Chemical constituents and cytotoxic activity of Ocimum gratissimum L.

Abstract

• The leaves of Ocimum gratissimum L. was subjected to identification of its chemical constituents. • The in vitro cytotoxic activity of compounds against lung adenocarcinoma (A549), breast carcinoma (MCF-7), acute monocytic leukemia (THP-1), murine macrophages Raw 264.7 cancer cell lines and the normal fibroblast A7R5 cell line were studied. • THP-1 was the most sensitive to compounds 1-6 . • Compound 4 and paclitaxel have similar IC 50 value against THP-1 cells. Malignancies constitute a global health concern and chemotherapy remains the main mode of treatment. The present study was designed to evaluate the cytotoxicity of metabolites isolated from Ocimum gratissimum L. The phytochemical investigation of the leaves of O. gratissimum L. (Lamiaceae) led to the isolation and characterization of eight compounds. Structures of isolated compounds were elucidated using 1D and 2D NMR, as well as MS. The purified compounds, were identified as five triterpenes ( 1-5 ), one flavonoid ( 6 ) and two steroidal compounds ( 7-8 ). The cytotoxicity effects of purified compounds were assessed in vitro by the WST-1 assay on three cancer cell lines including lung adenocarcinoma (A549), breast carcinoma (MCF-7), acute monocytic leukemia (THP-1), murine macrophages (Raw 264.7) and the normal fibroblast (A7R5) cells. Compound 4 had an IC 50 value of 3.21±0.4 µM similar to that of the reference drug, paclitaxel against THP-1 cells. The THP-1 cell lines were the most sensitive to compounds 1-6 . All the compounds showed low cytotoxicity against the normal cell line A7R5 as compared to cancer cell lines. The constituents of Ocimum gratissimum L. and especially pomolic acid ( 4 ) is a potent cytotoxic compound that deserves more investigations toward developing novel antiproliferative drugs against acute monocytic leukemia (THP-1).