The Potential Pharmacological Effects of Natural Product Withaferin A in Cancer: Opportunities and Challenges for Clinical Translation

ABSTRACT

Cancer is one of the biggest health concerns with a complex pathophysiology. Currently, available chemotherapeutic drugs are showing deleterious side effects, and tumors often show resistance to treatment. Hence, extensive research is required to develop new treatment strategies to fight against cancer. Natural resources from plants are at the forefront of hunting novel drugs to treat various types of cancers. Withaferin A (WA) is a naturally occurring withanolide, a biologically active component obtained from the plant Ashwagandha. Various in vitro and in vivo oncological studies have reported that Withaferin A (WA) has shown protection from cancer. WA shows its activity by inhibiting the growth and proliferation of malignant cells, apoptosis, and inhibiting angiogenesis, metastasis, and cancer stem cells (CSCs). In addition, WA also showed chemo- and radio-sensitizing properties. Besides the beneficiary pharmacological activities of WA, a few aspects like pharmacokinetic properties, safety, and toxicity studies are still lacking, hindering this potent natural product from entering clinical development. In this review, we have summarized the various pharmacological mechanisms shown by WA in in vitro and in vivo cancer studies and the challenges that must be overcome for this potential natural productʼs clinical translation to be effective.

Keywords

Withania somnifera - Solanaceae - Withaferin A - cancer - apoptosis - chemoprevention - metastasis.

Publication History

Received: 16 October 2023

Accepted after revision: 06 March 2024

Article published online:
08 April 2024

• References

• 1 Araújo F, Gouvinhas C, Fontes F, La Vecchia C, Azevedo A, Lunet N. Trends in cardiovascular diseases and cancer mortality in 45 countries from five continents (1980–2010). Eur J Prev Cardiol 2014; 21: 1004-1017
• 2 ReFaey K, Tripathi S, Grewal SS, Bhargav AG, Quinones DJ, Chaichana KL, Antwi SO, Cooper LT, Meyer FB, Dronca RS. Cancer mortality rates increasing vs. cardiovascular disease mortality decreasing in the world: future implications. Mayo Clin Proc Innov Qual Outcomes 2021; 5: 645-653
• 3 Siegel Rebecca L, Miller Kimberly D. Jemal Ahmedin. Cancer statistics, 2019. CA Cancer J Clin 2019; 69: 7-34
• 4 World Health Organization. Cancer. In: WHO.
• 5 Links M, Lewis C. Chemoprotectants: a review of their clinical pharmacology and therapeutic efficacy. Drugs 1999; 57: 293-308
• 6 Gordaliza M. Natural products as leads to anticancer drugs. Clin Transl Oncol 2007; 9: 767-776
• 7 Naeem A, Hu P, Yang M, Zhang J, Liu Y, Zhu W, Zheng Q. Natural products as anticancer agents: Current status and future perspectives. Molecules 2022; 27: 8367
• 8 Martino E, Casamassima G, Castiglione S, Cellupica E, Pantalone S, Papagni F, Rui M, Siciliano AM, Collina S. Vinca alkaloids and analogues as anti-cancer agents: Looking back, peering ahead. Bioorg Med Chem Lett 2018; 28: 2816-2826
• 9 National Cancer Institute. A to Z List of Cancer Drugs. In: NIH.
