3-Desoxyanthocyanidins from Arrabidaea chica

Abstract

The new 3-desoxyanthocyanidins 6,7,3′-trihydroxy-5,4′-dimethoxy-flavylium and 6,7,3′,4′-tetrahydroxy-5-methoxy-flavylium and the known 6,7-dihydroxy-5,4′-dimethoxy-flavylium (Carajurin) were isolated by bioguided fractionation from the leaves of Arrabidaea chica, with transcription factor NF-κB as target. The structure of Carajurone was revised to be 6,7,4′-trihydroxy-5-methoxy-flavylium. Additionally, the flavone acacetin was found. All structures were mainly established on the basis of MS- and NMR data (1H, 1H–1H COSY and partly 13C, GHMQCR and GHSQCR). Carajurin, which failed to give a positive result in the DPPH TLC assay completely inhibited NF-κB, but not NF-AT at a 500 μM concentration.