined also that 1 produces programed cell death by apoptosis, as evidenced by biochemical markers and distinct changes in cell morphology. These results imply that the antimitotic and proapoptotic effects of 1 may contribute significantly to the biological activities and potential medicinal properties of its plant of origin.

Biologically active withanolides from Withania coagulans

Bioassay-directed isolation and purification of the crude extract of Withania coagulans, using two assays for cancer chemopreventive mechanisms, led to the isolation of three new steroidal lactones, withacoagulin G (1), withacoagulin H (2), and withacoagulin I (3), along with six known derivatives (4-9). The structures and absolute stereochemistry of these compounds were determined on the basis of spectroscopic analyses, including 1D and 2D NMR, mass spectrometry, and CD analyses. The structure of 1 was confirmed using X-ray diffraction methods. Compounds 1-9 inhibited nitric oxide production in lipopolysaccharide-activated murine macrophage RAW 264.7 cells with IC(50) values in the range of 1.9-38.2 μM. Compounds 1 and 2 were the most active (IC(50) 3.1 and 1.9 μM, respectively). Withanolides 1-9 exhibited inhibition of tumor necrosis factor-α (TNF-α)-induced nuclear factor-kappa B (NF-κB) activation with IC(50) values in the range of 1.60-12.4 μM.

Withaferin A induces proteasome inhibition, endoplasmic reticulum stress, the heat shock response and acquisition of thermotolerance

In the present study, withaferin A (WA), a steroidal lactone with anti-inflammatory and anti-tumor properties, inhibited proteasome activity and induced endoplasmic reticulum (ER) and cytoplasmic HSP accumulation in Xenopus laevis A6 kidney epithelial cells. Proteasomal inhibition by WA was indicated by an accumulation of ubiquitinated protein and a decrease in chymotrypsin-like activity. Additionally, immunoblot analysis revealed that treatment of cells with WA induced the accumulation of HSPs including ER chaperones, BiP and GRP94, as well as cytoplasmic/nuclear HSPs, HSP70 and HSP30. Furthermore, WA-induced an increase in the relative levels of the protein kinase, Akt, while the levels of actin were unchanged compared to control. Northern blot experiments determined that WA induced an accumulation in bip, hsp70 and hsp30 mRNA but not eIF-1α mRNA. Interestingly, WA acted synergistically with mild heat shock to enhance HSP70 and HSP30 accumulation to a greater extent than the sum of both stressors individually. This latter phenomenon was not observed with BiP or GRP94. Immunocytochemical analysis indicated that WA-induced BiP accumulation occurred mainly in the perinuclear region in a punctate pattern, while HSP30 accumulation occurred primarily in a granular pattern in the cytoplasm with some staining in the nucleus. Prolonged exposure to WA resulted in disorganization of the F-actin cytoskeleton as well as the production of relatively large HSP30 staining structures that co-localized with F-actin. Finally, prior exposure of cells to WA treatment, which induced the accumulation of HSPs conferred a state of thermal protection since it protected the F-actin cytoskeleton against a subsequent cytotoxic thermal challenge.

Differential activities of the two closely related withanolides, Withaferin A and Withanone: bioinformatics and experimental evidences

Background and Purpose

Withanolides are naturally occurring chemical compounds. They are secondary metabolites produced via oxidation of steroids and structurally consist of a steroid-backbone bound to a lactone or its derivatives. They are known to protect plants against herbivores and have medicinal value including anti-inflammation, anti-cancer, adaptogenic and anti-oxidant effects. Withaferin A (Wi-A) and Withanone (Wi-N) are two structurally similar withanolides isolated from Withania somnifera, also known as Ashwagandha in Indian Ayurvedic medicine. Ashwagandha alcoholic leaf extract (i-Extract), rich in Wi-N, was shown to kill cancer cells selectively. Furthermore, the two closely related purified phytochemicals, Wi-A and Wi-N, showed differential activity in normal and cancer human cells in vitro and in vivo. We had earlier identified several genes involved in cytotoxicity of i-Extract in human cancer cells by loss-of-function assays using either siRNA or randomized ribozyme library.

Methodology/Principal Findings

In the present study, we have employed bioinformatics tools on four genes, i.e., mortalin, p53, p21 and Nrf2, identified by loss-of-function screenings. We examined the docking efficacy of Wi-N and Wi-A to each of the four targets and found that the two closely related phytochemicals have differential binding properties to the selected cellular targets that can potentially instigate differential molecular effects. We validated these findings by undertaking parallel experiments on specific gene responses to either Wi-N or Wi-A in human normal and cancer cells. We demonstrate that Wi-A that binds strongly to the selected targets acts as a strong cytotoxic agent both for normal and cancer cells. Wi-N, on the other hand, has a weak binding to the targets; it showed milder cytotoxicity towards cancer cells and was safe for normal cells. The present molecular docking analyses and experimental evidence revealed important insights to the use of Wi-A and Wi-N for cancer treatment and development of new anti-cancer phytochemical cocktails.

