Antioxidant activity of Ixora parviflora in a cell/cell-free system and in UV-exposed human fibroblasts

Polyphenols and flavonoids possess a variety of biological activities including antioxidant and anti-tumor activities. Ixora parviflora is a member of the flavonoid-rich Rubiaceae family of flowering plants and used as folk medicine in India. The aim of this study was to investigate the antioxidant activity of Ixora parviflora extract (IPE) in a cell-free system and erythrocytes, and the ability of IPE to inhibit reactive oxygen species (ROS) generation in human fibroblasts (Hs68) after ultraviolet (UV) exposure. Various in vitro antioxidant assays were employed in this study. The extraction yield of IPE was 17.4 ± 3.9%, the total phenolic content of IPE was 26.2 μg gallic acid equivalent (GAE)/mg leaves dry weight and the total flavonoids content was 54.2 ± 4.4 μg quercetin equvalent (QE)/mg extract. The content of chlorogenic acid was 9.7 ± 1.2 mg/g extract. IPE at 1000 μg/mL exhibited a reducing capacity of 90.5 ± 0.6%, a 1,1-diphenyl-2-picrylhydrazy (DPPH) radical scavenging activity of 96.0 ± 0.4%, a ferrous chelating activity of 72.2 ± 3.5%, a hydroxyl radical scavenging activity of 96.8 ± 1.4%, and a hydrogen peroxide scavenging activity of 99.5 ± 3.3%. IPE at 500 μg/mL also possessed inhibitory activity against 2,2'-azobis (2-methylpropionamidine) dihydrochloride (AAPH)-induced hemolysis of erythrocytes (89.4 ± 1.8%) and resulted in a 52.9% reduction in ROS generation in UV-exposed fibroblasts. According to our findings, IPE is a potent antioxidant and a potential anti-photoaging agent.