|
To induce the phytoalexins in plant cell culture systems, we surveyed the antimicrobial activity following the feeding of five naphthoquinones in cell cultures of petunia. Among naphthoquinones treated, 2,5,7-trihydroxy-3-(5´-hydroxyhexyl)-1,4-naphthoquinone (3-OH NQ) was most efficiently absorbed into the cells within 48 hr. The crude extracts of cells treated with 3-OH NQ showed a strong inhibition activity on spore germination of Aspergillus candidus (MIC: 32 ㎍/㎖), whereas the untreated cells showed no activity. The two active compounds, 4,2´,4´,β-tetrahydroxychalcone and 4´,7-dihydroxyflavone, were isolated from petunia cells treated with 3-OH NQ. The major phytoalexin, 4,2´,4´,β-tetrahydroxychalcone, inhibited strongly the spore germination of A. candidus (MIC: 16 ㎍/㎖).
|