A novel MMP-2 inhibitor 3-azidowithaferin A (3-azidoWA) abrogates cancer cell invasion and angiogenesis by modulating extracellular Par-4

BACKGROUND

Withaferin A, which is a naturally derived steroidal lactone, has been found to prevent angiogenesis and metastasis in diverse tumor models. It has also been recognized by different groups for prominent anti-carcinogenic roles. However, in spite of these studies on withanolides, their detailed anti-metastatic mechanism of action remained unknown. The current study has poised to address the machinery involved in invasion regulation by stable derivative of Withaferin A, 3-azido Withaferin A (3-azidoWA) in human cervical HeLa and prostate PC-3 cells.

METHODS AND PRINCIPAL FINDINGS

Sub-toxic concentration of 3-azidowithaferin A (3-azido WA) inhibited cancer cell motility and invasion in wound healing and Boyden chamber invasion by suppressing MMP-2 activity in gelatin zymography and its expression has proved to be a major obstacle in chemo-sensitivity. We have uncovered a novel mechanism of 3-azidoWA induced extracellular pro-apoptotic candidate tumor suppressor Par-4 protein stimulation in conditioned media and also noticed a concomitant marked reduction in pAkt and pERK signaling by immunoblot analysis. Furthermore, our zymography results suggest 3-azidoWA induced MMP-2 inhibition was mediated through secretory Par-4. The inhibition of apoptosis by 3-azidoWA could not restore MMP-2 gelatinase activity. In addition to this, our in vivo animal experiments data showed 3-azidoWA abrogated neovascularisation in dose dependent manner in mouse Matrigel plug assay.

CONCLUSION/SIGNIFICANCE

For this report, we found that 3-azidoWA suppressed motility and invasion of HeLa and PC-3 cells in MMP-2 dependent manner. Our in vitro result strongly suggests that sub-toxic doses of 3-azidoWA enhanced the secretion of extracellular Par-4 that abolished secretory MMP-2 expression and activity. Depletion of secretory Par-4 restored MMP-2 expression and invasion capability of HeLa and PC-3 cells. Further, our findings implied that 3-azidoWA attenuated internal phospho-ERK and phospho-Akt expression in a dose dependent manner might play a key role in inhibition of mouse angiogenesis by 3-azidoWA.

Withaferin-A reduces type I collagen expression in vitro and inhibits development of myocardial fibrosis in vivo

Type I collagen is the most abundant protein in the human body. Its excessive synthesis results in fibrosis of various organs. Fibrosis is a major medical problem without an existing cure. Excessive synthesis of type I collagen in fibrosis is primarily due to stabilization of collagen mRNAs. We recently reported that intermediate filaments composed of vimentin regulate collagen synthesis by stabilizing collagen mRNAs. Vimentin is a primary target of Withaferin-A (WF-A). Therefore, we hypothesized that WF-A may reduce type I collagen production by disrupting vimentin filaments and decreasing the stability of collagen mRNAs. This study is to determine if WF-A exhibits anti-fibrotic properties in vitro and in vivo and to elucidate the molecular mechanisms of its action. In lung, skin and heart fibroblasts WF-A disrupted vimentin filaments at concentrations of 0.5-1.5 µM and reduced 3 fold the half-lives of collagen α1(I) and α2(I) mRNAs and protein expression. In addition, WF-A inhibited TGF-β1 induced phosphorylation of TGF-β1 receptor I, Smad3 phosphorylation and transcription of collagen genes. WF-A also inhibited in vitro activation of primary hepatic stellate cells and decreased their type I collagen expression. In mice, administration of 4 mg/kg WF-A daily for 2 weeks reduced isoproterenol-induced myocardial fibrosis by 50%. Our findings provide strong evidence that Withaferin-A could act as an anti-fibrotic compound against fibroproliferative diseases, including, but not limited to, cardiac interstitial fibrosis.

Withaferin A synergizes the therapeutic effect of doxorubicin through ROS-mediated autophagy in ovarian cancer

Application of doxorubicin (Dox) for the treatment of cancer is restricted due to its severe side effects. We used combination strategy by combining doxorubicin (Dox) with withaferin A (WFA) to minimize the ill effects of Dox. Treatment of various epithelial ovarian cancer cell lines (A2780, A2780/CP70 and CaOV3) with combination of WFA and Dox (WFA/DOX) showed a time- and dose-dependent synergistic effect on inhibition of cell proliferation and induction of cell death, thus reducing the dosage requirement of Dox. Combination treatment resulted in a significant enhancement of ROS production resulting in immense DNA damage, induction of autophagy analyzed by transmission electron microscope and increase in expression of autophagy marker LC3B, and culminated in cell death analyzed by cleaved caspase 3. We validated combination therapy on tumor growth using an in vitro 3Dimension (3D) tumor model and the more classic in vivo xenograft model of ovarian cancer. Both tumor models showed a 70 to 80% reduction in tumor growth compared to control or animals treated with WFA or Dox alone. Immunohistochemical analysis of the tumor tissues from animals treated with WFA/Dox combination showed a significant reduction in cell proliferation and formation of microvessels accompanied by increased in LC3B level, cleaved caspase 3, and DNA damage. Taken together, our data suggest that combining WFA with Dox decreases the dosage requirement of Dox, therefore, minimizing/eliminating the severe side effects associated with high doses of DOX, suggesting the application of this combination strategy for the treatment of ovarian and other cancers with no or minimum side effects.

