Apolar Laurus nobilis leaf extracts induce cytotoxicity and apoptosis towards three nervous system cell lines

In the course of a bioactivity screening of Mediterranean plants, the assessment of neuroprotective properties of Laurus nobilis L. was of interest. Dried leaves were extracted by sonication using CHCl3 as solvent. The CHCl3 parental extract (CHCl3-pe) was fractionated to yield CHCl3 (LnC-1), EtOAc (LnC-2), MeOH (LnC-3) fractions. Each fraction underwent an extensive screening towards human neuroblastoma (SK-N-BE(2)-C, and SH-SY5Y) and rat glioma (C6) cell lines. MTT and SRB cytotoxicity tests were performed. The effect on the plasma membrane integrity was evaluated by assessment of LDH release. The caspase-3 activation enzyme and DNA fragmentation were also evaluated. The oxidant/antioxidant ability of all the extracts were evaluated using different methods. Furthermore, a metabolite profiling of the investigated extracts was carried out by GC-EI-MS. CHCl3-pe contained terpenes, allylphenols, and α-tocopherol. Dehydrocostus lactone was the main constituent. As result of the fractionation technique, the LnC-1 extract was mainly composed of α-tocopherol, whereas the LnC-2 fraction was enriched in guaiane and eudesmane terpenes. The most cytotoxic LnC-2 fraction induced apoptosis; it was ineffective in preventing in vitro free radicals production. Overall, the experimental results support a possible role of LnC-2 preparation as a chemopreventive agent for neuronal cells or other cells of the CNS.