Ibrahim Reham S, El-Mezayen Nesrine S, Khairy Asmaa, Zaatout Hala H, Hammoda Hala M, Metwally Aly M
Department of Pharmacognosy, Faculty of Pharmacy, Alexandria University, Alexandria, 21521, Egypt.
Department of Pharmacology, Faculty of Pharmacy and Drug Manufacturing, Pharos University in Alexandria, Alexandria, Egypt.
J Food Drug Anal. 2020 Sep 15;28(3):407-448. doi: 10.38212/2224-6614.1242.
Hyperthyroidism is a common endocrine disorder associated with increased risk of cardiovascular complications and mortality. Although antithyroid drugs (ATDs) are approved as first line option for many hyperthyroidism cases, including pregnancy and childhood, they exert significant toxic profile. Medicago sativa L. (alfalfa) also called "The father of all food" was among the diet consumed by mares that gave birth to foals with congenital hypothyroidism. Since, greenfeed was accused for the development of such condition, alfalfa may possess constituents with promising antithyroid potential that could be a valuable substitute for the conventional ATDs. The current work was designed to identify the most biologically active antithyroid phytoconstituent separated from alfalfa sprouts and comparing its antithyroid mechanism, efficacy and toxic profile to the standard ATD; propylthiouracil (PTU). The most biologically active solvent fractions from alfalfa sprouts extract were identified by in vitro screening for anti-thyroid peroxidase (TPO) activity, from which different phytoconstituents were separated and identified by interpretation of spectroscopic data. These compounds were then in vitro screened for anti-TPO and virtually screened via GLIDE XP docking into the crystal structures of the enzymes; bovine lactoperoxidase, as an alternative to TPO, and mammalian selenocysteine-dependent iodothyronine deiodinase (IDI), that are both uniquely dually prohibited by PTU. The compound that showed the least TPO IC and highest combined docking XP score was elected for comparing its antithyroid mechanism, efficacy, tendency to reverse hyperthyroidism-triggered complications and toxicity to PTU using L-thyroxine-induced hyperthyroidism model in rats. Seven compounds (1-7) were isolated from the most biologically active fraction, whilst, compounds (4-7) were reported for the first time from alfalfa sprouts. Compound 5 (apigenin) showed the least TPO IC and highest in-silico combined score, thus, apigenin was selected for further in-vivo investigations. Apigenin was found to more effectively interfere with type 1-IDI than with TPO in vivo. Apigenin therapy resulted in nearly euthyroid state, without incidence of hypothyroidism, thyroid hypertrophy, hepatotoxity or WBCs count reduction. In addition, apigenin, but not PTU, corrected hyperthyroidism-induced left ventricular hypertyrophy. Therefore, apigenin is a natural lead antithyroid drug that represents a possible safer alternative to conventional ATDs.
甲状腺功能亢进是一种常见的内分泌紊乱疾病，与心血管并发症和死亡率增加相关。尽管抗甲状腺药物（ATDs）被批准为许多甲状腺功能亢进病例（包括妊娠和儿童病例）的一线治疗选择，但它们具有显著的毒性。紫花苜蓿（Medicago sativa L.）也被称为“所有食物之父”，是患有先天性甲状腺功能减退症的马驹的母马所食用的食物之一。由于绿色饲料被指责导致了这种情况的发生，紫花苜蓿可能含有具有潜在抗甲状腺作用的成分，有望成为传统抗甲状腺药物的有价值替代品。当前的研究旨在鉴定从紫花苜蓿芽中分离出的最具生物活性的抗甲状腺植物成分，并将其抗甲状腺机制、疗效和毒性与标准抗甲状腺药物丙硫氧嘧啶（PTU）进行比较。通过体外筛选抗甲状腺过氧化物酶（TPO）活性，确定了紫花苜蓿芽提取物中最具生物活性的溶剂部分，从中分离出不同的植物成分，并通过光谱数据解释进行鉴定。然后对这些化合物进行体外抗TPO筛选，并通过GLIDE XP对接虚拟筛选到酶的晶体结构中，这些酶包括牛乳铁过氧化物酶（作为TPO的替代品）和哺乳动物硒代半胱氨酸依赖性碘甲状腺原氨酸脱碘酶（IDI），PTU对这两种酶都有独特的双重抑制作用。选择TPO IC值最低且对接XP综合得分最高的化合物，使用L-甲状腺素诱导的大鼠甲状腺功能亢进模型，比较其抗甲状腺机制、疗效、逆转甲状腺功能亢进引发并发症的趋势以及对PTU的毒性。从最具生物活性的部分分离出7种化合物（1-7），其中化合物（4-7）首次从紫花苜蓿芽中报道。化合物5（芹菜素）显示出最低的TPO IC值和最高的计算机模拟综合得分，因此，选择芹菜素进行进一步的体内研究。发现芹菜素在体内对1型-IDI的干扰比TPO更有效。芹菜素治疗导致甲状腺功能接近正常状态，没有甲状腺功能减退、甲状腺肿大、肝毒性或白细胞计数减少的情况发生。此外，芹菜素（而非PTU）纠正了甲状腺功能亢进引起的左心室肥厚。因此，芹菜素是一种天然的先导抗甲状腺药物，可能是传统抗甲状腺药物更安全的替代品。
