Antioxidant and Anti-inflammatory Activities of Ethanolic Extract from Hoya kerrii Craib

Abstract

Hoya kerrii Craib (HK) has long been used as folk medicines for curing inflammatory-related diseases. This study aimed to investigate the phytochemical constituents, antioxidant and anti-inflammatory effects of 95% ethanol extract of HK (HKE). The high-performance liquid chromatography diode array detection mass spectrometry (HPLC-DAD-MS) analyzes of polyphenolic composition indicated the presence of gallic acid, catechin, tannic acid, isoquercetin, kaempferol, quercetin, rutin, genistein, daidzein, genistin and daidzin in HKE as bioactive compounds. The extract exhibited antioxidant properties based on 2,2-diphenyl-1-picryl-hydrazyl (DPPH) radical scavenging activity and ferric reducing antioxidant power (FRAP) assays. HKE also alleviated the tert-butyl hydroperoxide (tBuOOH)-induced reactive oxygen species (ROS) generation in RAW264.7 cells as measured by using 2’,7’-dichlorofluorescin-diacetate (DCFH-DA) assay. HKE suppressed LPS plus IFN-γ-induced nitric oxide (NO) production in RAW264.7 cells as determined by using Griess reagent. HKE exhibited the immunomodulatory effects by suppressing the secretion of pro-inflammatory cytokines TNF-α and IL-6 from RAW264.7 cells activated by LPS plus IFN-γ which was performed by enzyme-linked immunosorbent assay (ELISA). Collectively, these results suggest that HK may be applied as a promising antioxidant and anti-inflammatory natural agent through modulation of inflammatory mediators NO and cytokines such as IL-6 and TNF-α.