Antioxidants, Enzyme Inhibitory Activities, and Phytochemical Profiles of Seven Medicinal Plants Grown With Organic Farming Techniques

Abstract

In this study, the potential antihyperlipidemic, antidiabetic, and antiobesity effects of extracts obtained via infusion techniques from Artemisia absinthium L., Achillea millefolium L., Calendula officinalis L., Fumaria officinalis L., Mentha piperita L., Origanum onites L., and Urtica dioica L. grown with organic farming techniques were investigated using enzyme inhibition methods (alpha-glucosidase, pan-creatic cholesterol esterase, pancreatic lipase, and alpha-amylase). It is important that natural compounds or extracts to be used in the treat-ment of metabolic problems have antioxidant effects. The antioxidant effects of these species were tested in terms of ABTS and DPPH radical scavenging activity, ferric reducing power, and metal chelating capacity. Extracts (2 mg/mL) of M. piperita (91.43 +/- 0.90%) and O. onites (70.18 +/- 2.02%) showed potent inhibitory effects on the alpha-glucosidase enzyme. Among all species, only O. onites extract ex-erted an inhibitory effect on the cholesterol esterase enzyme close to that of reference compound simvastatin. While all extracts were effective in the tested antioxidant activity methods, it was determined that the M. piperita and O. onites extracts displayed particularly significantly strong activities in terms of ferric reducing power, ABTS radical scavenging effect, and metal chelating capacity. The total flavonoid and phenolic contents of all extracts were determined. The compositions of the most active extracts were analyzed for pheno-lic acids and flavonoids using RP-HPLC. The results of RP-HPLC analysis showed that the levels of ellagic acid (0.923 +/- 0.000 g/100 g extract) in the M. piperita extract and rosmarinic acid (0.813 +/- 0.003 g/100 g extract) in the O. onites extract were high. As a result, all species grown with organic farming techniques except U. dioica were found to have high antioxidant effects. In light of these findings, it was concluded that M. piperita and O. onites grown with organic farming techniques showed strong inhibitory effects in terms of the tested activities, especially for alpha-glucosidase and pancreatic cholesterol esterase, and that in vivo studies and activity-guided isolation studies should be conducted on these species in the future.