Study of Components of Antifungal Antibiotic Imbricin by Using of Thin-Layer Chromatography and Bioautography

Valery V. Belakhov, Schulich Faculty of Chemistry, Technion, Haifa, Israel (chvalery@technion.ac.il)
Irina V. Boikova, Microbiological Plant Protection Laboratory, All Russian Institute Of Plant Protection, Saint Petersburg, Russia
Irina A. Antonova, Microbiological Plant Protection Laboratory, All Russian Institute Of Plant Protection, Saint Petersburg, Russia
Ekaterina O. Lukashevich, Department Of Biotechnology, Saint Petersburg State Chemical Pharmaceutical Academy, Saint Petersburg, Russia
Elena P. Yakovleva, Department Of Biotechnology, Saint Petersburg State Chemical Pharmaceutical Academy, Saint Petersburg, Russia
Vera A. Kolodyaznaya, Department Of Biotechnology, Saint Petersburg State Chemical Pharmaceutical Academy, Saint Petersburg, Russia

Imbricin, antifungal antibiotic of non-medical application, was obtained by means of biotechnology with an application of producer Streptomyces imbricatus. Imbricin is widely used in different branches of industry and agriculture due to its powerful antifungal action in the relation to various species of fungi, low toxicity and high stability. It was shown that imbricin belongs to a group of antifungal non-polyene macrolide antibiotics. However, the chemical structure and the content of imbricin components have not yet been determined. We used thin-layer chromatography (TLC) for the study of the content of imbricin components, which were prepared from culture medium of strain Streptomyces imbricatus LIA 0112 by using extraction with iso-propanol (extract I) and ethanol (extract II). The chromotography analysis was carried out by TLC on plates Merck Silica gel 60 F₂₅₄, 20х20 cm (CAMAG AMD 2) in system butanol : acetic acid : water (5 : 1 : 1). The active components of imbricin were studied by the method of bioautography on Czapek agar medium with using fungus Alternaria solani as a test-microorganism. It was found that extract I contains 3 components with R_f 0.31, R_f  0.38 and R_f  0.43. Two components of imbricin with R_f 0.31 and R_f  0.43 indicated high antifungal activity. The extract II contains 2 components with R_f 0.31 and R_f  0.38, and only the first component with R_f 0.31 had antifungal activity in the relation of Alternaria solani. The comparation analysis of antifungal activity of extracts I and II against wide spectrum of phythopathogeic fungi have not showed differences in biological activity. However, it was established that only extract I possessed phytoregulatory activity stimulating the growth of cucumber plant. Thus, we assumed that high phytoregulatory activity can be explained by presence of the component with R_f  0.43 in active complex.