**4. Materials and Methods**

The standardized echinochrome (pentahydroxyethylnaphthoquinone, Ech), registration number in the Russian Federation was P N002362/01 [Russian State Register of Drugs (as of 5 December 2016) Part 2]. It was obtained in powder form, from the G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Vladivostok. The purity of the Ech (99.0%) was confirmed by liquid chromatography, coupled with mass spectrometry (LC-MS) data (Shimadzu LCMS-2020, Kyoto, Japan). The purified Ech that looked like red-brown needles, was soluble in ethanol, had a melting point of 219–221.5 ◦C, and a similar nuclear magnetic resonance (NMR) spectra to that reported previously in Reference [36]. We used an ethanolic solution of the Ech, at a concentration 10 mg mL<sup>−</sup>1, as a stock solution.

The CRGs were isolated by aqueous extraction from the *Chondrus armatus* (Gigartinaceae), *Tichocarpus crinitus* (Tichocarpaceae), and *Anfeltiopsis flabelliformis* (Phyllophoraceae) red algae, harvested along the Russian coast of the Japanese Sea. The polysaccharides were separated into gelling KCl-insoluble and non-gelling KC1-soluble fractions and their structures were established according to the published protocols [20–22]. Viscosimetric molecular weights of the CRGs were calculated using the Mark-Houwink equation: [η] = KMα, where [η] is the intrinsic viscosity and K and α are empirical constants constituting 3 × <sup>10</sup>−<sup>3</sup> and 0.95 at 25 ◦C in 0.1 M NaCl, for the CRGs. The commercial LPS was from the bacterium *Escherichia coli* 055:B5 (Catalog No. L2880, Lot No. 102M4017V, Sigma, St. Louis, MO, USA). An APF probe (2-[6-(4-amino)phenoxy-3H-xanthen-3-on-9]benzoic acid) was purchased from Assay Designs (cat No 906-043).
