Nova Biotechnologica 9-3 (2009) 327 SECONDARY METABOLITES WITH ANTIBACTERIAL EFFECTS FROM LEAVES OF DIFFERENT HOP CULTIVARS DURING VEGETAL PERIODS EVA ÜRGEOVÁ, ĽUDOVÍT POLÍVKA Department of Biotechnology, University of SS. Cyril and Methodius, J. Herdu 2, Trnava, SK-917 01, Slovak Republic (eva.urgeova@ucm.sk) Abstract: According to the latest EU regulations it is necessary to cut down the consumption of chemically based pesticides. Several research programmes are focussed on the study of secondary metabolites of plants, which have antimicrobial or antifungal activity against microbial phytopathogens. Other reasons for using of natural biocides are the growth of resistance of phytopathogens against several pesticides; broaden microbial attacks to significant agricultural product for food industry due to the climate changes. The presentation is focussed on the determination of the contents of secondary metabolitesleaves of several cultivars of hop – polyphenols and flavonoids. Methanol crude leaves extracts were tested on biocide effects against selected microbial phytopathogens. Key words: hop, extracts, polyphenols, flavonoids, antibacterial effect 1. Introduction According to the latest EU regulations it is necessary to cut down the consumption of chemically based pesticides. Several research programmes are focussed on the study of secondary metabolites of plants which have antibacterial or antifungal activity against microbial phytopathogens. The plants synthesise and accumulate various secondary metabolites which are characterised by the diversity of their chemical structures, restricted distribution and protective function for an organism. In this perspective, increasing attention is being paid to the plant called common hop (Humulus lupulus L) (MOIR, 2000). Hop compounds are effective inhibitors of Gram-positive bacteria (BATTACHARYA et al., 2003), mycobacteria (STAVRI et al., 2004) and protozoa (SRINIVASAN et al., 2005). In addition, xanthohumol has been reported to be a broad spectrum anti-infective agent working against many bacteria, viruses, fungi, and protozoa (GERHÄUSER, 2005). In the study of antimicrobial activity of essential oils from the hop plant, LAGEZAAL et al. (1992) identified their inhibitive influence on Gram-positive bacteria Bacillus subtilis and Staphylococcus aureus, as well as on the fungus Trichophyton mentagrophyles. One of the big groups of substances contained in the hop plant is the group of polyphenol compounds, chalkones, flavanols, flavonols, and antocyanides (HOFTA et. al., 2004). Content of polyphenols in the leaves can be of potential benefit when speaking of using these as raw material for extraction of these substances (ČEH et al., 2007). The most interesting of them are flavonoids, belonging to the most widespread compounds in nature.