Joseph Kiambi Mworia
Cromwell Mwiti Kibiti
Joseph JN Ngeranwa
Mathew Piero Ngugi

Introduction: Pain is managed using conventional drugs like paracetamol, aspirin and diclofenac among others. Synthetic drugs have many side effects. This study aimed at evaluating the analgesic potential of the dichloromethane leaf extracts of Eucalyptus globulus and Senna didymobotrya in mice. Methods: The dichloromethane leaf extracts of E. globulus and S. didymobotrya were subjected to quantitative phytochemical analysis using gas chromatography-mass spectrophotometry (GC-MS). In vivo analgesic evaluation comprised of nine groups of animals (Swiss albino mice): normal, positive, negative control and six experimental groups that received ۲۵, ۵۰, ۱۰۰, ۱۵۰, ۲۰۰ and ۲۵۰ mg/kg body weight of each plant extract intraperitoneally. Thirty minutes later, they were injected with ۰.۰۱ mL of ۲.۵% formalin. The animals in positive control group were administered diclofenac (۱۵ mg/kg) and formalin, the normal control mice received ۳% dimethyl sulfoxide (DMSO) in normal saline, while the negative group received DMSO in normal saline and formalin. All the doses were administered intraperitoneally. The duration of shaking and licking of the injected paw was scored and analyzed. Results: The analysis revealed that E. globulus contained alpha-pinenes, endo-fenchol, α-eudesmol, myrcene, camphene, alpha-phellandrene, limonene, and camphor while S. dymobotrya possessed camphene, alpha-phellandrene, limonene, and camphor. In the late phase, E. globulus at the doses of ۲۵, ۵۰, ۱۰۰, ۱۵۰, ۲۰۰ and ۲۵۰ mg/kg reduced the paw licking time by ۳۴.۰۳%, ۶۰.۷۹%, ۸۴.۳۳ %, ۹۰.۶۵%, ۹۴.۴۹%, ۹۸.۵۲%, respectively while S. didymobotrya extract reduced the paw licking time by ۲۶.۴۸%, ۳۲.۹۶%, ۸۷.۰۴%, ۹۱.۲۷%, ۹۳.۴۰%, ۹۰.۹۷%, and ۹۶.۸۲%, respectively. Conclusion: The results of this study validate and support the traditional uses of these plants as analgesics.