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Devi PU, Akagi K, Ostapenko V, Tanaka Y, Sugahara T.
Int J Radiat Biol. 1996 Feb;69(2):193-7
Withaferin A: a new
radiosensitizer from the Indian medicinal plant Withania somnifera.
Department of Radiobiology, Kasturba Medical College, Manipal, India.
Withaferin A, a steroidal lactone isolated from the roots of the Indian
medicinal plant Withania somnifera, reduced survival of V79 cells in a
dose-dependent manner. LD50 for survival was 16 microM. One-hour treatment with
a non-toxic dose of 2.1 microM before irradiation significantly enhanced cell
killing, giving a sensitizer enhancement ratio (SER) of 1.5 for 37% survival and
1.4 for 10% survival. SER increased with drug dose, but at higher doses the
increased lethality appears to be due to two effects-- drug toxicity and
radiosensitization. The drug induced a G2/M block, with a maximum accumulation
of cells in G2-M phase at 4 h after treatment with 10.5 microM withaferin A in 1
h. The applicability of this drug as a radiosensitizer in cancer therapy needs
to be explored.
PMID: 8609455
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