Lipophilicity and antibacterial activity of flavonols: antibacterial activity of resinous exudates of Haplopappus litoralis, H. chrysantemifolius and H. scrobiculatus / Lipofilia y actividad antibacteriana de flavonoles: actividad antibacteriana de los exudados resinosos de Haplopappus litoralis, H. chrysantemifolius y H. scrobiculatus

The antibacterial properties of the resinous exudates from Haplopappus litoralis, H. chrysantemifolius and H. scrobiculatus from Central Chile were assessed against Gram negative and Gram-positive bacteria, and proved active against the latter. The results show that the antibacterial activities of the resinous exudates are independent from the flavonols isolated from each extract that proved to be inactive. The estimated lipophilicity of the flavonols isolated from the Haplopappus resinous exudates were compared with the lipophilicity of known antibacterial flavonols. This analysis showed that lipophilicity is an important variable to predict the antibacterial activity of flavonols.

La actividad antibacteriana de los exudados resinosos de Haplopappus litoralis, H. chrysantemifolius y H. scrobiculatus de la Zona Central de Chile fueron evaluadas frente a bacterias Gram-negativas y Gram-positivas, y resultaron activos frente a estas últimas. Los resultados mostraron que la actividad antibacteriana de los exudados resinosos es independiente de los flavonoles aisladas de cada extracto que no mostraron actividad antibacteriana. La lipofilia estimada de los flavonoles aislados de los exudados resinosos de Haplopappus se comparó con la lipofilia de conocidos flavonoles antibacterianos. Este análisis mostró que la lipofilia es una variable importante para predecir la actividad antibacteriana de los flavonoles.

The inhibitory effect of biofilms produced by wild bacterial isolates to the larval settlement of the fouling ascidia Ciona intestinalis and Pyura praeputialis

Marine biofouling is a present and potentially increasing future problem at molluscan culture centres. The problem is highly variable, exists on different scales, and its negative impact on cultured organisms and related economic losses at these centres has not been significantly controlled. One approach to fouling control has been the incorporation of natural substances into anti-fouling paints which inhibit the settlement of common fouling organisms. The main objective of the present study was the isolation of naturally occurring substances from marine bacteria which were inhibitory to the settlement of Ciona intestinalis and Pyura praeputialis, two tunicate species causing serious fouling problems in scallop culture systems in Chile. Numerous bacterial strains were isolated from microfouling on natural and artificial substrates submerged in the sea; of 73 strains isolated, 20 percent demonstrated inhibitory effects on the settlement of the larvae of the above cited tunicates. The inhibitory substances produced by the active bacteria were extracellular, and could be incorporated in an inert matrix (PhytagelTM) without losing their inhibitory properties. Some properties of the inhibitory substance isolated from bacterial strain Clon Nil-LEM (Alteromonas sp) included thermostability, MW < 3500 Da, peptidase lability (against C. intestinalis), and undiminished inhibitory activity when incorporated in the inert matrix.