[en] Syzygium cumini Linn. (family Myrtaceae), commonly known as Jamun, is a medicinal plant and utilizable species which is widely used for its antioxidant activities to treat different ailments in many parts of the world. The current study was undertaken to study the effect of seed extract of Syzygium cumini in normal as well as in tumor bearing mice against gamma radiation-induced cellular damage in biological tissues. This was done to mimic the clinical setting wherein, normal tissues of cancer patients undergoing, radiotherapy are exposed to the deleterious effects of radiation. The protection of cellular DNA was analyzed in peripheral blood leucocytes of whole-body irradiated mice following pretreatment with hydo-alcoholic seed extract of Syzygium cumini (100 mg/kg b. wt./day), using alkaline comet assay and by estimating biochemical parameters such as antioxidant enzymes i.e. (superoxide dismutase and catalase), GSH, LPO and total proteins in organs like spleen, liver and intestine. For this purpose, Swiss albino mice were administered Syzygium cumini extract (SCE) orally once daily for 5 consecutive days, then exposed to a single dose of 3, 6 and 9 Gy of gamma radiation. The results showed that the seed extract of Syzygium cumini protected the liver, spleen and intestine both in normal as well as tumor bearing mice. This study concludes that seed extract of Syzygium cumini has protective effects against radiation-induced cellular damage and biochemical alterations which could be attributed to the ability to scavenge free radicals and its antioxidant properties. Hence, seed extract of Syzygium cumini may be used in combination with radiation to protect against oxidative stress in normal tissues and improving the quality of life of cancer patients by mitigating side effects of radiation to normal tissues during radiotherapy. (author)