For example, many different studies have shown that there is a higher phenolic content in the peels of fruits and vegetables than in the flesh (Kujala et al. The outer layers of plants often contain higher levels of phenolics than their interior parts. Phenolic compounds are, however, not distributed evenly throughout different parts and sections of the plant. Another study determined the major polyphenols in mint as rosmarinic acid, caffeic acid, ferulic acid and eugenol (Tahira et al. ( 2007) reported that the main active components in mint were eriocitrin, rosmarinic acid, luteolin 7- O-rutinoside, hesperidin, and small quantities of pebrellin, gardenin B and apigenin. Previous studies have found the total polyphenolic content of peppermint leaves to be approximately 19–23% with total flavonoids of 12% (McKay and Blumberg 2006). Phenolics belong to an important class of compounds responsible for the antioxidant activity of mint. Additionally, mint extract has been shown to increase cellular superoxide dismutase activity, a natural protective mechanism against oxidative damage (Mimica-Dukic et al. Many of these medicinal effects of mint are closely associated with the high content of phenolic compounds the phenolics from mint tea and mint extracts have been shown to exhibit antimicrobial and antiviral activities (Mimica-Dukic and Bozin 2008). In vitro -based studies have also demonstrated the potential anti-depressant effects of mint extracts (Lopez et al. In addition, mint has been shown in clinical trials to treat headaches through analgesic properties, reduce painful muscle spasms in patients undergoing endoscopy of the upper and lower gastrointestinal (GI) tract, and reduce abdominal pain and dyspepsia (McKay and Blumberg 2006). Aqueous infusions obtained from mint leaves have long been used to treat anorexia, hypertension, and many spasmolytic and gastrointestinal problems (Mimica-Dukic and Bozin 2008). These products are now commercially available in the deflavored form. Extracts of rosemary and sage are routinely used to control oxidation of food lipids (Zheng and Wang 2001 Shahidi and Zhong 2010). Members of the Lamiaceae family such as mint, basil, rosemary, sage, savory, oregano, and thyme, are particularly well known for their use in food and traditional medicine (Park 2011). Spices and herbs are known to serve as powerful antioxidants. High performance liquid chromatography with online tandem electrospray ionization mass spectrometry (HPLC/ESI-MS/MS) analysis of the extracts revealed that rosmarinic acid was the major phenolic compound present in both mint samples. However, Medina mint was a more potent antioxidant than the Hasawi mint. Both varieties exhibited notable antioxidant activities and inhibition of LDL cholesterol oxidation, DNA scission and COX-2 gene expression at transcriptional level. Results showed that the soluble phenolics had a higher phenolic content and antioxidant activity than the insoluble-bound extracts and aqueous infusions in most of the assays. Furthermore, the potency of the mint extracts in the inhibition of radical-induced DNA scission, human low-density lipoprotein (LDL) cholesterol oxidation, formation of thiobarbituric acid reactive substances (TBARS) in a cooked ground meat system and LPS (lipopolysaccharide)-stimulated cyclooxygenase-2 ( COX-2) expression in J774A.1 mouse macrophage cells were monitored. Soluble and insoluble/bound phenolic compounds and an aqueous infusion of two mint species (Medina and Hasawi), were tested for their total phenolic content, 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonate (ABTS) and 1,1-diphenyl-2picrylhydrazyl (DPPH) radical scavenging activity, iron (III) reduction, iron (II) chelating and oxygen radical absorbance capacity (ORAC).
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