Griffithsin
Griffithsin, a lectin derived from red algae, binds on the surface of various viral glycoproteins to oligosaccharides including HIV glycoprotein 120 and SARS-CoV spike glycoprotein2. Griffithsin has low cytotoxicity, is likely to interfere with any coronavirus spike protein due to it is highly glycosylated nature, and may impede the role of coronavirus spike protein. GRFT has been shown to inhibit SARS-CoV replication and cytopathicity, as well as other coronaviridae viruses [48] [49]. In particular, in Vero 76 cells, GRFT inhibited various strains of SARS – infection with a low nanomolar EC50 with limited toxicity on control cells. GRFT can bind with glycans to the surface of the glycoprotein (S protein). A total of three GRFT molecules are capable of binding the S with very high affinity in a dose, a lower number compared to HIV which is presumably due to the lower number of highglycans on the S surface. Interestingly, such an association does not restrict the binding of SARS-CoV S glycoprotein to the human angiotensin I conversion enzyme 2 (ACE2) host cell [49]. Griffithsin has been studied as a gel or enema for HIV prevention in phase I trials, but the efficacy and delivery mechanisms of spike inhibitors should be re-evaluated for the 2019-nCoV treatment or prevention.