• 10 Tharakan A, Shukla H, Benny IR, Tharakan M, George L, Koshy S. Immunomodulatory effect of Withania somnifera (Ashwagandha) extract–a randomized, double-blind, placebo controlled trial with an open label extension on healthy participants. J Clin Med 2021; 10: 3644
• 11 Gupta A, Singh S. Evaluation of anti-inflammatory effect of Withania somnifera root on collagen-induced arthritis in rats. Pharm Biol 2014; 52: 308-320
• 12 Kumari M. Gupta Rá. In vitro antibacterial effect of Withania somnifera root extract on Escherichia coli . Veterinary world 2015; 8: 57
• 13 Yadav B, Bajaj A, Saxena M, Saxena A. In vitro anticancer activity of the root, stem and leaves of Withania somnifera against various human cancer cell lines. Indian J Pharm Sci 2010; 72: 659
• 14 Choudhary D, Bhattacharyya S, Bose S. Efficacy and safety of Ashwagandha (Withania somnifera (L.) Dunal) root extract in improving memory and cognitive functions. J Diet Suppl 2017; 14: 599-612
• 15 Nagy Z, Cheung BB, Tsang W, Tan O, Herath M, Ciampa OC, Shadma F, Carter DR, Marshall GM. Withaferin A activates TRIM16 for its anti-cancer activity in melanoma. Sci Rep 2020; 10: 19724
• 16 Atteeq M. Evaluating anticancer properties of Withaferin A–a potent phytochemical. Front Pharmacol 2022; 13: 975320
• 17 Berghe WV, Sabbe L, Kaileh M, Haegeman G, Heyninck K. Molecular insight in the multifunctional activities of Withaferin A. Biochem Pharmacol 2012; 84: 1282-1291
• 18 Fuska J, Fuskova A, Rosazza J, Nicholas A. Novel cytotoxic and antitumor agents. IV. Withaferin A: relation of its structure to the in vitro cytotoxic effects on P388 cells. Neoplasma 1984; 31: 31-36
• 19 Kim S-H, Singh KB, Hahm E-R, Singh SV. The role of forkhead box Q1 transcription factor in anticancer effects of Withaferin A in breast cancer. Cancer Prev Res (Phila) 2021; 14: 421-432
• 20 Yu Y, Hamza A, Zhang T, Gu M, Zou P, Newman B, Li Y, Gunatilaka AL, Zhan C-G, Sun D. Withaferin A targets heat shock protein 90 in pancreatic cancer cells. Biochem Pharmacol 2010; 79: 542-551
• 21 Liu X, Li Y, Ma Q, Wang Y, Song AL. Withaferin-A inhibits growth of drug-resistant breast carcinoma by inducing apoptosis and autophagy, endogenous reactive oxygen species (ROS) production, and inhibition of cell migration and nuclear factor kappa B (Nf-κB)/mammalian target of rapamycin (m-TOR) signalling pathway. Med Sci Monit 2019; 25: 6855
• 22 Stan SD, Zeng Y, Singh SV. Ayurvedic medicine constituent withaferin a causes G2 and M phase cell cycle arrest in human breast cancer cells. Nutr Cancer 2008; 60: 51-60
• 23 McKenna M, Gachuki B, Alhakeem S, Oben K, Rangnekar V, Gupta R, Bondada S. Anti-cancer activity of withaferin A in B-cell lymphoma. Cancer Biol Ther 2015; 16: 1088-1098
• 24 Touny LHE, Banerjee PP. Identification of both Myt‐1 and Wee‐1 as necessary mediators of the p 21‐independent inactivation of the Cdc‐2/cyclin B1 complex and growth inhibition of TRAMP cancer cells by genistein. Prostate 2006; 66: 1542-1555
• 25 Roy RV, Suman S, Das TP, Luevano JE, Damodaran C. Withaferin A, a steroidal lactone from Withania somnifera, induces mitotic catastrophe and growth arrest in prostate cancer cells. J Nat Prod 2013; 76: 1909-1915
• 26 Lv TZ, Wang GS. Antiproliferation potential of withaferin A on human osteosarcoma cells via the inhibition of G2/M checkpoint proteins. Exp Ther Med 2015; 10: 323-329
