Olive Leaf Extract and Its Main Component Oleuropein Prevent Chronic Ultraviolet B Radiation-Induced Skin Damage and Carcinogenesis in Hairless Mice

Abstract

Chronic exposure to solar UV radiation damages skin, increasing its thickness and reducing its elasticity, and causes skin cancer. Our aim in this study was to examine the effects of an olive leaf extract and its component oleuropein on skin damage and the incidence of skin tumors caused by long-term UVB irradiation in hairless mice. Male hairless mice (5 wk old) were divided into 6 groups, including a non-UVB group, a vehicle-treated UVB group (control), 2 olive leaf extract-treated UVB groups, and 2 oleuropein-treated UVB groups. Five groups were UVB irradiated (36-180 mJ/cm(2)) 3 times each week for 30 wk and skin thickness and elasticity after UVB irradiation were measured every week. Olive leaf extract (300 and 1000 mg/kg) and oleuropein (10 and 25 mg/kg) were administered orally twice daily every day for 30 wk. The extract and oleuropein significantly inhibited increases in skin thickness and reductions in skin elasticity, and skin carcinogenesis and tumor growth. Furthermore, they prevented increases in the expression of matrix metalloproteinase (MMP)-2, MMP-9, and MMP-13 as well as in levels of vascular endothelial growth factor (VEGF) and cyclooxygenase-2 (COX-2) in the skin. Based on histological evaluation, they prevented increases in the expression of Ki-67 and CD31-positive cells induced by the irradiation. These results suggest that the preventative effects of the olive leaf extract and oleuropein on chronic UVB-induced skin damage and carcinogenesis and tumor growth may be due to inhibition of the expression of VEGF, MMP-2, MMP-9, and MMP-13 through a reduction in COX-2 levels.

A review: benefit and bioactive properties of olive (Olea europaea L.) leaves

“…In addition, hydroxytyrosol protects against atherosclerosis and prevents diabetic neuropathy [102]. The secoiridoid derivatives (oleuropeoside) in olive leaves are responsible for the vasodilating and relaxing properties of their extracts [103].…”

“…The cardiovascular effects of olive leaf extracts have been well studied and attributed to the main components of the European cultivar leaves, oleuropein and oleacein [117]. The secoiridoid derivatives (oleuropeoside) in olive leaves are responsible for the vasodilating and relaxing properties of their extracts [103].…”

Olive by-products: Challenge application in cosmetic industry

“…Kimura and Sumiyoshi (2009) examined the effects on chronic UVB-induced skin damage and carcinogenesis of olive leaf extract and its main component, oleuropein, using hairless mice. The extract and oleuropein inhibited the increase in skin thickness and reduction in elasticity induced by long-term exposure to UVB (Kimura and Sumiyoshi, 2009). Furthermore, they reduced the incidence and growth of tumors in exposed skin (Kimura and Sumiyoshi, 2009).…”

Chemical Composition and UVA-Protecting Activity of Extracts from Ligustrum vulgare and Olea europaea Leaves

“…Based on the available data, it is considered that the aqueous extract of olive leaves enhances the development of fibroblasts and epithelialization, as well as reduces congestion and infiltration of neutrophils, while demonstrating a significant healing effect in rats and mice (Koca et al, 2011). Furthermore, the inhibitory activity of olive extracts on skin thickness and elasticity, along with inhibition of the expression of metalloproteinases and COX-2 level, has been proved in UV-irradiated mice (Kimura and Sumiyoshi, 2009).…”