Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-honmachi, Kumamoto 862-0973, Japan.
School of Pharmacy, Iwate Medical University, 2-1-1 Nishitokuta, Yahaba, Iwate 028-3694, Japan.
Bioorg Med Chem. 2018 May 1;26(8):1869-1874. doi: 10.1016/j.bmc.2018.02.034. Epub 2018 Feb 20.
The fungus Aspergillus japonicus MF275 produces himeic acid A (1), containing a 4-pyrone ring, along with its congeners, himeic acids B (2) and C (3). During culture, 1 was gradually converted to 3, the corresponding 4-pyridone derivative. A study of the relationship between the culture pH and the fungal metabolites showed that a decrease from pH 6.5 to pH 2 is essential for production of 1, while a subsequent increase to pH 5 is necessary for production of 3. In addition, we revealed that 1 was non-enzymatically converted to 3 by the incorporation of an ammonium nitrogen atom in a pH 5 buffer, and that 1 was converted to 2 at a conversion ratio of 50% during incubation in MeOH for five days.
日本曲霉 MF275 产生的海美酸 A（1）含有 4-吡喃酮环，以及其同系物海美酸 B（2）和 C（3）。在培养过程中，1 逐渐转化为 3，即相应的 4-吡啶酮衍生物。对培养 pH 值与真菌代谢物之间关系的研究表明，从 pH6.5 降至 pH2 对于 1 的产生是必不可少的，而随后增加到 pH5 对于 3 的产生是必要的。此外，我们还揭示了在 pH5 缓冲液中，1 通过掺入一个铵氮原子可以非酶促转化为 3，并且在甲醇中孵育五天时，1 以 50%的转化率转化为 2。