Molecular docking studies of withanolides against Cox-2 enzyme

Withaniasomnifera (Ashwaganda) belonging to the family solanaceae is the subject of our present study. Withanoloides which are the major chemical constituents have been proved of interest because of their structural variations in the hybrids of different races. Docking is the process which brings the two structures together. In the present study we focus the extensive use of tool and graphical software for the identification of the binding energy of selected Withanolides like Withaferin -A, Withanolide-D from Withaniasomnifera and to screen the phytoconstituents that will dock/bind to the active sites of COX-2 enzyme. The relief from the symptoms of inflammation and pain can be by the Pharmacological inhibition of COX which involves the prediction of potential ligand for the treatment of inflammation. The energy value of docking between the target and the phytoconstituents under investigation and comparison with Diclofenac sodium was taken into consideration for coming into conclusion regarding the best pose and the binding ability.

Withaferin a alters intermediate filament organization, cell shape and behavior

Withaferin A (WFA) is a steroidal lactone present in Withania somnifera which has been shown in vitro to bind to the intermediate filament protein, vimentin. Based upon its affinity for vimentin, it has been proposed that WFA can be used as an anti-tumor agent to target metastatic cells which up-regulate vimentin expression. We show that WFA treatment of human fibroblasts rapidly reorganizes vimentin intermediate filaments (VIF) into a perinuclear aggregate. This reorganization is dose dependent and is accompanied by a change in cell shape, decreased motility and an increase in vimentin phosphorylation at serine-38. Furthermore, vimentin lacking cysteine-328, the proposed WFA binding site, remains sensitive to WFA demonstrating that this site is not required for its cellular effects. Using analytical ultracentrifugation, viscometry, electron microscopy and sedimentation assays we show that WFA has no effect on VIF assembly in vitro. Furthermore, WFA is not specific for vimentin as it disrupts the cellular organization and induces perinuclear aggregates of several other IF networks comprised of peripherin, neurofilament-triplet protein, and keratin. In cells co-expressing keratin IF and VIF, the former are significantly less sensitive to WFA with respect to inducing perinuclear aggregates. The organization of microtubules and actin/microfilaments is also affected by WFA. Microtubules become wavier and sparser and the number of stress fibers appears to increase. Following 24 hrs of exposure to doses of WFA that alter VIF organization and motility, cells undergo apoptosis. Lower doses of the drug do not kill cells but cause them to senesce. In light of our findings that WFA affects multiple IF systems, which are expressed in many tissues of the body, caution is warranted in its use as an anti-cancer agent, since it may have debilitating organism-wide effects.

Antiproliferative activity of withanolide derivatives from Jaborosa cabrerae and Jaborosa reflexa. Chemotaxonomic considerations

Three withanolides were isolated from the aerial parts of Jaborosa reflexa Phil. Jaborosa cabrerae Barboza yielded five sativolide withanolides (including jaborosalactones R, S, 38, and 39) and two trechonolide withanolides epimeric at C-23 (trechonolide A and jaborosalactone 32). In addition, five derivatives were obtained by chemical derivatization of jaborosalactone 38, and all compounds were fully characterized by 1D and 2D NMR spectroscopic studies. The in vitro antiproliferative activities of the major natural withanolides and the semisynthetic derivatives were examined against HBL-100, HeLa, SW1573, T-47D, and WiDr human solid tumor cancer cell lines. Some chemotaxonomic considerations are discussed.

Bak compensated for Bax in p53-null cells to release cytochrome c for the initiation of mitochondrial signaling during Withanolide D-induced apoptosis

The goal of cancer chemotherapy to induce multi-directional apoptosis as targeting a single pathway is unable to decrease all the downstream effect arises from crosstalk. Present study reports that Withanolide D (WithaD), a steroidal lactone isolated from Withania somnifera, induced cellular apoptosis in which mitochondria and p53 were intricately involved. In MOLT-3 and HCT116p53+/+ cells, WithaD induced crosstalk between intrinsic and extrinsic signaling through Bid, whereas in K562 and HCT116p53−/− cells, only intrinsic pathway was activated where Bid remain unaltered. WithaD showed pronounced activation of p53 in cancer cells. Moreover, lowered apoptogenic effect of HCT116p53−/− over HCT116p53+/+ established a strong correlation between WithaD-mediated apoptosis and p53. WithaD induced Bax and Bak upregulation in HCT116p53+/+, whereas increase only Bak expression in HCT116p53−/− cells, which was coordinated with augmented p53 expression. p53 inhibition substantially reduced Bax level and failed to inhibit Bak upregulation in HCT116p53+/+ cells confirming p53-dependent Bax and p53-independent Bak activation. Additionally, in HCT116p53+/+ cells, combined loss of Bax and Bak (HCT116Bax−Bak−) reduced WithaD-induced apoptosis and completely blocked cytochrome c release whereas single loss of Bax or Bak (HCT116Bax−Bak+/HCT116Bax+Bak−) was only marginally effective after WithaD treatment. In HCT116p53−/− cells, though Bax translocation to mitochondria was abrogated, Bak oligomerization helped the cells to release cytochrome c even before the disruption of mitochondrial membrane potential. WithaD also showed in vitro growth-inhibitory activity against an array of p53 wild type and null cancer cells and K562 xenograft in vivo. Taken together, WithaD elicited apoptosis in malignant cells through Bax/Bak dependent pathway in p53-wild type cells, whereas Bak compensated against loss of Bax in p53-null cells.

