Antitumor and radiosensitizing effects of Withania somnifera (Ashwagandha) on a transplantable mouse tumor, Sarcoma-180.

Antitumor and radiosensitizing effects of alcoholic root extract of W. somnifera and their modification by heat were studied in vivo on Sarcoma-180 grown on the dorsum of adult BALB/c mouse. Ashwagandha (AT) was injected (ip) at a dose of 500 mg/kg body wt for 10 consecutive days into mouse bearing tumor of 50 +/- 5 mm3, with or without a local treatment of 10 Gy gamma radiation (RT) or hyperthermia at 43 degrees C for 30 min (HT) or both on 5th day of AT. The response was assessed on the basis of tumor regression, growth delay, animal survival and changes in the tumor GSH content. Ashwagandha, RT and HT individually produced 18, 38 and 45% complete response (CR) respectively, but RT gave the best long term survival. Ashwagandha increased the effect of radiation on tumor regression as well as growth delay, but AT + HT gave a better tumor cure. However, both these combinations gave almost identical long term survival, which was not much higher than that produced by RT alone. The combination of Ashwagandha for 10 days with one local exposure to RT followed by HT significantly increased the tumor cure, growth delay of partially responding tumors and animal survival. This combination also significantly and synergistically depleted the tumor GSH level, with no recovery even at 3 hr after treatment. It is concluded that Ashwagandha, in addition to having a tumor inhibitory effect, also acts as a radiosensitizer and heat enhances these effects. The severe depletion in the tumor GSH content by the combination treatment must have enhanced the tumor response, as the inherent protection by the thiol will be highly reduced.