Isolation and Identification of Aliphatic Compounds as Chlorophyll-Preserving and/or Degrading Substances From Artemisia capillaris Thunb.

Chlorophyll-preserving and degrading substances from Artemisia capillaris Thunb. were investigated using the oat leaf assay system. These substances were isolated and identified as 1-oxo-l-phenyl-2,4-hexadiyne (capillin), l-phenyl-2,4-hexadiyne (capillen) and 3-(2-butynyl)isocoumarin (capillarin) by GC-MS analysis. Capillin and capillen were effective in chlorophyllpreserving at concentrations of more than 10 or 25 μg · ml^-1 in the dark, and at 100 or 250 μg · ml^-1 the chlorophyll retention was about 80% of the initial value. However, capillen at 500 μg · ml^-1 was effective in chlorophyll-bleaching in the light. On the other hand, these compounds, at concentrations of less than 25 or 50 μg · ml^-1, stimulated the loss of chlorophyll and completely eliminated the chlorophyll-preserving effect of kinetin in the dark. Capillarin was not effective in chlorophyll-preserving at any concentrations tested in the dark, but it stimulated the loss of chlorophyll and counteracted the chlorophyll-preserving effect of kinetin in the dark. From these results it is concluded that capillin, capillen and capillarin are essentially chlorophyll-degrading substances, and that chlorophyll-preserving activities of capillin and capillen at higher concentrations in the dark are due to their nonspecific and/or toxic effects rather than the inhibition of normal senescence.