Antiparasitic Efficacy of Crude Plant Extracts and Compounds Purified from Plants against the Fish Monogenean Neobenedenia girellae

Abstract

Neobenedenia girellae is a pathogenic ectoparasite of many marine fishes, and it causes major epidemics in marine aquaculture. In this study, the efficacy of ethanol extracts of huangqi Astragalus membranaceus (known as milkvetch in North America), guanzhong Dryopteris setosa (known as beaded wood fern in North America), gancao Glycyrrhiza uralensis (known as Chinese licorice in North America), danshen Salvia miltiorrhiza (known as red sage in North America), and pomegranate Punica granatum, as well as seven phytochemicals (10‐gingerol, curcumin, cynatratoside‐C, emodin, kuwanon‐G, kuwanon‐O, and sophoraflavanone‐G), against adult N. girellae was investigated. In vitro results indicated that pomegranate extract killed all adult N. girellae at a 62.5‐mg/L concentration with an 8‐h exposure, but gancao extract did not cause 100% mortality until a 1,000‐mg/L concentration was used. Additionally, all adult N. girellae died after an 8‐h exposure to cynatratoside‐C, kuwanon‐G, kuwanon‐O, or sophoraflavanone‐G at a concentration of 125 mg/L. Curcumin, emodin, and 10‐gingerol at a concentration of 1,000 mg/L did not kill all parasites after an 8‐h exposure. These findings demonstrate that plant extracts and active phytochemicals are potential sources of botanical drugs for controlling N. girellae infection in aquaculture.

Antibacterial and Antiparasitic Activity of Propyl-Propane-Thiosulfinate (PTS) and Propyl-Propane-Thiosulfonate (PTSO) from Allium cepa against Gilthead Sea Bream Pathogens in In Vitro and In Vivo Studies

“…Among the different phytogenic compounds tested, curcumin and cedrol presented the lowest LC 50 values, garlicin and eucalyptol showed intermediate effects, while r-camphor was the least effective. Nevertheless, another in vitro study demonstrated that curcumin was not effective against the parasite Neobenedenia girellae [ 65 ]. These studies revealed that the use of compounds derived from Allium , to a greater or lesser extent, is effective for the control of gill parasites, although their degree of efficacy will depend, among other factors, on the species of the target parasite, the composition of the active ingredients and the dose of inclusion in the feed.…”