Cytotoxic withanolide constituents of Physalis longifolia

Fourteen new withanolides, 1-14, named withalongolides A-N, respectively, were isolated from the aerial parts of Physalis longifolia together with eight known compounds (15-22). The structures of compounds 1-14 were elucidated through spectroscopic techniques and chemical methods. In addition, the structures of withanolides 1, 2, 3, and 6 were confirmed by X-ray crystallographic analysis. Using a MTS viability assay, eight withanolides (1, 2, 3, 7, 8, 15, 16, and 19) and four acetylated derivatives (1a, 1b, 2a, and 2b) showed potent cytotoxicity against human head and neck squamous cell carcinoma (JMAR and MDA-1986), melanoma (B16F10 and SKMEL-28), and normal fetal fibroblast (MRC-5) cells with IC₅₀ values in the range between 0.067 and 9.3 μM.

Cytotoxic activity of withanolides isolated from Tunisian Datura metel L

Withanolide-type steroids, withametelin Q (1) and 12α-hydroxydaturametelin B (2) along with three known withanolides, were isolated from leaves of Datura metel L. (Solanaceae). The respective structures, characterized mainly by NMR spectroscopy, were identified as (20R,22R,24R)-21,24-epoxy-1α,3β-dihydroxywitha-5,25(27)-dienolide-3-O-β-D-glucopyranoside (1) and (20R,22R,24R)-12α,21,27-trihydroxy-1-oxowitha-2,5,24-trienolide-27-O-β-D-glucopyranoside (2). The cytotoxicity of isolated compounds was evaluated against human lung carcinoma cells (A549) and human colorectal adenocarcinoma cells (DLD-1), respectively. Compound 2 exhibited cytotoxicity against A549 and DLD-1 cell lines, with IC50 values of 7 and 2.0 μM, respectively. However, for compounds 6 and 7, cytotoxicities were higher against DLD-1 cells with IC(50) values of 0.6 and 0.7 μM. Both compounds blocked the cell cycle in the S-phase and induced apoptosis.

Withaferin A-induced apoptosis in human breast cancer cells is mediated by reactive oxygen species

Withaferin A (WA), a promising anticancer constituent of Ayurvedic medicinal plant Withania somnifera, inhibits growth of MDA-MB-231 and MCF-7 human breast cancer cells in culture and MDA-MB-231 xenografts in vivo in association with apoptosis induction, but the mechanism of cell death is not fully understood. We now demonstrate, for the first time, that WA-induced apoptosis is mediated by reactive oxygen species (ROS) production due to inhibition of mitochondrial respiration. WA treatment caused ROS production in MDA-MB-231 and MCF-7 cells, but not in a normal human mammary epithelial cell line (HMEC). The HMEC was also resistant to WA-induced apoptosis. WA-mediated ROS production as well as apoptotic histone-associated DNA fragment release into the cytosol was significantly attenuated by ectopic expression of Cu,Zn-superoxide dismutase in both MDA-MB-231 and MCF-7 cells. ROS production resulting from WA exposure was accompanied by inhibition of oxidative phosphorylation and inhibition of complex III activity. Mitochondrial DNA-deficient Rho-0 variants of MDA-MB-231 and MCF-7 cells were resistant to WA-induced ROS production, collapse of mitochondrial membrane potential, and apoptosis compared with respective wild-type cells. WA treatment resulted in activation of Bax and Bak in MDA-MB-231 and MCF-7 cells, and SV40 immortalized embryonic fibroblasts derived from Bax and Bak double knockout mouse were significantly more resistant to WA-induced apoptosis compared with fibroblasts derived from wild-type mouse. In conclusion, the present study provides novel insight into the molecular circuitry of WA-induced apoptosis involving ROS production and activation of Bax/Bak.

