Seaweeds represent a rich source of sulfated polysaccharides with similarity to heparan sulfate, a facilitator of myriad virus host cell attachment. For this reason, attention has been drawn to their antiviral activity, including the potential for anti-SARS-CoV-2 activity. We have identified and structurally characterized several fucoidan extracts, including those from different species of brown macroalga, and a rhamnan sulfate from a green macroalga species. A high molecular weight fucoidan extracted from (FRPI-27), and a rhamnan sulfate extracted from (RS), showed potent competitive inhibition of spike glycoprotein receptor binding to a heparin-coated SPR chip. This inhibition was also observed in cell-based assays using hACE2 HEK-293 T cells infected by pseudotyped SARS-CoV-2 virus with IC values <1 μg/mL. Effectiveness was demonstrated using hACE2–transgenic mice. Intranasal administration of FRPI-27 showed protection when dosed 6 h prior to and at infection, and then every 2 days post-infection, with 100 % survival and no toxicity at 10 plaque-forming units per mouse buffer control. At 5-fold higher virus dose, FRPI-27 reduced mortality and yielded reduced viral titers in bronchioalveolar fluid and lung homogenates buffer control. These findings suggest the potential application of seaweed-based sulfated polysaccharides as promising anti-SARS-CoV-2 prophylactics.

中文翻译：

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海藻衍生的岩藻依聚糖和鼠李聚糖硫酸盐可作为有效的抗 SARS-CoV-2 药物，具有预防潜力

海藻是硫酸多糖的丰富来源，与硫酸乙酰肝素相似，硫酸乙酰肝素是多种病毒宿主细胞附着的促进剂。因此，它们的抗病毒活性受到关注，包括抗 SARS-CoV-2 活性的潜力。我们已经鉴定并结构表征了几种岩藻依聚糖提取物，包括来自不同种类的棕色大型藻类的提取物，以及来自绿色大型藻类的硫酸鼠李聚糖。从 (FRPI-27) 中提取的高分子量岩藻依聚糖和从 (RS) 中提取的硫酸鼠李聚糖，对刺突糖蛋白受体与肝素包被的 SPR 芯片的结合显示出有效的竞争性抑制作用。在使用受假型 SARS-CoV-2 病毒感染的 hACE2 HEK-293 T 细胞进行的基于细胞的测定中也观察到了这种抑制作用，IC 值 <1 μg/mL。使用 hACE2 转基因小鼠证明了有效性。鼻内施用 FRPI-27 在感染前和感染时 6 小时给药，然后在感染后每 2 天给药一次，显示出保护作用，每小鼠缓冲液对照 10 个噬菌斑形成单位时，存活率为 100%，且无毒性。在病毒剂量提高 5 倍时，FRPI-27 降低了死亡率，并降低了支气管肺泡液和肺匀浆缓冲液对照中的病毒滴度。这些发现表明基于海藻的硫酸多糖作为有前途的抗 SARS-CoV-2 预防剂的潜在应用。