Hydroxamic acid 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-one (DIMBOA) was isolated from maize phloem sap as a compound enhancing the degradation of isopentenyl adenine by maize cytokinin dehydrogenase (CKX), after oxidative conversion by either laccase or peroxidase. Laccase and peroxidase catalyze oxidative cleavage of DIMBOA to 4-nitrosoresorcinol-1-monomethyl ether (coniferron), which serves as a weak electron acceptor of CKX. The oxidation of DIMBOA and coniferron generates transitional free radicals that are used by CKX as effective electron acceptors. The function of free radicals in the CKX-catalyzed reaction was also verified with a stable free radical of 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid. Application of exogenous cytokinin to maize seedlings resulted in an enhanced benzoxazinoid content in maize phloem sap. The results indicate a new function for DIMBOA in the metabolism of the cytokinin group of plant hormones.
- MeSH
- Benzoxazines chemistry metabolism MeSH
- Biocatalysis MeSH
- Cytokinins metabolism MeSH
- Phloem enzymology MeSH
- Zea mays enzymology MeSH
- Laccase metabolism MeSH
- Molecular Structure MeSH
- Oxidation-Reduction MeSH
- Oxidoreductases metabolism MeSH
- Peroxidase metabolism MeSH
- Free Radicals metabolism MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
The flavoenzyme cytokinin dehydrogenase (CKX) catalyzes an irreversible deactivation of plant hormones cytokinins through oxidative cleavage of the cytokinin side chain to yield adenine or adenosine and an aldehyde. In the catalytic cycle of CKX, the cytokinin-reduced flavin cofactor is reoxidized by a suitable electron acceptor. We have recently demonstrated that the oxidation products of natural hydroxamic acid 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) function as effective electron acceptors of apoplastic CKX from maize. The stable oxidation product of DIMBOA reacting with peroxidase or laccase was identified as 4-nitrosoresorcinol 1-monomethyl ether (coniferron), which, however, is only a weak electron acceptor of CKX. Further analyses suggested formation of transient free radicals that were estimated to reoxidize the cytokinin-reduced flavin cofactor of CKX with the rates comparable to those of flavin reduction.
Rhomboids are intramembrane serine proteases with diverse physiological functions in organisms ranging from archaea to humans. Crystal structure analysis has provided a detailed understanding of the catalytic mechanism, and rhomboids have been implicated in various disease contexts. Unfortunately, the design of specific rhomboid inhibitors has lagged behind, and previously described small molecule inhibitors displayed insufficient potency and/or selectivity. Using a computer-aided approach, we focused on the discovery of novel scaffolds with reduced liabilities and the possibility for broad structural variations. Docking studies with the E. coli rhomboid GlpG indicated that 2-styryl substituted benzoxazinones might comprise novel rhomboid inhibitors. Protease in vitro assays confirmed activity of 2-styryl substituted benzoxazinones against GlpG but not against the soluble serine protease α-chymotrypsin. Furthermore, mass spectrometry analysis demonstrated covalent modification of the catalytic residue Ser201, corroborating the predicted mechanism of inhibition and the formation of an acyl enzyme intermediate. In conclusion, 2-styryl substituted benzoxazinones are a novel rhomboid inhibitor scaffold with ample opportunity for optimization.
- MeSH
- Benzoxazines chemical synthesis chemistry MeSH
- Chymotrypsin chemistry MeSH
- DNA-Binding Proteins antagonists & inhibitors chemistry genetics MeSH
- Drosophila chemistry MeSH
- Endopeptidases chemistry genetics MeSH
- Enzyme Assays MeSH
- Escherichia coli enzymology MeSH
- Serine Proteinase Inhibitors chemical synthesis chemistry MeSH
- Catalytic Domain MeSH
- Humans MeSH
- Membrane Proteins antagonists & inhibitors chemistry genetics MeSH
- Mutation MeSH
- Drug Discovery MeSH
- Drosophila Proteins metabolism MeSH
- Escherichia coli Proteins antagonists & inhibitors chemistry genetics MeSH
- Serine chemistry MeSH
- Molecular Docking Simulation MeSH
- Cattle MeSH
- Styrenes chemical synthesis chemistry MeSH
- Transforming Growth Factor alpha metabolism MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Cattle MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
N-(α-ketoacyl)anthranilic acids reacted with phenylhydrazinium chloride in boiling acetic acid to afford 2-(indol-2-carboxamido)benzoic acids in good to excellent yields and 2-indolyl-3,1-benzoxazin-4-ones as by-products. The formation of the latter products could easily be suppressed by a hydrolytic workup. Alternatively, by increasing the reaction temperature and/or time, 2-indolyl-3,1-benzoxazin-4-ones can be obtained exclusively. Optimisations of the reaction conditions as well as the scope and the course of the transformations were investigated. The products were characterized by (1)H, (13)C and (15)N NMR spectroscopy. The corresponding resonances were assigned on the basis of the standard 1D and gradient selected 2D NMR experiments ((1)H-(1)H gs-COSY, (1)H-(13)C gs-HSQC, (1)H-(13)C gs-HMBC) with (1)H-(15)N gs-HMBC as a practical tool to determine (15)N NMR chemical shifts at the natural abundance level of (15)N isotope.