• 27 Das T, Roy KS, Chakrabarti T, Mukhopadhyay S, Roychoudhury S. Withaferin A modulates the Spindle Assembly Checkpoint by degradation of Mad2–Cdc20 complex in colorectal cancer cell lines. Biochem Pharmacol 2014; 91: 31-39
• 28 Yeh ES, Means AR. PIN1, the cell cycle and cancer. Nat Rev Cancer 2007; 7: 381-388
• 29 Nakashima M, Meirmanov S, Naruke Y, Kondo H, Saenko V, Rogounovitch T, Shimizu-Yoshida Y, Takamura N, Namba H, Ito M. Cyclin D1 overexpression in thyroid tumours from a radio‐contaminated area and its correlation with Pin1 and aberrant β‐catenin expression. J Pathol 2004; 202: 446-455
• 30 Samanta SK, Lee J, Hahm ER, Singh SV. Peptidyl‐prolyl cis/trans isomerase Pin1 regulates withaferin A‐mediated cell cycle arrest in human breast cancer cells. Mol Carcinog 2018; 57: 936-946
• 31 Elmore S. Apoptosis: a review of programmed cell death. Toxicol Pathol 2007; 35: 495-516
• 32 Majno G, Joris I. Apoptosis, oncosis, and necrosis. An overview of cell death. Am J Pathol 1995; 146: 3
• 33 Srinivasan S, Ranga RS, Burikhanov R, Han S-S, Chendil D. Par-4-dependent apoptosis by the dietary compound withaferin A in prostate cancer cells. Cancer Res 2007; 67: 246-253
• 34 Gross A, McDonnell JM, Korsmeyer SJ. BCL-2 family members and the mitochondria in apoptosis. Genes Dev 1999; 13: 1899-1911
• 35 Stan SD, Hahm E-R, Warin R, Singh SV. Withaferin A causes FOXO3a-and Bim-dependent apoptosis and inhibits growth of human breast cancer cells in vivo. Cancer Res 2008; 68: 7661-7669
• 36 Liou G-Y, Storz P. Reactive oxygen species in cancer. Free Radic Res 2010; 44: 479-496
• 37 Xia S, Miao Y, Liu S. Withaferin A induces apoptosis by ROS-dependent mitochondrial dysfunction in human colorectal cancer cells. Biochem Biophys Res Commun 2018; 503: 2363-2369
• 38 Chang H-W, Li R-N, Wang H-R, Liu J-R, Tang J-Y, Huang H-W, Chan Y-H, Yen C-Y. Withaferin A induces oxidative stress-mediated apoptosis and DNA damage in oral cancer cells. Front Physiol 2017; 8: 634
• 39 Munagala R, Kausar H, Munjal C, Gupta RC. Withaferin A induces p 53-dependent apoptosis by repression of HPV oncogenes and upregulation of tumor suppressor proteins in human cervical cancer cells. Carcinogenesis 2011; 32: 1697-1705
• 40 Mathew R, Karantza-Wadsworth V, White E. Role of autophagy in cancer. Nat Rev Cancer 2007; 7: 961-967
• 41 Gewirtz DA. The four faces of autophagy: implications for cancer therapy. Cancer Res 2014; 74: 647-651
• 42 Ghosh K, De S, Mukherjee S, Das S, Ghosh AN, Sengupta SB. Withaferin A induced impaired autophagy and unfolded protein response in human breast cancer cell-lines MCF-7 and MDA-MB-231. Toxicol In Vitro 2017; 44: 330-338
• 43 Yin X, Yang G, Ma D, Su Z. Inhibition of cancer cell growth in cisplatin-resistant human oral cancer cells by withaferin-A is mediated via both apoptosis and autophagic cell death, endogenous ROS production, G2/M phase cell cycle arrest and by targeting MAPK/RAS/RAF signalling pathway. J BUON 2020; 25: 332-337
• 44 Fong MY, Jin S, Rane M, Singh RK, Gupta R, Kakar SS. Withaferin A synergizes the therapeutic effect of doxorubicin through ROS-mediated autophagy in ovarian cancer. PLoS One 2012; 7: e42265
• 45 Siddharth S, Muniraj N, Saxena NK, Sharma D. Concomitant inhibition of cytoprotective autophagy augments the efficacy of withaferin A in hepatocellular carcinoma. Cancers (Basel) 2019; 11: 453
• 46 Romero-Figueroa MDS, de Jesus Garduno-Garcia J, Duarte-Mote J, Matute-Gonzalez G, Gómez-Villanueva A, De la Cruz-Vargas J. Insulin and leptin levels in obese patients with and without breast cancer. Clin Breast Cancer 2013; 13: 482-485
• 47 Samanta SK, Sehrawat A, Kim S-H, Hahm ER, Shuai Y, Roy R, Pore SK, Singh KB, Christner SM, Beumer JH. Disease subtype–independent biomarkers of breast cancer chemoprevention by the ayurvedic medicine phytochemical withaferin A. J Natl Cancer Inst 2017; 109: djw293
• 48 Manoharan S, Panjamurthy K, Menon VP, Balakrishnan S, Alias LM. Protective effect of Withaferin-A on tumour formation in 7, 12-dimethylbenz [a] anthracene induced oral carcinogenesis in hamsters. Indian J Exp Biol 2009; 47: 16-23
• 49 Chandrasekaran B, Pal D, Kolluru V, Tyagi A, Baby B, Dahiya NR, Youssef K, Alatassi H, Ankem MK, Sharma AK. The chemopreventive effect of withaferin A on spontaneous and inflammation-associated colon carcinogenesis models. Carcinogenesis 2018; 39: 1537-1547
• 50 Yang ES, Choi MJ, Kim JH, Choi KS, Kwon TK. Combination of withaferin A and X-ray irradiation enhances apoptosis in U937 cells. Toxicol In Vitro 2011; 25: 1803-1810
• 51 Yang ES, Choi MJ, Kim JH, Choi KS, Kwon TK. Withaferin A enhances radiation-induced apoptosis in Caki cells through induction of reactive oxygen species, Bcl-2 downregulation and Akt inhibition. Chem Biol Interact 2011; 190: 9-15
• 52 Sharada AC, Solomon FE, Devi PU, Udupa N, Srinivasan KK. Antitumor and radiosensitizing effects of withaferin A on mouse Ehrlich ascites carcinoma in vivo. Acta Oncol 1996; 35: 95-100
• 53 Kalthur G, Pathirissery UD. Enhancement of the response of B16F1 melanoma to fractionated radiotherapy and prolongation of survival by withaferin A and/or hyperthermia. Integr Cancer Ther 2010; 9: 370-377
• 54 Craene BD, Berx G. Regulatory networks defining EMT during cancer initiation and progression. Nat Rev Cancer 2013; 13: 97-110
• 55 Kyakulaga AH, Aqil F, Munagala R, Gupta RC. Withaferin A inhibits epithelial to mesenchymal transition in non-small cell lung cancer cells. Sci Rep 2018; 8: 15737
• 56 Wu M, Bai X, Xu G, Wei J, Zhu T, Zhang Y, Li Q, Liu P, Song A, Zhao L. Proteome analysis of human androgen‐independent prostate cancer cell lines: Variable metastatic potentials correlated with vimentin expression. Proteomics 2007; 7: 1973-1983
• 57 Lee J, Hahm ER, Marcus AI, Singh SV. Withaferin A inhibits experimental epithelial–mesenchymal transition in MCF‐10A cells and suppresses vimentin protein level in vivo in breast tumors. Mol Carcinog 2015; 54: 417-429
• 58 Thaiparambil JT, Bender L, Ganesh T, Kline E, Patel P, Liu Y, Tighiouart M, Vertino PM, Harvey RD, Garcia A. Withaferin A inhibits breast cancer invasion and metastasis at sub‐cytotoxic doses by inducing vimentin disassembly and serine 56 phosphorylation. Int J Cancer 2011; 129: 2744-2755
• 59 Gialeli C, Theocharis AD, Karamanos NK. Roles of matrix metalloproteinases in cancer progression and their pharmacological targeting. FEBS J 2011; 278: 16-27
• 60 Loechel F, Fox JW, Murphy G, Albrechtsen R, Wewer UM. ADAM 12-S cleaves IGFBP-3 and IGFBP-5 and is inhibited by TIMP-3. Biochem Biophys Res Commun 2000; 278: 511-515
• 61 Lee DH, Lim I-H, Sung E-G, Kim J-Y, Song I-H, Park YK, Lee T-J. Withaferin A inhibits matrix metalloproteinase-9 activity by suppressing the Akt signaling pathway. Oncol Rep 2013; 30: 933-938
• 62 Hurst DR, Welch DR. Metastasis suppressor genes: at the interface between the environment and tumor cell growth. Int Rev Cell Mol Biol 2011; 286: 107-180