Withanolides from the rhizomes of Dioscorea japonica and their cytotoxicity

Edible yams are tropical crops that serve as important staple foods in many parts of the world. The rhizome of Dioscorea japonica , well-known as "Japanese yam", is a food and medicinal source known as "San Yak" in Korea. Bioassay-guided fractionation and chemical investigation of the extract of this yam resulted in the identification of two new withanolides, named dioscorolide A (1) and dioscorolide B (2). The structures of these new compounds were determined by spectroscopic methods, including 1D and 2D nuclear magnetic resonance (NMR) techniques, high-resolution mass spectrometry (HRMS), and chemical methods. The cytotoxic activities of the isolates (1 and 2) were evaluated by determining their inhibitory effects on four human tumor cell lines (A549, SK-OV-3, SK-MEL-2, and HCT15) and a human normal cell line (HUVEC) using a sulforhodamine B (SRB) bioassay. Compounds 1 and 2 showed cytotoxicity against tumor cell lines (A549, SK-OV-3, SK-MEL-2, and HCT15) with IC(50) values ranging from 6.3 to 26.9 μM and exhibited lower activity against the normal cell line (HUVEC) with IC(50) values ranging from 27.1 to 28.8 μM, suggesting selective toxicity among tumor and normal cells.

Paraminabeolides A-F, cytotoxic and anti-inflammatory marine withanolides from the soft coral Paraminabea acronocephala

Six new withanolides, paraminabeolides A-F (1-6), along with five known compounds, minabeolides-1, -2, -4, -5, and -8 (7-11), were isolated from a Formosan soft coral, Paraminabea acronocephala. The structures of these compounds were elucidated by extensive spectroscopic analysis and chemical transformation. The absolute configuration of 4 was determined by the application of Mosher's method. Compounds 1 and 7 were cytotoxic toward Hep G2 cancer cells. Compounds 1-4 and 7-10 were found to significantly inhibit the accumulation of the pro-inflammatory iNOS protein. Compounds 7-10 also could effectively reduce the expression of COX-2 protein.

Dinoxin B, a withanolide from Datura inoxia leaves with specific cytotoxic activities

A new withanolide, dinoxin B (12,21-dihydroxy-1-oxowitha-2,5,24-trienolide-27-O-β-D-glucopyranoside, 1), was isolated from a methanol extract of Datura inoxia leaves, using bioassay-guided fractionation. The structure was determined by spectroscopic techniques, including (1)H, (13)C, and 2D NMR experiments as well as by HRMS. Extracts and the purified compound were tested for their antiproliferative activities toward a panel of human normal and cancer cell lines. Dinoxin B (1) and its aglycone (2) exhibited submicromolar IC(50) values against multiple human cancer cell lines. Among the most sensitive were several breast cancer cell lines. Dinoxin B (1) was found only in D. inoxia and was not detected in D. metel or D. stramonium. The accumulation of this compound was limited largely to leaf tissue, with little to none detected in extracts from the flowers, fruits, roots, or stems of D. inoxia.

Hsp90/Cdc37 chaperone/co-chaperone complex, a novel junction anticancer target elucidated by the mode of action of herbal drug Withaferin A

BACKGROUND

HSPs (Heat shock proteins) are highly conserved ubiquitous proteins among species which are involved in maintaining appropriate folding and conformation of other proteins and are thus referred to as molecular chaperones. Hsp90 (Heat-shock protein 90 kDa) is one of a group of molecular chaperones responsible for managing protein folding and quality control in cell environment. However it is also involved in the maturation and stabilization of a wide range of oncogenic client proteins which are crucial for oncogenesis and malignant progression. Hsp90 requires a series of co-chaperones to assemble into a super-chaperone complex for its function. These co-chaperones bind and leave the complex at various stages to regulate the chaperoning process. Arresting the chaperone cycle at these stages by targeting different co-chaperone/Hsp90 interactions seems to be quite a viable alternative and is likely to achieve similar consequences as that of Hsp90 direct inhibition with added favors of high specificity and reduced side effect profile. The study conducted here is an attempt to explore the potential of Withania somnifera's major constituent WA (Withaferin A) in attenuating the Hsp90/Cdc37 chaperone/co-chaperone interactions for enhanced tumor arresting activity and to elucidate the underlying mode of action using computational approaches.

RESULTS

Formation of active Hsp90/Cdc37 complex is one of the essential steps for facilitation of chaperone client interaction, non-assembly of which can lead to prevention of the chaperone-client association resulting in apoptosis of tumor cells. From our flexible docking analysis of WA into active Hsp90/Cdc37 complex in which key interfacing residues of the complex were kept flexible, disruption of the active association complex can be discerned. While docking of WA into segregated Hsp90 leaves the interface residues untouched. Thus the molecular docking analysis of WA into Hsp90 and active Hsp90/Cdc37 complex conducted in this study provides significant evidence in support of the proposed mechanism of chaperone assembly suppression by inhibition or disruption of active Hsp90/Cdc37 complex formation being accounted by non-assembly of the catalytically active Hsp90/Cdc37 complex. Results from the molecular dynamics simulations in water show that the trajectories of the protein complexed with ligand WA are stable over a considerably long time period of 4 ns, with the energies of the complex being lowered in comparison to the un-docked association complex, suggesting the thermodynamic stability of WA complexed Hsp90/Cdc37.

