A comparative study on the protective effect on human fibroblast cell line NHDFof Olea europaea and Ligustrum vulgare leaves extracts

Considering the traditional use of olive (Olea europaea L., Oleaceae) leaves on cuts, wounds and burns, we have studied the protective effect of extracts from olive leaves in fibroblast line (NHDF) in vitro. Furthermore, due to the limited knowledge on wound healing activity of common privet (Ligustrum vulgare L., Oleaceae) leaves, it has been justified to compare the composition and activity of these two species. Firstly, we determined the content of the main secoiridoid glucoside oleuropein in different extracts (aqueous, ethanolic, infusion, decoction) using HPTLC-photodensitometry method (Fig. 1). Secondly, we aimed to study the protective effect of extracts on human fibroblast cell (NHDF) viability (MTT assay), apoptosis rate (Annexin V/iodide propodium staining) and ROS production after UVA-irritation and H₂O₂-induced (2.5 mM) oxidative stress. It was established that none of extracts at the concentrations of 5, 25 and 50 µg/mL affected cells viability. The UVA-irritation triggered the reduction of cell viability by 51.4 ± 4.9%. Aqueous extracts, infusions and decoctions of both plants have protective effect on NHDF cell against UVA. Olive leaves extracts inhibited ROS production more significantly than privet leaves extracts after UVA-irritation. The percentage of ROS generation by cells treated with ethanolic and aqueous extracts, infusion or decoction of olive leaves (50 µg/mL) was 104.0 ± 0.4%, 72.5 ± 16.7%, 67.6 ± 18.0%, 75.9 ± 3.7% vs. (+) UVA control 100.0 ± 20.6%, respectively. In conclusion, O. europaea leaves extracts characterised by higher content of oleuropein showed more significant inhibition of ROS production and protection against UVA-irritation than L. vulgare extracts.

Fig. 1: Stationary phase – Silica Gel F254; Eluent – dichloromethane: methanol: formic acid: water (80:25:4:1.5, v/v/v/v); Visualisation – anisaldehyde (0.5%, methanolic) and sulphuric acid (5%, methanolic).