Show me some studies that show that Withaferin A affects cancer cells IN-VIVO, and spares normal, healthy cells, and I will recant everything I just said. Until then, I consider leaf extracts and Withaferin A useless for any purposes.
First of all, it's impossible to show that in an in vivo study. At best you can show that the net effect is positive. And while there seems to be no reason to believe withaferin A is in any way harmful in moderate doses, nobody has claimed that there are no possible negative effects at very high levels.
Anyway here are some IN-VIVO studies showing that it has powerful cancer-fighting ability. It's not the only substance in ashwagandha with beneficial effects. It's perhaps not even the most powerful, although it is certainly the most comprehensively studied. The only point I'm making is that, as a component of the ashwagandha plant it's not necessarily to be avoided.
P.S. Despite "roots good, leaves bad" (green tea anyone?), it is still an open question whether withaferin A is found in the root extract or not. So far I have found one study that did an analysis showing that root extract levels were undetectable, and another showing that root extract levels were quite high.
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Tumor Size Reduction With Withaferin A In A Murine Model Of Uveal Melanoma
http://www.abstracts...B-6A8D7B26EDB3}"Control tumors showed a 60% increase in largest diameter over a 14-day treatment period. Treatment groups showed a 64% and 50% decrease"
Natural withanolide Withaferin A induces apoptosis in Uveal Melanoma cells by suppression of Akt and c-MET activation
http://www.ncbi.nlm....pubmed/22477711"In vivo studies using WA reduced tumor growth in 100% of animals (p = 0.015)."
Radiosensitization of a mouse melanoma by Withaferin A: in vivo studies.
http://www.ncbi.nlm....pubmed/11272405[Treatment of tumours with withaferin A produced a dose dependent increase in growth delay and volume doubling time. Injection of withaferin A, followed by local gamma irradiation, significantly enhanced the tumour response. No systemic or local adverse reactions were noted in these groups.]
Enhancement of the Response of B16F1 Melanoma to Fractionated Radiotherapy and Prolongation of Survival by Withaferin A and/or Hyperthermia
http://ict.sagepub.c...t/9/4/370.short"Withaferin A is a better radiosensitizer than hyperthermia in fractionated regimen and the response of radioresistant tumors like melanoma can be significantly enhanced by combining nontoxic doses of Withaferin A with fractionated radiotherapy, with or without hyperthermia, allowing decrease in radiation dose."
Withaferin A Inhibits the Proteasome Activity in Mesothelioma In Vitro and In Vivo
http://www.ncbi.nlm..../?report=reader"Together our in vitro and in vivo studies suggest that WA suppresses Malignant Pleural Mesothelioma growth by targeting multiple pathways that include blockage of proteasome activity and stimulation of apoptosis, and thus holds promise as an anti-MPM agent."
Metabolic Alterations in Mammary Cancer Prevention by Withaferin A in a Clinically Relevant Mouse Model
http://jnci.oxfordjo...5/15/1111.short"Withaferin A administration resulted in a statistically significant decrease in macroscopic mammary tumor size, microscopic mammary tumor area, and the incidence of pulmonary metastasis. For example, the mean area of invasive cancer was lower by 95.14% in the Withaferin A treatment group compared with the control group."
Myeloid-derived suppressor cell [MDSC] function is reduced by Withaferin A, a potent and abundant component of Withania somnifera root extract
http://link.springer...3-1470-2#page-1"Thus, adjunctive treatment with Withaferin A reduced myeloid cell-mediated immune suppression, polarized immunity toward a tumor-rejecting type 1 phenotype, and may facilitate the development of anti-tumor immunity."
Edited by joelcairo, 25 January 2014 - 07:43 PM.