Treatment of mice with stem bark extract of Aphanamixis polystachya reduces radiation-induced chromosome damage.

PURPOSE: Normal tissue radiosensitivity is the major limiting factor in radiotherapy of cancer. The use of phytochemicals may reduce the adverse effects of radiation in normal tissue. The effect of ethyl acetate fraction of Aphanamixis polystachya (EAP) was investigated on the radiation-induced chromosome damage in the bone marrow cells of Swiss albino mice exposed to various doses of gamma-radiation. MATERIALS AND METHODS: The mice were divided into two groups, one group was exposed to 0, 1, 2, 3, 4 or 5 Gy of gamma-radiation, while another group received 7.5 mg/kg body weight (BW) of EAP 1 h before exposure to 0, 1, 2, 3, 4 or 5 Gy of gamma-radiation. Various asymmetrical chromosome aberrations were studied in the bone marrow cells of mice at 12, 24 or 48 h post-irradiation. To understand the mechanism of action of the free radical scavenging activity of 0, 5, 10, 20, 30, 40, 50, 60 or 70 microg/ml EAP, assays were carried out in vitro. RESULTS: Irradiation of mice to different doses of gamma radiation caused a dose dependent elevation in the frequency of aberrant cells and chromosome aberrations like chromatid breaks, chromosome breaks, dicentrics, acentric fragments and total aberrations at all the post-irradiation times studied. The maximum asymmetrical aberrations were scored at 24 h post-irradiation except chromatid breaks that were highest at 12 h post-irradiation. A maximum number of polyploid and severely damaged cells (SDC) were recorded at 24 h post-irradiation in the SPS+irradiation group. Treatment of mice with 7.5 mg/kg BW of EAP before exposure to 1-5 Gy of whole body gamma-radiation significantly reduced the frequencies of aberrant cells and chromosomal aberrations like acentric fragments, chromatid and chromosome breaks, centric rings, dicentrics and total aberrations at all post-irradiation scoring times (p<0.01). The EAP showed a concentration dependent scavenging of hydroxyl, superoxide, 2,2'-diphenyl-1-picryl hydrazyl (DPPH) radicals and the 2,2-azino-bis-3-ethyl benzothiazoline-6-sulphonic acid (ABTS) cation radicals in vitro. EAP treatment also reduced lipid peroxidation in bone marrow cells in a concentration dependent manner. CONCLUSION: Our study demonstrates that EAP protects mouse bone marrow cells against radiation-induced chromosomal aberrations and this reduction in radiation-induced chromosome damage may be due to free radical scavenging and reduction in lipid peroxidation. The radioprotection by EAP is best comparable to that of protection demonstrated by the grape fruit flavonone, naringin, in our earlier studies in mouse bone marrow cells.

Influence of naringin on ferric iron induced oxidative damage in vitro.

BACKGROUND: Iron is essential for oxygen transport and a variety of cellular processes like respiration and DNA synthesis. It may become toxic when not handled carefully by cellular proteins and shielded from surrounding media. Naringin treatment may help to overcome the iron-induced toxic effects in vitro. METHODS: HepG2 cells were treated with 0.5, 1, 2.5, and 5 mmol/l naringin 1 h before exposure to 0.1, 0.25, 0.5, and 1 mmol/l ferric iron. The effect of iron or naringin or their combination treatment was studied on cell survival, DNA double-strand break induction, DNA oxidation, lipid peroxidation, and various antioxidants. RESULTS: The exposure of cells to iron caused a dose-dependent decline in their clonogenic potential, while naringin pretreatment resulted in a significant elevation in the cell survival. Exposure of cells to iron resulted in a time-dependent elevation in DNA strand breaks and a peak level of DNA strand breaks was observed at 24 h, while naringin pretreatment inhibited the DNA double-strand breaks accompanied by an early repair. Similarly, treatment of HepG2 cells with iron caused increased DNA oxidation that showed reduction when cells were pretreated with naringin. The iron overload caused a significant elevation in the lipid peroxidation accompanied by depletion in glutathione (GSH) concentration, while naringin inhibited lipid peroxidation and arrested the iron-induced depletion in the GSH concentration. Iron treatment also reduced various antioxidant enzymes like glutathione peroxidase (GSHPx), catalase, and superoxide dismutase (SOD). Pretreatment of HepG2 cells with naringin resulted in an elevation in all the antioxidant enzymes. CONCLUSIONS: Enhanced antioxidant status by naringin could compensate the oxidative stress and may facilitate an early recovery from iron-induced genomic insult in vitro.

Naringin, a citrus flavonone, protects against radiation-induced chromosome damage in mouse bone marrow.

Free radicals are responsible for the induction of damage to the cellular DNA that leads to the formation of chromosome aberrations. Antioxidants are known to scavenge free radicals, thereby decreasing the degree of such effects. Radiation is a well-known inducer of free radicals and compounds that can scavenge free radicals may reduce radiation-induced DNA damage. Naringin, a bioflavonoid predominant in grapefruit and other citrus fruits, has been found to scavenge free radicals, therefore it may also reduce radiation-induced damage. The aim of the present study was to evaluate the radioprotective action of 2 mg/kg naringin in the bone marrow of mice exposed to different doses of (60)Co gamma-radiation by scoring the frequency of asymmetrical chromosomal aberrations. The irradiation of mice resulted in a dose-dependent elevation in the frequency of aberrant cells, acentric fragments, chromatid and chromosome breaks, dicentrics and exchanges. All these aberrations were elevated with scoring time up to 24 h post-irradiation and declined thereafter, except chromatid breaks, which were maximum at 12 h post-irradiation. Treatment of mice with 2 mg/kg body wt naringin before exposure to various doses of gamma-radiation resulted in a significant reduction in the frequencies of aberrant cells and chromosomal aberrations like acentric fragments, chromatid and chromosome breaks, centric rings, dicentrics and exchanges. The evaluation of free radical scavenging activity of naringin revealed a dose-dependent scavenging of hydroxyl, superoxide and 2,2 equal to or precedes -diphenyl-1-picryl hydrazyl radical. Naringin at 5 microM scavenged the 2,2-azino-bis-3-ethyl benzothiazoline-6-sulphonic acid cation radical very efficiently, where a 90% scavenging was observed. Our study demonstrates that naringin can protect mouse bone marrow cells against radiation-induced chromosomal damage.