Nematicidal Effect and Histological Modifications Induced by Hydrolysable Tannin Extract on the Third-Stage Infective Larvae of Haemonchus contortus

SIMPLE SUMMARY: Haemonchus contortus is the most frequent and most important nematode parasite in the ruminants production of tropical and subtropical regions. The conduction of research to find resources that allow effective control of this parasitic disease, preferably focusing on green production, is necessary. Hydrolysable tannins (HT) are an important group of compounds synthetized by plants, some of them exhibit anti-cancer, antioxidant, anti-inflammatory, anti-ulcerative, or antiparasitic properties. We evaluated the effect of hydrolysable tannin extract (HTE) on larvae of H. contortus (L(3)). L(3) were exposed to different HTE concentrations and times to analyze the mortality, and microscopically we explored physical damage on L(3) caused by HTE. After 72 h of incubation with 2 mg/mL of HTE, we found a half of death larvae, and by microscopy we observed larvae destruction. Our results suggest that hydrolysable tannin extracted from chestnut could be considered as an alternative for parasitic control as a food additive in cattle. ABSTRACT: Haemonchus contortus is the most frequent and most important nematode parasite in the ruminants production of tropical and subtropical regions. There are strains resistant to all families of available anthelmintics. Consequently, the conduction of research to find other resources that allow effective control of this parasitic disease, preferably focusing on green production, is necessary. The aim of this study was to evaluate the effect of hydrolysable tannin extract (HTE) on larvae 3 (L(3)) of H. contortus in vitro. L(3) were exposed to different HTE concentrations and times. In addition, both light and scanning electron microscopy were used to explore physical damage on L(3) subjected to HTE activity. After 72 h of incubation, the mean lethal concentration of HTE was 2 mg/mL; this concentration has been previously referred to as safe for consumption in cattle. Scanning electron microscopy revealed H. contortus L(3) destruction, damage was evident by separation of the sheath mainly in the cervical and caudal regions of the larva and by rupture of the cuticle with larval evisceration. Our results suggest that hydrolysable tannin extract from chestnut could be considered as a green alternative for parasitic control in ruminants.