PTGS2 and viral infectious disease: Humic substances indirect protection of host systems from viral infection via the suppression of tumor necrosis factor alpha (TNF-α), prostaglandin E2 (PGE2) and cyclooxygenase 2 (COX-2) expression in human monocyte culture is also potentially clinically relevant (Hafez et al., 2020); as is its direct reduction of oxidative stress by complexing with intermediate free radicals and activation of the immune system via the promotion of IL-2 secretion (Vetvicka et al., 2013).