Evaluation of Analgesic and Anti-inflammatory Activities of Methanolic Leaf and Root Extracts of Gomphocarpus purpurascens A. Rich (Asclepiadaceae) in Mice

Abstract

Background

Regardless of the availability of drugs many people still experienced pain and inflammation because current medications often trigger potentially serious adverse effects. A range of medicinal plants with analgesic and anti-inflammatory properties have been widely used by traditional healers. Among them, Gomphocarpus purpurascens is one however there are no experimental studies that support this traditional use.

Objective

This study aimed to evaluate the analgesic and anti-inflammatory activities of 80% methanolic leaf and root extracts of G. purpurascens.

Methods

Air-dried leaves and roots of G. purpurascens were extracted with 80% methanol and an acute oral toxicity study was conducted for the 80% methanolic extract of G. purpurascens according to OECD guideline version eighteen. Preliminary phytochemical screening for the presence of different constituents was carried out. The hot plate method was used to evaluate centrally mediated analgesic activity while peripheral analgesic activity was tested by an acetic acid-induced writhing test. Carrageenan-induced paw edema test and formalin-induced pedal edema test were used to evaluate anti-inflammatory activity.

Results

Dose-dependent inhibition of acetic acid-induced writhing test was observed in mice by 100 mg/kg, 200 mg/kg, and 400 mg/kg of root extract with respective values of 16.6%, 68.9%, and 83%. In the hot plate method, the root extract at doses of 200mg/kg and 400 mg/kg showed a significant (p < 0.05) analgesic effect. Maximum anti-inflammatory effects by all doses of leaf extracts were observed from 2–4hr post-induction in carrageenan-induced paw edema; and all tested doses of the extract inhibited the formalin-induced inflammation significantly (p < 0.001, p < 0.01). The presence of saponins, alkaloids, flavonoids, tannins, terpenoids, anthraquinone, steroids, and phenols might be responsible for these activities.

Conclusion

This study shows that the extract had potential analgesic and anti-inflammatory activity which supports the traditional claim.

Keywords:

• Gomphocar puspurpurascens
• anti-inflammatory
• analgesic
• mice
• carrageenan
• formalin

Abbreviations

ASA, Acetylsalicylic acid, BK, Bradykinin CNS, Central Nervous System, COX, Cyclooxygenase, GP, GomphocarpusPurpurasence, IL, Interleukin, iNOS, Inducible Nitric Oxide Synthase, NO, nitric oxide, NSAID, Non-steroidal Anti-inflammatory Drug, NF-κ, nuclear factor Kappa, PGs, prostaglandins, TNF, Tumor necrosis factor.

Data Sharing Statement

All data are available in the manuscript; additional data may be acquired from the corresponding author as needed via email.

Ethics Approval and Consent

Ethical clearance was obtained from the Department of Pharmacology, School of Pharmacy College of Medicine and Health Science University of Gondar to conduct the study in animal models. Besides, all possible steps were taken to avoid animal suffering at each stage of the experiment based on the Eighth Edition of the Guide for the Care and Use of Laboratory Animals. However, no consent was needed for this study.

Acknowledgment

We would like to acknowledge the University of Gondar for allowing using the laboratory setup and for sponsoring the study (This is the MSc. thesis of the first author).

Disclosure

The authors report no conflicts of interest in this work.