In vitro anthelmintic activity of Psidium guajava hydroalcoholic extract against gastro-intestinal sheep nematodes

Abstract Tanniferous plants have been used for ruminants verminosis control and represent a possibility to minimize the pharmacological resistance against conventional antiparasitics. This study aimed to evaluate the antihelminthic activity of the hydroalcoholic extract of stem bark of guava tree (PgHA). It was performed the hatchability and larval migration inhibition assays to evaluate PgHA at the following concentrations 0.62, 1.25, 2.5 and 5.0 mg mL-1 and the control treatments. The total polyphenol, flavonoid and tannin contents were determined by phytochemical analysis, high performance liquid chromatography coupled to mass spectrometry. The antioxidant activity was evaluated by 1,1-diphenyl-2-picrylhydrazyl, ferric reducing antioxidant power and thiobarbituric acid reactive substances tests. It was also determinated total protein, intracellular H2O2 and antioxidant activity of enzimes: glutathione S-transferase and superoxide dismutase. PgHA was able to inhibit both hatchability and larval migration, but only hatchability inhibition presented dose-dependent pattern. The antioxidant activity was demonstrated by linear regression with IC50 corresponding to 534.02 μg mL-1. The antiparasitic mechanism occurred through pro-oxidative activity by the increase of total proteins, intracellular H2O2 and the lipid peroxidation products, as well as the increase of the enzymes above related. Thus, the PgHA showed antiparasitic activity in vitro.摘要：含鞣质植物已被用于反刍动物蠕虫病的防治，为降低传统抗寄生虫药物的耐药性提供了可行的替代方案。本研究旨在评估番石榴树茎皮水醇提取物（PgHA）的抗蠕虫活性。实验设置0.62、1.25、2.5、5.0 mg·mL⁻¹四个浓度梯度的PgHA及空白对照组，采用卵孵化率试验与幼虫迁移抑制试验对其活性进行评价。通过植物化学分析、高效液相色谱-质谱联用法测定了总多酚、总黄酮与总鞣质含量；采用1,1-二苯基-2-苦基肼（1,1-diphenyl-2-picrylhydrazyl, DPPH）法、铁还原抗氧化能力（ferric reducing antioxidant power, FRAP）法与硫代巴比妥酸反应物（thiobarbituric acid reactive substances, TBARS）试验评估其抗氧化活性；此外还测定了总蛋白含量、细胞内过氧化氢（H₂O₂）水平，以及谷胱甘肽S-转移酶与超氧化物歧化酶的抗氧化酶活性。结果显示，PgHA可同时抑制卵孵化率与幼虫迁移，但仅卵孵化抑制率呈现剂量依赖性模式。通过线性回归分析得到其抗氧化活性的半数抑制浓度（IC₅₀）为534.02 μg·mL⁻¹。其抗寄生虫作用机制为通过促氧化活性，上调总蛋白含量、细胞内H₂O₂水平与脂质过氧化产物生成，并激活上述相关抗氧化酶。综上，PgHA在体外具有明确的抗寄生虫活性。