ホザキノフサモが放出した4種のアレロパシー物質 (ポリフェノール) の藻類に対する増殖抑制効果

抄録

Four polyphenols, gallic acid (GA), ellagic acid (EA), pyrogallic acid (PA), and (+)-catechin (CAT), released from Myriophyllum spicatum, are anti-algal allelochemicals. In this paper, we investigated the inhibitory effects of each of these polyphenols on blue-green algae (Microcystis aeruginosa and Phormidium tenue), green algae (Selenastrum capricornutum and Scenedesmus quadricauda), and diatoms (Nitzschia palea and Achnanthes minutissima). We also determined the collective actions of the 4 polyphenols on the inhibition of algal growth.
Among the 6 algae, M. aeruginosa was the only one whose growth was significantly inhibited by each of the 4 polyphenols, while PA, GA, and EA each caused some degree of growth inhibition in P. tenue and the 2 green algae. Because none of the 4 polyphenols showed any inhibitory effect on growth of N. palea and growth of A. minutissima was not inhibited by PA, GA or CAT, diatoms appear to have strong resistance to such polyphenols. The algal assays we used to investigate the collective effects of polyphenols showed that (i) blue-green algae, M. aeruginosa and P. tenue were most sensitive to the synergistic actions of PA, GA and CAT, and (ii) the synergistic actions toward the 2 green algae and the 2 diatoms were concentration-dependent. These results indicate the possible feasibility of selectively controlling growth of blue-green algae through use of these polyphenols and/or the allelopathic effects of M. spicatum. Measurement of the autoxidation rates of the 4 polyphenols suggests that (i) their inhibitory effects on the growth of M. aeruginosa could be caused by products of their autoxidation, such as radicals, and (ii) the synergistic action of PA, GA and CAT might be due to acceleration of their autoxidation resulting in increasing production of such autoxidation products.