CHEMICAL CONSTITUENTS FROM THE LEAVES OF Eriodictyon californicum (Hook. & Arn.) Torr. (Boraginaceae)

Abstract

Eriodictyon californicum is a species belonging to Boraginaceae family, popularly known as “yerba santa” and used in folk medicine to treat rheumatism, headaches, inflammation, and respiratory complications. In the present work, we performed phytochemical analyses of extracts from the leaves of E. californicum in order to isolate its chemical constituents. According to thin-layer chromatography (TLC) analyses, preliminary phytochemical screening indicated the presence of anthocyanins derivatives, flavonoids, condensed and hydrolysable tannins. Furthermore, classical chromatographic techniques (column chromatography, analytical and preparative thin-layer chromatography) led to the isolation of secondary metabolites. The compounds were elucidated by 1D and 2D nuclear magnetic resonance (NMR) (correlation spectroscopy (COSY), heteronuclear single quantum correlation (HSQC) and heteronuclear multiple bond correlation (HMBC)) analysis, Fourier transform infrared (FTIR) spectroscopy, mass spectrometry (MS) analysis, and comparison with literature data. In this study, seven metabolites were identified: sterubin (1), chrysoeriol (2), apigenin (3), hydroxygenkwanin (4), 5,4’-dihydroxy-7,3’-dimethoxyflavanone (5), ethyl cinnamate (6) and 5-hydroxy-7 methoxychromone (7). The compounds 1-5 were previously identified in this species, and the compounds 6 and 7 are being reported for the first time in the species E. californicum, as well as in Boraginaceae family. The ¹H and ¹³C NMR data for some compounds have been reviewed. These results revealed that E. californicum is an important source of secondary metabolites, mainly flavonoids with chemophenetic relationships with Boraginaceae family.

Keywords:
Boraginaceae; Eriodictyon californicum; flavonoids; phytochemistry