Invasive Biomass Algae Valorization: Rugulopteryx okamurae as a Sustainable Source of Natural Antioxidants

Abstract

Pigments content, total phenolics (TPC) and total flavonoids (TFC), as well as the antioxidant activity (AA) of ethyl acetate (EtOAc), methanol, and chloroform extracts of Rugulopteryx okamurae were measured to find novel potential sources of natural pigments and antioxidants. The extraction of chlorophylls (a, b, c, and d), carotenoid, fucoxanthin, and phycobiliproteins was carried out using six solvents, namely acetone 90%, dimethyl sulfoxide-water (4: 1, v/ v), pure methanol, and pH 6.8 phosphate buffer, respectively. TPC and TFC were assessed using the Folin Ciocalteu and aluminum chloride assays, respectively, while, the antioxidant activity was assessed by using two different methods: DPPH (2,2-diphenyl-1-picrylhydrazyl radical) and ABTS [2,20‐azino‐bis‐(3‐ethylbenzothiazoline‐6‐ sulfonic) acid)]. The findings revealed a high content of chlorophyll a [263.87± 5.88µg/ g DW (dry weight)] and fucoxanthin (18.54± 0.73µg/ g DW) in R. okamurae. In addition, this species presented values as high as 17.67± 0.13mg GAE (gallic acid equivalent) / g and 42.99± 0.46mg QE (quercetin equivalent) / g, of phenolic and flavonoid contents, respectively. The antioxidant activity of R. okamurae extracts in both assays was highest in the most polar solvents: methanol≥ EtOAc> chloroform. There was a negative correlation between TPC and DPPH (r= -0,4888) test, and a moderate positive correlation with ABTS test (r= 0,4888), while there was a strong positive correlation between ABTS assay and carotenoid (r= 0,8735). In conclusion, the R. okamurae extract is a potential natural source of natural pigment and antioxidants.