• 63 Szarc vel Szic K, Op de Beeck K, Ratman D, Wouters A, Beck IM, Declerck K, Heyninck K, Fransen E, Bracke M, De Bosscher K. Pharmacological levels of Withaferin A (Withania somnifera) trigger clinically relevant anticancer effects specific to triple negative breast cancer cells. PLoS One 2014; 9: e87850
• 64 Nishida N, Yano H, Nishida T, Kamura T, Kojiro M. Angiogenesis in cancer. Vasc Health Risk Manag 2006; 2: 213-219
• 65 Saha S, Islam MK, Shilpi JA, Hasan S. Inhibition of VEGF: a novel mechanism to control angiogenesis by Withania somniferaʼs key metabolite Withaferin A. In Silico Pharmacol 2013; 1: 1-9
• 66 Wang Y-X, Ding W-B, Dong C-W. Withaferin A suppresses liver tumor growth in a nude mouse model by downregulation of cell signaling pathway leading to invasion and angiogenesis. Tropical J Pharmaceut Res 2015; 14: 1005-1011
• 67 Mohan R, Hammers H, Bargagna-Mohan P, Zhan X, Herbstritt C, Ruiz A, Zhang L, Hanson A, Conner B, Rougas J. Withaferin A is a potent inhibitor of angiogenesis. Angiogenesis 2004; 7: 115-122
• 68 Bao B, Ahmad A, Azmi AS, Ali S, Sarkar FH. Overview of cancer stem cells (CSCs) and mechanisms of their regulation: implications for cancer therapy. Curr Protoc Pharmacol 2013; 61: 14.25-11-14.25-14
• 69 Li F, Tiede B, Massagué J, Kang Y. Beyond tumorigenesis: cancer stem cells in metastasis. Cell Res 2007; 17: 3-14
• 70 Aliebrahimi S, Kouhsari SM, Arab SS, Shadboorestan A, Ostad SN. Phytochemicals, withaferin A and carnosol, overcome pancreatic cancer stem cells as c-Met inhibitors. Biomed Pharmacother 2018; 106: 1527-1536
• 71 Chen H-C, Chou AS-B, Liu Y-C, Hsieh C-H, Kang C-C, Pang S-T, Yeh C-T, Liu H-P, Liao S-K. Induction of metastatic cancer stem cells from the NK/LAK-resistant floating, but not adherent, subset of the UP-LN1 carcinoma cell line by IFN-γ . Lab Invest 2011; 91: 1502-1513
• 72 Ting L-L, Chou AS-B, Hsieh C-H, Hsiung S-C, Pang S-T, Liao S-K. Withaferin A targeting both cancer stem cells and metastatic cancer stem cells in the UP-LN1 carcinoma cell model. J Cancer Metastasis Treat 2016;
• 73 Young M-J, Wu Y-H, Chiu W-T, Weng T-Y, Huang Y-F, Chou C-Y. All-trans retinoic acid downregulates ALDH1-mediated stemness and inhibits tumour formation in ovarian cancer cells. Carcinogenesis 2015; 36: 498-507
• 74 Kakar SS, Parte S, Carter K, Joshua IG, Worth C, Rameshwar P, Ratajczak MZ. Correction: Withaferin A (WFA) inhibits tumor growth and metastasis by targeting ovarian cancer stem cells. Oncotarget 2020; 11: 3103
• 75 Nishi M, Akutsu H, Kudoh A, Kimura H, Yamamoto N, Umezawa A, Lee SW, Ryo A. Induced cancer stem-like cells as a model for biological screening and discovery of agents targeting phenotypic traits of cancer stem cell. Oncotarget 2014; 5: 8665
• 76 Issa ME, Cuendet M. Withaferin A induces cell death and differentiation in multiple myeloma cancer stem cells. Medchemcomm 2017; 8: 112-121
• 77 Kim S-H, Singh SV. Mammary cancer chemoprevention by withaferin A is accompanied by in vivo suppression of self-renewal of cancer stem cells. Cancer Prev Res (Phila) 2014; 7: 738-747
• 78 Whiteside T. The tumor microenvironment and its role in promoting tumor growth. Oncogene 2008; 27: 5904-5912
• 79 Chung SS, Wu Y, Okobi Q, Adekoya D, Atefi M, Clarke O, Dutta P, Vadgama JV. Proinflammatory cytokines IL-6 and TNF-α increased telomerase activity through NF-κB/STAT1/STAT3 activation, and withaferin A inhibited the signaling in colorectal cancer cells. Mediators of inflammation 2017;
