RESUMO
A new cyclopeptide, ophiorrhisine A (1), a new tetrahydroisoquinoline alkaloid, 7',10-dide-O-methylcephaeline (2), two known ß-carboline alkaloids, and four known tetrahydroisoquinoline alkaloids were isolated from Ophiorrhiza nutans (Rubiaceae). Compound 1 is a tetrapeptide possessing a 14-membered paracyclophane ring and a novel N,N,N-trimethyltyrosine residue in the side chain. The stereochemistry at the aryl-alkyl ether bond was different from that of other known 14-membered paracyclophanes. The structure of 2 was established by spectroscopic analysis and semisynthesis.
Assuntos
Alcaloides/isolamento & purificação , Rubiaceae/química , Alcaloides/química , Carbolinas , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Peptídeos Cíclicos/química , Tetra-Hidroisoquinolinas , TailândiaRESUMO
HIV-1 nucleocapsid (NC) becomes an attractive target for the development of novel anti-HIV-1 agents. Discovering of non-antibody scaffolds that disrupt the function of NC will be a potential aspect for disturbing viral maturation process. Correspondingly, we explored the specific binding site of the thermoresistant-scaffold protein, αRep9A8 which formerly demonstrated the inhibitory effect on HIV-1 replication. The portion of Gag, CA21-SP1-NC has been used as a template for designing nine overlapping peptides (P4-P12). The P9 peptide showed the strongest binding activity followed by P8 and P12 respectively. The amino acid sequences on those peptides resemble the N-terminal domain of the NC proximity to the SP1-NC initial cleavage site and across the conserved CCHC zinc finger 1 (ZF1) of NC. The interaction KD between αRep9A8 with its target was 224.9 ± 57.4 nM. Consequently, αRep9A8 demonstrated the interference of the HIV-1 protease function by hindering a protease cleavage site. The released NC product from CA21-SP1-NC was diminished. The present study provided an additional information of αRep9A8 function in interfering of viral maturation processes resulting in the decremental efficiency of viral infectivity.
Assuntos
Inibidores da Protease de HIV/farmacologia , Protease de HIV/metabolismo , HIV-1/efeitos dos fármacos , Sítios de Ligação , Domínio Catalítico , Protease de HIV/química , Inibidores da Protease de HIV/química , HIV-1/enzimologia , Ligação Proteica , Conformação Proteica , Desnaturação Proteica , Estabilidade Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/farmacologia , Relação Estrutura-Atividade , Especificidade por Substrato , TemperaturaRESUMO
The tuberous roots of Pueraria candollei Grah. ex Benth. (Fabaceae), commonly known as white Kwao Krua, are used to relieve menopausal symptoms in Thai traditional medicine because they contain phytoestrogens. Black and red Kwao Krua crude drugs exist as well, but they have different botanical origins and pharmacological activities. There is a high demand for white Kwao Krua products, but because of the limited availability of the plant material, it is suspected that the adulteration and misidentification of white Kwao Krua crude drugs and products occur. In this study, we authenticated white Kwao Krua products collected from Thai herbal markets by molecular, chemical, and microscopic analyses. The nucleotide sequences in the internal transcribed spacer (ITS) and trnH-psbA regions of 23 samples of authentic P. candollei were analyzed, and both regions were found to have intraspecific DNA polymorphisms. Based on the single nucleotide polymorphisms in the ITS1 region, species-specific primer sets of P. candollei were designed to authenticate white Kwao Krua and differentiate it from red and black Kwao Krua. Only the PCR products of KWP02 were not amplified by the primer sets. Isoflavonoid contents and microscopic features were used to support the results of molecular analysis to clarify the botanical origin of white Kwao Krua. Molecular, chemical and microscopic methods confirmed that all the Thai Kwao Krua products examined in this study contained authentic "white Kwao Krua" as claimed on their labels.