Enhancement of antibacterial effects of extracts from Cirsium species using sodium picolinate and estimation of their toxicity.

In this study, antimicrobial properties and toxicity of extracts from Cirsium spp.: Cirsium arvense, C. oleraceum, C. palustre, C. rivulare and C. vulgare in combination with sodium picolinate (PS) or sodium benzoate (BS), were investigated. Three micro-organisms were used: Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa. Minimum inhibitory concentration (MIC) of extracts was found at 1.56-50.0 mg mL(-1). Unlike the case of BS, adding PS to extracts from flowers of C. palustre and C. arvense enhanced their antimicrobial effect on S. aureus (MIC from 6.25-12.5 mg mL(-1) to 1.25-5.0 mg mL(-1)). An MTT test was used to study toxicity effects. The extracts from C. palustre or C. arvense mixed with PS had a concentration-dependent, slightly cytotoxic or stimulating effect on the viability of normal human skin fibroblasts. The total phenolic content (TPC) of samples varied from 44 to 178 mg gallic acid equivalent per 1 g of extract. The highest TPC was observed in C. palustre (l) and C. oleraceum (f). Our results did not show any correlation between antimicrobial activities and TPC. Cirsium palustre (f) and C. arvense (f) extracts were analysed by gas chromatography/mass spectrometry (GC/MS). About 30 compounds were found to be present in extracts from two Cirsium species in amounts of not less than 0.2% of TIC.

Polyphenolic compounds and in vitro antimicrobial and antioxidant activity of aqueous extracts from leaves of some Cirsium species.

Crude aqueous extracts from leaves of Cirsium arvense, C. oleraceum, C. palustre, C. rivulare and C. vulgare were investigated. The content of tannins in mentioned sources, determined by the weight method with hide powder, varied between 1 and 7.63%. Total phenolic content, analysed by using Folin-Ciocalteau's method, ranged between 54 and 96 mg g(-1), was expressed as milligrams of gallic acid per gram of dry extract. Phenolic acids were identified by HPLC method. Antimicrobial activity of those extracts was examined. Cirsium palustre extract was the most active against investigated microorganisms. It was observed that the content of small-molecular phenolic compounds had greater influence on the activity of extracts than tannins. The total antioxidant activity indicated by radical cation 2,2'-azini-di-(3-ethylbenzthiazoline sulphonate) ABTS(*+), expressed as total antioxidant status (TAS) ranged from 2.31 to 2.78 mM L(-1).