density functional theory (DFT)-calculated data. In karamomycin C (4), the thiazole of 2 is connected to an unusual iminothiazolo[4,3- c][1,4]thiazepinone, for which we proposed a biosynthetic origin from two cysteine residues. It is closely related to ulbactin F; however, the heterocycle is enantiomeric to the latter and connected to phenol instead of 4-methoxy-1-naphthol. Karamomycins A (2) and C (4) were
分离出第一种天然的2-
萘-2-基-
噻唑衍
生物Karamomycins AC(2-4)以及可能的前体分子1-hydroxy-4-methoxy-2-naphthoic acid(1),尿
嘧啶1 -乙酰基-β-咔啉和来自地面放线菌菌株GW58 / 450的培养液中的
放线菌素C2,被鉴定为内生野村菌。这些化合物通过对其NMR和质谱(MS)数据进行分析来表征;通过比较13C NMR,NOESY和圆二色性(CD)光谱与密度泛函理论(DFT)计算的数据,确定2和4的绝对构型。在卡拉霉素C(4)中,
噻唑2与不寻常的亚
氨基
咪唑并[4,3- c] [1,4]
噻嗪酮有关,我们为此提出了两个半胱
氨酸残基的
生物合成来源。它与ulbactin F密切相关;然而,杂环是后者的对映异构体,并且与
苯酚而不是
4-甲氧基-1-萘酚连接。Karamomycins A(2)和C(4)具有细胞毒性。