Evaluation of anti inflammatory properties and toxicity of aqueous and ethanolic extracts of Plectranthus cyaneus in Swiss albino mice

Abstract

Traditional medicinal plants have been used over the years for the treatment of health problems including acute and chronic inflammation in management of inflammation associated diseases. This study was aimed at evaluating the oral acute toxicity and anti-inflammatory property of the aqueous and ethanolic extract of Plectranthus cyaneus in Swiss albino mice. Healthy mice (20-30g) were selected for the efficacy and safety study model. All rats had free access to pelleted food and water. For the safety study, animals were divided into 6 groups (n=3) positive control (distilled water), negative control, aqueous extract (2000 and 5000 mg/kg) as well as the ethanolic extract (2000 and 5000 mg/kg). The mice were observed for clinical signs, mortality and weight was measured at different time intervals. This was used to estimate the LD50 (≥5000mg/kg) according to OECD guidelines 423 for both extracts that were found to be safe at both doses since no mortality was seen. The weight reduction with time was significant at p<0.05. Then efficacy of Plectranthus cyaneus from aqueous and ethanolic leaf extracts dissolved in distilled water was compared with that of ibuprofen (positive control) and the negative control (distilled water). Inflammation was induced with 0.1mls of diluted egg albumen in the hind paw for anti-inflammatory activity in the mice. The mice were divided into five groups(n=3); different doses(250 and 500 mg/kg) of extracts were given. The results were expressed as mean paw diameter(cm). The significance of differences at P<0.05, between the means was analyzed using one-way ANOVA. Paw diameter reduction of 45.6% was observed with positive control, 46.8% with aqueous extract, 47.6% with ethanolic extract and 11.70% with the negative control as shown in table 9. Both extracts were equally effective with the ethanolic having a greater effect than the aqueous extract however the difference in efficacy of two extracts was not significant at both time intervals. The ethanolic and aqueous extracts all showed significant anti-inflammatory properties compared to the negative control at both doses and time intervals as shown in table 7 and 8. The anti-inflammatory activity may be attributed to the various phytochemicals such as flavonoids, terpenoids, saponins and tannins found present. The results provide valuable insights into the anti-inflammatory properties and toxicity profile of the aqueous and ethanolic extracts of Plectranthus cyaneus, laying a foundation for potential therapeutic applications with caution towards toxicity management.