Evaluation of Aesculus hippocastanum tincture mother for antioxidant and antimicrobial activities and its effects on protein expression of different bacterial strains

The beneficial health effects of extracts from many types of plants have been known for centuries1 and the search for new natural extracts (such as tincture mother TM), to be used in the food and cosmetics industry, is very important at present2. The aim of this study was to investigate the antioxidant and the antimicrobial activities of Aesculus hippocastanum TM, a fresh plant juice extracted by maceration and solubilised in 65% hydroalcoholic solution. To evaluate the antioxidant, radical scavenging and antiperoxidative activities of extract, FRAP (Ferric Reducing Antioxidant Power), ABTS radical and β-carotene bleaching (BCB) assays were performed. Results indicated the TM possesses elevated activity for radical scavenging and a potent antioxidant ability. The antimicrobial activity and the minimal inhibitory concentration (MIC) were evaluated against selected bacterial strains of significant importance for human health and food production, by using the agar well diffusion assay. A total of thirty-two gram-negative and gram-positive bacteria were employed as screening microorganisms to determine the antimicrobial effect, the action spectrum and the antimicrobial effectiveness of each extract. Results showed that TM provided an high antimicrobial effect against a wide range of bacteria with a MIC <120 μg/ml for 67% of strains. The inhibitory activity showed a moderate efficacy on the growth of 70% of strains in presence of different extract concentrations, while 15% of strains (Hafnia alvei, Enterococcus faecium and Enterococcus gallinarum) presented a count reduction of 2 log cycles in presence of TM at 40 µg/ml concentration. Moreover, the TM effect on protein expression of strains in presence of different MIC was evaluated. Whole-cell protein patterns were analyzed by SDS-PAGE in strains grown in presence/absence of TM and interesting results were obtained. The presence of TM at different concentrations represented a stress condition for strains causing changes in protein profiles. Results of this study underlined important abilities of Aesculus hippocastanum that could be an interesting field for applications within pharmaceutical and food supplement industries. [1]. Russo D, Bonomo MG, Salzano G, Martelli G, Milella L. Nutraceutical properties of Citrus clementina juices. Pharmacol OnLine. 2012; 1:84-93. [2]. Kaushik P, Goyal P. Evaluation of various crude extracts of Zingiber officinale rhizome for potential antibacterial activity: a study in vitro. Adv Microbiol. 2011; 1:7-12.