Abstract:The present study aimed to evaluate acetylcholinesterase (AChE) inhibitory and antioxidant activities of Lamiaceae medicinal plants growing wild in Croatia. Using Ellman's colorimetric assay all tested ethanolic extracts and their hydroxycinnamic acid constituents demonstrated in vitro AChE inhibitory properties in a dose dependent manner. The extracts of Mentha x piperita, M. longifolia, Salvia officinalis, Satureja montana, Teucrium arduini, T. chamaedrys, T. montanum, T. polium and Thymus vulgaris at 1 mg/mL showed strong inhibitory activity against AChE. The antioxidant potential of the investigated Lamiaceae species was assessed by DPPH • scavenging activity and total antioxidant capacity assays, in comparison with hydroxycinnamic acids and trolox. The extracts differed greatly in their total hydroxycinnamic derivatives content, determined spectrophotometrically. Rosmarinic acid was found to be the predominant constituent in most of the investigated medicinal plants (by RP-HPLC) and had a substantial influence on their AChE inhibitory and antioxidant properties, with the exception of Teucrium species. These findings indicate that Lamiaceae species are a rich source of various natural AChE OPEN ACCESSMolecules 2014, 19 768 inhibitors and antioxidants that could be useful in the prevention and treatment of Alzheimer's and other related diseases.

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Antioxidant activities of three selected Micromeria species growing in Croatia (M. croatica, M. juliana and M. thymifolia) were evaluated using five different antioxidant assays, in comparison with plant polyphenolic constituents and reference antioxidants. All studied ethanolic extracts exhibited considerable activity to scavenge DPPH and hydroxyl free radicals, reducing power, iron chelating ability and total antioxidant capacity in the order: M. croatica > M. juliana > M. thymifolia. Total polyphenol (9.69-13.66%), phenolic acid (5.26-6.84%), flavonoid (0.01-0.09%) and tannin (3.07-6.48%) contents in dried plant samples were determined spectrophotometrically. A strong positive correlation between antioxidant activities and contents of phenolic acids and tannins was found, indicating their responsibility for effectiveness of tested plants. Our findings established Micromeria species as a rich source of antioxidant polyphenols, especially the endemic M. croatica. OPEN ACCESSMolecules 2011, 16 1455

Aim: To investigate the mechanisms underlying the protective effects of quercetin-rutinoside (rutin) and its aglycone quercetin against CCl 4 -induced liver damage in mice. Methods: BALB/cN mice were intraperitoneally administered rutin (10, 50, and 150 mg/kg) or quercetin (50 mg/kg) once daily for 5 consecutive days, followed by the intraperitoneal injection of CCl 4 in olive oil (2 mL/kg, 10% v/v). The animals were sacrificed 24 h later. Blood was collected for measuring the activities of ALT and AST, and the liver was excised for assessing Cu/Zn superoxide dismutase (SOD) activity, GSH and protein concentrations and also for immunoblotting. Portions of the livers were used for histology and immunohistochemistry. Results: Pretreatment with rutin and, to a lesser extent, with quercetin significantly reduced the activity of plasma transaminases and improved the histological signs of acute liver damage in CCl 4 -intoxicated mice. Quercetin prevented the decrease in Cu/Zn SOD activity in CCl 4 -intoxicated mice more potently than rutin. However, it was less effective in the suppression of nitrotyrosine formation. Quercetin and, to a lesser extent, rutin attenuated the inflammation in the liver by down-regulating the CCl 4 -induced activation of nuclear factor-kappa B (NF-κB), tumor necrosis factor-α (TNF-α) and cyclooxygenase (COX-2). The expression of inducible nitric oxide synthase (iNOS) was more potently suppressed by rutin than by quercetin. Treatment with both flavonoids significantly increased NF-E2-related factor 2 (Nrf2) and heme oxygenase (HO-1) expression in injured livers, although quercetin was less effective than rutin at an equivalent dose. Quercetin more potently suppressed the expression of transforming growth factor-β1 (TGF-β1) than rutin. Conclusion: Rutin exerts stronger protection against nitrosative stress and hepatocellular damage but has weaker antioxidant and antiinflammatory activities and antifibrotic potential than quercetin, which may be attributed to the presence of a rutinoside moiety in position 3 of the C ring.

The present study aimed to evaluate antioxidant and acetylcholinesterase (AChE) inhibitory activities of the ethanolic extracts of six selected Thymus species growing in Croatia (T. longicaulis, T. praecox subsp. polytrichus, T. pulegioides, T. serpyllum subsp. serpyllum, T. striatus, and T. vulgaris). Antioxidant effectiveness was assessed using six different assays, in comparison with rosmarinic acid, luteolin, and reference antioxidants. All tested Thymus extracts possessed DPPH (IC50 = 3–6 μg/mL) and nitric oxide (IC50 = 70–177 μg/mL) free radical scavenging activities, strong reducing properties (IC50 = 11–15 μg/mL), ferrous ion chelating activity (IC50 = 126–389 μg/mL), ability to inhibit lipid peroxidation (IC50 = 34–80 μg/mL), and high total antioxidant capacities (238–294 mg AAE/g). AChE inhibitory activity was examined using Ellman's colorimetric method and all tested extracts showed anti-AChE activity in a dose dependent manner. The values of 10–28%, 23–39%, and 64–86% were obtained for tested concentrations of 0.25, 0.5, and 1 mg/mL, respectively. Additionally, the contents of total hydroxycinnamic derivatives, flavonoids, and tannins in dried plant samples were determined spectrophotometrically. Our results highlighted Thymus species as a rich source of natural antioxidants and AChE inhibitors that could be useful in preventing and treating Alzheimer's disease and other neurodegenerative disorders.