Deriváty 3-fenyl-2H-1,3-benzoxazin-2,4(3H)-dionu jsou aktivní vůči Mycobacterium avium, pokud jsou substituovány v poloze 7 methylem. Jedna nebo dvě karbonylové skupiny musí být zaměněny za thioxo skupiny. Nejaktivnější sloučeniny nebyly substituovány na fenylu, nebo byly substituovány na fenylu v poloze 3 nebo 4 chlorem, bromem či methylem. Substituce v poloze 3 a 4 dvěma atomy chloru však aktivitu snižuje. Sloučeniny jsou aktivní vůči INH rezistentním kmenům. Připravili jsme dalších 44 derivátů s podobnou strukturou studovaným látkám, avšak s jiným substituentem v ploze 7 (chlor, brom, methoxy). Aktivita vůči M. avium byla nízká. Můžeme uzavřít, že se jedná o novou skupinu významně aktivních látek vůči Mycobacterium avium.
Derivatives of 3-phenyl-2H-1,3-benzoxazine-2,4(3H)-dione are active against Mycobacterium avium when substituted in position 7 with a methyl. One or two carbonyl groups have to be replaced with a thioxo group. High active derivatives are the compounds without substitution on the phenyl, or those substituted on the phenyl in position 3 or 4 with chlorine, bromine or a methyl. The substitution in position 3 and 4 with two atoms of chlorine lowers the activity. The compounds are active against INH resistant strains. We synthesized other 44 derivatives with a similar structure of the compounds as in the paper but substituted in position 7 with other substituents (chlorine, bromine methoxy). The activity against M. avium was poor. It can be concluded that a new group of compounds with an excellent activity against M. avium has been found.
- MeSH
- Anti-Bacterial Agents chemistry MeSH
- Benzoxazines chemistry MeSH
- Humans MeSH
- Mycobacterium avium MeSH
- Drug Design MeSH
- Tuberculosis drug therapy MeSH
- Structure-Activity Relationship MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
A series of 6-chloro-3-(4-alkylphenyl)-4-thioxo-2H-1,3-benzoxazine-2(3H)-ones, 7-chloro-3-(4-alkylphenyl)-4-thioxo-2H-1,3-benzoxazine-2(3H)-ones, 6-bromo-3-(4-alkylphenyl)-4-thioxo-2H-1,3-benzoxazine-2(3H)-ones, 6,8-dibromo-3-(4-alkylphenyl)-4-thioxo-2H-1,3-benzoxazine-2(3H)-ones, 6-chloro-3-(4-alkylphenyl)-2H-1,3-benzoxazine-2,4(3H)-dithiones, 7-chloro-3-(4-alkylphenyl)-2H-1,3-benzoxazine-2,4(3H)-dithiones, 6-bromo-3-(4-alkylphenyl)-2H-1,3-benzoxazine-2,4(3H)-dithiones and 6,8-dibromo-3-(4-alkylphenyl)-2H-1,3-benzoxazine-2,4(3H)-dithiones was synthesized. The compounds exhibited in-vitro activity against Mycobacterium tuberculosis, M. kansasii (two strains), and M. avium. 6-bromo-3-(4-propylphenyl)-4-thioxo-2H-1,3-benzoxazin-2(3H)-one and 6-bromo-3-(4-propylphenyl)-2H-1,3-benzoxazin-2,4(3H)-dithione are the most active compounds against M. tuberculosis. The activity is similar to isoniazid (INH). The compounds under study have a broad spectrum of activity against potential pathogenic strains. The replacement of the oxo group by thioxo group of 3-(4-alkylphenyl)-2H-1,3-benzoxazine-2,4(3H)-diones often led to an improvement in the antimycobacterial activity against M. tuberculosis.
