In vitro nematocidal activity of commercial fatty acids and ß-sitosterol against Haemonchus contortus.

Haemonchus contortus is a haematophagous gastrointestinal nematode (GIN) that causes severe anaemia and even death in small ruminants, negatively impacting the economic viability of farms. Traditionally, this parasite has been controlled with chemical compounds; however, inadequate use of these types of products has favoured the emergence of anthelmintic resistance. Therefore, it is necessary to search for alternatives for GIN control. Previous studies have reported the anthelmintic activity of edible mushroom extracts against H. contortus. A recent study reported that a fraction constituted of different fatty acids and ß-sitosterol isolated from the basidiomata of the edible mushroom Pleurotus djamor ECS-123 has ovicidal and larvicidal activity against H. contortus. Thus, this study aimed to assess the anthelmintic activity of the pure molecules: pentadecanoic acid, palmitic acid, ß-sitosterol, stearic acid and linoleic acid. For this purpose, an egg-hatching inhibition test was carried out in which the compounds were evaluated individually and in combination at a final concentration of 20 mg mL-1. Furthermore, larval mortality was assessed using a combination of the five commercial compounds previously mentioned at different concentrations (1.25-20 mg mL-1). Palmitic acid and stearic acid, in some combinations, inhibited H. contortus egg hatching by 100%. On the other hand, in the larval mortality test, the combination of the five compounds showed dose-dependent behaviour, and 100% mortality was obtained 24 h post-incubation. Pure molecules and their combinations have anthelmintic-like activity against the eggs and larvae of H. contortus.

In vitro larvicidal and in vivo anthelmintic effects of Oxalis tetraphylla (Oxalidaceae) hydroalcoholic extract against Haemonchus contortus in lambs.

The in vitro larvicidal and in vivo anthelmintic effects of Oxalis tetraphylla hydroalcoholic extract (HE), against Haemonchus contortus in experimentally infected lambs, were assessed. We used a microtitration plate method, comprising the following two stages. Stage 1: 20 µl of water containing 200 sheathed H. contortus infective larvae (ShHcl) were deposited in every well of three series; then, the series 2 and 3 wells were treated with 80 µl 1% ivermectin and O. tetraphylla HE at 20 mg/ml, respectively. Stage 2: the same procedure was performed replacing the ShHcl with exsheathed larvae (ExShHcl). Evaluations were performed after 24 and 48 h. The total numbers of dead and live larvae were counted. A second experiment evaluated the reduction in nematode egg populations in the faeces of lambs treated orally with the O. tetraphylla HE. The 27 lambs used were divided into Groups 1, 2 and 3 (n = 9), which were administered water (positive control), levamisole 1 m (7.5 mg/kg body weight (BW), as a unique dose) and O. tetraphylla HE (20 mg/kg BW), respectively. The plant HE was administered daily for 8 days. The in vitro assay showed 80.9% and 86.5% larval mortality of ShHcl after 24 and 48 h, respectively, while the corresponding mortality values for ExShHcl were 97 and 99%, respectively. The in vivo assay showed variability in the eggs/gram of faeces (epg) values; however, at the end of the trial, the average reduction in the epg values of the O. tetraphylla HE group was 45.6% (P < 0.05). Oxalis tetraphylla HE contains compounds that belong to the flavonol group with anthelmintic activity.