Determination of Antioxidant Strength of Unknowns, Foods, Drinks and Biological Samples - Lab Report Example

Determination of antioxidant strength of unknowns, foods, drinks and biological samples al affiliation Background information: Antioxidants are useful in prevention of oxidative stress that results from reactive oxygen species (ROS). Chronic oxidative stress is associated with cardiovascular disease and cancer. Certain fruits and vegetables have been found to contain higher levels of antioxidant capacity compared to others. This experiment aimed find out the antioxidant strength of unknown, known (cranberry and apple juice) and biological samples (saliva). Method: The experiment was done by conducting a FRAP assay and plotting a calibration curve for antioxidant capacity to determine the antioxidant capacity of the two unknowns, cranberry and apple juice and saliva from the group members. Statistical analysis was done by MINITAB 17 to find the linear regression and analysis of variance (ANOVA) Results: The unknown 1 and 2 samples had an antioxidant capacity of 0.303 and 1.070 µM respectively. The cranberry juice had a lower antioxidant capacity compared to apple juice and this is inconsistent with previous literature. In addition, according to the findings, the smokers and the pregnant participants had quite high antioxidant strengths which is contrary to previous studies. Conclusion: In vitro antioxidant potency does not prove in vivo biological activity. However, pregnant women and smokers should increase foods that have high antioxidant strength in their diet so as to avoid oxidative stress due to accumulation of reactive oxygen species (ROS). Key words: antioxidant, FRAP assay, diet Introduction During normal cellular metabolism, reactive oxygen species (ROS) is produced. ROS could function as cytotoxic agents against bacteria or parasites and may induce damage on normal tissue. In this regard, living cells produce and store numerous antioxidant compounds as well as use several enzymes with antioxidant activity such as superoxide dismutase in order to counteract the deleterious effects of oxidative molecules. Antioxidants are important since they protect cells and their macromolecules from damage by free radicals. For the survival and function of aerobic organisms, the balance between prooxidants and antioxidants is critical. The imbalance in favour of prooxidants against antioxidants is referred to as oxidative stress and is involved in several hepatic diseases. Biological oxidants include uric acid, Vitamin C and E. Glurathione, vitamin A, albumin, vitamin E, uric acid are key antioxidants. Fruit and vegetables provides vitamin C which due to its reducing power quenches various ROS by acting as an electron donor (Panglossi, 2006). Cranberries and apples have higher antioxidant activity compared to other berries. Aims This laboratory experiment was done in three weeks, with different aims each week. Aim 1 was to determine the antioxidant content of two unknowns. Aim 2 was to find out the antioxidant strength of drinks. Aim 3 was to determine whether antioxidants can be found in saliva samples. Methods For the first and second week, refer to laboratory protocol. In the third week, the experiment was done to find out whether antioxidants could be found in saliva samples from 4 members of the group. One of the members was aged 34, was a smoker and had chinch, manna, flat bread, cranberry grapefruit squash and coffee for breakfast. The other member was 21 year old, was a smoker and had grummet with butter and black current squash for breakfast. Another was 20 year a non-smoker and had toast, butter, water and green tea for breakfast. Finally, the last member was pregnant, non-smoker and had toast with no butter, sausage and tea with no milk and sugar for breakfast. The calibration curve of iron (II) sulphate was repeated as previously and each member of the group provided a sample of their saliva and FRAP analysis carried out using 80 µl. The saliva antioxidant level for each member was recorded. The mean saliva antioxidant level for the group was established. Statistical analysis was done by MINITAB 17 and all results presented are means. One way ANOVA was presented at a confidence level of 95%. Results Table 1: The mean absorbance of iron (II) sulphate (1-7), unknowns and drinks. Concentration (µl) Absorbance Week 1 Week 2 Week 3 Mean Blank 0.000 0.000 0.000 0.000 1 0.042 0.005 -0.13 -0.027 2 0.100 0.023 0.010 0.044 3 0.197 0.065 0.043 0.102 4 0.529 0.206 0.176 0.304 5 0.866 0.337 0.292 0.498 6 1.252 0.499 0.471 0.741 7 1.566 0.608 0.560 0.911 Unknown 1 0.303 - - - Unknown 2 1.070 - - - Cranberry juice 40µl - 0.428 - - Cranberry juice 20 µl - 0.704 - - Apple juice 40 µl - 0.628 - - Apple juice at 20 µl - 0.820 - - Figure 1: Calibration curve for antioxidant capacity To find out the values of the unknowns, the equation y=0.0007x-0.0209 is used. This is done by; The absorbance of unknown 1 is at 0.303 therefore concentration is 0.303=0.0007x-0.0209 Antioxidant strength of Unknown 1 = 462 µM The absorbance of unknown 2 is at 1.070 therefore concentration is 1.070=0.0007x-0.0209 Antioxidant strength of Unknown 2 = 1558 µM In determination of the antioxidant strength of cranberry and apple juice, the calibration curve was used. Therefore; Antioxidant strength of cranberry juice 40 µl = (0.428+0.0209)/0.0007 = 641.29 µM Antioxidant strength of cranberry juice at 20 µl = (0.704+0.0209)/0.0007 = 1035.57 µM Antioxidant strength of apple juice 40 µl = (0.628+0.0209)/0.0007 = 927 µM Antioxidant strength of apple juice 20 µl = (0.820+0.0209)/0.0007 = 1201.29 µM Table 2: The mean saliva antioxidant level for the group members Sample Person Aged 34 (Smoker) Person aged 21 (Smoker) Person aged 20 (Non-smoker) Person Aged 26 (Non-Smoker) 1 0.571 0.664 0.221 0.345 2 0.686 0.612 0.227 0.246 3 0.508 0.627 0.201 0.318 Mean 0.5883 0.6343 0.216 0.303 SD 0.0903 0.0268 0.0136 0.0512 95% CI 0.5164, 0.6602 0.5624, 0.7062 0.14443, 0.28824 0.2311, 0.3749 The confidence level was at 95%. The F value was at 44.05 and (p Read More