Antiviral and Immunomodulatory Activities of Clinacanthus nutans (Burm. f.) Lindau.

Clinacanthus nutans (Burm. f.) Lindau has been used as a traditional herbal medicine for treating snake bites, scalds, burns, and viral and bacterial infections. It has been attracting an increasing amount of attention because of its biological activities, including its antidiabetic, antioxidant, antibacterial, anticancer, anti-inflammatory, antiviral, and immunoregulatory activities. Here, we conducted a panoramic survey of the literature regarding the immunoregulatory, anti-inflammatory, and antiviral activities of C. nutans. We discovered that C. nutans extracts have virucidal activities against herpes simplex virus types 1 and 2, varicella-zoster virus, cyprinid herpesvirus 3, porcine reproductive and respiratory syndrome virus, mosquito-borne chikungunya virus, and potentially SARS-CoV-2; such activities likely result from C. nutans interfering with the entry, penetration, infection, and replication of viruses. We also reviewed the phytochemicals in C. nutans extracts that exhibit anti-inflammatory and immunoregulatory activities. This updated review of the antiviral, anti-inflammatory, and immunoregulatory activities of C. nutans may guide future agricultural practices and reveal clinical applications of C. nutans.