Toona sinensis Roem tender leaf extract inhibits SARS coronavirus replication

AIM OF THE STUDY: Severe acute respiratory syndrome (SARS) is a life-threatening disease caused by the SARS coronavirus (SARS-CoV). The development of new antiviral agents for SARS-CoV is an important issue. We tried to find potential resource from Traditional Chinese medicine (TCM) for development of new drugs against SARS-CoV. MATERIALS AND METHODS: Our team recruited the potential TCM formulae (also known as Kampo) from two TCM books, Shang-Han Lun (Discussion of Cold-Induced Disorders) and Wen-Bing Tiau-Bein (Differential Management of Febrile Diseases). Several herbs, which were believed to be beneficial for SARS by experienced TCM doctors were also recruited. In addition, a vegetable polular in Taiwan, China and Malaysia, the tender leaf of Toona sinensis Roem (also known as Cedrela sinensis, belongs to the family Meliacceae) was also recruited under the suggestion of botanic experts. These TCM products and plant extrats were then tested for the effectiveness against SARS-CoV in vitro. RESULTS: Only TSL-1, the extract from tender leaf of Toona sinensis Roem was found to have an evident effect against SARS-CoV with selectivity index 12∼17. CONCLUSION: This paper reports for the first time that extract from a vegetable, the tender leaf of Toona sinensis Roem, can inhibit SARS-CoV in vitro. Thererfore, the tender leaf of Toona sinensis Roem may be an important resource agninst SARS-CoV.