• 80 Draghiciu O, Lubbers J, Nijman HW, Daemen T. Myeloid derived suppressor cells–an overview of combat strategies to increase immunotherapy efficacy. Oncoimmunology 2015; 4: e954829
• 81 Sinha P, Ostrand-Rosenberg S. Myeloid-derived suppressor cell function is reduced by Withaferin A, a potent and abundant component of Withania somnifera root extract. Cancer Immunology, Immunotherapy 2013; 62: 1663-1673
• 82 Choi BY, Kim B-W. Withaferin-A inhibits colon cancer cell growth by blocking STAT3 transcriptional activity. J Cancer Prev 2015; 20: 185
• 83 Straughn AR, Kakar SS. Withaferin A ameliorates ovarian cancer-induced cachexia and proinflammatory signaling. J Ovarian Res 2019; 12: 1-14
• 84 Cohen SM, Mukerji R, Timmermann BN, Samadi AK, Cohen MS. A novel combination of withaferin A and sorafenib shows synergistic efficacy against both papillary and anaplastic thyroid cancers. Am J Surg 2012; 204: 895-901
• 85 Royston KJ, Udayakumar N, Lewis K, Tollefsbol TO. A novel combination of withaferin A and sulforaphane inhibits epigenetic machinery, cellular viability and induces apoptosis of breast cancer cells. Int J Mol Sci 2017; 18: 1092
• 86 Royston KJ, Paul B, Nozell S, Rajbhandari R, Tollefsbol TO. Withaferin A and sulforaphane regulate breast cancer cell cycle progression through epigenetic mechanisms. Exp Cell Res 2018; 368: 67-74
• 87 Kakar SS, Jala VR, Fong MY. Synergistic cytotoxic action of cisplatin and withaferin A on ovarian cancer cell lines. Biochem Biophys Res Commun 2012; 423: 819-825
• 88 Kakar SS, Ratajczak MZ, Powell KS, Moghadamfalahi M, Miller DM, Batra SK, Singh SK. Withaferin a alone and in combination with cisplatin suppresses growth and metastasis of ovarian cancer by targeting putative cancer stem cells. PLoS One 2014; 9: e107596
• 89 Li X, Zhu F, Jiang J, Sun C, Wang X, Shen M, Tian R, Shi C, Xu M, Peng F. Synergistic antitumor activity of withaferin A combined with oxaliplatin triggers reactive oxygen species-mediated inactivation of the PI3K/AKT pathway in human pancreatic cancer cells. Cancer Lett 2015; 357: 219-230
• 90 Hsu JH-M, Chang PM-H, Cheng T-S, Kuo Y-L, Wu AT-H, Tran T-H, Yang Y-H, Chen J-M, Tsai Y-C, Chu Y-S. Identification of withaferin A as a potential candidate for anti-cancer therapy in non-small cell lung cancer. Cancers (Basel) 2019; 11: 1003
• 91 Hernandez A, Smith F, Wang Q, Wang X, Evers BM. Assessment of differential gene expression patterns in human colon cancers. Ann Surg 2000; 232: 576
• 92 Lee T-J, Um HJ, Park J-W, Choi KS, Kwon TK. Withaferin A sensitizes TRAIL-induced apoptosis through reactive oxygen species-mediated up-regulation of death receptor 5 and down-regulation of c-FLIP. Free Radic Biol Med 2009; 46: 1639-1649
• 93 Patil D, Gautam M, Mishra S, Karupothula S, Gairola S, Jadhav S, Pawar S, Patwardhan B. Determination of withaferin A and withanolide A in mice plasma using high-performance liquid chromatography-tandem mass spectrometry: Application to pharmacokinetics after oral administration of Withania somnifera aqueous extract. J Pharm Biomed Anal 2013; 80: 203-212
• 94 Devkar ST, Kandhare AD, Sloley BD, Jagtap SD, Lin J, Tam YK, Katyare SS, Bodhankar SL, Hegde MV. Evaluation of the bioavailability of major withanolides of Withania somnifera using an in vitro absorption model system. J Adv Pharm Technol Res 2015; 6: 159
