Abstract

In this research, the effect of extraction solvent on the phenolic content, Flavonoid content and antioxidant capacity of clove bud (Syzygium aromaticum) was investigated. The extraction of clove bud was carried out with water, methanol (80%) and acetone (80%). The Flavonoid and phenolic contents of the extracts were evaluated by standard Aluminum chloride and Folin-Ciocalteu methods respectively while their antioxidant capacity was assayed by determining their total reducing power as well as their free radical scavenging effect on 2, 2-diphenyl-2-picrylhydrazyl (DPPH) radical. The percentage yield of the crude extracts ranged from 15.1±0.32% to 18.33±0.41% with the 80% acetone showing the highest yield while water extract showed the least. The flavonoid contents of all the extracts of clove bud evaluated were higher than the phenolic contents. The highest flavonoid content (501±0.58mgQE/g), phenolic content (200.2mgGAE/g), average percentage DPPH free radical inhibition (73.67±0.34%) and highest reducing power (0.88±0.10) were exhibited by the 80% acetone extract. The water extract on the other-hand gave the lowest values for all the parameters tested with 161.67±0.88mgQE/g, 118.40±0.06 mgGAE/g, 62.05±0.22% and 0.76±0.01 for Flavonoid content, phenolic content, average DPPH free radical inhibition and reducing power respectively. A positive correlation was found between the concentrations of flavonoids and phenolics and the antioxidant capacity of the different solvent extracts of clove bud. From the results of this study, it was shown that the flavonoid and phenolic contents of clove bud are best extracted with aqueous semi-polar organic solvents such as aqueous acetone since the most polar solvent; water, gave the least concentration of the phytochemicals determined in this work. This study therefore showed that extraction solvent is not only a crucial determinant in phytochemical recovery from plants but also an important factor to note when considering the antioxidant capacity of plants extracts. Further work is recommended to determine a detailed chemical composition of the different solvent extracts of clove bud in other to ascertain the presence of other phytochemicals which in addition to the phenolics and flavonoids may account for the antioxidant activity of these extracts.