CONCLUSIONS

The molecular chaperone Hsp90 has been a promising target for cancer therapy. Cancer is a disease marked by genetic instability. Thus specific inhibition of individual proteins or signalling pathways holds a great potential for subversion of this genetic plasticity of cancers. This study is a step forward in this direction. Our computational analysis provided a rationalization to the ability of naturally occurring WA to alter the chaperone signalling pathway. The large value of binding energy involved in binding of WA to the active Hsp90/Cdc37 complex consolidates the thermodynamic stability of the binding. Our docking results obtained substantiate the hypothesis that WA has the potential to inhibit the association of chaperone (Hsp90) to its co-chaperone (Cdc37) by disrupting the stability of attachment of Hsp90 to Cdc37. Conclusively our results strongly suggest that withaferin A is a potent anticancer agent as ascertained by its potent Hsp90-client modulating capability.

Anti-inflammatory effect of Ajuga bracteosa Wall Ex Benth. mediated through cyclooxygenase (COX) inhibition

ETHNOPHARMACOLOGICAL RELEVANCE

Ajuga bracteosa Wall Ex Benth. (Labiateae) is described in Ayurveda for the treatment of rheumatism, gout, palsy and amenorrhea.

AIM OF THE STUDY

The aim of present investigation is to study anti-inflammatory activity of Ajuga bracteosa, to understand possible mechanism of action and to identify the constituents responsible for its activity.

MATERIALS AND METHODS

The anti-inflammatory activity of 70% ethanolic extract was evaluated in TPA-induced mouse ear edema assay and in vitro cyclooxygenase (COX)-1 and COX-2 inhibitory activity was determined using EIA kits employing appropriate reference standards. Aajugarin I, lupulin A, withaferin A, reptoside and 6-deoxyharpagide were isolated from the 70% ethanolic extract by silica gel column chromatography.

RESULTS

The 70% ethanol extract of whole plants of Ajuga bracteosa showed a significant (p<0.05) and dose-dependent anti-inflammatory activity in an acute inflammation model at the dose of 0.5 and 1.0 mg/ear. The extract also exhibited a strong in vitro COX-1 and COX-2 inhibitory activity at 25 and 50 μg/mL concentration. Among the isolated compounds 6-deoxyharpagide exhibited highest COX-2 inhibition while rest of the compounds exhibited weak to moderate COX-1 and COX-2 inhibition at 30 μM concentration.

CONCLUSIONS

The results suggest that the 70% ethanol extract of Ajuga bracteosa possesses promising anti-inflammatory activity, which is possibly mediated through inhibition of COX-1 and COX-2 enzymes. The isolated constituents could be responsible in part for its anti-inflammatory and COX inhibitory activity. The study supports traditional use of Ajuga bracteosa for inflammatory diseases.

Endoplasmic reticulum stress mediates withaferin A-induced apoptosis in human renal carcinoma cells

The accumulation of misfolded proteins in the lumen of the endoplasmic reticulum (ER) results in cellular stress that initiates a specialized response designated as the unfolded protein response. ER stress has been implicated in a variety of common diseases, such as diabetes, ischemia and neurodegenerative disorders. Withaferin A, a major chemical constituent of Withania somnifera, has been reported to inhibit tumor cell growth. We show that withaferin A induced a dose-dependent apoptotic cell death in several types of human cancer cells, as measured by FACS analysis and PARP cleavage. Treatment of Caki cells with withaferin A induced a number of signature ER stress markers, including phosphorylation of eukaryotic initiation factor-2α (eIF-2 α), ER stress-specific XBP1 splicing, and up-regulation of glucose-regulated protein (GRP)-78. In addition, withaferin A caused up-regulation of CAAT/enhancer-binding protein-homologous protein (CHOP), suggesting the induction of ER stress. Pretreatment with N-acetyl cysteine (NAC) significantly inhibited withaferin A-mediated ER stress proteins and cell death, suggesting that reactive oxygen species (ROS) mediate withaferin A-induced ER stress. Furthermore, CHOP siRNA or inhibition of caspase-4 activity attenuated withaferin A-induced apoptosis. Taken together, the present study provides strong evidence supporting an important role of the ER stress response in mediating withaferin A-induced apoptosis.

Chlorinated and diepoxy withanolides from Withania somnifera and their cytotoxic effects against human lung cancer cell line

Phytochemical studies on the aerial parts of Withania somnifera L. Dunal. (Solanaceae) led to the isolation of a chlorinated steroidal lactone (27-acetoxy-4β,6α-dihydroxy-5β-chloro-1-oxowitha-2,24-dienolide), a diepoxy withanolide (5β,6β,14α,15α-diepoxy-4β,27-dihydroxy-1-oxowitha-2,24-dienolide), and withaferin A. Their structures were elucidated by using spectroscopic techniques. All three compounds exhibited a growth inhibition and cytotoxic activity against human lung cancer cell line (NCI-H460), with withaferin A being the most potent (GI(50)=0.18 μg/mL and LC(50)=0.45 μg/mL) among three compounds tested.

