RESUMO
Prolyl oligopeptidase (POP) is a serine protease highly expressed in the brain that hydrolyses peptide bonds at the carboxyl terminal of prolyl residues. There is evidence that this enzyme participates in several functions of the central nervous system. Scutellaria racemosa Pers demonstrated significant and selective POP inhibition. Fractionation of the hydroalcoholic extract resulted in the isolation of four main constituents identified for the first time from S. racemosa Pers, the triterpenoid lupeol (1) and the flavonoids oroxylin A (5,7-dihydroxy-6-methoxyflavone, 2), hispidulin (4',5,7-trihydroxy-6-methoxyflavone, 3), and oroxyloside (oroxylin A 7-O-glucuronide, 4). Inhibitory assays indicated that 3 and 4 at a concentration of 100 microM inhibit 43 and 34% of total POP activity, respectively.
Assuntos
Inibidores da Dipeptidil Peptidase IV , Flavonas/isolamento & purificação , Flavonoides/isolamento & purificação , Glucuronídeos/isolamento & purificação , Triterpenos Pentacíclicos/isolamento & purificação , Scutellaria/química , Serina Endopeptidases/química , Inibidores Enzimáticos/química , Inibidores Enzimáticos/isolamento & purificação , Flavonas/química , Flavonoides/química , Glucuronídeos/química , Estrutura Molecular , Plantas Medicinais/química , Prolil OligopeptidasesRESUMO
A phytochemical investigation of the stems of Waltheria douradinha resulted in isolation of two 4-quinolone alkaloids, waltherione B and vanessine, along with three known alkaloids, waltherione A, antidesmone and O-methyltembamide. Their structures were elucidated on the basis of their 2D NMR spectroscopic analyses, and from X-ray crystallographic analysis of waltherione A and the O-methyl derivative of waltherione B. Additionally, waltherione B and vanessine, and the O- and N-methyl derivatives of waltherione A and waltherione B, were evaluated for their antimicrobial activities; only vanessine displayed any (weak) antimicrobial activity.
Assuntos
Alcaloides/química , Malvaceae/química , Extratos Vegetais/química , Quinolonas/química , Alcaloides/farmacologia , Compostos Aza/química , Compostos Aza/farmacologia , Bactérias/efeitos dos fármacos , Cristalografia por Raios X , Espectroscopia de Ressonância Magnética , Testes de Sensibilidade Microbiana , Estrutura Molecular , Extratos Vegetais/farmacologia , Quinolinas/química , Quinolinas/farmacologia , Quinolonas/farmacologia , EstereoisomerismoRESUMO
Investigation of the chemical constituents from the roots of Melochia chamaedrys (Sterculiaceae) resulted in the isolation of two quinolinone alkaloids: a new alkaloid, named chamaedrone (1), and a known alkaloid, antidesmone (2). Their structures and stereochemistry were elucidated on the basis of 2D NMR and X-ray crystallographic analysis. Furthermore, alkaloids 1 and 2, and the synthetic analogues 3-6 obtained from 2, were screened for antimicrobial activities.