Unfortunately results of serum plasma AC

Unfortunately, results of serum/plasma AC assessment after food antioxidant intake are rather controversial: although some papers reported an increase of AC after food antioxidant intake (Khan et al., 2015, Torabian et al., 2009), unexpectedly, in a lot of long-term intervention studies (days, weeks) no AC increase (Fernández-Panchón et al., 2008, Lettieri-Barbato et al., 2013) or, in some cases, an AC decrease (Lettieri-Barbato et al., 2013) were observed. No AC change was sometimes reported accompanied by a decrease of serum/plasmaoxidation level (Matthaiou et al., 2014). In the light of this, blood AC appears an unsuitable tool to derive information on food antioxidant effectiveness or to infer effects on human health. Consistently, the European Food Safety Authority (EFSA), providing guidance on the scientific requirements for health claims related to antioxidants, oxidative damage and cardiovascular health, stated that changes in plasma AC measured by TRAP, TEAC, FRAP, ORAC and FOX assays do not reflect necessarily a beneficial effect on human health (EFSA Panel on Dietetic Products Nutrition and Allergies, 2011). The incoherence between population studies, indicating a central role of food antioxidants in promoting health and preventing diseases, and studies about food effect on serum/plasma AC, providing contrasting results, may be, at least in part, dependent on some unsuitability of methodological approach. To solve these literature inconsistencies regarding AC measurements alone, very recently a novel parameter for measurement of serum antioxidant status was proposed, the Antioxidant/Oxidant Balance (AOB) (Laus et al., 2017). The AOB approach simultaneously considers food effects on both the antioxidant and the oxidative status of serum/plasma; so, it is calculated as ratio between serum AC and serum Diclofenac level, expressed as Peroxide Level (PxL). In the light of this, the advantage of the AOB approach is the capability to reveal also the AC fraction consumed to counteract oxidation status, that it cannot measured by AC measurements alone. For AOB determination, serum AC was measured by using Oxygen Radical Absorbance Capacity (ORAC) (Ou, Hampsch-Woodill, & Prior, 2001), Trolox Equivalent Antioxidant Capacity (TEAC) (Re et al., 1999) and the lipoxygenase-fluorescein (LOX-FL) methods, the last recently developed from the LOX/4-nitroso-N,N-dimethylaniline (LOX/RNO) assay (Pastore et al., 2009) and showing high performance in serum assays (Soccio et al., 2016). PxL was evaluated by a simple alkylamine reaction properly modified to increase reliability of results and to be related to serum level of oxidized LDL (Laus et al., 2017). AOB approach was found to show excellent performance in evaluating serum antioxidant status during the first four hours after intake of two antioxidant-enriched pastas, as well as Lisosan G, an antioxidant rich-supplement (Laus et al., 2017).
Materials and methods
Results Cherry puree was used as an antioxidant-rich plant source in a three-week investigation since cherry is considered as a healthy fruit and is largely appreciated by consumers. Antioxidant properties of puree were evaluated and control was made to verify that they did not significantly change during storage. For this purpose, FSP, representing the main antioxidant fraction in cherry (Cao et al., 2015), were extracted four times and analysed for AC as well as for content in some antioxidant compounds. Cherry puree showed total phenolic content equal to 108 ± 1 mg gallic acid eq./kg f.w. (SE, n = 4 different experiments), with flavonoid and anthocyanin contents equal to 151 ± 2 mg of catechin eq./kg f.w. and 109 ± 2 mg cyanidin 3-glucoside eq./kg f.w., respectively. The respective contents by serving (250 g f.w. of puree) were equal to 27 ± 0.3 mg gallic acid eq., 38 ± 0.5 mg of catechin eq. and 27 ± 0.5 mg cyanidin 3-glucoside eq. Consistently, AC values equal to 5.1 ± 0.21, 19.1 ± 0.1 and 6.5 ± 0.1 μmol Trolox eq./g f.w. were measured by LOX-FL, ORAC and TEAC methods, respectively. In the light of these results, the enrolled subjects assumed a supplementation of about 1300, 4800 and 1600 μmol Trolox eq., as evaluated by LOX-FL, ORAC and TEAC methods, when consumed 250 g f.w./day cherry puree.