Effect of plagiochin E, an antifungal macrocyclic bis(bibenzyl), on cell wall chitin synthesis in Candida albicans.
OBJECTIVE
To investigate the effect of plagiochin E (PLE), an antifungal macrocyclic bis(bibenzyl) isolated from liverwort Marchantia polymorpha L, on cell wall chitin synthesis in Candida albicans.


METHODS
The effect of PLE on chitin synthesis in Candida albicans was investigated at the cellular and molecular levels. First, the ultrastructural changes were observed under transmission electron microscopy (TEM). Second, the effects of PLE on chitin synthetase (Chs) activities in vitro were assayed using 6-O-dansyl-N-acetylglucosamine as a fluorescent substrate, and its effect on chitin synthesis in situ was assayed by spheroplast regeneration. Finally, real-time RT-PCR was performed to assay its effect on the expression of Chs genes (CHS).


RESULTS
Observation under TEM showed that the structure of the cell wall in Candida albicans was seriously damaged, which suggested that the antifungal activity of PLE was associated with its effect on the cell wall. Enzymatic assays and spheroplast regeneration showed that PLE inhibited chitin synthesis in vitro and in situ. The results of the PCR showed that PLE significantly downregulated the expression of CHS1, and upregulated the expression of CHS2 and CHS3. Because different Chs is regulated at different stages of transcription and post-translation, the downregulation of CHS1 would decrease the level of Chs1 and inhibit its activity, and the inhibitory effects of PLE on Chs2 and Chs3 would be at the post-translational level or by the inhibition on the enzyme-active center.


CONCLUSIONS
These results indicate that the antifungal activity of PLE would be attributed to its inhibitory effect on cell wall chitin synthesis in Candida albicans.
Wu
Xiu-zhen
XZ
School of Pharmaceutical Sciences, Shandong University, Ji-nan 250012, China.
Cheng
Ai-xia
AX
Sun
Ling-mei
LM
Lou
Hong-xiang
HX
D000818:Animals; D000935:Antifungal Agents / Q000737:chemistry / Q000494:pharmacology*; D001632:Bibenzyls / Q000737:chemistry / Q000494:pharmacology*; D001952:Bridged-Ring Compounds / Q000737:chemistry / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects / Q000648:ultrastructure; D002473:Cell Wall / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D002686:Chitin / Q000096:biosynthesis*; D002687:Chitin Synthase / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D006801:Humans; D015394:Molecular Structure; D013267:Stilbenes / Q000737:chemistry / Q000494:pharmacology*
D000935:Antifungal Agents; D001632:Bibenzyls; D001952:Bridged-Ring Compounds; D005656:Fungal Proteins; D013267:Stilbenes; C529889:plagiochin E; D002686:Chitin; D002687:Chitin Synthase