RESUMO
Methyl gallate (MG) is a medicinal herbal product that is isolated from Paeonia lactiflora that inhibits cyclooxygenase-2 (COX-2) dependent phases of prostaglandin D2 (PGD2) generation in bone marrow-derived mast cells (BMMC) in a concentration-dependent manner with an IC50 values of 17.0 microM. This compound also found inhibited the COX-2-dependent conversion of the exogenous arachidonic acid to PGD2 in a dose-dependent manner with an IC50 values of 19.0 microM, using a COX enzyme assay kit. However, at concentrations up to 80 microM, MG did not inhibit COX-2 protein expression in BMMC, indicating that MG inhibits COX-2 activity directly. Furthermore, MG consistently inhibited the production of leukotriene C4 (LTC4) in a dose dependent manner, with an IC50 value of 5.3 microM. These results demonstrate that MG has a dual cyclooxygenase-2/5-lipoxygenase inhibitory activity, which might provide the basis for novel anti-inflammatory drugs.
Assuntos
Araquidonato 5-Lipoxigenase/metabolismo , Ácido Araquidônico/metabolismo , Células da Medula Óssea/efeitos dos fármacos , Ciclo-Oxigenase 2/metabolismo , Ácido Gálico/análogos & derivados , Mastócitos/efeitos dos fármacos , Animais , Células da Medula Óssea/enzimologia , Linhagem Celular Tumoral , Inibidores de Ciclo-Oxigenase/isolamento & purificação , Inibidores de Ciclo-Oxigenase/farmacologia , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/química , Inibidores Enzimáticos/isolamento & purificação , Inibidores Enzimáticos/farmacologia , Ácido Gálico/química , Ácido Gálico/isolamento & purificação , Ácido Gálico/farmacologia , Interleucina-10/farmacologia , Leucotrieno C4/antagonistas & inibidores , Leucotrieno C4/biossíntese , Lipopolissacarídeos/farmacologia , Masculino , Mastócitos/enzimologia , Camundongos , Camundongos Endogâmicos BALB C , Estrutura Molecular , Paeonia/química , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/farmacologia , Folhas de Planta/química , Caules de Planta/química , Prostaglandina D2/antagonistas & inibidores , Prostaglandina D2/biossíntese , Fator de Células-Tronco/farmacologiaRESUMO
We isolated and artificially expressed a cDNA clone of the Capsicum annuum squalene synthase (CASS) gene to elucidate the pattern of alternatively regulated two-branch point enzymes. The 1,674-bp CASS cDNA contained an open reading frame of 411 amino acids, yielding a predicted molecular mass of about 45 kDa. A deduced amino acid sequence comparison to other squalene syntheses showed identities with Nicotiana tabacum (91%), Nicotiana benthamiana (90%), Arabidopsis thaliana (79%), and rats (40%). The artificially expressed soluble form of the CASS enzyme was identified by the enzyme activity that converted FPP to squalene and by SDS-PAGE. A Southern blot analysis indicated that at least two copies of the squalene synthase gene exist in the hot pepper genome. In hot pepper, the regulation of the branch point enzymes, squalene synthase and sesquiterpene cyclase was investigated in the UV-challenged leaves of Capsicum annuum. The transcript level and enzyme activity of the CASS were slightly reduced by UV. However, those of the CASC were rapidly induced within 24 h and slowly decreased thereafter.
