Comparative Antioxidant Activities of Clinacanthus Nutans and Strobilanthes Crispus Extracts Produced Using Different Methods

Saw, Yu Wei (2018) Comparative Antioxidant Activities of Clinacanthus Nutans and Strobilanthes Crispus Extracts Produced Using Different Methods. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Free radical is an oxygen-containing unstable molecule that has one or more unpaired electrons, making it highly reactive with other molecules. Free radicals are produce as a by-product in mitochondria during metabolism. Antioxidants are compounds that delay auto-oxidation by inhibiting formation of free radicals or by interrupting propagation of the free radical by several mechanisms. The objective of this study is to compare the antioxidant properties of Clinacanthus nutans and Strobilanthes crispus prepared using different extraction methods (soxhlet method, sonication method and cold maceration method. Based on DPPH assay and ABTS assay, C. nutans showed higher radical scavenging ability as compared to S. crispus regardless of the extraction method used. This plant extract also demonstrated higher reducing power of FRAP assay and this could be due to higher amount of phenolic content found in C. nutans (40 ±3.57mgGAE/g extract) than S. crispus (15 ± 0.765 mgGAE/g extract). By comparing the extraction methods (maceration, sonication and soxhlet) among two plants, soxhlet is the best way to extract phytochemical in C. nutans which exhibited highest amount of total flavonoid content (11 ± 0.185 mg CAT/g extract) as compared to maceration (9 ± 0.185 mg CAT/g extract) and sonication (8 ± 0.107 mg CAT/g extract).However, cold maceration (35 ± 0.107 mg CAT/g extract) is the best flavonoid extraction method for S. crispus followed by sonication (21 ± 0.283 mg CAT/g extract) and soxhlet (12 ± 0.214 mg CAT/g extract. In conclusion, C. nutans exhibited stronger antioxidant activity than S. crispus in all extraction methods. Despite of the antioxidant activity, soxhlet is the best extraction method for C. nutans in all extraction methods (maceration, sonication, soxhlet) carried out. However, maceration was found to be the most suitable extraction method for S. crispus as compared to sonication and soxhlet.