Antimicrobial and antioxidative enrichment of oak (Quercus robur) bark by rotation planar extraction using ExtraChrom.
ABSTRACT The multifunctional ExtraChrom instrument was used in the extraction of antimicrobial and radical scavenging components from oak (Quercus robur L.) bark. Milled and sieved oak bark was extracted with 80% (v/v) methanol solution in water on the ExtraChrom instrument using step-gradient in the preparative separation. Extracts were tested using agar diffusion method on Staphylococcus aureus, Enterobacter aerogenes and Candida albicans. Some extracts showed moderate bactericidal, fungicidal, bacteriostatic and fungistatic activity. The composition related to activity of the fractions and extracts was screened simultaneously by thin-layer chromatography (TLC) detected by UV and by spraying the plate with radical scavenging reagent 1,1-diphenyl-2-picrylhydrazyl (DPPH) to detect antioxidant activity. Thus, we could demonstrate the antiradical and antimicrobial activity of oak beneficial in the storage of wine against the oxidation and human microbial exposure.
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ABSTRACT: Background. Thirty−six extracts were obtained from nine plant raw materials and investigated for phenolic com− pound content, antiradical activity, and antimicrobial activity. Objectives. The aim of this study was to investigate the antiradical activity of plant raw materials and extracts from these plants with a new method based on using defined antiradical activity units and to study the antimicrobial activities of these extracts. Material and Methods. Methanol water (1:1) extract was obtained from the plant raw materials. Part of the extract was concentrated to dryness under reduced pressure (extract WA). Methanol was evaporated from the remaining extract and the precipitate separated (extract WD). An aqueous solution was extracted with ethyl acetate after pre− cipitate separation. The ethyl acetate extract and aqueous solution remaining after ethyl acetate extraction was con− centrated to dryness under reduced pressure to obtain extracts WB and WC, respectively. The dry extracts (WA, WB, WC, and WD) were investigated for antiradical activity (DPPH radical method) and for antimicrobial activi− ty (disk−diffusion). A method of presenting antiradical activity in defined activity units is proposed. The amounts of phenolic compounds were measured with reagent containing phosphotungustic acid. Results. The highest antiradical activity was measured for the extracts from oak bark, common bistort rhizome, and silverweed herb and the lowest for those from black cumin seed, ginseng root, and Siberian ginseng root. The strongest antibacterial activity (MIC) was observed for extracts from oak bark. The extract from black cumin seed also exhibited antifungal activity. Conclusions. Raw materials such as oak bark, silverweed herb, and common bistort rhizome exhibited the strongest antiradical features. Among investigated raw materials only oak bark exhibited an interesting antimicro− bial activity against bacterial as well as fungal strains. The use of antiradical activity units is convenient for esti− mating the yield of extraction of substances with antiradical activity (Adv Clin Exp Med 2008, 17, 3, 275–283).Adv Clin Exp Med. 01/2008; 17(3):275-283.