Therefore, research on antioxidants with low cytotoxicity from plants, has become an important branch of biomedicine. The results obtained in the present work indicated that guaraná powder can be a potential source of antioxidants in food and biological systems. As previously pointed out by Majhenič et al. (2007) guarana seed extracts can be potential natural antioxidants in the food industries and useful for the preservation of foodstuffs against a range of food-related Ipilimumab bacterial and fungal species. Majhenič et al. (2007) tested the antioxidant and radical-scavenging activities of guarana seed extracts. The extracts displayed strong antioxidant

and radical-scavenging properties. Moreover, according to Majhenič et al. (2007), guarana extracts showed antimicrobial activity against Escherichia coli, Bacillus cereus, Pseudomonas fluorescens and spoilage fungi, such as Aspergillus niger, Trichoderma viride and Penicillium cyclopium. Due the presence of high levels of caffeine and other alkaloids, guarana powder is used by the Brazilian population mainly for its pharmacological activity as a stimulant. The powder is commercialised in capsules, and the recommended

daily intake is five capsules, wherein each capsule has 550 mg of powder. According to this recommendation, 3.3 g of guarana powder are consumed daily, which corresponds to a daily intake of 5.5 mg

of the polysaccharide GHW-IIET. DAPT At this concentration, the scavenging activities Megestrol Acetate of GHW-IIET would be expected to be ∼50% and 65% for DPPH and hydroxyl radicals, respectively. In addition to the phenolic compounds, our results suggest that polysaccharides can contribute to the antioxidant effect of guarana powder. According to the literature, a diet rich in antioxidants appears to correlate with a reduced risk of cardiovascular disease, among other beneficial effects (Khramova et al., 2011 and Michiels et al., 2012; Salman et al., 2008). Although, it is unclear whether active compounds remain active after being absorbed and metabolised in the body, the interest in plant antioxidants is increasing among scientists, food manufacturers, and consumers (Michiels et al., 2012). Although previous studies have reported the antioxidant activity of guarana seed extracts (Basile et al., 2005 and Majhenič et al., 2007), to our knowledge, there are no reports on the antioxidant activity of the polysaccharides from these seeds. According to Basile et al. (2005), the antioxidant activity of guarana could explain the use of guarana to prevent atherosclerosis, as reported by Bydlowski et al. (1988). In addition, it has been shown that many polysaccharides, including pectins, can function as biological response modifiers (Schepetkin and Quinn, 2006 and Yang et al., 2006).