Antioxidants have numerous applications due to their multiple roles in diminishing harmful effects of oxidative stress. The objective of this work was to highlight the importance of green tea by evaluating the antioxidant activity of the most popular green tea brands in Saudi Arabia, Lipton and Rabea. To our knowledge, no studies have so far been done to estimate the antioxidant activity of these brands. To determine the antioxidant activities of these two brands, 10 mg/ml of each brand was extracted and their total phenolic content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, hydrogen peroxide scavenging activity, ferric reducing power and ferrous ion chelating effect were measured. The TPC of Lipton tea was 678.7 µg of gallic acid equivalents (GAE)/10mg, whereas in Rabea tea, the TPC was 647.1 µg GAE/10mg. The presence study indicated that there were no significant differences in total phenolic contents and the percentage inhibition as shown in DPPH and H 2 O 2 assays among Lipton and Rabea green teas. Moreover, it was found that all assays have exhibited high antioxidant activity in both green teas. In conclusion, our study showed evidence for evenness and stability of the antioxidant activity of the two commercial green teas available in the markets of Saudi Arabia. Continued researches are needed to further the current knowledge on the health-promoting effects of this popular beverage using different supplements by different mechanisms.
KEYWORDS ABSTRACTThe purpose of the current study is to determine the antioxidant activity of the most commonly used coffee brews in the Western region of Saudi Arabia. Further, total phenolic and flavonoid contents were measured and antioxidants properties including ferric reducing antioxidant power and ferrous ion chelating activity, DPPH radical scavenging activity, and scavenging of hydrogen peroxide assays were also determined. Results of study revealed that phenolic contents were 741, 835 and 578 µg/ml of gallic acid/2 g of coffee, and the total flavonoid contents were 711, 802, and 828 µg/ml of catechin/2 g of coffee for Nescafé red mug, Turkish coffee and Espresso, respectively. The inhibition percentage of hydrogen peroxide showed highly significant reduction (p<0.001) in Turkish coffee compared to Nescafé red mug. Further, DPPH activity also showed highly significant reduction (p<0.01) in Espresso and Turkish coffee compared to Nescafé red mug, whereas, Espresso showed a highly significant increase (p<0.01) in reducing power activity. Regarding the metal chelating activity, Espresso showed a significant decrease (p<0.05) in metal chelation activity as compared to Nescafé red mug. The current study demonstrated that Nescafé red mug, Turkish coffee and Espresso, were the most consumed coffee types in the Western region of Saudi Arabia according to the survey. These three types of coffee showed high phenolic and flavonoid contents as well as a high antioxidant activity.
Tea is the most widely consumed beverage throughout the world, after water and is considered as a good antioxidant nutrient against free radical reactions. Lemons are citrus fruits that are very common in many parts of the world and are well known for their health benefits. In this study, different assays were used to evaluate total phenolic content and antioxidant activities of green tea with and without lemon. Our results showed that green tea with lemon has higher phenolic content, stronger reducing power than green tea without lemon; and exhibits a significant inhibition of 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and hydrogen peroxide (H2O2). However, both samples exhibited high ferrous chelating activity with no significant difference among each other indicating a good antioxidant potential for both. This is a comparative study between green tea and green tea supplemented with lemon. The study contributes to a better understanding about how the addition of supplements like lemon might influence the antioxidant activity of tea.
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