Hydrolyzable tannins from hydroalcoholic extract from Poincianella pluviosa stem bark and its wound-healing properties: Phytochemical investigations and influence on in vitro cell physiology of human keratinocytes and dermal fibroblasts

Extracts from Poincianella pluviosa stem bark are used in traditional medicine of South America for its wound healing properties. For validation of this traditional use and for rationalizing a potential pharmaceutical development towards standardized preparations bioassay-guided fractionation of EtOH–water (1:1 v/v) extract (crude extract, CE) of P. pluviosa bark was performed. HaCaT keratinocytes cell line and human primary dermal fibroblasts (pNHDF) were used as in vitro systems. Significant stimulation of mitochondrial activity was found for CE on both cell types, which caused a strong increase of cell proliferation of keratinocytes. Fractionation of CE over Sephadex LH20 revealed two inactive fractions (FA and FB) and an active fraction FC, which was further fractionated by MPLC into 4 subfractions. Subfraction FC1 increased mitochondrial activity and proliferation of keratinocytes and dermal fibroblasts in a dose dependent manner (10 to 100 μg/mL) and did not show necrotic cytotoxicity on keratinocytes (LDH release assay). FC1 was investigated by ESI–MS/MS and solid-state 13C NMR which confirmed the presence of various polyphenols and hydrolyzable tannins. MS studies suggest the presence of pyrogallol (1), gallic acid (2), gallic acid methyl ester (3), ellagic acid (4), corilagin (5), 1,4,6-tri-O-galloyl-glucose (6), tellimagrandin I (7), 1,2,3,6-tetra-O-galloyl-glucose (8), mallotinic acid (9), tellimagrandin II (10), 1,2,3,4,6-penta-O-galloyl-glucose (11), geraniin (12), and mallotusinic acid (13).

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