Growth-inhibitory components in Sugi (Cryptomeria japonica) extracts active against Microcystis aeruginosa

Abstract The growth-inhibitory activity of extracts obtained from Sugi (Cryptomeria japonica) effective against Microcystis aeruginosa, an alga that causes harmful algal blooms in freshwater environments, was examined. Each sample of the inner bark, outer bark, heartwood, and leaves of Sugi was extracted with hexane, ethyl acetate, and methanol successively. Inhibitory activities were observed in the inner bark ethyl acetate and methanol extracts, the heartwood hexane extract, the outer bark hexane extract, and the leaf ethyl acetate extract. The inner bark ethyl acetate and methanol extracts showed stronger activities than the other extracts. Catechin, epicatechin, and procyanidin B3 were identified as the active components in the inner bark ethyl acetate and methanol extracts. The terpenoids 1-epicubenol, 4-epicubebol, cubenol, δ-cadinol, sandaracopimarinal, and sandaracopimarinol were the active components of the heartwood hexane extract. Thus, it was indicated that not only the polyphenolic components but also non-phenolic terpenoids had growth inhibition activity against M. aeruginosa.