RESUMO
BACKGROUND: The genus Hypericum (family Clusiaceae) comprises various species that are used in traditional medicine, such as wound healing, antidepressant, and anticancer agents. OBJECTIVE: The aim of this study was to evaluate the inhibitory capacity of extracts and fractions from two Hypericum species used in the Brazilian folk medicine (H. brasiliense and H. connatum) against the enzymes prolyl oligopeptidase (POP), dipeptidyl peptidase-IV (DPP-IV), and acetylcholinesterase (AChE), as well as to identify their main active constituents. METHODS: Dried aerial parts of H. connatum and H. brasiliense were subjected to extraction with 8:2 methanol-H2O. Each hydroalcoholic extract was fractioned resulting in ethyl acetate and aqueous fractions. The activity of POP, DPP-IV and AChE was determined in vitro in 96-well microplates. RESULTS: The main components identified in the plant extracts were chlorogenic acid (1), quercitrin (2), rutin (3), quercetin (4), and isoquercitrin (5). Hydroalcoholic extracts, ethyl acetate and aqueous fractions showed high POP inhibitory activity with IC50 values of 2.6 to 3.7 µg/mL. AChE and DPP-IV inhibitory effects were very low for all extracts and substances. CONCLUSION: Chlorogenic acid (1) and quercetin (4) were the main constituent responsible for the activity observed against POP. Parallel artificial membrane permeability assay of ethyl acetate fractions of both species showed that the metabolite that can effectively pass through the lipid membrane is 4, the aglycone form of 2, 3 and 5.
Assuntos
Acetilcolinesterase/química , Inibidores da Colinesterase/química , Extratos Vegetais/química , Serina Endopeptidases/química , Inibidores de Serina Proteinase/química , Ácido Clorogênico/química , Ácido Clorogênico/isolamento & purificação , Inibidores da Colinesterase/isolamento & purificação , Difusão , Dipeptidil Peptidase 4/química , Inibidores da Dipeptidil Peptidase IV/química , Inibidores da Dipeptidil Peptidase IV/isolamento & purificação , Ensaios Enzimáticos , Hypericum , Membranas Artificiais , Permeabilidade , Fosfolipídeos/química , Extratos Vegetais/isolamento & purificação , Prolil Oligopeptidases , Quercetina/química , Quercetina/isolamento & purificação , Inibidores de Serina Proteinase/isolamento & purificaçãoRESUMO
A screening of the natural product chlorogenic acid, isolated from the Brazilian medicinal plant Hypericum brasiliense, caffeic acid, cinnamic acid, and p-methoxycinnamic acid, and derivatives of caffeoylquinic, caffeoyl, and cinnamoyl against the enzymes prolyl oligopeptidase and dipeptidyl peptidase IV was carried out. Caffeoylquinic, caffeoyl, and cinnamoyl derivatives were prepared using simple derivatization procedures and through coupling reactions with the amino acid proline. The dipeptidyl peptidase IV assay showed inhibitory activity of the tested compounds at a high concentration (500 µM) in the range of 81.5-7.2â%. In contrast, the derivatives methyl ester and 1,7-acetonide obtained from chlorogenic acid, and caffeic acid and its methyl ester derivative showed selectivity and activity as prolyl oligopeptidase inhibitors, with IC50 values of 3 to 14 mM.
Assuntos
Ácidos Cafeicos/química , Cinamatos/química , Dipeptidil Peptidase 4/química , Serina Endopeptidases/química , Inibidores de Serina Proteinase/química , Ácidos Cafeicos/isolamento & purificação , Cinamatos/isolamento & purificação , Dipeptidil Peptidase 4/isolamento & purificação , Espectrometria de Massas , Ressonância Magnética Nuclear Biomolecular , Rotação Ocular , Prolil OligopeptidasesRESUMO
The phenylpropanoid glycoside verbascoside [2-(3,4-dihydroxyphenylethyl)-1-O-α-L-rhamnopyranosyl-(1â3)-ß-D-(4-O-caffeyl)-glucopyranoside] (1) has been isolated as the main constituent of the crude extract of Buddleja brasiliensis Jacq. ex Spreng from Southern Brazil. The crude extract, main fractions and the compound 1 were evaluated for inhibition of the enzymes acetylcholinesterase (AChE), dipeptidyl peptidase-IV (DPP-IV) and prolyl oligopeptidase (POP). Compound 1 showed weak activity against DPP-IV with an IC(50) >> 150 µM and was inactive against AChE, with a pMIQ determined by bioautography of 9.6. In contrast, 1 displayed significant inhibition of POP in a dose-dependent manner with an IC(50) value of 1.3 ± 0.2 µM, similar to the positive control, baicalin, with a POP IC(50) of 12 ± 3 µM.
Assuntos
Buddleja/química , Glucosídeos/química , Fenóis/química , Serina Endopeptidases/química , Inibidores de Serina Proteinase/química , Fracionamento Químico , Inibidores da Colinesterase/química , Inibidores da Colinesterase/isolamento & purificação , Inibidores da Dipeptidil Peptidase IV/química , Inibidores da Dipeptidil Peptidase IV/isolamento & purificação , Glucosídeos/isolamento & purificação , Concentração Inibidora 50 , Fenóis/isolamento & purificação , Extratos Vegetais/química , Prolil Oligopeptidases , Inibidores de Serina Proteinase/isolamento & purificaçãoRESUMO
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.