Evaluation of Anti Hypoxic Activities of Pomegranate (Punica Granatum) Seeds and Peels in Mice

Hypoxia, a decrease in available oxygen reaching the tissues, may cause a variety of physiological abnormalities. It is linked to the pathology of stroke, cardiovascular disease, and acute mountain sickness. Hypoxia occurs especially in heart diseases, ischemia, and heart attack, and finally causing death. Hypoxia causes oxidative stress involving the production of reactive oxygen species (ROS). Compounds with antioxidant activity can scavenge ROS and can exhibit anti-hypoxic properties. Pomegranate (Punica granatum) is a well-known fruit with very good anti-ischemic and antioxidant activities. Little is known about the protective effects of pomegranate against hypoxia-induced lethality. Several medicinal plants have accepted anti-hypoxic activities. In the present study, the protective effect of this fruit against hypoxia-induced lethality in mice was determined by three different experimental models.

Protective effects of methanolic extract of Pomegranate's seed and peel against hypoxia-induced lethality in mice were evaluated by three experimental models of hypoxia, i.e. asphyctic, haemic, and circulatory models. The latencies for death for mice were recorded. All the experimental procedures were conducted by the NIH guidelines of the Laboratory Animal Care and Use. The Institutional Animal Ethical Committee of Mazandaran University of Medical Sciences also approved the experimental protocol. In the asphyctic hypoxic model, phenytoin (50 mg/kg, i.p.) and in the next two tests, propranolol (20 and 30 mg/kg, i.p.) were used as the positive control. In all tests, Normal saline (0.5 ml, i.p.) was used as the negative control. One-way analysis of variance (ANOVA) was performed followed by the Newman-Keuls multiple comparisons test was used to determine the differences in means. All p values less than 5% were considered as significant.

Extracts showed good anti-hypoxic activities in some tested models in mice. In the hemic model, Peel extract at 250 mg/kg significantly prolonged mice survival time for about 4.8 minutes (P<0.001). At this dose, it showed the same activity of propranolol 20 mg/kg which was used as positive control. In the circulatory antihypoxic model, peel extract at 250 mg/kg, significantly increased the survival time by about 5.4 minutes (P<0.0001). At this dose, the extract showed the same activity as propranolol 30 mg/kg (P>0.05). In the asphyctic anti hypoxic model, seed extract at 250 mg/kg prolonged the survival time for 2.4 minutes in the control group. But this increase was not statistically significant (P>0.05). Peel extract at 62.5 mg/kg prolonged the survival time for 4.2 minutes in the control group, but this increase was also not statistically significant (P>0.05). Peel extract showed good activity in an asphyctic model where at 125 mg/kg. It increased the survival time of mice about 2 times (P<0.0001). At this dose, extract showed higher activity than phenytoin 50 mg/kg. The survival time for the group that received phenytoin was 29.60 ± 2.51 minutes which was statistically significant than that of the control group (P<0.001).

Extracts showed very good protective effects against hypoxia in some tested models. In particular, the effects in the asphyctic model of hypoxia were high. Peel extract was stronger than seed extract. Phenolic compounds may be responsible for the anti-hypoxic activities of these extracts