We now would like to report briefly that a new type of pyrazine metabolite (I) which is hydroxylated on β-position of an isobutyl side chain has first been isolated as a fungal product from a strain of A. ochraceus together with flavacol and neoaspergillic acid. Colorless needles of I, mp 122.5—123° were afforded by crystallization from ethyl acetate of an eluate with CHCl3 in silica gel chromatography and its molecular formula, C12H20O2N2 was given by mass spectrometry (M+ m/e 224) and elementary analysis (found: C, 64.49%; H, 9.35%; N, 12.50%). Pale purple fluorescence was observed under ultraviolet light but negative with FeCl3 solution. Ultraviolet absorption spectrum of I in ethanol showed a close resemblance to that of flavacol in which the absorption maxima at 230 (ε 5016) and 326.5 (ε 5528) nm were observed. The presence of hydroxyl and amide groups was suggested by infrared absorption spectrum: IRKBr cm-1 3290, 2945, 1907, 1634, 1520, 1464, 1364, 1174. It was thus indicated from above spectral data that 2-hydroxypyrazine ring would be contained in its structure. Furthermore, in nuclear magnetic resonance (NMR) spectrum, signals at 0.99 (6H, doublet, J=6.5 Hz), 2.47 (1H, multiplet) and 2.89 ppm (2H, doublet, J=6.5 Hz) were observed, indicating the presence of an isobutyl group. On the other hand, two singlets at 1.37 (6H) and 2.75 ppm (2H) suggested an another presence of isobutyl side chain in which the carbon atom bearing two methyl groups might be substituted. A singlet of one proton on pyrazine ring was observed at 7.40 ppm also in the spectrum. In addition, the observation of the peaks of m/e 166 (C9H14ON2) and 59 (base peak, C3H6OH) other than 224 (parent peak) and 123 (C6H7ON2) in mass spectrometry supported a supposition that the hydroxyl was present at β-position of one of the side chain. By comparing with the NMR data of flavacol, it would therefore be probable to assume that the substitution of the hydroxylated side chain on pyrazine ring should be on 6 but not 3. Conclusively the structure of newly isolated pyrazine metabolite was postulated as being I. Of interest is that I is the first pyrazine compound having hydroxyl group on the β-carbon of side chain in contrast to that all of the hydroxyl on side chain of the fungal pyrazines having been known in attached to the α-carbon. As a plausible way of β-hydroxylation,a following route may be considered: α-hydroxylation->dehydration->re-hydroxylation on β-carbon (via epoxidation and reduction?). Besides above three metabolities, a red pigment, mp 129—133° (reaflets from aq. acetone) has been isolated from ethyl acetate extract of mycelia by silica gel column chromatography. By treatment of the pigment with 2N NaOH-MeOH, dark brown precipitates were obtained and subsequently determined as ferric hydroxide by coloring with ferrocyanide ion. From the filtrate, colorless needles of neoaspergillic acid, mp 123—125° were obtained and identified with authentic specimen by comparison of the spectral data and mixed fusion. The isolation of pyrazine metabolites from Aspergillus ochraceus WILH. IFM 4443 has been reported in our preceding paper. Besides above pyrazines, a colorless crystalline compound has now been isolated by silica gel column chromatography of chloroform extract from culture filtrates of the same fungus. By culturing the fungus in 40 liter of liquid media, 32 mg of the compound was yielded. The compound (Ia) was obtained as colorless needles, mp >300° by recrystalization from methanol. Blue fluorescence was shown under ultraviolet (UV) light but negative with FeCl3. From the resemblance of the character on thin-layer chromatography including its fluorescent property and the fact that the various isocoumarin metabolites have been isolated from this fungus, Ia seems to be an isocoumarin derivative.