Anti-Inflammatulatory Activity of Hydro-Ethanolic Bark Extracts of Piliostigma reticulatum Hochst (Caesalpiniaceae) and Analysis by HPLC-DAD and HPLC-MS of its Methanol Fraction

Use of plants as remedies dates back to the time of the oldest civilizations. Among these active ingredients, polyphenols play an important role. Piliostigma reticulatum, a plant whose barks are rich in condensed tannin is often used as an anti-inflammatory. The purpose of this work was to correlate the anti-inflammatory activity of extracts with their chemical composition through chromatography fractionation analyses (HPLC-DAD and HPLC-MS). The barks were extracted by moderate hydroethanol decoction followed by silica gel splitting with successively ethyl acetate, methanol and water. Anti-inflammatory activity was evaluated by the method of carrageenan induced hind paw edema in Wistar rats. The chemical study was carried out by HPLC-DAD and HPLC-MS after isolation of the compounds by fractionation on Sephadex LH-20 gel. The bark hydroethanolic extract had shown ability to inhibit significantly the inflammation induced by carraghenan. Among the hydroethanolic bark extract fractions that methanol fraction had the best activity at 10 mg/kg with inhibition percentages similar to those of acetylsalicylic acid with 48.51% ± 2.26; 54.71% ± 5.13; 64.19% ± 6.70 vs. 54.69% ± 7.23; 57.83% ± 9; 65.13% ± 8.44 respectively. The HPLC-DAD analysis showed that the SF5 sub-fraction presented the best chromatogram with several peaks, three of which were high intensity. The latter would correspond to monomer, dimer and trimer of catechin according to the weights [M-H] + m / z: 291.07; 579.18; 867.27 obtained by HPLC-MS. The compounds responsible for anti-inflammatory activity would be condensed tannins. The latter would consist mainly of catechin oligomers. Keys words: Piliostigma reticulatum, bark, anti-inflammatory activity, HPLC-DAD, HPLC-MS