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  • Author: Corina Bubueanu x
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Abstract

Lamium album and Lamium purpureum are species belonging to the genus Lamium. Aerial parts of the two species and roots of Lamium album have applications in human and veterinary traditional medicine. Haemostatic properties of butanolic extracts of Lamium species were investigated by two experimental models in Wistar rats: haemostatic test by tail bleeding time determination and acenocoumarolcarrageenan test. Results of the haemostatic test by tail bleeding determination demonstrated haemostatic activity of both extracts. In the acenocoumarol-carrageenan test, only the Lamium album extract showed haemostatic activity, comparable to that of vitamin K. Based on the qualitative chemical data on iridoid glycosides (HPTLC), 8-acetylshanzhiside methyl ester might be assumed to be responsible for haemostatic activity. Based on the acute toxicity test, none of the extracts showed toxicity.

Abstract

The excessive use of synthetic pesticides for plant pathogens control could cause possible harmful side-effects to humans and animals, environmental pollution, residual toxicity, affects soil characteristics or induce the development of fungal resistance. Alternative ways for fungal contamination control involve natural products, based on microorganisms, many of them being already available for use. The selection and characterization of new biological agents useful for plant pathogens control are permanent goals for plant protection researches. In the last decade, several studies revealed that Streptomyces species are promising biocontrol agents against a wide range of phytopathogenic fungi, including Fusarium spp., one of the most important wheat pathogens. In our study, 60 strains of Streptomyces spp. were isolated from soil or compost and evaluated for in vitro antifungal abilities by dual confrontation method. At least 30% of the isolates presented inhibitory activity against F. culmorum and F. graminearum. The bacterial strains were also tested for their ability to produce various bioactive compounds, possible involved in fungal inhibition. The capacity of some of the bacterial isolates to produce cellulases, amylases, lipases and volatile metabolites was proved. In addition, a new screening method for chitinases production was developed, based on the use of a combination of Congo red and Lugol solutions, which allowed the detection of chitinases in several Streptomyces spp. strains. Moreover, the reduction of the level of some Fusarium mycotoxins was detected by HPTLC analysis. As a conclusion, antagonistic interactions between Streptomyces isolates and fusaria could involve antibiosis, competition and parasitism and suggested that at least some of the selected isolates could be used in obtaining biological control products.