Chemical Compositions And Antioxidant Activities Of Pepper (Capsicum Annuum L.) Varieties Of Omo Nada District, Jimma Zone, Ethiopia

Abstract

Capsicum annuum L. (Solanaceae family) is one of the common peppers that are used as spices to flavor dishes and consumed as a vegetable. Peppers contain many bioactive compounds most of which are related to antioxidant activity. The major bioactive constituents as well as the major determinants of consumer attraction such as pleasant pungent taste and hotness can vary with agronomical practice, crop region, and drying conditions in addition to others. The current study focused on chemical compositions and antioxidant activities of the three Capsicum annuum varieties of Omo Nada district, Jimma zone, Ethiopia. The samples of three varieties of C. annuum (Gojeb, Kolesha, and Marako) were collected purposively from the Omo Nada district of Jimma Zone. GC-MS analysis of the n-hexane extracts of C. annuum fruits revealed the presence of 43, 47, and 42 compounds in the Marako, Kolesha, and Gojeb varieties, respectively. Meanwhile, the n-hexane extract of the Gojeb cultivar showed the highest 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity which would have been due to the highest percentage of capsaicin, dihydrocapsaicin, and vitamin E. Moreover, the total phenolic content (TPC), total flavonoid contents (TFC), and DPPH radical scavenging activity were investigated by UV-Vis spectroscopy using methanol and chloroform extracts which were independently obtained by maceration. The TPC of methanol extracts was 15.18 ± 0.03, 18.50 ± 0.42, and 22.98 ± 0.08 mgGAE/g for Kolesha, Marako, and Gojeb cultivars, respectively. In the same order, TPC was 12.03 ± 0.03, 13.85 ± 0.74, and 14.63 ± 0.09 mgGAE/g for chloroform extracts. The TFC was also the highest in methanol extracts; 5.5 ± 0.052, 5.73 ± 0.02, and 7.67 ± 0.07 mgQE/g for Kolesha, Marako, and Gojeb varieties, respectively. Chloroform extracts exhibit lower TFC, which varied from 3.72 ± 0.07 to, 4.73 ± 0.32 mgQE/g. Regarding the antioxidant activity, the IC50 values for the DPPH radical scavenging were 0.92 ± 0.01, 1.36 ± 0.06 mg/mL, 0.39 ± 0.004, 0.82 ± 0.01 mg/mL, and 1.40 ± 0.02, 1.52 ± 0.03 mg/mL for methanol and chloroform extracts of Marako, Gojeb, and Kolesha, respectively. The result of the current study showed three varieties of peppers could be considered as a source of antioxidant bioactive compounds.