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Methanolic extracts of fl owers and leaves of Gentiana lutea L., together with the isolated compounds mangiferin, isogentisin and gentiopicrin, were used to investigate the antimicrobial activity of the plant. A variety of Gram-positive and Gram-negative bacteria as well as the yeast Candida albicans has been included in this study. Both extracts and isolated compounds showed antimicrobial activity with MIC values ranging from 0.12 -0.31 mg/ml. Our study indicated that the synergistic activity of the pure compounds may be responsible for the good antimicrobial effect of the extracts. Quantifi cation of the secondary metabolites was performed using HPLC.

The essential oil isolated from flowers of Arnica montana and A chamissonis grown on Tara mountain and neighbourhood of Užice was analyzed. Three samples of A. montana and three of A. chamissonis were tested. The oil was isolated by distillation in a Clevenger type apparatus and analyzed by gas chromatography. The content of the oil was lower than 0.1% (up to 0.08%) in all the samples. Among about hundred recorded constituents, 84 were identified and quantified. Sum of contents of identified components ranged between 96.1 and 98.8%. The most abundant constituents of the A. montana oil were p-caryophyllene (31.5-34.6%), germacrene D (12.5-16.3%), trans-a-ionone (3.9-4.3%) and decanal (2.7-5.3%), while, in the case of A. chamissonis these were germacrene D (18.0-38.3%), a-pinene (6.6-19.1%), p-cymene (2.9-9.0%) and P-caryophyllene (2.7-4.7%). Along with detail chemical analysis of essential oil of these two commercially important herbal drugs it should be noticed that gas chromatographic technique can be used for differentiation of A. montana and A. chamissonis

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Physical methods for weeds suppression in cultivation encompass many methods but our article focuses on application of various mulches. They belong to integrated non-chemical weed management strategies and are very useful in organic farming. Mulching might be performed either by the use of biodegradable mulching materials or by various mulch films. The main benefits of organic mulches are that they can be collected from the nature, thus providing cheaper crop production. In addition, they use to be biodegradable and with no harmful effects on environment. Physical methods of weed control can cause both, positive and negative effects; they certainly influence weed suppression leading to a higher yield of cultivated herbs and vegetables but if applied as living mulches in a main crop production, they compete for essential resources. In addition, apart from the weeds, living cover crop at the same time also suppress the main crop. Therefore, a great attention should be paid when selecting the most appropriate living mulch for the purpose of weed suppression in any specific cultivation. In this article, experiences with various biodegradable mulches (straw, chopped newspapers, biodegradable and photodegradable films, gravel and compost) are well described, with a special attention devoted to their use in cultivation of medicinal plants. Presented data support application of physical methods of weeds control in cultivated crops and suggest them as efficient for use in cultivation of medicinal plants.