Evaluation of the anti-inflammatory activity of a gel based on Afzelia africana (fabaceae) leaves

Afzelia africana is a plant used by traditional healers in the treatment of several inflammatory pathologies, in particular edema, rheumatism, lumbago. The effectiveness of its barks in treating inflammation is well established. Ethnobotanical data led researchers to formulate a stable topical hydrogel based on bark extract, the tolerance and effectiveness of which in animals have been found to be satisfactory. As excessive use of the bark may impair the survival of the plant, further leaf studies have been performed and the anti-inflammatory effect has been confirmed in rats. The objective of the present study was to evaluate the anti-inflammatory efficacy of a topical gel based on the hydro-ethanolic extract of these leaves in patients with inflammatory symptoms, compared to a diclofenac gel. Using hydroxyethyl cellulose and glycerol a stable gel was produced and used for the evaluation of the anti-inflammatory activity of the leaves of the plant. The dry extract obtained from the leaves was rich in flavonoids (57.26 mg quercetin equivalent per gram), phenols, tannins, alkaloids, anthraquinones and steroids. We carried out a randomized pilot study on 52 patients who came for consultation at the « Cliniques Universitaires des Montagnes » and at the Bangangté District Hospital for inflammatory symptoms between June 1 and July 17, 2020; pregnant women were excluded from the study. Topical administration on 15 inflammatory pathologies revealed that the Afzelia africana leaf extract gel exhibits a better onset of action (4.29 ± 1.89 min) than the diclofenac gel (16.96 ± 4, 73 min). The decrease in pain visual analogue scale (VAS): values ​​for Afzelia africana gel was greater than for diclofenac gel, with P < 0.05 on day 2 and P < 0.001 from day 3 to day 7. The difference in First Hour Sedimentation Rate was significant between the two gels (P < 0.05); but this difference was no longer statistically significant after the second hour (P ˃ 0.05). In addition, Afzelia africana leaf extract gel reduced swelling (P = 0.001) and stiffness (P < 0.001) better than diclofenac gel. These results clarify the effectiveness of Afzelia africana leaf extract gel in the management of inflammatory pathologies and / or symptoms.