Michel, P.; Dobrowolska, A.; Kicel, A.; Owczarek, A.; Bazylko, A.; Granica, S.; Piwowarski, J.P.; Olszewska, M.A. Polyphenolic Profile, Antioxidant and Anti-Inflammatory Activity of Eastern Teaberry (Gaultheria procumbens L.) Leaf Extracts. Molecules 2014, 19, 20498-20520.
Abstract
Dry leaf extracts of eastern teaberry (Gaultheria procumbens L.) were evaluated as a source of bioactive phytocompounds through systematic activity testing and phytochemical profiling. The antioxidant efficiency was tested using five complementary in vitro models (DPPH; FRAP; linoleic acid (LA) peroxidation assay; O2•− and H2O2 scavenging tests) in parallel with standard antioxidants. The 75% methanol extract and its diethyl ether, ethyl acetate (EAF), n-butanol and water fractions exhibited the dose-dependent responses in all assays, with the highest capacities found for EAF (DPPH EC50 = 2.9 μg/mL; FRAP = 12.8 mmol Fe2+/g; IC50 for LA-peroxidation = 123.9 μg/mL; O2•− SC50 = 3.9 μg/mL; H2O2 SC50 = 7.2 μg/mL). The EAF had also the highest anti-inflammatory activity in the inhibition tests of lipoxygenase and hyaluronidase (60.14% and 21.83% effects, respectively, at the concentration of 100 μg/mL). Activity parameters of the extracts correlated strongly with the levels of total phenolics (72.4–270.7 mg GAE/g), procyanidins, and phenolic acids, whereas for flavonoids only moderate effects were observed. Comprehensive UHPLC-PDA-ESI-MS3 and HPLC-PDA studies led to the identification of 35 polyphenols with a procyanidin A-type trimer, quercetin 3-O-glucuronide, isomers of caffeoylquinic acids, and (‒)-epicatechin being the dominant components. Significant activity levels, high phenolic contents and high extraction yields (39.4%–42.5% DW for defatted and crude methanol extracts, respectively) indicate the value of eastern teaberry leaves as bioactive products.
Conclusions
Leaves of G. procumbens contain considerable quantities of antioxidant polyphenols, which can be effectively extracted with 75% (v/v) aqueous methanol and further concentrated by ethyl acetate.
The obtained extracts possess significant and dose-dependent SET- and HAT-type antioxidant capacities in vitro, as well as moderate anti-inflammatory activity, which correlate with their phenolic composition.
Among the phenolic constituents, low- and medium-molecular-weight proanthocyanidins and phenolic acids are primarily responsible for the tested antioxidant capacity, whereas flavonoids are the main determinants of the anti-inflammatory effects. Regarding the potent activity of Gaultheria extracts in comparison with phenolic standards, the results of the present study partly explain the ethnobotanical use of the plant and support the idea that Ericaceae leaves may be good sources of beneficial prophylactic phenolic antioxidants with anti-inflammatory potential. However, further research is needed to confirm the present results in cell-based or in vivo studies, and to investigate in detail the dominant phenolic constituents of the analyzed extracts,
Link:
Nenhum comentário:
Postar um comentário