Wakako Ohmura, Seiji Ohara
Improvement of Antitermitic Activities of Catechin by Combination with Heavy Metals
Summary
Antitermitic activities of catechin-metal complexes were investigated for further utilization of catechin
as a termite control agent. Catechin (CA), heavy metal salts (NiCl2, CuCl2, ZnCl2) and CA/metal mixtures
with Ni(II), Cu(II) and Zn(II) were subjected to bioassays using a subterranean termite, Coptotermes
formosanus Shiraki. The astringent properties of each system were assessed by measuring the
weight of precipitate with bovine serum albumin (BSA). Changes in UV spectra of the CA/metal mixtures
were also measured. CA caused less than 30% mortality after the 21-day test period, and had no
BSA-precipitating capacity. The effects of heavy metals on CA activities varied with metal. CA/Ni(II)
showed the highest termiticidal activity among tested materials, but exhibited no BSA-precipitating
capacity and little change in UV spectrum. On the other hand, both CA/Cu(II) and CA/Zn(II) increased
the BSA-precipitating capacity and UV absorption with time after preparing the CA/metal solutions, but
their termiticidal activity was almost equal to CA. Termiticidal activity of CA was improved by the addition
of Ni(II) but hardly changed by Cu(II) or Zn(II), while astringent properties of CA were hardly
changed by addition of Ni(II) but improved by Cu(II) or Zn(II). Termiticidal activity was negatively correlated
with astringent property.
Holzforschung, Walter de Gruyter
Print ISSN: 0018-3830
Volume: 54, 09/2000
Pages: 457 - 460
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