[Antibacterial activity of aspen bark extracts against some pneumotropic microorganisms].

Extractive substances obtained from the bark of aspen (Populus tremula L.) with the use of petroleum ether (lipids I) and diethyl ether (lipids II) have exhibited high antibacterial activity with respect to Streptococcus pneumoniae and Haemophilus influenzae, causing 100% cell destruction. The minimum inhibiting concentration for S. pneumoniae has been found to be 0.5 - 50 mg/ml for lipids I and 0.0005 - 0.5 mg/ ml for lipids II, depending on the strain of bacteria. The antibacterial activity of rhytidome extracts is somewhat higher than that of phloem extracts. To suppress the growth of H. influenzae, more concentrated solutions of these extracts from 30 to 50 mg/ml are needed. Staphylococcus aureus was resistent in lipids. The action of temperature, mineral acids and alkali on lipids, as well as prolonged storage of strains in a refrigerator decreases the antibacterial activity of extracts under study.