title: Discovery of inhibitors and substrates of brassinin hydrolase: Probing selectivity with dithiocarbamate bioisosteres.
abstract: Brassinin hydrolase (BHAb), an inducible enzyme produced by the plant pathogen Alternaria brassicicola under stress conditions, catalyzes the hydrolysis of the methyl dithiocarbamate group of the phytoalexin brassinin, to indolyl-3-methanamine, methane thiol and carbonyl sulfide. Thirty four substrate inspired compounds, bioisosteres of brassinin and a range of related compounds, were evaluated as potential substrates and inhibitors of BHAb for the first time. While six compounds containing thiocarbamate, carbamate and carbonate groups displayed inhibitory activity against BHAb, only two were found to be substrates (thionecarbamate and dithiocarbamate). Methyl naphthalen-1-yl-methyl carbamate, the most potent inhibitor of the six, and methyl N'-(1-methyl-3-indolylmethyl)carbamate inhibited BHAb through a reversible noncompetitive mechanism (K(i)=89±9 and 695±60μM, respectively). Importantly, these carbamate inhibitors were resistant to degradation by A. brassicicola. Carbonates were also inhibitory of BHAb, but a quick degradation by A. brassicicola makes their potential use as crop protectants less likely. Overall, these results indicate that indolyl and naphthalenyl carbamates are excellent lead structures to design new paldoxins that could inhibit the detoxification of brassinin by A. brassicicola.
authors.affiliation: Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Canada SK S7N 5C9. soledade.pedras@usask.ca
authors.forename: M Soledade C
authors.initials: MS
authors.lastname: Pedras
authors.forename: Zoran
authors.initials: Z
authors.lastname: Minic
authors.forename: Sajjad
authors.initials: S
authors.lastname: Hossain
mesh_terms: D000528:Alternaria / Q000201:enzymology; D000935:Antifungal Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D015195:Drug Design; D004353:Drug Evaluation, Preclinical; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D006867:Hydrolases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D007211:Indoles / Q000737:chemistry; D007700:Kinetics; D013379:Substrate Specificity; D013859:Thiocarbamates / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D000094162:Phytoalexins
chemical_list: D000935:Antifungal Agents; D004791:Enzyme Inhibitors; D006867:Hydrolases; D007211:Indoles; D013859:Thiocarbamates; C089020:brassinin; D000094162:Phytoalexins; C546105:brassinin hydrolase