*4.2. Complexes CGN:CH*

The complexes of κ-CGN with CH were prepared by mixing solutions of the initial components at the given ratios as described in [33]. The concentration of the component in excess in the complex for all experiments was 0.1 mg/mL. The mixture was incubated for 15 min.

#### *4.3. Dynamic Light Scattering (DLS) and Electrophoretic Properties of the CGN:CH Complexes*

The sizes and ζ-potentials of the initial polysaccharides and their PECs in solution were determined using a ZetaSizer NanoZS system (Malvern PANalytical, Malvern, UK) operating at 633 nm. The measurements were performed at 25 ◦C. The hydrodynamic diameters of the particles were automatically calculated with the instrument's software based on analysis of the autocorrelation function. The ζ-potentials were calculated from the experimentally determined.

#### *4.4. Determination of NO Scavenging Capacity (Microplate)*

The reaction mixture containing sodium nitroprusside (10 mM, 75 μL) in phosphate buffered saline (PBS) and samples or reference compound were incubated at 25 ◦C for 150 min. Then, the Griess reagen<sup>t</sup> (1% sulfanilamide, 0.1% naphthylethylene diamine dihydrochloride in 2% H3PO4) was added to the reaction mixture (1:1 = *v*:*v*). The absorbance of the chromophore formed during the diazotization of nitrite with sulfanilamide and subsequent coupling with napthylethylenediamine was measured at 546 nm. The percentage inhibition of NO generated was measured by comparing the absorbance values of the control and a sample in quadruplicate. Ascorbic acid was used as a positive control [63].

All data were expressed as mean ± standard deviation. Statistical analysis was done by one-way ANOVA. Differences were considered to be statistically significant if *p* < 0.05.

#### *4.5. IL-10 and TNF-*α *Inducing Activity on the Human Blood Cells*

Blood processing was performed using procedure of De Groote et al. [64]. Peripheral blood was collected by vena puncture into sterile siliconized tubes containing 30 IU of lithium heparinate per 5 mL tube diluted 1:5 in sterile Medium 199 (Sigma-Aldrich, Saint Louis, MO, USA) containing 300 mg/<sup>L</sup> of glutamine (Gibco, Life Technology, Darmstadt, Germany) and 50 μg/mL of gentamicin. Diluted blood (0.1 mL) was transferred into sterile polypropylene plates and then incubated with the samples or with LPS *E. coli* 10 μg (10 min), then with the samples (37 ◦C, 5% CO2). After 24 h the supernatants were collected and frozen followed by cytokine determination using a specific ELISA kit ("Cytokine", Saint-Petersburg, Russia). The study protocol was approved by the medical ethics committee of the local hospital (Vladivostok, Russian Federation). Informed consent was obtained from all subjects who participated in the study. All donors were free of medicines administration for 14 days prior to blood sampling. Blood was drawn from the antecubital vein of normal healthy human volunteers and anticoagulated in plastic tubes (Greiner Bio-One International AG, Kremsmuenster, Austria) with 30 IU lithium heparinate used as an anticoagulant.

All data were expressed as mean ± standard deviation. Statistical analysis was done by one-way ANOVA. Di fferences were considered to be statistically significant if *p* < 0.05.

#### *4.6. Biological Activity In Vivo*
