PHYTOCHEMICAL COMPOSITION, ANTINOCICEPTIVE, ANTI INFLAMMATORY AND ANTIOXIDANT ACTIVITIES OF Fagaropsis angolensis AND Fagaropsis hildebrandtii

Abstract

Fagaropsis angolensis and Fagaropsis hildebrandtii have been widely used in African traditional medicine to treat various illnesses, particularly those associated with pain, inflammation and oxidative stress. However, experimental data on the antinociceptive, anti-inflammatory and antioxidant activities of F. angolensis leaves, and F. hildebrandtii stem bark was still limited. The objectives of this study were to evaluate the antinociceptive, anti-inflammatory, antioxidant activities and phytochemical composition of F. angolensis leaves and F. hildebrandtii stem bark through an experimental controlled design. The study area was Embu and Makueni Counties. Extraction was done by maceration using water and methanol solvents. Increasing concentrations of the extracts (2-250 mg/Kg) were then evaluated for antinociceptive and anti-inflammatory activities using acetic acid-induced writhing and carrageenan induced paw edema animal models, respectively, in comparison with aspirin 150 mg/kg and dexamethasone 10 mg/kg as standards. Antioxidant activity was assayed by 2,2 Diphenyl-1-picrylhydrazyl (DPPH) method, against standard ascorbic acid at 1mg/1ml. Standard qualitative methods were used for preliminary analysis of phytochemicals. Later, total phenolic and total flavonoid content was determined by Folin-Ciocalteu and Aluminium chloride calorimetric methods, respectively. Data was analyzed by one way/two-way ANOVA followed by Tukey’s post hoc test for multiple comparison using GraphPad Prism version 7. Statistical significance level was set at p≤0.05. Results of the percentage writhing inhibition did not show any significant difference between tested doses of both F. angolensis and F. hildebrandtii methanolic extract at 250 mg/kg and aspirin (81.95 ± 10.76% vs. 84.99 ± 3.26% and 80.24 ± 12.59 % vs. 84.99 ± 3.26%; p>0.05), respectively, indicative of potent in vivo anti-nociceptive activity. Similarly, there was no significant difference in percentage paw edema inhibition between all the F. angolensis and F. hildebrandtii extract doses and dexamethasone standard at 10 mg/kg (p>0.05), indicative of potent in vivo anti-inflammatory activity. Altogether, these results indicate that F. angolensis leaves, and F. hildebrandtii stem bark have good antinociceptive and anti-inflammatory activity at maximum concentration. F. angolensis and F. hildebrandtii water and methanol extracts exhibited potent antioxidant activity, as demonstrated by the comparable percentage radical scavenging activity to ascorbic acid (p>0.05) and a much lower IC50 of 0.01 µg/ml vs. 0.90 µg/ml and 0.98 µg/ml vs. 0.987 µg/ml, respectively compared to 5.674 µg/ml for ascorbic acid. Qualitatively, phenols, steroids, flavonoids, alkaloids and coumarins were present in all the extracts of F. angolensis leaves and F. hildebrandtii stem bark. However, anthocyanins were absent in both water and methanolic extracts of both plants. F. angolensis methanol and water extract had significantly higher total phenolic content of 55.523±3.050 mgGAE/g vs. 48.00±0.185 mgGAE/g (p<0.05) while flavonoid content was 172.53±7.095 mgCE/g vs. 42.225±0.10 mgCE/g (p<0.05). F. hildebrandtii showed significantly high total phenolic levels in methanol extract compared to water extract (34.590 ± 2.490 mgGAE/g vs. 7.893 ± 1.619 mgGAE/g and total flavonoid content of 132.18 ± 0.26 mgCE/g vs. 42.68 ± 0.93 mgCE/g (p<0.05). These high levels of phenols and flavonoids might account for the observed antinociceptive, anti inflammatory and antioxidant activities of the plant parts studied. The study confirmed that both leaves and stem bark of F. angolensis and F. hildebrandtii used in Embu and Makueni Counties respectively, have antinociceptive, anti-inflammatory and antioxidant activities. Study recommends plant preservation, active pharmaceutical ingredient identification, testing in non-human primates and in clinical trials.