Abstract

Background and Aim: Haemonchus contortus is a highly pathogenic blood-feeding nematode of small ruminants, responsible for severe anemia, production losses, and mortality. Excessive use of synthetic anthelmintics, especially benzimidazoles, has led to widespread drug resistance, prompting a need for alternative therapeutics. Nicotiana tabacum (tobacco) contains bioactive alkaloids such as nicotine, which target nematode acetylcholine receptors and may provide sustainable parasite control. This study aimed to isolate, characterize, and evaluate the in vitro and in vivo anthelmintic efficacy and safety of alkaloid-rich fractions of N. tabacum against benzimidazole-resistant H. contortus in goats, in line with the One Health approach and the United Nations Sustainable Development Goals (SDGs 2, 3, 12, and 15).

Materials and Methods: Leaves of N. tabacum were authenticated and subjected to sequential solvent extraction. Alkaloid fractions were confirmed by TLC and HPLC. In vitro assays, including adult motility and egg hatch tests, were conducted at concentrations of 1–5 mg/mL against resistant H. contortus isolates. The most active fraction (ethyl acetate) was administered orally in naturally infected Beetal goats (n = 25) at low (0.8 mg/kg), medium (1.2 mg/kg), and high (1.6 mg/kg) doses for 14 days, alongside negative (saline) and positive (oxfendazole 4.5 mg/kg) controls. Fecal egg counts, hematology, and liver enzyme levels were analyzed to determine efficacy and safety.

Results: The ethyl acetate fraction exhibited complete (100%) adult worm mortality at 3–5 mg/mL and total egg-hatch inhibition at 4–5 mg/mL (p < 0.05). The LD₅₀ for adult worm mortality was 0.323 mg/mL. In vivo, the high-dose group (1.6 mg/kg) achieved a 76.2% fecal-egg-count reduction, exceeding oxfendazole (69.7%). No significant changes in alanine aminotransferase or aspartate aminotransferase were observed (p > 0.05), confirming hepatic safety, while serum proteins and red-blood-cell indices improved significantly (p < 0.05).

Conclusion: Purified alkaloid fractions of N. tabacum, particularly the ethyl acetate extract containing nicotine, demonstrated strong, dose-dependent anthelmintic activity, and safety against benzimidazole-resistant H. contortus. These findings support N. tabacum as a sustainable, plant-based alternative to synthetic anthelmintics. The work advances the One Health framework and contributes directly to SDG 2 (Zero Hunger), SDG 3 (Good Health and Well-being), SDG 12 (Responsible Consumption and Production), and SDG 15 (Life on Land).

Keywords: alkaloids, anthelmintic resistance, benzimidazoles, goats, Haemonchus contortus, Nicotiana tabacum, One Health, Sustainable development goals 12 – Responsible consumption and production, Sustainable development goals 15 – Life on land, Sustainable development goals 2 – Zero Hunger, Sustainable development goals 3 – Good health and well-being, sustainable livestock.