Investigation of Extracts from Tunisian Ethnomedicinal Plants as Antioxidants, Cytotoxins, and Antimicrobials.

ABSTRACT

OBJECTIVE: To determine the medicinal potential of various plants and their parts extracted with different solvents. METHODS: The total phenolic content of acetonitrile/water (60%-40%) (ACN/W) and aqueous (W) extract fractions was determined by high-performance liquid chromatography (HPLC), and terpenic compounds were detected by gas chromatography/mass spectrometry (GC/MS). Antioxidant activity of the samples was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and ß-carotene bleaching method. Cell viability was investigated by thiazolyl blue tetrazolium bromide [3-(4,5-dimethylthiazol)-2-yl 2,5-diphenyltetrazolium bromide] (MTT) assay. The mechanisms involved in cytotoxic activity were investigated in a murine macrophage cell line (RAW 264.7) and cancer lines. RESULTS: Our findings show that 11 plant species exhibited biological activity. In addition, moderate antibacterial activity was reported against one or more of the tested bacterial strains at two concentrations 300 µg and 3 mg/disc. Furthermore, our data reveal that among all plants investigated, some extract and hydrophobic fractions were potent scavengers of the DPPH radical (6.78 µg/mL < EC50 < 8.55 µg/mL). Taken together, our results show that Nerium oleander (NOACN/W) and Pituranthos tortuosus (PTACN/W) were highly cytotoxic against RAW 264.7 cells with IC80 values of 0.36, and 1.55 µg/mL, respectively. In contrast, murine macrophage cell lines had low growth and were significantly sensitive to water extracts of Thymus hirtus sp. algeriensis (THW), Lavandula multifida (LMW), and ACN/W extract of Erica multiflora (EMACN/W) at doses > 400, 47.20, and 116.74 µg/mL, respectively. The current work demonstrates that RAW 264.7 cell proliferation was inhibited by samples in a dose-dependent manner. CONCLUSION: Our findings, validated through free radical scavenging activity, agar diffusion assay, and cytotoxicity of essential oils towards cancer cells, show that ethnomedicinal plants used in this work have a novel application as a tumor suppressor.