Quantification and in vitro photo-protective studies of phenolic compounds from Baccharis papillosa Rusby

Context: The ethanolic extract of the leaves from Baccharis papillosa, a plant used in Bolivian folk medicine, presents high UVB/UVA absorption spectrum, and therefore, it could have photo-protective potential. Aims: To isolate, identify and quantify the compounds of an enriched extract in phenolic compounds obtained from the ethanolic extract of Baccharis papillosa in different seasons and geographical altitudes, and evaluate its photo-protective potential. Methods: The enriched extract in phenolic compounds was submitted to phytochemical analysis for compound isolation. The enriched extract and isolated compounds were identified by NMR, and monitored by HPLC and spectroscopic methods. The enriched extract with photo-protective potential was analyzed to determine its Spectroscopic Sun Protection Factor (SSPF), its Broad Spectrum Index (BSI) and its photo-protective activity on Escherichia coli bacteria. Results: Six flavonoids and two cinnamic acid derivatives were isolated and identified. Four of them are reported in B. papillosa for the first time in this study. The highest concentration of total flavonoids was observed in spring and at the highest altitude. The major compound, drupanin, was the main responsible of the high UVB (290-320 nm) absorption spectrum. The high presence of flavonoids in the extract explains the absorption spectrum in the UVA (320-400 nm) region. Conclusions: The phenolic compounds enriched extract has photo-protective properties comparable to standard commercial synthetic sunscreens and presents an attractive BSI.