A new inhibitor of protein kinase C (PKC), UCN-01, was isolated from the culture broth of Streptomyces sp. N-126. We have found that this strain also produces UCN-02 which is a stereoisomer of UCN-01. The inhibitors have the molecular formula C28H26N4O4 and have an indolo[2,3-alpha]carbazole chromophore. Their structures have been elucidated by mass and NMR spectra. UCN-01 has been shown to inhibit PKC and protein kinase A (PKA) with IC50 values of 0.0041 and 0.042 microM, respectively, and UCN-02 has been shown to inhibit PKC and PKA with IC50 values of 0.062 and 0.25 microM, respectively. UCN-01 and UCN-02 also showed the cytotoxic effect on the growth of HeLa S3 cells.

中文翻译：

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UCN-01和UCN-02，蛋白激酶C的新型选择性抑制剂。纯化，理化性质，结构测定和生物活性。

从链霉菌属菌种的培养液中分离出一种新的蛋白激酶C（PKC）抑制剂UCN-01。N-126。我们发现该菌株还产生UCN-02，它是UCN-01的立体异构体。抑制剂的分子式为C28H26N4O4，并且具有吲哚[2，3-α咔唑]发色团。通过质谱和NMR光谱已经阐明了它们的结构。已显示UCN-01抑制PKC和蛋白激酶A（PKA），IC50值分别为0.0041和0.042 microM，而UCN-02已显示抑制PKC和PKA，IC50值分别为0.062和0.25 microM。UCN-01和UCN-02还显示出对HeLa S3细胞生长的细胞毒性作用。