Antiinflammatory, Antinociceptive and Antioxidant activities of aqueous and methanolic stem bark extracts of Fagaropsis hildebrandtii (Engl.) Milne-Redh. (Rutaceae)
Authors: Maloba Peter , Mandela Elias , Kimoloi Sammy , Onyancha Jared 
Published: September 2023

Background: Fagaropsis hildebrandtii has been widely used in African traditional medicine to treat various illnesses, particularly those associated with inflammation, pain and oxidative stress. However, experimental data on the anti-inflammatory, anti-nociceptive and antioxidant of the different parts of F. hildebrandtii is still limited. Objectives: The objectives of this study were to determine the phytochemical composition, anti-inflammatory, antinociceptive and antioxidant activities of stem bark extract of F. hildebrandtii from Makueni County, Kenya. Materials and Methods: The stem bark of F. hildebrandtii was extracted by maceration using water and methanol. Standard qualitative methods were then used to determine the presence or absence of various phytochemicals in the extracts. Total phenolic and flavonoid contents were determined by Folin-Ciocalteu and aluminium chloride calorimetric methods, respectively. Anti-inflammatory and anti-nociceptive activities of increasing water and methanol extracts doses (2-250mg/Kg) were tested using carrageenan-induced paw edema and acetic acid-induced writhing animal models, respectively in comparison with dexamethasone and aspirin as standard. Antioxidant activities of plant extracts were assayed by 2,2-Diphenyl-1-picrylhydrazyl (DPPH) method, with ascorbic acid as the standard. Data analysis was conducted by two-way ANOVA with appropriate post hoc tests. Statistical significance level was set at p ≤ 0.05. Results: Phenols, flavonoids, alkaloids, saponins, tannins, terpenoids and coumarin were detected in the extracts. However, anthocyanins and anthraquinones were absent in both water and methanolic extracts. Notably, methanol extract had a high total phenolic level compared to water extract (34.590 ± 2.490 mgGAE/g vs. 7.893 ± 1.619 mgGAE/g; p<0.05). Total flavonoid content of F. hildebrandtii methanol extract was also higher in comparison to water extract (132.18 ± 0.26 mgCE/g vs. 42.68 ± 0.93mgCE/g; p<0.05). F. hildebrandtii water and methanol extracts had a radical scavenging activity IC50 of 0.98 µg/ml and 0.987 µg/ml respectively, which was significantly lower than 5.674 µg/ml for ascorbic acid, indicating a higher antioxidant potency. The percentage inhibition of carrageenan-induced hind paw edema by F. hildebrandtii extracts was not significantly different in comparison with 10 mg/Kg of dexamethsone standard over a 5-hour test period (p>0.05). F. hildebrandtii water and methanol extracts exhibited a dose-dependent inhibition of acetic acid-induced writhing in mice, reaching a maximum of 53.1 ± 6.1% and 80.24 ± 12.59%, respectively, at 250 mg/Kg. Notably, the percentage inhibition of acetic acid-induced writhing by 50 mg/kg and 250 mg/kg of F. hildebrandtii methanolic extract was similar to that of aspirin standard at 150 mg/kg (77.75 ± 19.64% vs. 80.24 ± 12.59% vs. 84.99 ± 3.26%, p>0.05, two-way ANOVA). Conclusion: F. hildebrandtii has anti-inflammatory, antinociceptive and antioxidant activities. These findings validate the use of F. hildebrandtii crude extracts among Kenyan ethnic groups in management of diseases associated with inflammation, pain, and oxidative stress.