Biochemical characterization of radical scavenging polyphenols from Nyctanthes arbortristis

Context: Antioxidants are quenchers of free radical that are responsible for inducing oxidative stress generated via reactive oxygen species-induced degenerative diseases such as cancer, diabetes, and cardiovascular diseases etc. Plant and plant products are recognized as safe and potential health promoting and nutritive sources. Aims: To investigate the antioxidant potency of polyphenol extract (PE) of Nyctanthes arbortristis leaves and identification of the active constituent by HPLC. Materials and Methods: PE of N. arbortristis leaves was investigated for antioxidant activity employing various established in vitro systems, such as lipid peroxidation in liposome, DPPH and hydroxyl radical scavenging, reducing power assay, and iron ion chelation. Identification of active constituent in PE of N. arbortristis responsible for antioxidant activity by HPLC. Statistical analysis used: All experiments were carried out in triplicates. Data were shown as mean +/- standard deviation (SD). SPSS 10.0.5 version for windows (SPSS software Inc., USA) computer program was used for statistical analysis. Results: Identification of active constituent in PE revealed gallic acid 75.8 +/- 0.21, protocatechuic acid 14.6 +/- 0.5, chlorogenic acid 6.79 +/- 0.43, and caffeic acid 5.34 +/- 0.2 mu g/ml. PE showed strong inhibitory activity of 73% at 200 mu g/ml toward lipid peroxidation in egg lecithin, concentration-dependent inhibition of deoxyribose oxidation at 200 mu g/ml was 85% inhibition, and considerable antioxidant activity in DPPH radical assay system at 200 mu g/ml was 79% inhibition. BHA and gallic acid showed significant observations. Conclusion: The antioxidant potency significantly correlated with the phenolic content of PE. Considering that medicinal herbs contain potent phytochemicals, which is effectively utilized for various degenerative disease, these in vitro results showed that N. arbortristis leaves could be effectively employed in functional food, to alleviate oxidative stress.