Antioxidant and cytotoxic properties of an aqueous extract from the Argentinean plant Hedeoma multiflorum.

Context: Hedeoma multiflorum Benth. (Lamiaceae) is widely used in Argentinean popular medicine for digestive and anti-spasmodic purposes. However, knowledge about its pharmacological properties has been poorly investigated.

Objective: The antioxidant and cytotoxic properties of an aqueous extract from the plant were investigated for the first time.

Material And Methods: Scavenging of stable free radicals of 2,2-azino-bis (3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS(+)) and 2,2-diphenyl-1-picryl hydrazyl (DPPH), reducing of ferric (III) iron of ferric reducing ability of plasma (FRAP) reagent, and inhibition of lipid peroxidation (LP) of human plasma and rat brain homogenates were assessed. Cytotoxicity was tested on human polymorphonuclear (PMN) cells using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Cytotoxicity was assessed by flow cytometric techniques.

Results: Extract scavenged ABTS(+) and DPPH (1.78 and 0.78 µmol Trolox equivalent/mg dry extract, respectively) and reduced FRAP reagent (0.66 µmol ascorbic acid equivalent/mg dry extract). LP of human plasma and rat brain was also inhibited in a dose-dependent way (inhibitory concentration 50%=27.0 and 86.0 µg/mL, respectively). Extract is rich in polyphenol compounds (0.96 ± 0.08 µmol equivalent caffeic acid/mg dry matter). Treatment of PMN decreased significantly the cell ability to reduce the MTT salt and increased the hypodiploid nuclei from 4 to 18% quantified using propidium iodide (PI). In the annexin V-Fluorescein isothiocyanate (annexin V-FITC) assay, 26% of treated cells were annexin V-FITC positive and PI negative. Using the 3,3'-dihexyloxacarbocyanine iodide uptake method, the negative fraction of cells was calculated as 29%.

Discussion And Conclusion: H. multiflorum extract was found to have a significant antioxidant and pro-apoptotic activities, and a great potential as a source of healthy products.