Previous research found that the polysaccharides isolated from Hohenbuehelia serotina possessed various biological activities, such as antioxidant, immunomodulation and radioprotective effects. However, the structural information of H. serotina polysaccharides has not yet been reported. Therefore, based on the investigation of the antioxidative tracking, a novel polysaccharide named as NTHSP-A1 was isolated from H. serotina by ultrasonic-assistance extraction and anion-exchange and gel permeation chromatography approaches. Structural characterization revealed that NTHSP-A1 had an average molecular weight of 8.09 × 103 Da and composed of arabinose, mannose, glucose and galactose in a molar ratio of 4:16:28:11. The polysaccharide was semi-crystalline substance with multi-branching structure. The backbone of NTHSP-A1 was shown to contain →3,6)-α-D-Glcp-(1→, with branches substituted at C-3 of →2)-α-L-Arap-(1→, C-3 of α-D-Manp-(1→, and C-6 of →6)-β-D-Galp-(1→, respectively. This study provides a theoretical basis for the further research on the relationship between biological activity and structure of NTHSP-A1.

polysaccharide, Structural characterization, Antioxidant activity

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
3,2	Me
3	aLArap	102.7	78.3	69.0	68.2	69.2
	aDGlcp	98.8	72.1	75.6	73.9	71.1	68.2


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
3,2	Me
3	aLArap	5.3	3.9	4.1	3.7	3.7
	aDGlcp	5.3	3.6	4.1	3.7	3.6	3.7


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
3,2	Me
3	aLArap	102.7/5.3	78.3/3.9	69.0/4.1	68.2/3.7	69.2/3.7
	aDGlcp	98.8/5.3	72.1/3.6	75.6/4.1	73.9/3.7	71.1/3.6	68.2/3.7

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

[*]OC[C@H]1O[C@H]([*])[C@H](O)[C@@H](O[C@@H]2OC[C@H](O)[C@H](O)[C@H]2OC)[C@@H]1O

308.283 g/mol (C₁₂H₂₀R₂O₉, R = next and previous repeats, not counted in mol weight)

A water-soluble glycopeptide (PGY), fractionated and purified from the aqueous extract of the fruiting bodies of Ganoderma lucidum via two-step dialysis, anion exchange, and gel permeation chromatography, was constituted of two moieties of carbohydrate and peptide. Carbohydrate characterization with component analysis, methylation analysis, periodate oxidation. Smith degradation, enzymic hydrolysis, and IR and NMR experiments demonstrated that the carbohydrate moiety possessed a backbone of approximately 33 (1-3)-linked β-D-glucopyranosyl residues and side chains, at positions 6, of single α-L-arabinofuranosyl residues for every three Glcp residues in the main chain. On the basis of the results of amino acid composition and trypsin digestion, the peptide moiety, shown to consist of Arg, Ser, Ala, and Gly in a ratio of 1:1:2:2, exhibited the sequence of Ser-Arg-[(Ala)2(Gly)2] and was O-attached to the carbohydrate moiety via Ser. To contribute toward our understanding of the structure-activity relationship, a series of expected derivatives generated from PGY by trypsin digestion, debranching, and NalO 4 oxidation following reduction experiments, including PTC, DB-PGY, and PPP, were obtained. All of them, as well as PGY and a reference compound (butylated hydroxytoluene, BHT), were evaluated with two conventional antioxidant testing systems of 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide radical scavenging and found to have their respective antioxidant activities in a concentration-dependent manner. Comparable radical-scavenging activities observed between PTC and PGY demonstrated that the removal of Ala and Gly in a peptide moiety did not result in the variation of biological functions of PGY. However, it was very interesting to note that the scavenging activity of PPP was higher for DPPH radicals, with an SC 50 value of 116.4 ± 5.1 μg/mL, and lower for superoxide radicals, with an SC 50 value of 205.2 ± 14.4 μg/mL, than that of PGY with corresponding SC 50 values of 133.5 ± 5.5 and 140.5 ± 7.7 μ/mL, and, moreover, DB-PGY displayed the weakest scavenging potency in the tested samples, indicating that the carbohydrate moiety, in particular the side chain of nonreducing end units of Araf residues as the functional region, played a vital role in the structure and antioxidant activity. In addition, compared with the SC 50 value of BHT, PGY showed lower DPPH radical-scavenging activity but possessed higher superoxide radical-quenching potency, suggesting that it could be presented as a possible new source of natural antioxidants.

