Papain-like cysteine proteases (PLCPs) in plants are essential to prevent phytopathogen invasion. In order to search for cysteine protease inhibitors and to investigate compounds that could be associated to pineapple Fusarium disease, a chemistry investigation was performed on Fusarium proliferatum isolated from Ananas comosus (pineapple) and cultivated in Czapek medium. From F. proliferatum extracts, nine secondary metabolites were isolated and characterized by nuclear magnetic resonance spectroscopy and mass spectrometry experiments: beauvericin (1), fusaric acid (2), N-ethyl-3-phenylacetamide (3), N-acetyltryptamine (4), cyclo(L-Val-L-Pro) cyclodipeptide (5), cyclo(L-Leu-L-Pro) cyclodipeptide (6), cyclo(L-Leu-L-Pro) diketopiperazine (7), 2,4-dihydroxypyrimidine (8), and 1H-indole-3-carbaldehyde (9). Compounds 1, 3, and 6 showed significant inhibition of papain, with IC50 values of 25.3 ± 1.9, 39.4 ± 2.5, and 7.4 ± 0.5 μM, respectively. Compound 1 also showed significant inhibition against human cathepsins V and B with IC50 of 46.0 ± 3.0 and 6.8 ± 0.7 μM, respectively. The inhibition of papain by mycotoxins (fusaric acid and beauvericin) may indicate a mechanism of Fusarium in the roles of infection process.

中文翻译：

---

来自增殖镰刀菌的霉菌毒素：木瓜蛋白酶样半胱氨酸蛋白酶的新抑制剂


植物中的类木瓜蛋白酶（PLCP）对于防止植物病原体入侵至关重要。为了寻找半胱氨酸蛋白酶抑制剂并研究可能与菠萝镰刀菌病相关的化合物，对从 Ananas comosus（菠萝）中分离并在 Czapek 培养基中培养的增殖镰刀菌进行了化学研究。从 F. proliferatum 提取物中分离出 9 种次生代谢物，并通过核磁共振波谱和质谱实验进行表征：白僵菌素 (1)、镰刀菌酸 (2)、N-乙基-3-苯乙酰胺 (3)、N-乙酰色胺 (4) ), 环(L-Val-L-Pro) 环二肽 (5), 环(L-Leu-L-Pro) 环二肽 (6), 环(L-Leu-L-Pro) 二酮哌嗪 (7), 2,4 -二羟基嘧啶(8)和1H-吲哚-3-甲醛(9)。化合物 1、3 和 6 对木瓜蛋白酶具有显着抑制作用，IC50 值分别为 25.3 ± 1.9、39.4 ± 2.5 和 7.4 ± 0.5 μM。化合物 1 还表现出对人组织蛋白酶 V 和 B 的显着抑制作用，IC50 分别为 46.0 ± 3.0 和 6.8 ± 0.7 μM。霉菌毒素（镰刀菌酸和白僵菌素）对木瓜蛋白酶的抑制可能表明镰刀菌在感染过程中的作用机制。