S. Direkbusarakom et al., PROTECTIVE EFFICACY OF CLINACANTHUS NUTANS ON YELLOW-HEAD DISEASE IN BLACK TIGER SHRIMP (PENAEUS-MONODON), Gyobyo kenkyu, 33(4), 1998, pp. 401-404
The leaves of Clinacanthus nutans Lindua, a well-known Thai traditiona
l medicine against viral disease in human being, were used to extract
antiviral substances by ethanol using soxhlet apparatus. The extract w
as tested for its activity against yellow-head rhabdovirus (YRV) in bl
ack tiger shrimp (Penaeus monodon). Virucidal effect was investigated
by observation of mortality of the shrimp injected with the extract-tr
eated virus. The results showed that extract of C. nutans inhibited YR
V in vitro with the minimum concentration of 1 mu g/ml. Protective eff
icacy of the extract on YRV infection in shrimp was tested by oral adm
inistration of the extract mixed pellet. As the result, the protective
efficacies obtained were 44.6, 57.4 and 4.2% in the shrimp groups fed
the extract at 0.1, 1 and 10 g/kg pellet, respectively, indicating th
at the C. nutans extract mixed with pellet at 1 g/kg could most effect
ively control YRV infection in shrimp.