Chemical Composition and Inhibitory Effects of Hypericum brasiliense and H. connatum on Prolyl Oligopeptidase and Acetylcholinesterase Activities.
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.


CONCLUSIONS
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.
Maura Z
MZ
Dos Santos
Núcleo de Pesquisa de Produtos Naturais- NPPN, Departamento de Química, Universidade Federal de Santa Maria, 97105-900. Santa Maria/RS, Brazil. iidalcol@gmail.com.
Ionara I
II
Dalcol
Luciana
L
Adolpho
Meritxell
M
Teixidó
Teresa
T
Tarragó
Ademir
A
Morel
Ernest
E
Giralt
D000110:Acetylcholinesterase / Q000737:chemistry*; D002726:Chlorogenic Acid / Q000737:chemistry / Q000302:isolation & purification; D002800:Cholinesterase Inhibitors / Q000737:chemistry* / Q000302:isolation & purification; D004058:Diffusion; D018819:Dipeptidyl Peptidase 4 / Q000737:chemistry; D054873:Dipeptidyl-Peptidase IV Inhibitors / Q000737:chemistry / Q000302:isolation & purification; D057075:Enzyme Assays; D020902:Hypericum; D008567:Membranes, Artificial; D010539:Permeability; D010743:Phospholipids / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry* / Q000302:isolation & purification; D000085822:Prolyl Oligopeptidases; D011794:Quercetin / Q000737:chemistry / Q000302:isolation & purification; D012697:Serine Endopeptidases / Q000737:chemistry*; D015842:Serine Proteinase Inhibitors / Q000737:chemistry* / Q000302:isolation & purification
D002800:Cholinesterase Inhibitors; D054873:Dipeptidyl-Peptidase IV Inhibitors; D008567:Membranes, Artificial; D010743:Phospholipids; D010936:Plant Extracts; D015842:Serine Proteinase Inhibitors; D002726:Chlorogenic Acid; D011794:Quercetin; D000110:Acetylcholinesterase; D018819:Dipeptidyl Peptidase 4; D012697:Serine Endopeptidases; D000085822:Prolyl Oligopeptidases