Ginger (Zingiber officinale Rosc.), a dietary supplement, protects mice against radiation-induced lethality:: Mechanism of action

The radioprotective effect of hydroalcoholic extract of ginger rhizome (Zingiber officinale; ZOE) was studied in mice administered 250 mg/kg ZOE orally using oral gavage once daily for 5 consecutive days before exposure to 6, 7, 8, 9, 10, or 11 Gy of gamma-radiation. The animals were monitored daily up to 30 days postirradiation for the development of symptoms of radiation sickness and mortality. Pretreatment of mice with ZOE reduced the severity of symptoms of radiation sickness and mortality at all the exposure doses and also increased the number of survivors in a ZOE + irradiation group compared to the concurrent double-distilled water + irradiation group. The ZOE treatment protected mice against gastrointestinal-related deaths as well as bone-marrow-related deaths. The dose-reduction factor was found to be 1.2. The administration of ZOE after exposure to irradiation was not effective, as no survivors lasted up to 30 days postirradiation. Reducing the administration schedule to 3 days or increasing the schedule to 7 days was not as effective compared to a 5 consecutive days' schedule. The irradiation of animals resulted in a dose-dependent elevation in the lipid peroxidation, while depletion in the glutathione (GSH) contents occurred on day 31 postirradiation. Treatment of mice with ZOE before irradiation caused a significant depletion in lipid peroxidation followed by a significant elevation in GSH concentration in the livers of mice at 31 days postirradiation. The mechanism of action of ZOE was determined by evaluating its free-radical scavenging capability. Ginger was found to scavenge (OH)-O-., O-2(.-) and ABTS(.-) radicals in a dose-dependent manner in vitro. The drug was nontoxic up to a dose of 1500 mg/kg body weight, the highest drug dose that could be tested for acute toxicity.