Phytochemical profile and antioxidant activity of various solvent extracts of two varieties of ginger and garlic

Jolly Oder Akullo; Beatrice N Kiage-Mokua; Dorothy Nakimbugwe; Jeremiah Ng'ang'a; John Kinyuru

doi:10.1016/j.heliyon.2023.e18806

Phytochemical profile and antioxidant activity of various solvent extracts of two varieties of ginger and garlic

Heliyon. 2023 Jul 30;9(8):e18806. doi: 10.1016/j.heliyon.2023.e18806. eCollection 2023 Aug.

Authors

Jolly Oder Akullo^{1

2}, Beatrice N Kiage-Mokua², Dorothy Nakimbugwe³, Jeremiah Ng'ang'a⁴, John Kinyuru^{4

5}

Affiliations

¹ Department of Animal Production and Management, Faculty of Agriculture and Animal Sciences, Busitema University, Uganda.
² Department of Human Nutrition Sciences, School of Food and Nutrition Sciences, Jomo Kenyatta University of Agriculture and Technology, Kenya.
³ Department of Food Technology and Nutrition, School of Food Technology, Nutrition and Bio-engineering, Makerere University, Uganda.
⁴ Department of Food Science and Technology, School of Food and Nutrition Sciences, Jomo Kenyatta University of Agriculture and Technology, Kenya.
⁵ African Institute for Capacity Development, P.O. Box 46179 - 00100, Nairobi, Kenya.

Abstract

There is limited information on the phytochemical profile and antioxidant activity of ginger and garlic consumed in Uganda. This could have an impact on its widespread use and industrial application. Thus, this study was done to determine the phytochemical profile and antioxidant activity of two varieties of ginger and garlic commonly consumed in Uganda. Fresh ginger rhizomes and garlic cloves of "local" and "hybrid" varieties were acquired from a local food market, washed, grated, and extracted using acetone, ethanol, methanol, and water. Standard techniques were used to determine the phytochemical composition. Total phenolic and flavonoid content were measured using Folin-Ciocalteu and aluminium chloride assays, respectively. Antioxidant activity was determined using the 2, 2-Diphenyl-1-picryl hydrazyl (DPPH) assays. Ginger extracts exhibited significantly higher total phenolic and flavonoid content compared to garlic (p˂0.05). The highest total phenolic and flavonoid content was in ethanol and methanol extracts of local ginger: 1968.49 and 2172.65 mg GAE/100 g; 254.24 and 184.62 mg QE/100 g, respectively. Tannins, alkaloids, saponins, and terpenoids were in varying concentrations in the extracts. Levels of Vitamin C were significantly high in aqueous extracts (p˂0.05), 38.34 and 40.80 AAE/100 g in local and hybrid ginger; 33.65 and 35.24 mg AAE/100 g in local and hybrid garlic, respectively. The free radical scavenging activity of extracts varied depending on concentration, with a strong positive correlation between antioxidant activity and total phenolic and flavonoid content. The half maximal inhibitory concentration (IC50) ranged from 0.16 to 8.93 mg/ml in local ginger, 4.43-6.44 mg/ml in hybrid ginger, 3.93-5.64 mg/ml in local garlic, and 4.44-5.27 mg/ml in hybrid garlic. The best antioxidant activity was exhibited by ethanol extracts of the local ginger. According to the findings, the two varieties of ginger and garlic have strong antioxidant activity due to their different phytochemical compositions, which could make them useful as natural antioxidants in food and medicine applications.

Keywords: Flavonoids; Inhibitory concentration; Natural antioxidants; Phenolic.