Johan Michael T. Arnaiz (March 2009)
Philippine Science High School Western Visayas Campus – Department of Science and Technology (DOST-PSHS WVC), Brgy. Bito-on, Jaro, Iloilo City 5000, Philippines
ABSTRACT
Antioxidants are compounds that inhibit the activities of radicals, compounds that degrade cellular constituents, causing severe illnesses known to man, and aging Synthetic antioxidants are available, but safety concerns have been identified with use of them. Natural antioxidants have the advantage of being generally free from chemical contamination. It has been recently discovered that seaweeds are a source of natural antioxidants. Thus, this study aims to determine the antioxidant activity of seaweeds collected from coastal areas around Panay and obtain extracts. Once the extracts are obtained, DPPH assay will be conducted on them, and compare the antioxidant activity of extracts with that of BHT, a synthetic antioxidant.
Seaweeds are collected from Nogas Island in Anini-y, Antique. The seaweeds are freeze-dried before extraction. Crude extracts were first obtained, and then the antioxidant activity was determined using the DPPH assay. Final extraction was done using three different solvents, namely petroleum ether, ethyl acetate and butanol. After the extracts were obtained using the solvents, DPPH assay was again conducted to determine the antioxidant activity of the extracts. The antioxidants activities were then compared with that of BHT.
The mean scavenging activity of Sargassum crassifolium obtained using different extracts are as follows: petroleum ether, 0.882 ± 0.065, ethyl acetate, 0.589±0.017; butanol, 0.947 0.049. For Padina australis petroleum ether, 0.920 0.036; ethyl acetate, 0.849 0.076; butanol, 0.744 0.025. The mean scavenging activity of BHT solutions is 0.865 0.041. Butanol extracts of S. crassifolium showed the greatest scavenging activity. Using One-Way ANOVA, it is found out that only the scavenging activity of ethyl acetate extracts of S crassifolium showed significant difference when compared with BHT. In general, seaweed extracts showed significant difference when compared with ВНТ.
With the results that were obtained, seaweed extracts Sargassum crassifolium and Padina australis can compete with synthetic antioxidants in terms of efficiency. This information may be useful for researchers who wish to know the seaweed species that could be studied on. Such studies can be conducted to exactly identify and isolate the compounds that are responsible for the seaweeds’ antioxidant activity.