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

Abstract

The aim of this study is to perform phytochemical screening of the leaves of <i>Piliostigma reticulatum</i> and <i>Piliostigma thonningii</i>, 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 <i>P. reticulatum</i> and 4% to 16% for <i>P. thonningii</i>. The phenolic content in the methanolic extract of <i>P. reticulatum</i> is 74.66 ± 1.76 <i>μ</i>g GAE/mL, which is significantly higher than that of <i>P. thonningii</i> (56.54 ± 1.24 <i>μ</i>g GAE/mL). Both plants showed good antioxidant activity. In fact, for the DPPH test, the IC50 value is 8.88 ± 0.11 <i>μ</i>g/mL for <i>P. reticulatum</i> and 17.64 ± 0.68 <i>μ</i>g/mL for <i>P. thonningii</i>. For the ABTS assay, the IC₅₀ values of the two plants are, respectively, 9.78 ± 1.83 <i>μ</i>g/mL and 13.47 ± 2.62 <i>μ</i>g/ml, statistically comparable and significantly higher than the IC₅₀ of the standard 30.76 ± 0.18 <i>μ</i>g/ml. Leaf extracts from both plants were effective against heat-induced denaturation of albumin. The activity of <i>P. reticulatum</i> is indeed comparable to that of the standard with an IC₅₀ value of 121.43 ± 1.55 <i>μ</i>g/mL and higher than that of <i>P. thonningii</i> with an IC₅₀ value of 170.15 ± 1.09 <i>μ</i>g/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.