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1.
Antioxidants (Basel) ; 11(8)2022 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-36009244

RESUMO

Oxo-carotenoids containing conjugated carbonyl groups in their chains were designed to be more efficient superoxide radical scavengers than natural carotenoids, ß-carotene and canthaxanthin. A practical chain-extension method for polyene dials (e.g., crocetin dial) was also proposed based on Horner-Wadsworth-Emmons olefination. Double aldol condensation between polyene dials and acetophenones with ring substituents produced oxo-carotenoids with substituted benzene rings. The antioxidant activity of oxo-carotenoids was measured using DPPH (radical) and ABTS (cationic radical) scavenging assays and compared with the analysis with the superoxide (anionic radical) probe. An effective conjugation length by carbon-carbon double bonds is important to provide superior antioxidant activity for oxo-carotenoids, regardless of the type of radical probe used in the assay. Increasing electron density is favorable to strong antioxidant activity in DPPH, and the phenol group is favored in ABTS, whereas electron deficient oxo-carotenoids are very potent in the superoxide radical assay. All oxo-carotenoids exhibited 105~151% better superoxide radical scavenging activity compared to beta-carotene (100%), whereas 38~155% in DPPH and 16~96% in ABTS radical scavenging activities were observed.

2.
ACS Omega ; 6(38): 25096-25108, 2021 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-34604688

RESUMO

A series of para-phenolic carotenes 1 with ortho- and meta-substitutions were respectively prepared utilizing the benzenesulfonyl protection method, which demonstrated the importance of the ring substituents on their effective conjugation, evaluated by their UV absorption values. The corresponding apo-12'-carotenals 2 were devised to improve the conjugation effect of the para-phenolic radical with the polyene chain by the conjugated aldehyde group. Apo-12'-carotenals 2b and 2c without ortho-substituents exhibited superior antioxidant activities to their corresponding symmetrical carotenes 1 as well as ß-carotene and apo-12'-ß-carotenal in 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging assays.

3.
Mol Plant Pathol ; 22(12): 1613-1623, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34459564

RESUMO

The functions of ubiquitin-conjugating enzymes (E2) in plant immunity are not well understood. In this study, OsUBC26, a rice ubiquitin-conjugating enzyme, was characterized in the defence against Magnaporthe oryzae. The expression of OsUBC26 was induced by M. oryzae inoculation and methyl jasmonate treatment. Both RNA interference lines and CRISPR/Cas9 null mutants of OsUBC26 reduced rice resistance to M. oryzae. WRKY45 was down-regulated in OsUBC26 null mutants. In vitro E2 activity assay indicated that OsUBC26 is an active ubiquitin-conjugating enzyme. Yeast two-hybrid assays using OsUBC26 as bait identified the RING-type E3 ligase UCIP2 as an interacting protein. Coimmunoprecipitation assays confirmed the interaction between OsUBC26 and UCIP2. The CRISPR/Cas9 mutants of UCIP2 also showed compromised resistance to M. oryzae. Yeast two-hybrid screening using UCIP2 as bait revealed that APIP6 is a binding partner of UCIP2. Moreover, OsUBC26 working with APIP6 ubiquitinateds AvrPiz-t, an avirulence effector of M. oryzae, and OsUBC26 null mutation impaired the proteasome degradation of AvrPiz-t in rice cells. In summary, OsUBC26 plays important roles in rice disease resistance by regulating WRKY45 expression and working with E3 ligases such as APIP6 to counteract the effector protein AvrPiz-t from M. oryzae.


Assuntos
Resistência à Doença/genética , Magnaporthe , Oryza , Doenças das Plantas , Proteínas de Plantas , Enzimas de Conjugação de Ubiquitina , Ascomicetos , Magnaporthe/patogenicidade , Oryza/enzimologia , Oryza/microbiologia , Doenças das Plantas/microbiologia , Imunidade Vegetal , Proteínas de Plantas/genética , Enzimas de Conjugação de Ubiquitina/genética
4.
Org Lett ; 21(3): 714-718, 2019 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-30648872

RESUMO

C20 heptaenyl diphosphonate 4 was prepared for one-pot synthesis of carotenoids 1. Olefination with various aromatic aldehydes allowed fast assembly of the corresponding carotenoids. The SAR of carotenoids was investigated by high-throughput screening of ABTS and DPPH assays and their hierarchical clustering analysis. Antioxidant activity of carotenoids increased with the number of electron-donating substituents. Carotene 1a with multiple electron-donating substituents was most proficient, which showed better radical scavenging activities than ß-carotene and lycopene.

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