Traditional Crude Drugs Against Encephalitis Infection: Ethnopharmacology, Chemistry, and Clinical and Preclinical Studies

Encephalitis infection is an infection in the brain causing inflammation of the brain. An infection or an autoimmune response generally causes encephalitis. The most common causes of encephalitis infection are herpes simplex, varicella zoster, measles, mumps, and rubella viruses. Viruses spread by animals – tick-borne encephalitis, Japanese encephalitis, and rabies – may cause encephalitis infection. The other causes of encephalitis infection are bacteria, fungi, and parasites. Encephalitis often produces flu-like signs and symptoms such as a fever and headache; it can also cause confused thinking, seizures, or problems with movement. In some cases, encephalitis can be life-threatening. Therefore, timely diagnosis and treatment are vital because it’s difficult to predict how encephalitis will affect each individual. Several allopathic drugs are used to treat encephalitis infection but have some adverse effects. Some herbal medicines are used to treat encephalitis infection, such as arctigenin, indirubin, and extracts of Isatis indigotica. These herbal medicines are produced against encephalitis infection by different mechanisms, such as arctigenin inhibiting the replication of Japanese encephalitis virus (JEV). It has been reported that JEV infection increases p38 and p-JNK. At the same time, treatment with arctigenin significantly downregulated the level of p38 and p-JNK; therefore, arctigenin inhibits Japanese encephalitis virus (JEV), reducing the viral replication within the brain, neuronal death, secondary inflammation, and oxidative stress resulting from microglial activation. At the same time, indirubin exerts its effects against encephalitis infection by downregulating the expression of genes. Herbal medicines are thought not to have negative consequences; hence, crude drugs are better choices for treating encephalitis infection.