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Antiviral activity study of over-sulfated polysaccharides derived from red algae against Herpes viruses
Nof Karshan; sarensara8@gmail.com
Prof. Oshrat Levy-Ontman1, Prof. Mahmoud Huleihel2 1SCE - Shamoon College of Engineering, Be’er-Sheva 2Ben-Gurion University of the Negev, Be’er-Sheva, Israel
Herpes viruses can establish persistent infections by remaining dormant in nerve cells. While current treatments, like acyclovir, help manage symptoms and reduce outbreak frequency, they cannot eliminate the virus itself and may lead to resistance and side effects. This underscores the need for alternative therapies. Sulfated polysaccharides from natural sources, which have demonstrated antiviral activity against herpes viruses, present a promising potential treatment option.
The prominent objective of this research is to enhance the antiviral activity of sulfated polysaccharides derived from red algae against Herpes simplex virus type 1 )HSV-1( and Varicella-zoster virus )VZV( by increasing their sulfur content via chemical sulfation. The studied polysaccharides were derived from two red microalgae strains, Porphyridium cruentum )P.cr.( and Porphyridium sp. )P.sp.(, as well as the Kappa )K( carrageenan from red macroalgae.
The chemical sulfation performed using the sulfur trioxide-pyridine method at various time intervals )up to 7 h(, after sodium borohydride pretreatment, significantly increased the sulfate content of all three polysaccharides. The degree of sulfation in P.cr. and P.sp. showed a time-dependent increase, ranging from 14.2-26.1 wt% and 12.9-27.5 wt%, respectively, while K reached saturation after 1 h, with its sulfate content stabilizing up to 36.5 wt%.
The cytotoxicity of the tested sulfated polysaccharides was evaluated in the Vero cells using microscopy and an XTT tetrazolium salt assay. Both P.cr. and P.sp. showed no significant cytotoxicity before or after sulfation; however, K, sulfated for up to 7 h, caused about 30% cell death at 1000 μg/ mL. The antiviral activity of sulfated polysaccharides was tested against HSV-1 and VZV in Vero cells at concentrations of 1 μg/mL and 10 μg/mL, during and after infection for 48 h, using the plaque method. Porphyridium-derived polysaccharides treated with sodium borohydride, followed by sulfation for up to 3 h, exhibited higher antiviral activities than their untreated native counterparts, correlating with increased sulfate content. For instance, P.cr. and P.sp., subjected to reduction and 3-h sulfation at 10 μg/mL concentration, achieved 100% viral inhibition for both, compared to their untreated counterparts, yielding 40.0% and 37.3% inhibition, respectively, against HSV-1. However, prolonged sulfation )7 h( resulted in decreased antiviral activity, compared to untreated polysaccharides. Moreover, pretreatment with sodium borohydride was found to be a vital step in the sulfation procedure for the enhancement of antiviral activity. Contrary to porphyridium-derived polysaccharides, K, pretreated with sodium borohydride and then sulfated for 1, 3, or 7 h, showed lower viral inhibition rates )16.0%-67.5%( at 10 μg/mL, compared to the native K, which exhibited 89.4% at the same concentration. Antioxidant activity was assessed using a total antioxidant capacity
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