Antioxidant Activity of Brown Seaweed, Ecklonia maxima, Collected from South Africa

남아프리카공화국 갈조류 Ecklonia maxima 줄기의 항산화 활성 평가

Abstract

In the present study, the alcoholic and enzymatic extracts of Ecklonia maxima were prepared and their antioxidant activities were evaluated via the free radical scavenging activities. The lyophilized seaweed powder was extracted by 70% ethanol and the resultant extract was obtained, named as the alcoholic extract of E. maxima stem (EMSE) obtained. The residue after EMSE preparation was continuously by Celluclast-assistant extraction and then the obtained enzymatic extract was identified as polysaccharides-rich extract of E. maxima stem (EMSP). The results indicated that the extraction yields of EMSE and EMSP were 2.18% and 5.43%, respectively. In addition, the free radical scavenging activities of EMSE and EMSP were determined using an electron spin resonance (ESR) spectrometer. EMSE containing 5.36% of polyphenol and 1.56% of polysaccharide scavenged DPPH and alkyl radicals at the $IC_{50}$ values of 0.48 and 0.63 mg/mL, respectively. EMSP containing 0.33% of polyphenol and 41.58% of polysaccharide showed at the $IC_{50}$ values of 0.33 and 0.55 mg/mL, respectively. These results demonstrate that EMSP containing a high amount of polysaccharides possesses a strong free radical scavenging activity which might be a potential ingredient in pharmacological and cosmeceutical industries.

Figure 1. The protocol of 70% EtOH and polysaccharide extraction of Ecklonia maxima stem.

Figure 2. DPPH radical scavenging activities of 70% ethanol extract and polysaccharide extract of Ecklonia maxima stem. (A) DPPH radical scavenging activities of EMSE and EMSP at the different concentrations; (B) IC₅₀ values of DPPH radical scavenging activities of EMSE and EMSP. DPPH radical scavenging activity was determined using ESR spectrometer. The data were expressed as the mean ± standard error (S.E). EMSE: Ecklonia maxima stem 70% EtOH extract; EMSP: Ecklonia maxima stem polysaccharide.

Figure 3. Alkyl radical scavenging activities of 70% ethanol extract and polysaccharide extract of Ecklonia maxima stem. (A) Alkyl radical scavenging activities of EMSE and EMSP at the different concentrations; (B) IC₅₀ values of alkyl radical scavenging activities of EMSE and EMSP. Alkyl radical scavenging activity was determined using ESR spectrometer. The data were expressed as the mean ± standard error (S.E). EMSE: Ecklonia maxima stem 70% EtOH extract; EMSP: Ecklonia maxima stem polysaccharide.

Table 1. Yields, polyphenol and polysaccharide contents of Ecklonia maxima stem extract.