Phytochemical profile and the antioxidant activity of Chilean wild black-berry fruits, Aristotelia chilensis (Mol) Stuntz (Elaeocarpaceae)

From ethanolic, water extracts and their fractions of mature fruits of wild black-berry Aristotelia chilensis (Mol) Stuntz (Elaeocarpaceae), different phenolic compounds were identified by chromatographic (HPLC) and unequivocally assignments by spectroscopic (UV, NMR) data analysis. Anthocyanidins, flavonoids and phenolic acids fractions were obtained using flash and open column chromatography. The main compounds gentisic acid, ferulic acid, gallic acid, p-coumaric acid, sinapic acid, 4-hydroxybenzoic acid, delphinidin, cyanidin, vanillic acid, delphinidin gallate, gallocatechin gallate, quercetin, rutin, myricetin, catechin and epi-catechin as mixture 1:1, and several glycosides of anthocyanidins (delphinidin-3-sambubioside-5-glucoside, delphinidin-3,5-diglucoside, cyanidin-3-sambubioside-5-glucoside, cyanidin-3,5-diglucoside, delphinidin-3-sambubioside, delphinidin-3-glucoside, cyanidin-3-sambubioside, and cyanidin-3-glucoside), and proanthocyanidin B were detected. In addition to phytochemical analysis the antioxidant activities of extracts, partitions and fractions were strongly correlated with the highest polyphenol contents. The most active samples were the ethanolic and acetone extracts in all bioassays used and all samples were compared for activity against butylated hydroxy toluene (BHT), quercetin and tocopherol used as pattern samples. The juice (E), EtOH extract (A) and acetone partition (B) were found to have IC₅₀ values of 4.7, 1.7 and 7.4 ppm, respectively against DPPH and 5.9, 2.1 and 3.9 ppm, respectively against TBARS formation. Additionally, the fraction F-4 showed a strong activity with IC₅₀ of 4.9 and 6.5 ppm, against DPPH and TBARS respectively. Consistent with this finding, EtOH extract had the greatest ORAC and FRAP values as percentage of activity. On the other hand the IC₅₀ values for the inhibitory activity against O₂^{{radical dot} -} of extract B, F-3 and F-4 were 9.7, 13.2 and 10.7 ppm, respectively and against OH^{{radical dot}-} were 29.1, 7.0 and 6.3 ppm, respectively. The EtOH extract protects against stress oxidative reducing the concentration of the MDA a lipid peroxidation index. These results shows that this fruit could be useful as antioxidant and nutraceutical sources.