structure, glycopeptide, relationship, Antioxidants, Ganoderma lucidum, functional regions

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
3,3,6	aLAraf	107.7	82.6	77.8	85.7	61.4
3,3	bDGlcp	103.8	73.7	84.1	69.8	77.0	66.8
3	bDGlcp	104.5	74.7	84.2	71.5	80.7	61.0
	bDGlcp	104.5	74.7	84.2	71.5	80.7	61.0


1H NMR data:
missing...

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

[*]O[C@H]1[C@H](O)[C@@H](CO[C@@H]2O[C@@H](CO)[C@H](O)[C@H]2O)O[C@@H](O[C@@H]2[C@@H](O)[C@H](O[C@@H]3[C@@H](O)[C@H]([*])O[C@H](CO)[C@H]3O)O[C@H](CO)[C@H]2O)[C@@H]1O

618.538 g/mol (C₂₃H₃₈R₂O₁₉, R = next and previous repeats, not counted in mol weight)

A water-soluble glycopeptide (PGY), fractionated and purified from the aqueous extract of the fruiting bodies of Ganoderma lucidum via two-step dialysis, anion exchange, and gel permeation chromatography, was constituted of two moieties of carbohydrate and peptide. Carbohydrate characterization with component analysis, methylation analysis, periodate oxidation. Smith degradation, enzymic hydrolysis, and IR and NMR experiments demonstrated that the carbohydrate moiety possessed a backbone of approximately 33 (1-3)-linked β-D-glucopyranosyl residues and side chains, at positions 6, of single α-L-arabinofuranosyl residues for every three Glcp residues in the main chain. On the basis of the results of amino acid composition and trypsin digestion, the peptide moiety, shown to consist of Arg, Ser, Ala, and Gly in a ratio of 1:1:2:2, exhibited the sequence of Ser-Arg-[(Ala)2(Gly)2] and was O-attached to the carbohydrate moiety via Ser. To contribute toward our understanding of the structure-activity relationship, a series of expected derivatives generated from PGY by trypsin digestion, debranching, and NalO 4 oxidation following reduction experiments, including PTC, DB-PGY, and PPP, were obtained. All of them, as well as PGY and a reference compound (butylated hydroxytoluene, BHT), were evaluated with two conventional antioxidant testing systems of 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide radical scavenging and found to have their respective antioxidant activities in a concentration-dependent manner. Comparable radical-scavenging activities observed between PTC and PGY demonstrated that the removal of Ala and Gly in a peptide moiety did not result in the variation of biological functions of PGY. However, it was very interesting to note that the scavenging activity of PPP was higher for DPPH radicals, with an SC 50 value of 116.4 ± 5.1 μg/mL, and lower for superoxide radicals, with an SC 50 value of 205.2 ± 14.4 μg/mL, than that of PGY with corresponding SC 50 values of 133.5 ± 5.5 and 140.5 ± 7.7 μ/mL, and, moreover, DB-PGY displayed the weakest scavenging potency in the tested samples, indicating that the carbohydrate moiety, in particular the side chain of nonreducing end units of Araf residues as the functional region, played a vital role in the structure and antioxidant activity. In addition, compared with the SC 50 value of BHT, PGY showed lower DPPH radical-scavenging activity but possessed higher superoxide radical-quenching potency, suggesting that it could be presented as a possible new source of natural antioxidants.

structure, glycopeptide, relationship, Antioxidants, Ganoderma lucidum, functional regions

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

[*]O[C@H]1[C@H](O)[C@@H](CO[C@@H]2O[C@@H](CO)[C@H](O)[C@H]2O)O[C@@H](O[C@@H]2[C@@H](O)[C@H](O[C@@H]3[C@@H](O)[C@H]([*])O[C@H](CO)[C@H]3O)O[C@H](CO)[C@H]2O)[C@@H]1O

618.538 g/mol (C₂₃H₃₈R₂O₁₉, R = next and previous repeats, not counted in mol weight)