Phenolic compounds of Triplaris gardneriana can protect cells against oxidative stress and restore oxidative balance.

This work aimed to add value to an underexploited plant species from Brazil, Triplaris gardneriana. To that, the phenolic compounds profile of its seed ethanolic extract and fractions was examined by HPLC and the antioxidant capacity assessed using chemical assays as well as in vitro cell imaging. Twelve compounds were quantified and classified as either phenolic acids or flavonoids. The fractionation process did not generate fractions with different compositions except for chloroformic fraction, which showed only 6 out of 12 standard compounds used. DPPH assay revealed samples with a concentration-dependent radical scavenging activity, being methanolic fraction the one with the largest activity (SC50 11.45±0.02µg/mL). Lipid peroxidation assessment, in the presence and absence of stress inducer, showed that particularly the ethanol extract (IC50 26.75±0.08µg/mL) and the ethyl acetate fraction (IC50 6.14±0.03µg/mL) could inhibit lipid peroxidation. The ethyl acetate fraction performed best in chelating iron (48% complexation at 1000µg/mL). Cell imaging experiments showed that the ethanolic extract could protect cells against oxidative stress as well as restore the oxidative balance upon stress induction. In conclusion, T. gardneriana seeds showed a promising phenolic compounds profile and antioxidant activity that may be further exploited.

Impact of bioaccessibility and bioavailability of phenolic compounds in biological systems upon the antioxidant activity of the ethanolic extract of Triplaris gardneriana seeds.

The most studied bioactive potential of phenolic compounds corresponds to antioxidant activity, which in turn, is associated with a reduction in the incidence of various human diseases. However, the total quantity of these bioactive substances in foods and medicinal preparations does not reflect the amount absorbed and metabolized by the body. The present study aimed to investigate the bioaccessibility of Triplaris gardneriana seeds ethanolic extract (EETg) by determination of phenolic composition and antioxidant activities before and after in vitro digestion as well as to estimate its bioavailability by chemical analysis of plasma and urine in animal models after oral administration. The bioaccessibility indexes of phenolic compounds in EETg were 48.65 and 69.28% in the presence and absence of enzymes, respectively. Among the identified phenolics classes, flavonoids, represented by galloylated procyanidins type B, proved to be more bioaccessible, 81.48 and 96.29% in the post-intestinal phase with and without enzymes, respectively. The oral administration in Wistar rats resulted in a significant decrease in plasma of the total antioxidant capacity, TAC, by FRAP assay 4h after beginning the experiment. For urine samples, an increase in TAC by DPPH and FRAP was observed from 1 and 4h after administration, respectively. UPLC-QTOF analysis of urine detected 2 metabolites originated from the degradation of phenolic compounds, i.e. hippuric acid and phenylacetil glycine. These results suggest that phenolic compounds in T. gardneriana are unstable under gastrointestinal conditions, being flavonoids the components with higher bioaccessibility; besides that, they showed limited bioavailability due to their rapid biotransformation and urinary elimination.