Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, People's Republic of China.
Bioorg Med Chem Lett. 2011 Jul 1;21(13):4005-7. doi: 10.1016/j.bmcl.2011.05.002. Epub 2011 May 8.
Two new quinazolinones alkaloids, R(+)-2-(heptan-3-yl)quinazolin-4(3H)-one (1) and (2R,3'R)+(2S,3'R)-2-(heptan-3-yl)-2,3-dihydroquinazolin-4(1H)-one (2) (a pair of epimers), as well as seven known analogues, 2-methylquinazolin-4(3H)-one (3), 2-benzylquinazolin-4(3H)-one (4), cyclo-(Pro-Ile), cyclo-(Pro-Leu), cyclo-(Pro-Val), cyclo-(Pro-Phe), and cyclo-(Tyr-Pro) were isolated from the n-butyl alcohol extract of the marine-derived bacterium Bacillus cereus 041381. The new compounds were identified by spectroscopic analysis and chemical synthesis. Four optical isomers 5-8 were also synthesized. Compounds 1-8 all showed moderate antifungal activity against Candida albicans with MIC values of 1.3-15.6 μM. Compound 5 exhibits the most powerful antifungal activity, which may reveal that S-configuration and 2,3-double bond were necessary for antifungal activity, and the racemization at C-2 and C-3' reduced the antifungal activity.
从海洋来源的芽孢杆菌 041381 的正丁醇提取物中分离得到两个新的喹唑啉酮生物碱，R(+)-2-(庚烷-3-基)喹唑啉-4(3H)-酮（1）和（2R,3'R）+（2S,3'R）-2-(庚烷-3-基)-2,3-二氢喹唑啉-4(1H)-酮（2）（一对差向异构体），以及 7 个已知类似物，2-甲基喹唑啉-4(3H)-酮（3）、2-苄基喹唑啉-4(3H)-酮（4）、环-(脯氨酰-异亮氨酸)、环-(脯氨酰-亮氨酸)、环-(脯氨酰-缬氨酸)、环-(脯氨酰-苯丙氨酸)和环-(酪氨酸-脯氨酸)。新化合物通过光谱分析和化学合成进行鉴定。还合成了四个光学异构体 5-8。化合物 1-8 对白色念珠菌均显示出中等的抗真菌活性，MIC 值为 1.3-15.6 μM。化合物 5 表现出最强的抗真菌活性，这可能表明 S 构型和 2,3-双键对于抗真菌活性是必要的，而 C-2 和 C-3'处的外消旋化降低了抗真菌活性。
