Antispasmodic and antioxidant activities of fractions and bioactive constituent davidigenin isolated from Mascarenhasia arborescens

Ethnopharmacological relevanceMascarenhasia arborescens A. DC. (Apocynaceae) is used in traditional medicine in the North of Madagascar to treat intestinal disorders, intestinal spasms and diarrhoea.Aim of the studyThe main objective of this work was to evaluate the antispasmodic activity of the crude methanolic extract of Mascarenhasia arborescens and of its four partitions and to identify the effective compound responsible for this effect.Materials and methodsIsolation and structure elucidation techniques were performed in order to identify the bioactive constituent of Mascarenhasia arborescens and HPLC analysis was used for its quantification. Total phenolic content (TPC) of crude extracts and partitions were determined using the Folin–Ciocalteu method. Crude methanolic extract, partitions and the bioactive compound were investigated for their spasmolytic activity on several isolated organs. Their antiradical activity was also investigated by the DPPH test.ResultsBioassay-guided fractionation using isolated guinea pig ileum pre-contracted with histamine 3 × 10−6 M led to the isolation of davidigenin (DG), a dihydrochalcone, as the main active constituent from the most promising methylene chloride partition (McP). This partition was effective on isolated guinea pig ileum pre-contracted with 3 × 10−6 M histamine, with a median effective concentration (EC50) of 41.19 ± 3.74 μg/ml. The DG content of this partition was shown to be 26.5% by HPLC. DG induced a concentration-dependent relaxation of the histamine pre-contracted guinea pig ileum with an EC50 of 8.04 ± 0.81 μg/ml and a concentration-dependent relaxation of the acetylcholine pre-contracted rat duodenum with an EC50 of 9.35 ± 0.30 μg/ml. It inhibited in a non-competitive manner histamine-induced isolated ileum contraction and the acetylcholine-induced isolated duodenum contraction. Moreover, DG does not have any antiradical activity.ConclusionsWe demonstrated for the first time antispasmodic and antioxidant effects of Mascarenhasia arborescens. This study supports its use in traditional medicine. Furthermore, we highlighted the crucial role of davidigenin in the antispasmodic activity of this plant.

Bioassay-guided fractionation led to the identification of davidigenin as the main active constituent responsible for the antispasmodic activity of Mascarenhasia arborescens. It inhibited, in a non-competitive manner, the intestinal contractile effects of histamine and acetylcholine. The results may explain, at least partially, the traditional use of Mascarenhasia arborescens in intestinal spasms and diarrhoea.Figure optionsDownload as PowerPoint slide