A method of preventing or treating Coronavirus infection in a subject in need thereof is provided. The method comprising administering to the subject an effective amount of a plant species or genus thereof-derived component selected from the group consisting of a plant part, extract thereof, fraction thereof, active ingredient thereof, synthetic analog thereof, mimetic thereof or combination thereof, wherein the component is capable of ameliorating symptoms of Coronavirus infection and wherein the plant species is selected from the group consisting of Nigella sativa, Thymus capitatus, Thymus vulgaris, Origanum syriacum, Thymbra spicata, Satujera thymbra, Sesamum indicum and Rhus coriaria Gynostemma petaphyllum, Boswellia sacra and Panax ginseng, or any plant containing tryptophan preventing or treating Coronavirus in the subject.