Antimicrobial activity against periodontopathogenic bacteria, antioxidant and cytotoxic effects of various extracts from endemic Thermopsis turcica.

OBJECTIVE: To investigate the in vitro antimicrobial potential of Thermopsis turcica Kit Tan, Vural & Küçüködük against periodontopathogenic bacteria, its antioxidant activity and cytotoxic effect on various cancer cell lines.

METHODS: In vitro antimicrobial activities of ethanol, methanol, ethyl acetate (EtAc), n-hexane and water extracts of Thermopsis turcica herb against periodontopathogenic bacteria, Aggregatibacter actinomycetemcomitans ATCC 29523 and Porphyromonas gingivalis ATCC 33277 were tested by agar well diffusion, minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). Antioxidant properties of the extracts were evaluated by 1,1-diphenyl-2-picryl-hydrazyl radical scavenging activity and β-carotene bleaching methods. Amounts of phenolic contents of the extracts were also analysed by using the Folin-Ciocalteu reagent. Additionally, cytotoxic activity of the extracts on androgen-insensitive prostate cancer, androgen-sensitive prostate cancer, chronic myelogenous leukemia and acute promyelocytic leukemia human cancer cell lines were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Human gingival fibroblast cells were used as a control.

RESULTS: Our data showed that EtAc extract had the highest antimicrobial effect on Aggregatibacter actinomycetemcomitans (MIC: 1.562 mg/mL, MBC: 3.124 mg/mL) and Porphyromonas gingivalis (MIC: 0.781 mg/mL, MBC: 1.562 mg/mL). In antioxidant assays, EtAc extract exhibited also the highest radical scavenging activity [IC50=(30.0±0.3) µg/mL] and the highest inhibition [(74.35±0.30)%] against lineloic acide oxidation. The amount of phenolic content of it was also the highest [(162.5±1.2) µg/mg gallic acid]. In cytotoxic assay, only ethanol [IC50=(80.00±1.21) µg/mL] and EtAc extract [IC50=(70.0±0.9) µg/mL] were toxic on acute promyelocytic leukemia cells at 20-100 µg/mL (P<0.05). However, no toxic effect was observed on human gingival fibroblast cells.

CONCLUSIONS: According to our findings, owing to its antioxidant and cytotoxic potential, EtAc extract might include anticancer agents for acute promyelocytic leukemia.