Epoxinnamide: An Epoxy Cinnamoyl-Containing Nonribosomal Peptide from an Intertidal Mudflat-Derived Streptomyces sp.

Abstract

Cinnamoyl-containing nonribosomal peptides (CCNPs) form a unique family of actinobacterial secondary metabolites and display various biological activi-ties. A new CCNP named epoxinnamide (1) was discovered from intertidal mudflat-derived Streptomyces sp. OID44. The structure of 1 was determined by the analysis of one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) data along with a mass spectrum. The absolute configuration of 1 was assigned by the combination of advanced Marfeys method, 3JHH and rotating-frame Overhauser effect spectroscopy (ROESY) analysis, DP4 calculation, and genomic analysis. The putative biosynthetic pathway of epoxinnamide (1) was identified through the whole-genome se-quencing of Streptomyces sp. OID44. In particular, the thioesterase domain in the nonribosomal peptide synthetase (NRPS) biosynthetic gene cluster was proposed as a bifunctional enzyme, which catalyzes both epimerization and macrocyclization. Epoxinnamide (1) induced quinone reductase (QR) activity in murine Hepa-1c1c7 cells by 1.6-fold at 5 μM. It also exhibited effective antiangiogenesis activity in human umbilical vein endothelial cells (IC50 = 13.4 μM).

신남산-포함 비리보솜 펩타이드 (cinnamoyl-containing nonribosomal peptide, CCNP)는 방선균의 독특한 이차대사물질군 중 하나로 다양한 생리활성을 나타낸다. 갯벌 퇴적물 유래 Streptomyces sp. OID44 균주가 신규 CCNP 물질인 epoxinnamide (1)를 생산하는 것을 발견하였다. 1의 구조는 1차원 (one-dimensional, 1D) 및 2차원 (two-dimensional, 2D) 핵자기공명분광법 (nuclear magnetic resonance, NMR)과 질량분석법 (mass spectrometry, MS)을 통해 결정하였다. 1의 절대적 입체배열은 advanced Marfeys method, 인접 수소-수소 간의 결합 상수(3JHH)와 ROESY (rotating-frame Overhauser effect spectroscopy) 분석, DP4 계산 및 유전체분석을 통하여 결정하였다. Streptomyces sp. OID44 균주의 전장유전체 분석 결과, epoxinnamide (1)의 생합성 경로를 예측하였다. 특히 비리보솜 펩타이드 합성효소 (nonribosomal peptide synthetase, NRPS) 생합성 유전자군 내의 thioesterase 도메인은 에피머화와 거대고리화 기능을 동시에 가지는 이기능성 도메인임을 제안하였다. Epoxinnamide (1)은 5 μM 농도에서 쥐의 Hepa-1c1c7 세포에서 퀴논 환원효소 (quinone reductase, QR) 활성이 1.6배 증가하도록 유도하였다. 또한 인간 제대정맥 내피세포에서 효과적인 항혈관신생 활성을 나타냈다 (IC50 = 13.4 μM).