The Journal of Phytopharmacology 2026; 15(4):250-255 DOI:10.31254/phyto.2026.15407
Evaluation of Carissa spinarum methanol extracts and flavonoid-rich fractions for pain management: insights into receptor-mediated mechanisms
Jeptoo N Serem1 , Stanley N Wambugu2 , John K. Mwonjoria1 , Marion B. Warigia1
1. Department of Biochemistry, Microbiology and Biotechnology, Kenyatta University, Nairobi, Kenya
2. Department of Veterinary Anatomy and Physiology, University of Nairobi, Nairobi, Kenya
*Author to whom correspondence should be addressed.
Received: 21st April, 2026 / Accepted: 17th July, 2026 / Published : 31st August, 2026
Background: Herbal remedies have played an essential role in the development of modern medicine. One herbal medicine used to treat pain is Carissa spinarum. Pain remains a constant health issue despite the presence of many pain medications, which are sometimes costly, unavailable, and have undesired side effects. This underscores the need to identify affordable and safer alternatives from medicinal plants and their bioactive fractions for pain management. Objective: To evaluate the antinociceptive effects of the crude methanol extract and flavonoid-rich fraction of C. spinarum and investigate their possible mechanism of action. Materials and Methods: Antinociceptive activity was evaluated in Swiss albino mice using the formalin-induced paw-licking test and the hot water tail-flick test. Diclofenac was used as the standard drug. Pain was determined by recording the time mice displayed pain behavior in the formalin and the time it took for mice to flick their tails in the tail-flick test. The mechanism of action was determined by administering blockers (atropine, ketamine, and naloxone), known to target cholinergic, N-methyl-D-aspartate (NMDA), and opioid receptors, before administration of the extracts. Results: The crude extracts and flavonoid-rich fractions of C. spinarum significantly reduced pain responses in both the formalin and tail-flick tests (p < 0.05 and p <0.01). Pretreatment with ketamine and atropine significantly (p < 0.05) altered the antinociceptive effects of the extracts. In contrast, pretreatment with naloxone did not, suggesting the possible involvement of cholinergic and NMDA receptor pathways. Conclusion: The results demonstrate that the crude extracts and flavonoid-rich fractions of C. spinarum possess significant antinociceptive activity. The analgesic effect of the fraction appears to be mediated via cholinergic and NMDA receptor pathways, supporting the plants’ traditional use in pain management and highlighting them as a potential source of new analgesic compounds.
C. spinarum, Antinociceptive, Flavonoids, Pain mechanisms, Receptor-mediated mechanisms, Analgesic activity