Biochemical characteristics and antioxidant activity of crude and purified sulfated polysaccharides from Gracilaria fisheri

Figures & data

Fig. 1. Schematic diagram of the extraction and purification of SP extracts from Gracilaria fisheri.

Table 1. Extraction yield, chemical compositions, and scavenging of the DPPH free radical by crude SP extracts obtained from Gracilaria fisheri with water extraction at different temperatures.

Sample (9.0 g)	Temperature of extraction (°C)	Yield of extract (%)^e	Protein content (%)^f	Total Sugar (%)^g	SO4^2− content (%)^h	Phenolic content (mg)^i	IC50 DPPH (mg mL^−1)
G. fisheri	25	6.03^d	3.33 ± 0.12^a	67.09 ± 2.71^c	7.05 ± 0.52^d	9.87 ± 1.52^a	3.07^d
	35	6.50^c	3.18 ± 0.15^a	74.87 ± 0.58^b	9.06 ± 1.43^c	9.09 ± 0.18^a	3.46^c
	45	7.42^b	2.96 ± 0.03^b	79.31 ± 0.81^b	9.82 ± 1.75^b	8.13 ± 0.45^b	4.16^b
	55	9.49^a	2.73 ± 0.05^c	85.99 ± 3.04^a	10.71 ± 1.0^a	7.19 ± 0.36^c	6.01^a

Note: a–d Mean separation within columns with different letters differ significantly (p ≤ 0.05) by multiple range test.

^e Percentages based on dried seaweed material.

^f Lowry method,²⁴⁾ percentages in crude SP.

^g Phenol-sulfuric acid method,²¹⁾ percentages in crude SP.

^h Turbidimetric method,²⁵⁾ percentages in crude SP.

ⁱ mg of gallic acid equivalent (GAE) per gram of extract.

Fig. 2. TLC analysis of the monosaccharide composition in crude (A), and purified (B) SP extracts from Gracilaria fisheri.

Notes: Crude SP extracts were purified, hydrolyzed with sulfuric acid, autoclaved, and analyzed by TLC. Crude SPs were obtained at 25 and 55 °C. The purified fractions of SPs were obtained from anion-exchange chromatography on a Toyopearl DEAE-650M column of crude SP (25 °C). G, standard glucose oligosaccharides (G1-G6); X, standard xylose oligosaccharides (X1-X6); Glu, standard glucose; Ga, standard galactose; 1, acid-treated SP (25 °C); 2, acid-treated SP (55 °C); F1 and F2, acid-treated purified fractions of F1 and F2, respectively.

Table 2. Pearson’s correlation coefficients (r) of antioxidant activity against DPPH and chemical compositions, phenolic compound, sulfate, total sugar, and protein.

	Phenolic compound	Sulfate content	Sugar	Protein
DPPH activity	.996**	−.965*	−.995**	.995**
Phenolic compound		−.960*	−.990**	.999**
Sulfated content			.985*	−.946
Sugar				−.985*

^* Correlation is significant at p ≤ 0.05.

^** Correlation is significant at p ≤ 0.01.

Fig. 3. Anion-exchange chromatography of the crude SP extract (25 °C) obtained from Gracilaria fisheri on a Toyopearl DEAE 650 M column.

Table 3. Chemical compositions of crude SP extract (25 °C) of Gracilaria fisheri and purified fractions of SP obtained from anion-exchange chromatography on DEAE-Toyopearl 650 M.

Component	Protein (%)^a	Total sugar (%)^b	SO4^2− content (%)^c	Phenolic content (mg)^d	IC50 DPPH (mg mL^−1)
Crude SP	3.33 ± 1.21^a	67.09 ± 2.71^a	7.05 ± 0.52^c	9.87 ± 1.52^a	3.07^b^,^c
F1	2.79 ± 1.87^b	56.33 ± 3.42^b	16.39 ± 0.91^b	0.05 ± 0.04^b	4.70^b
F2	2.62 ± 0.53^b	55.63 ± 1.70^b	20.30 ± 0.54^a	0.05 ± 0.03^b	9.74^a

Notes: Mean separation within columns with different letters differs significantly (p ≤ 0.05) by multiple range test.

Percentages based on 100 mg dried extracts.

^a Lowry method.²⁴⁾

^b Phenol-sulfuric acid method.²¹⁾

^c Turbidimetric method.²⁵⁾

^d mg of gallic acid equivalent (GAE) per gram of extracts.

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