Phytochemistry and bioactivities of selected plant species with volatile secondary metabolites

Abstract

Medicinal plants still represent an interesting and a challenging field of science. Plants generally contain complex mixtures of biologically active secondary metabolites with multiple target effects and often low toxicity. In this study, well-known analytical, chemical and biological methods were used in order to investigate the phytochemistry and bioactivities of secondary metabolites of 28 medicinal plant from the flora of Tajikistan and Germany. Many of these plants are endemic plants of Tajikistan and Central Asia, which are widely used in traditional medicine. For the first time, the chemical composition and bioactivity of the essential oils of Ferula clematidifolia, Galagania fragrantissima, Philadelphus x purpureomaculatus, Polychrysum tadshikorum and Salvia discolor were investigated. The main component of the essential oils of Ferula clematidifolia, Galagania fragrantissima, Philadelphus x purpureomaculatus, Polychrysum tadshikorum and Salvia dsicolor were analysed by GLC-MS and identified as pinene, 2E-dodecenal, viridiflorol, terpinen-4-ol and trans-caryophyllene, respectively. The antioxidant activity of essential oils are strongly dependent to the presence of phenolic metabolites. Essential oil of Origanum tyttanthum which contain phenols (carvacrol and thymol) exhibited a high antioxidant activity with an IC50 value of 0.1-0.3 mg/ml. Also the antioxidant activity of methanol extracts is directly proportional to their phenol contents. Galagania fragrantissima essential oil (GFEO) was very active against gram-positive bacteria (methicillin resistant Staphylococcus aureus). MIC and MBC values were 0.04 and 0.08 mg/ml respectively. GFEO shows high anti-inflammatory activity, it inhibited 5-LOX enzyme with an IC50 value of 7.3 μg/ml. Essential oils from Origanum tyttanthum, Galagania fragrantissima and Mentha longifolia exhibited a high cytotoxic effect against five human tumour cell lines (HeLa, CaCo-2, MCF-7, CCRF-CEM and CEM/ADR 5000). Their IC50 values ranged between 7.5-78 μg/ml. The combinations of doxorubicin with essential oils of Mentha longifolia, Anethum graveolens, Origanum tyttanthum, Galagania fragrantissima and Artemisia absinthium exhibit synergistic activity. The ratio of IC50 values of doxorubicin could be enhanced in dual combinations with essential oils 3-15 fold. Synergistic effects of essential oils seem promising area for future research. Methanol extracts from Polychrysum tadshikorum and Tanacetum parthenium were most cytotoxic against CCRF-CEM and CEM/ADR 5000 cell lines. Their IC50 ranged between 7.3-32.5 μg/ml. Results of cytotoxicity for the total extracts show that CCRF-CEM cells, which do not express ABC transporters were more sensitive than the derived CEM/ADR5000 (multidrug resistant) cells. This indicate that some components of the extracts are substrates of ABC transporters. In general, essential oils from Galagania fragrantissima, Origanum tyttanthum and methanol extracts from Polychrysum tadshikorum and Tanacetum parthenium are interesting candidates for a use in phytotherapy.