Phytochemical and anti-inflammatory activities of aqueous leaf extract of Indian borage (oregano) on rats induced with inflammation.

BACKGROUND

The Indian borage (Plectranthus amboinicus) also called Oregano contains many effective antioxidants, which includes caffeic acid, rosmarinic acid and flavonoids. It has been employed in traditional medicine for its several health benefits including the prevention and cure of many debilitating diseases. Anti-inflammatory properties of Plectranthus amboinicus grown within this environment have not been adequately explored.

OBJECTIVE

The protective and therapeutic effects of Oregano against endotoxaemia and inflammation were evaluated using lipopolysaccharide (LPS)-induced rat models.

METHODS

A total of 30 Wistar rats were randomly selected for this study and divided into six groups, with each group having 5 rats. Inflammation was induced on appropriate animal groups using LPS injection at a concentration of 4 mg/kg. Aqueous leaf extract of Indian borage was administered orally in four doses (100 mg/kg, 200 mg/kg, 400 mg/kg post-LPS exposure and 150 mg/kg pre-LPS exposure) to respective treatment rat groups. Haematological profile, toxicity profile of liver and kidney and levels of biomarkers of inflammation were assayed using standard methods.

RESULTS

Rats injected with LPS showed severe anaemia and marked leucopoenia with significant decrease in monocytes compared to the control group (p< 0.05). There was increased expression of interleukin-8 (IL-8) and tumor necrosis factor-α (TNF-α) (p< 0.05) in the peripheral circulation of rats exposed to LPS. Treatment with Indian borage significantly (p< 0.05) reduced the toxic effects in the LPS-treated animals and attenuated the increase in the expression of circulating proinflammatory cytokines; tumor necrosis factor alpha (TN-Fα) and interleukin-8 (IL-8) caused by LPS. Indian borage pretreatment also significantly (p< 0.05) counteracted the associated haematological dyscrasias caused by exposure to LPS. The extract elicited a significant protective effect on the kidney and liver as evidenced by the decreased renal markers and hepatic enzyme activities when compared with the control. The extract demonstrated protective and suppressive role against the overexpression of inflammatory mediators by ameliorating the induced inflammation and endotoxaemic conditions in the affected rat groups thereby validating its folkloric use.

CONCLUSIONS

Our study thus reveals that the extract might be an active, natural and non-toxic drug lead against endotoxaemia-induced inflammation and toxicity.