Abstract

The antioxidative and neuroprotective effects of Loranthus parasiticus (L.) Merr(Loranthaceae) were investigated for the first time. L. parasiticus ethanol extract (LPEE), L. parasiticus ethyl acetate fraction (LPEAF), and L. parasiticus aqueous fraction (LPAF) were evaluated and exhibited antioxidative activity in a dose-dependent manner. LPAF exhibited the lowest IC₅₀ values of 16.82 ± 0.27 μg/ml and 1.05 ± 0.04 mg/ml in 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and lipid peroxidation activities, respectively. Moreover, LPAF possessed the strongest reducing power activity and the highest total phenolic content. The neuroprotective activity was investigated in NG108-15 hybridoma cells against hydrogen peroxide (H₂O₂)-induced oxidative stress by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell viability assay. Both LPEE and LPAF exhibited neuroprotective activity on NG108-15 cells in a dose-dependent manner with the highest cell viability (78.00 ± 1.85%) observed with LPAF at the highest treatment concentration of 100 μg/ml. A close correlation was evident between antioxidative and neuroprotective activities with the total phenolic content in LPAF. These results suggested that LPAF may be used as a potent antioxidant and neuroprotectant in treating or preventing neurodegenerative diseases where oxidative stress is implicated.

Key words: Loranthus parasiticus, 2,2-diphenyl-1-picrylhydrazyl (DPPH), lipid peroxidation, reducing power, total phenolic content, antioxidant, neuroprotectant.

Abbreviation

LPEE, Loranthus parasiticus ethanol extract; LPEAF, Loranthus parasiticusethyl acetate fraction; LPAF, Loranthus parasiticus aqueous fraction; NG108-15, mouse neuroblastoma x rat glioma hybrid cells; H₂O₂, hydrogen peroxide; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide.