WF14865A and B, novel cathepsins B and L inhibitors, were produced and isolated separately from the culture mycelium of a fungal strain Aphanoascus fulvescens No. 14865. Spectroscopic analysis revealed that both WF14865A and B were composed of trans-epoxysuccinyl moieties, 1-H-imidazole-2-ylamine, and isoleucine or leucine. These compounds inhibited human cathepsins B and L with IC50 values in the range of 8.4 approximately 72nM in vitro. Though their in vitro properties were typical as trans-epoxysuccinyl type inhibitors, they exerted strong bone resorption inhibitory effects in low-calcium-diet-fed mouse model at 3.2 approximately 10 mg/kg.

中文翻译：

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WF14865A和WF B，由富水隐孢子虫生产的新型组织蛋白酶B和L抑制剂。I.分类学，生产，纯化和生物学特性。

WF14865A和B，新的组织蛋白酶B和L抑制剂，是从真菌菌株Aphanoascus fulvescens No. 14865的培养菌丝体中分别生产和分离的。光谱分析表明WF14865A和B都由反式环氧琥珀酰部分1-H-咪唑-2-基胺和异亮氨酸或亮氨酸。这些化合物在体外抑制人组织蛋白酶B和L的IC50值为8.4，约为72nM。尽管它们的体外特性是典型的反式环氧琥珀酰型抑制剂，但它们在低钙饮食喂养的小鼠模型（3.2约10 mg / kg）中发挥了强大的骨吸收抑制作用。