The Myxomycetes (true slime molds) are an unusual group of primitive organisms that may be assigned to one of the lowest classes of eukaryotes. As their fruit bodies are very small and it is very difficult to collect much quantity of slime molds, chemical studies on the secondary metabolites of the myxomycetes to date have been limited. Early explorative studies carried out by Steglich 1) and Asakawa's 2)groups have demonstrated that myxomycetes have developed a rather unique secondary metabolism. During our studies on the search for natural products from myxomycetes, 3) we recently investigated a field-collected sample of fruit bodies of Lindbladia tubulina. Here we describe the isolation and structure elucidation of three naphtoquinone pigments, lindbladione (1), 7-methoxylindbladione (2), and 6,7-dimethoxylindbladione (3). The name and structure of lindbladione (1) were found in a symposium proceedings by Steglich's group, 1) but a SciFinder ® search found no description of experimental details or spectral data of compound 1 in the literature. This is the first report on full characterizations of compound 1 and isolation of two new compounds 2 and 3.The fruit bodies of Lindbladia tubulina, collected in Kochi Prefecture, Japan, were extracted with MeOH. The MeOH extract was partitioned between EtOAc and water, and the water-soluble fraction containing pigments was then subjected to chromatography on ODS and/or Sephadex LH-20, followed by further purification with HPLC on ODS to give three pigments (1-3).Lindbladione (1) was obtained as a dark brown solid, and shown to have the molecular formula C 16 H 14 O 7 by the high resolution (HR)-FAB-MS data (m/z 319.0816, [MϩH] ϩ , D Ϫ0.1 mmu). The UV spectrum of 1 showed absorption maxima at 265 and 367 nm, which were shifted to 271 and 379 nm, respectively, with the addition of alkali (NaOH), indicating the presence of phenol group(s). The 13 C-NMR spectrum of 1 (Table 1) H-1 H correlation spectroscopy (COSY) spectrum. Since eight out of ten unsaturation degrees were accounted for by 13 C-NMR data, 1 was inferred to have two rings. The presence of the npropyl group was further corroborated by the heteronuclear multiple bond connectivity (HMBC) correlations (from H 3 -16 to C-15 and C-14, from H 2 -15 to C-16 and C-14, and from H 2 -14 to C-16 and C-15), and this n-propyl group was shown to be attached to the carbonyl group resonating at d C 206.4 (C-13) by the HMBC correlations (from H 2 -14 to C-13 and from H 2 -15 to C-13). In the HMBC spectrum of 1, one olefinic proton at d H 8.07 (H-11) showed long-range connectivities with two carbonyl carbons at d C 206.4 (C-13) and 189.6 (C-4) and also with sp 2 carbons at d C 176.4 (C-2) and 122.5 (C-12), while another olefinic proton at d H 7. 45 (H-12) showed correlations with the carbonyl carbon at d C 206.4 (C-13) and the sp 2 carbon at d C 113.3 (C-3). From these observations, a 3-oxo-hex-1-enyl group was inferred to be at- * To whom correspondence should be addressed. Kochi 780-8039, Japan: and c The Kitasato Ins...

Three new naphthoquinone pigments, 6,7-dimethoxydihydrolindbladione (1), dihydrolindbladione (2), and 6-methoxydihydrolindbladione (3), have been isolated from a myxomycete Lindbladia tubulina, and their structures were elucidated by spectral data. Compound 3 appreciably exhibited a reversal effect of multidrug resistance. Lindbladione (4), the major pigment of this myxomycete, was also isolated from Cribraria intricata.

Other natural productsOther natural products U 0800 Lindbladione and Related Naphthoquinone Pigments from a Myxomycete Lindbladia tubulina. -(ISHIKAWA, Y.; ISHIBASHI*, M.; YAMAMOTO, Y.; HAYASHI, M.; KOMIYAMA, K.; Chem.