A Novel Compound and Biological Evaluation of Phytoconstituents Isolated from Erythrina corallodendron L. Flowers

Objective: This study aimed at phytochemical investigation of the 70% alcoholic extract of Erythrina corallodendron L. flowers and biological evaluation of the isolated compounds for their activity as antiprotozoal drugs also evaluation the binding affinity to opioid and cannabinoid receptors as well as the inhibition activity against monoamine oxidase (MAO) enzymes. Method: The 70% alcoholic extract was subjected to successive column chromatographic (CC) separations using silica gel normal phase, reversed phase RP-18, Diaion HP-20, and Sephadex LH-20. The structural elucidation of the isolated compounds was achieved using HR-ESI-MS, UV, 1D and 2D NMR spectroscopic analysis. The isolated compounds were screened in vitro for the binding affinity to opioid and cannabinoid receptors using receptor binding assay as well as the inhibition activity against MAO enzymes using kynuramine deamination assay, while their antiprotozoal activity was evaluatedusing parasitelactate dehydrogenase serum assay (pLDH). Results: The phytochemical evaluation of the alcoholic extract of E.corallodendron flowers, afforded the isolation of an indole alkaloid Hypaphorine 1, a new flavonoid glucoside; Kaempferol-3-O-α-sophoroside 2 and three known flavonoid C-glycosides vis;, Neoschaftoside 3, Isoschaftoside 4 and Vicenin-II 5. Compounds 3 and 4 are reported for the first time from genus Erythrina. Compounds 4 and 5 showed significant antimalarial activity both with IC50 value 1.7µg/mL against (D6) strain and with IC50 1.4 and 1.1 µg/mL against (W2) strain, respectively. Compound 3 showed selective inhibition to MAO-B with IC50 value of 32.08 µM and selective index (SI) > 3.12. Conclusion: The significant antiplasmodial activity of compounds 4 and 5 correlated the known antimalarial activity of different Erythrina species to flavonoid C-glycosides, Also compounds 3 and 4 are position isomers but exhibited different response against MAO-B which gives indication about the selectivity pattern of the flavonoid C-glycosides with MAO-B receptor subtype.