Evaluation of Analgesic, Anti- Inflammatory Activities, Acute and Sub-Acute Toxicity Profile of Methanolic Extract of Lettuce Cornuta Leaves

Author(s): Maibouge Tanko Mahamane Salissou, Sibongile Chituku, Idi Claire Musimwa, Brenda Makonyere, Vigillance Zibako, Blessing Chikore, Brooklyn Nhema

Background: Despite being beneficial, conventional Non-steroidal anti- inflammatory, anti-nociceptive drugs triggers serious adverse side effects associated with their usage as synthetic compounds which include heart attack, gastric ulcers, and liver and kidney diseases. Hence the necessity to continue investigating in natural product as alternatives. However the possible toxicity of natural products must be tested before being used in the market. Although Launaea cornuta ( LC ) has been used traditionally to pain and inflammation and other oxidative-stress-related syndromes; however,Its analgesic, anti-inflammatory efficacy including its toxicity has not been extensively investigated and validated, prompting this study.

Methods: The methanolic extract of Lettuce cornuta leaves (LC ) was generated through extraction with methanol using Soxhlet extractor apparatus. The phytochemical screening of the extract was conducted according to methods describe by Trease α Evans. Acute oral toxicity and sub-acute toxicity of the extract was examined in rats. In the sub-acute toxicity study lasting (28 days), the animals were divided into three groups (5 rats): control, low-dose group (food supplemented with 250 mg/kg of the LC extract), and high-dose group (500 mg/kg of LC extract). While the formalin test was used to test the analgesic anti-inflammatory activity of LC extract.

Results: The phytochemical screening of the extract showed presence of phenols, alkaloids, flavonoids, glycosides. In acute toxicity study the extract was safe and did not cause any clinical signs of acute oral toxicity in rat all doses and no mortality was observed (LD50 > 5000 mg/kg BW) however in sub-acute toxicity study despite no mortality was observed the histo-pathological examination of the kidney as vital organs showed mild lesion in the higher dose group. Moreover, the extract significantly showed analgesic anti-inflammatory potential in a dose-dependent manner, in formalin test compared with respective controls group (p<0.05).

Conclusion: The extract dose of 500 mg/kgbw had higher potency than the standard drug tramadol. Some of these phytochemicals like flavonoids are antioxidant- and anti-inflammatory-associated phytochemicals and were likely responsible for the reported pharmacologic efficacy further empirical studies are needed to determine and characterize the extract’s specific analgesic anti-inflammatory compounds, specific mechanisms of action, and complete toxicity profiles.