Isolation and Structural Determination of the Antifouling Diketopiperazines from Marine-Derived <i>Streptomyces praecox</i> 291-11
作者:Ji Young CHO、Ji Young KANG、Yong Ki HONG、Hyo Hyun BAEK、Hyoun Woong SHIN、Myoung Sug KIM
DOI:10.1271/bbb.110943
日期:——
Marine derived actinomycetes constituting 185 strains were screened for their antifouling activity against the marine seaweed, Ulva pertusa, and fouling diatom, Navicula annexa. Strain 291-11 isolated from the seaweed, Undaria pinnatifida, rhizosphere showed the highest antifouling activity and was identified as Streptomyces praecox based on a 16S rDNA sequence analysis. Strain 291-11 was therefore named S. praecox 291-11. The antifouling compounds from S. praecox 291-11 were isolated, and their structures were analyzed. The chemical constituents representing the antifouling activity were identified as (6S,3S)-6-benzyl-3-methyl-2,5-diketopiperazine (bmDKP) and (6S,3S)-6-isobutyl-3-methyl-2,5-diketopiperazine (imDKP) by interpreting the nuclear magnetic resonance and high-resolution mass spectroscopy data. Approximately 4.8 mg of bmDKP and 3.1 mg of imDKP were isolated from 1.2 g of the S. praecox 291-11 crude extract. Eight different compositions of culture media were investigated for culture, the TBFeC medium being best for bmDKP and TCGC being the optimum for imDKP production. Two compounds respectively showed a 17.7 and 21 therapeutic ratio (LC50/EC50) to inhibit zoospores, and two compounds respectively showed a 263 and 120.2 therapeutic ratio to inhibit diatoms.
对 185 株海洋放线菌进行了筛选,以检测它们对海洋海藻百舌莼和污点硅藻 Navicula annexa 的防污活性。根据 16S rDNA 序列分析,从海藻 Undaria pinnatifida 根瘤中分离出的 291-11 株菌株显示出最高的防污活性,并被鉴定为 praecox 链霉菌。因此,菌株 291-11 被命名为 S. praecox 291-11。从 S. praecox 291-11 中分离出了防污化合物,并对其结构进行了分析。通过解释核磁共振和高分辨率质谱数据,确定了代表防污活性的化学成分为(6S,3S)-6-苄基-3-甲基-2,5-二酮哌嗪(bmDKP)和(6S,3S)-6-异丁基-3-甲基-2,5-二酮哌嗪(imDKP)。从 1.2 克 S. praecox 291-11 粗提取物中分离出约 4.8 毫克 bmDKP 和 3.1 毫克 imDKP。研究了八种不同成分的培养基,其中 TBFeC 培养基最适于生产 bmDKP,TCGC 培养基最适于生产 imDKP。两种化合物分别显示出 17.7 和 21 的治疗比(LC50/EC50)来抑制动物孢子,两种化合物分别显示出 263 和 120.2 的治疗比来抑制硅藻。