In vitro α-glucosidase inhibitory activity of phenolic constituents from aerial parts of Polygonum hyrcanicum.
OBJECTIVE
The early stage of diabetes mellitus type 2 is associated with postprandial hyperglycemia. Hyperglycemia is believed to increase the production of free radicals and reactive oxygen species, leading to oxidative tissue damage. In an effort of identifying herbal drugs which may become useful in the prevention or mitigation of diabetes, biochemical activities of Polygonum hyrcanicum and its constituents were studied.


METHODS
Hexane, ethylacetate and methanol extracts of P. hyrcanicum were tested for α-glucosidase inhibitory, antioxidant and radical scavenging properties. Active constituents were isolated and identified from the methanolic extract in an activity guided approach.


RESULTS
A methanolic extract from flowering aerial parts of the plant showed notable α-glucosidase inhibitory activity (IC50 = 15 μg/ml). Thirteen phenolic compounds involving a cinnamoylphenethyl amide, two flavans, and ten flavonols and flavonol 3-O-glycosides were subsequently isolated from the extract. All constituents showed inhibitory activities while compounds 3, 8 and 11 (IC50 = 0.3, 1.0, and 0.6 μM, respectively) were the most potent ones. The methanol extract also showed antioxidant activities in DPPH (IC50 = 76 μg/ml) and FRAP assays (1.4 mmol ferrous ion equivalent/g extract). A total phenol content of 130 mg/g of the extract was determined by Folin-Ciocalteu reagent.


CONCLUSIONS
This study shows that P. hyrcanicum contains phenolic compounds with in vitro activity that can be useful in the context of preventing or mitigating cellular damages linked to diabetic conditions.
Department of Pharmacognosy, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran. yasa@sina.tums.ac.ir.
Fahimeh
F
Moradi-Afrapoli
Behavar
B
Asghari
Soodabeh
S
Saeidnia
Yusef
Y
Ajani
Mobina
M
Mirjani
Maryam
M
Malmir
Reza
R
Dolatabadi Bazaz
Abbas
A
Hadjiakhoondi
Peyman
P
Salehi
Mattias
M
Hamburger
Narguess
N
Yassa