Anti-nociceptive and anti-inflammatory effects of the hydroethanolic extract of a polyherbal preparation (Cov-Pla 2) in laboratory animals

Symptoms of Coronavirus Disease-2019 include pulmonary hyper-inflammation;managing local and systemic inflammatory responses may be key in treatment. This study evaluated the anti-inflammatory, analgesic and antipyretic effects of a mixture (Cov-Pla 2) containing five medicinal plants in laboratory animals. The antinociceptive activity of Cov-Pla 2 was evaluated using acetic acid-induced writhing, Brewer's Yeast Pyrexia test in rats and hot plate tests in mice. The egg albumin-induced rat paw oedema test was employed to evaluate the extract's anti-inflammatory activity. The extract produced a dose-dependent (125-500 mg/kg, p.o.) inhibition of pain response elicited by acetic acid, compared to normal saline and increased reaction latency in the hot plate test. The antiinflammatory test showed a significant (P<0.05) reduction in paw size diameter at 125 mg/kg from 2 hours, compared to control. In the antipyretic test, the extract produced a significant (P<0.05) time-dependent decrease in rectal temperature at 125 mg/kg after 2 and 3 hours and at 250 and 500 mg/kg after 3 hours, compared to normal saline. The extract did not produce mortality up to 5000 mg/kg per oral. The results indicated that the extract possesses antinociceptive and anti-inflammatory properties, which support its recommendation for trials in the treatment of symptoms associated with COVID-19.