Studies On Inhibitive Effect Of Two Kinds Allelochemicals On HABs Algae

In recent years, HABs have occurred frequently in China and all over the world, which have made a great negative impact on marine ecosystem, aquaculture and human health. Therefore, it is a spotlight in HABs field how to control HABs effectively. In this paper, in order to provide information on the screening of new algaecide, the inhibitory effects of different fatty acid and flavonoids on the growth of Prorocentrum donghaiense Lu and Alexandrium tamarense were observed. The relationships between the inhibitory activities and structure of fatty acids and flavonoids were analyzed such as the numbers of total carbons and double bonds in fatty acids, and the numbers and sites of hydroxyls in flavonoids. The results showed that fatty acids had inhibitory effects on the growth of A. tamarense and P. donghaiense in a dose-dependent relationship. The inhibitory activities of various fatty acids were different as follow: stearic acid＜lauric acid＜honadecanoic acid＜myristic acid＜linolenic acid＜linoleic acid＜oleic acid, which suggested that the unsaturated fatty acids had higher inhibitory activities than the saturated fatty acids did. Similar to the fatty acids, baicalein, baicalin, luteolin and kaempferol had remarkable inhibition on A. tamarense and P donghaiense in a dose-dependent relationship as follow: baicalein＜baicalin＜luteolin＜kaempferol. These results indicated that the anti-algal actions of the saturated fatty acids were related to the carbon chain length. The longer the carbon chain length was, the less the inhibitive effect was from C14 to C18. For unsaturated fatty acids, however, the inhibitory effects were related with the un-satumtion. The anti-algal activities increased with the increasing number of the double bonds. As for flavones, the inhibitory effects were related to the numbers and sites of hydroxyls. When C4=O in C-ring existed, the positions and numbers of hydroxyls in A-ring are the key group to the inhibition. The anti-algal activities increased with the increasing number of hydroxyls, and the replacement of hydroxyl by glycoside could decrease the inhibitory effect of flavones. When C4'-OH in B ring existed, C3'-OH or C5'-OH could reduce the inhibitory activity of flavones.