Withanolides from Withania aristata and their cytotoxic activity

Seven new withanolides (1-7), along with three known ones (8-10), were isolated from the leaves of Withania aristata. Their structures were elucidated on the basis of spectroscopic analysis, including 2D NMR experiments and spectrometric techniques, and the absolute configuration of 1 and 2 was established by CD analysis. In the search for new cytotoxic compounds from Withania species, the isolated compounds 1-9, along with two derivatives, were assayed for their cytotoxicity against HeLa, MCF-7 and A-549 human tumor cell lines. Derivative (4S,20R,22R)-27-acetoxy-4-p-bromobenzoyloxy-1-oxo-witha-2,5,16,24-tetraenolide (13) showed cytotoxicity against all the cell lines assayed with IC(50) values ranging from 2.8 to 3.6microM, and (4S,20R,22R)-4,27-diacetoxy-4-hydroxy-1-oxo-witha-2,5,16,24-tetraenolide (12) exhibited an IC(50) value of 5.4microM on the MCF-7 cell line.

Withaferin A, a cytotoxic steroid from Vassobia breviflora, induces apoptosis in human head and neck squamous cell carcinoma

As part of a program to discover drug leads from plant biodiversity, the present investigation was undertaken to explore the anticancer potential of compounds derived from selected Latin American plants. Bioassay-guided fractionation of a crude extract of the aerial parts of Vassobia breviflora led to the isolation of the withanolide-type steroidal lactone withaferin A (1). This compound was tested for antiproliferative activity against the head and neck squamous cell carcinoma (HNSCC) cell lines, MDA1986, JMAR, UM-SCC-2, and JHU011. The inhibitory concentrations to reduce cell viability to 50% (IC(50)) were determined by the MTS cytotoxicity assay, and 1 reduced cell viability with IC(50) values in the range 0.5-2.2 μM. A mechanistic study showed that 1 induces apoptosis and cell death in HNSCC cells as well as a cell-cycle shift from G(0)/G(1) to G(2)/M. Cells treated with 1 exhibited inactivation of Akt and a reduction in total Akt concentration. This investigation constitutes the first report of the antiproliferative activity of withaferin A (1) against head and neck squamous carcinoma.

Antifungal and cytotoxic activity of withanolides from Acnistus arborescens

Three compounds were isolated from Acnistus arborescens, a tree commonly used in South and Central America in traditional medicine against several infectious diseases, some of which are caused by fungi. Bioassay-guided fractionation of a MeOH extract of leaves, based on its anti-Pneumocystis carinii activity, led to the isolation of compounds 1-3. Mono- and bidimensional NMR analyses enabled identification of two new withanolides, (20R,22R)-5beta,6beta-epoxy-4beta,12beta,20-trihydroxy-1-oxowith-2-en-24-enolide (1) and (20R,22R)-16beta-acetoxy-3beta,4beta;5beta,6beta-diepoxy-12beta,20-dihydroxy-1-oxowith-24-enolide (2), and withanolide D (3). Antifungal activity on 13 fungi responsible for human infections (five dermatophytes, one nondermatophyte mold, six yeasts, and Pneumocystis carinii) was examined. Cytotoxicity of these compounds was also evaluated in vitro.

Antiproliferative activity of withanolides against human breast cancer cell lines

The in vitro antiproliferative activity of a series of 22 naturally occurring withanolides was examined against the T-47D, MCF7, MCF7/BUS, MDA-MB-231, and SK-Br-3 human solid tumor breast cancer cell lines. The most active compound showed GI(50) values in the range 0.16-0.71 muM. The aromatic withanolide 19 exhibited specific activity for the estrogen-receptor-positive cell lines (T-47D, MCF7, and MCF7/BUS). Overall, the results demonstrated the relevance of the substitution pattern on the A and B rings on the resultant antiproliferative activity.

Vimentin is a novel anti-cancer therapeutic target; insights from in vitro and in vivo mice xenograft studies

BACKGROUND

Vimentin is a ubiquitous mesenchymal intermediate filament supporting mechano-structural integrity of quiescent cells while participating in adhesion, migration, survival, and cell signaling processes via dynamic assembly/disassembly in activated cells. Soft tissue sarcomas and some epithelial cancers exhibiting "epithelial to mesenchymal transition" phenotypes express vimentin. Withaferin-A, a naturally derived bioactive compound, may molecularly target vimentin, so we sought to evaluate its effects on tumor growth in vitro and in vivo thereby elucidating the role of vimentin in drug-induced responses.

METHODS AND FINDINGS

Withaferin-A elicited marked apoptosis and vimentin cleavage in vimentin-expressing tumor cells but significantly less in normal mesenchymal cells. This proapoptotic response was abrogated after vimentin knockdown or by blockade of caspase-induced vimentin degradation via caspase inhibitors or overexpression of mutated caspase-resistant vimentin. Pronounced anti-angiogenic effects of Withaferin-A were demonstrated, with only minimal effects seen in non-proliferating endothelial cells. Moreover, Withaferin-A significantly blocked soft tissue sarcoma growth, local recurrence, and metastasis in a panel of soft tissue sarcoma xenograft experiments. Apoptosis, decreased angiogenesis, and vimentin degradation were all seen in Withaferin-A treated specimens.