• 95 Pires N, Gota V, Gulia A, Hingorani L, Agarwal M, Puri A. Safety and pharmacokinetics of Withaferin-A in advanced stage high grade osteosarcoma: A phase I trial. J Ayurveda Integr Med 2020; 11: 68-72
• 96 Yadav DK, Kumar S, Saloni. Singh H, Kim MH, Sharma P, Misra S, Khan F. Molecular docking, QSAR and ADMET studies of withanolide analogs against breast cancer. Drug Des Devel Ther 2017; 11: 1859-1870
• 97 Pugsley MK, Authier S, Curtis M. Principles of safety pharmacology. Br J Pharmacol 2008; 154: 1382-1399
• 98 Arome D, Chinedu E. The importance of toxicity testing. J Pharm BioSci 2013; 4: 146-148
• 99 Gupta Y. Clinical Trials of Traditional Herbal Medicines in India. 2011
• 100 Shan JJ, Rodgers K, Lai C, Sutherland SK. Challenges in natural health product research: The importance of standardization. In: Proceedings-Western Pharmacology Society: [Western Pharmacology Society] 1998; 2007: 188
• 101 Babiker HM, Davis L, Larson K, Placencia C, Swensen C, Tenneti P, Lim M, Cañamar R, Curtis J, Castillo E. A Multidisciplinary Evaluation of Barriers to Enrolling Cancer Patients into Early Phase Clinical Trials: Challenges and Patient-centric Recommendations. Expert Opin Investig Drugs 2019; 28: 675-686
• 102 Tavhare SD, Nishteswar K, Shukla VJ. Effect of seasonal variations on the phytoconstituents of Aśvagandhā wr to lunar cycles. Anc Sci Life 2016; 35: 150
• 103 Nair AR, Praveen N. Biochemical and phytochemical variations during the growth phase of Withania somnifera (L.) Dunal . Journal of Pharmacognosy and Phytochemistry 2019; 8: 1930-1937
• 104 Kumar A, Kaul M, Bhan M, Khanna PK, Suri K. Morphological and chemical variation in 25 collections of the Indian medicinal plant, Withania somnifera (L.) Dunal (Solanaceae). Genet Res Crop Evol 2007; 54: 655-660
• 105 Shipkowski KA, Betz JM, Birnbaum LS, Bucher JR, Coates PM, Hopp DC, MacKay D, Oketch-Rabah H, Walker NJ, Welch C. Naturally complex: Perspectives and challenges associated with Botanical Dietary Supplement Safety assessment. Food Chem Toxicol 2018; 118: 963-971
• 106 Jachak SM, Saklani A. Challenges and opportunities in drug discovery from plants. Current science 2007; DOI: 1251-1257
• 107 Joshi P, Misra L, Siddique AA, Srivastava M, Kumar S, Darokar MP. Epoxide group relationship with cytotoxicity in withanolide derivatives from Withania somnifera . Steroids 2014; 79: 19-27
• 108 Yu Y, Katiyar SP, Sundar D, Kaul Z, Miyako E, Zhang Z, Kaul SC, Reddel RR, Wadhwa R. Withaferin-A kills cancer cells with and without telomerase: chemical, computational and experimental evidences. Cell Death Dis 2017; 8: e2755
• 109 Li A-X, Sun M, Li X. Withaferin-A induces apoptosis in osteosarcoma U2OS cell line via generation of ROS and disruption of mitochondrial membrane potential. European Review for Medical & Pharmacological Sciences 2017; 21
• 110 Malik F, Kumar A, Bhushan S, Khan S, Bhatia A, Suri KA, Qazi GN, Singh J. Reactive oxygen species generation and mitochondrial dysfunction in the apoptotic cell death of human myeloid leukemia HL-60 cells by a dietary compound withaferin A with concomitant protection by N-acetyl cysteine. Apoptosis 2007; 12: 2115-2133
• 111 Lahat G, Zhu Q-S, Huang K-L, Wang S, Bolshakov S, Liu J, Torres K, Langley RR, Lazar AJ, Hung MC. Vimentin is a novel anti-cancer therapeutic target; insights from in vitro and in vivo mice xenograft studies. PLoS One 2010; 5: e10105