Phytochemicals, antioxidant and antiproliferative properties of Rosmarinus officinalis L on U937 and CaCo-2 cells

Rosmarinus officinalis L., a medicinal herb from the labiates family, has been reported to be of potential benefit in the treatment and prevention of several diseases. In particular its phenolics have demonstrated protective effects on various types of cancer through several mechanisms. The present study aimed to determine the effects of rosemary phenolic extracts on human cell functions, with particular regard to their anti-proliferative properties in three cell types U937, CaCo-2 and the peripheral blood mononuclear cells (PBMCs). The radical scavenging and Ferric reducing abilities of the extracts have been assessed as well as their cyto-toxicity and effects on cell cycle distribution and apoptosis. About 13 compounds were identified with dominance of rosmarinic acid in the methanolic extract and phenolic diterpens in the ethyl acetate fraction (Carnosol, Carnosic acid and methyl Carnosate). The total polyphenolic content was important in the first extract with 2.589±0.005 g/100g in gallic acid equivalent compared to 0.763±0.005 g/100g. The methanolic fraction displayed higher antioxidant activity (DPPHIC50: 0.510mg/ml and FRAP: 1.714±0.068 mmol Fe2+/g) while ethyl acetate showed pronounced antiproliferative effects (IC50: 14.85±0.20µg/ml and 14.95±2.32µg/ml respectively for U937 and CaCo-2 cells). The anti-proliferative effect was associated with a cell cycle arrest in S phase for U937 (62% of the population at 5µg/ml) with a concomitant decrease in G1 and G2/M phases. Tested extracts displayed in addition early apoptotic effects in U937 and late apoptosis in CaCo-2 cells. The obtained data indicate that the identified phenolics are at least partially responsible for the observed cytotoxicity.