CONCLUSIONS

In light of these findings, evaluation of Withaferin-A, its analogs, or other anti-vimentin therapeutic approaches in soft tissue sarcoma and "epithelial to mesenchymal transition" clinical contexts is warranted.

Withanolides from Whitania aristata and their diuretic activity

AIM OF THE STUDY

Withania aristata is an endemic plant used traditionally in Canary Islands as a diuretic. In this paper, we report on this pharmacological activity in several extracts of the dry vegetal material collected and the identification and diuretic activity of two withanolides, one of them previously not reported, isolated from the most active fraction.

MATERIAL AND METHODS

Four Whitania aristata extracts at 100 mg/kg were orally administered to laboratory animals to evaluate their diuretic activity. From the most active fraction, two withanolides were isolated. Both and a mixture of them at 5 and 10 mg/kg were analyzed too as diuretics. Water excretion rate and content of Na(+) and K(+) electrolytes were measured in the urine of saline-loaded animals.

RESULTS

Whitania aristata water fraction, the two withanolides and the mixture of these compounds displayed high diuretic activity, with a significant excretion of sodium and potassium ions in laboratory animals.

CONCLUSIONS

This research supports the ethno-medicinal use of Whitania aristata as diuretic. This activity seems to be associated to the presence of a new type of natural diuretic agents, such as withaferin A and witharistatin.

Constituents of the stem bark of Discopodium penninervium and their LTB4 and COX-1 and -2 inhibitory activities

The stem bark of Discopodium penninervium afforded a withanolide, 6alpha,7alpha-epoxy-1-oxo-5alpha,12alpha,17alpha-trihydroxywitha-2,24-dienolide (1) and a coloratane sesquiterpene, 7alpha,11alpha-dihydroxy-4(13),8-coloratadien-12,11-olide (4) along with five known compounds, withanone (2), 5alpha,17beta-dihydroxy-6alpha,7alpha-epoxy-1-oxowitha-2,24-dienolide (3), 7alpha,11alpha-dihydroxy-8-drimen-12,11-olide (5), withasomnine (6), and (E,Z)-9-hydroxyoctadeca-10,12-dienoic acid (7). The identity of the compounds was established on the basis of spectroscopic data analysis. All compounds were assessed for inhibition of leukotriene metabolism in an in vitro bioassay using activated human neutrophile granulocytes, and for in vitro cycloxygenase-1 and -2 inhibition from sheep cotyledons and seminal vesicles, respectively. In the leukotriene biosynthesis assay all compounds tested at a concentration of 50 microM exhibited activity with percentage inhibitions ranging from 11.5 to 36.6. The withanolide, 1, displayed a 46.4% inhibition of COX-2 and a 22.9% inhibition of LTB(4) formation at 50 microM concentration. Compounds 4 and 6 inhibited LTB(4) biosynthesis but showed minor inhibition of COX-1 and COX-2. The remaining compounds, on the other hand, were found to be inactive on COX enzymes.

Withania somnifera inhibits NF-kappaB and AP-1 transcription factors in human peripheral blood and synovial fluid mononuclear cells

Withania somnifera (WS) is an important herb with known antiinflammatory activity. Its molecular mechanism of action has not been investigated. The effect of a WS crude ethanol extract was studied on peripheral blood mononuclear cells of normal individuals and rheumatoid arthritis (RA) patients and synovial fluid mononuclear cells of RA patients in vitro. The WS extract significantly suppressed lipopolysaccharide (LPS) induced production of proinflammatory cytokines TNF-alpha, IL-1beta and IL-12p40 in normal individuals and RA patients, but had no effect on IL-6 production at the protein and transcript level. WS also suppressed LPS activated nitric oxide production in the mouse macrophage cell line, RAW 264.7. The extract inhibited nuclear translocation of the transcription factors NF-kappaB and AP-1 and phosphorylation of IkappaBalpha in normal and RA patients' mononuclear cells. HPLC analysis of the crude extract showed the presence of withaferin A and pure withaferin A also inhibited NF-kappaB translocation. The study demonstrated that the WS crude ethanol extract suppressed the production of proinflammatory molecules in vitro. This activity is partly through the inhibition of transcription factors NF-kappaB and AP-1 by the constituent withanolide. The role of additional constituents needs to be studied. Studies on the mechanism of action of the extract may yield potentially useful compounds for the treatment of inflammatory diseases.

Withanolides from Jaborosa kurtzii

Two new withanolides were isolated and characterized from the aerial parts of Jaborosa kurtzii, namely, jaborosalactone 43 (1), with a spiranoid delta-lactone at C-22, and jaborosalactone 44 (2), a 12-oxowithanolide, which may function as a biosynthetic precursor to 1. These new compounds were fully characterized by a combination of spectroscopic methods. Compound 1 showed selective phytotoxicity toward a dicotyledon species, Lactuca sativa (lettuce).