Study of the Phytochemical Composition, the Antioxidant and the Anti-Inflammatory Effects of Two Sub-Saharan Plants: Piliostigma reticulatum and Piliostigma thonningii.

The aim of this study is to perform phytochemical screening of the leaves of Piliostigma reticulatum and Piliostigma thonningii, to determine the phenolic, flavonoids, tannins, and sugars content in their methanolic extracts, evaluate their antioxidant activity using the DPPH and the ABTS tests, and test their anti-inflammatory effect in vitro using the heat-induced albumin denaturation inhibition method. Phytochemical screening revealed the presence of polyphenols and alkaloids in the leaves of both plants. Yields of the extracts in this study ranged from 7% to 18% for P. reticulatum and 4% to 16% for P. thonningii. The phenolic content in the methanolic extract of P. reticulatum is 74.66 ± 1.76 μg GAE/mL, which is significantly higher than that of P. thonningii (56.54 ± 1.24 μg GAE/mL). Both plants showed good antioxidant activity. In fact, for the DPPH test, the IC50 value is 8.88 ± 0.11 μg/mL for P. reticulatum and 17.64 ± 0.68 μg/mL for P. thonningii. For the ABTS assay, the IC50 values of the two plants are, respectively, 9.78 ± 1.83 μg/mL and 13.47 ± 2.62 μg/ml, statistically comparable and significantly higher than the IC50 of the standard 30.76 ± 0.18 μg/ml. Leaf extracts from both plants were effective against heat-induced denaturation of albumin. The activity of P. reticulatum is indeed comparable to that of the standard with an IC50 value of 121.43 ± 1.55 μg/mL and higher than that of P. thonningii with an IC50 value of 170.15 ± 1.09 μg/mL. These results show that both plants exhibit significant antioxidant and anti-inflammatory activities. Therefore, their chemical compounds could have potential applications as antioxidant and anti-inflammatory drugs.