Isolation of Quercetin and Avicularin from Dennettia tripetala (G. Baker) Seeds, and Evaluation of the Oxidative Stress Management Capacity and Cytotoxic Activities of Its Acetone Extract and Fractions

Analysis of the phytochemical content of the acetone extract of Dennettia tripetala G. Baker seeds, DPPH radical scavenging activity (RSA) and oxidative burst assay of the extract and its fractions led to the isolation of quercetin and avicularin. Structural elucidation of these compounds was performed using NMR, ES1-MS and FT-IR spectroscopic techniques. Phytochemicals including volatile oils, steroids, terpenoids, alkaloids, glycosides, saponins, phenols, tannins and flavonoids were revealed. Phenols (111.45 +/- 0.45 mgGAE/g) and flavonoids (44.11 +/- 0.39 mgQE/g) were high, while tannins (3.80 +/- 0.69 mgTAE/g) and alkaloids (3.76 +/- 1.22%) were in low concentrations. Potent DPPH-RSA was observed for the extract (98.2 +/- 0.12%) which was expressed in its DCM (80.32 +/- 0.73%) and ethylacetate fractions (96.3 +/- 2.57%); isolates were obtained from the latter. No suppression of phagocytic oxidative burst was observed for the extract; however, moderate activities in comparison with the standard (73.27 +/- 0.28%) were obtained for the DCM (36.73 +/- 0.19%) and ethylacetate (35.72 +/- 0.62%) fractions. Cytotoxic evaluation on brine shrimp revealed moderate toxicity for the extract (LC50 = 296.09) expressed in its hexane (LC50 = 258.81) and residual aqueous (LC50 = 431.10) fractions. However, no toxicity was recorded for the extract and fractions on 3T3 cells at 30 mu g/mL, except for the DCM fraction which exhibited a mild toxicity (IC50 = 17.19 +/- 1.8); Also, no toxicity was observed for the extract and fractions on HeLa cells at similar concentration. Since the extract makes up a very small percentage of the seeds, there exist a huge margin of safety in the application of the seeds in nutrition and in the management of oxidative stress-related diseases.

Automated summary

This study analyzed the phytochemical content of acetone extract from Dennettia tripetala seeds and identified quercetin and avicularin as the major compounds. The extract exhibited high antioxidant activity and low suppression of phagocytic oxidative burst. Moderate toxicity was observed in the cytotoxic evaluation on brine shrimp, but no toxicity was found in 3T3 cells and HeLa cells, except for the DCM fraction which showed mild toxicity.