Abstract:
Natural products, especially those of spices origin, have always been an important source of
therapeutic agents against chronic oxidative stress-related diseases. This study was aimed to
analyse polyphenolic metabolites and antioxidant activity of Ethiopian Clove or kirunfud (Syzygium
aromaticum (L.) Merr.) and Fennel or ensilal (Foeniculum vulgare Mill.) extracts. Seeds of fennel
and flower of clove were purchased and extraction was done using chloroform, ethyl acetate,
methanol and water solvents in triplicate. Qualitative identification analysis of the obtained extracts
was performed using standard procedure, and quantitative estimation of representative polyphonic
content were determined using spectrophotometer technique at different UV light. Antioxidant
capacity of extracts of the spices was determined using Dipenyl Picryl Hydrazyl (DPPH), nitric
oxide, hydrogen peroxide scavenging and reducing power assays. The result showed that, the
phenols and flavonoids were predominantly presented in more polar solvent extracts of fennel and
clove. The aqueous extracts of both spices showed significantly the highest total phenolic compound.
Methanolic fennel and aqueous clove extracts showed significantly higher total flavonoid content.
Antioxidant activity tests showed that ethyl acetate fennel extracts showed the highest DPPH
scavenging at all concentrations compared to the standard Butyl Hydroxy Toluene (BHT).
Chloroform fennel extracts showed the highest NO- radical scavenging activity at all concentration
compared to the BHT and other extracts, except at 400 μg/mL, and chloroform clove extracts
showed the highest NO- radical scavenging activity at all concentration compared to the standard
(BHT) and other extracts, except at 25 μg/mL. Among the fennel and clove spice solvent extracts,
the potent H2O2
free radical scavenger was methanolic extract at all concentrations, except at 400
μg/mL for fennel and 25 μg/mL for clove. For fennel, the best reducing power was showed by ethyl
acetate extract for clove, the best reducing power was showed by methanolic extract. The study
showed that the extracts have the proton – donating ability and could serve as free radical inhibitors
or scavengers, acting possibly as primary antioxidants. In vivo antioxidant activity and isolation of
antioxidant components of the tested spices are recommended to be carried out.
