Aya Nagai

New sesquiterpenes, JBIR-27 and -28, isolated from a tunicate-derived fungus, Penicillium sp. SS080624SCf1

In the course of our screening program for novel metabolites from tunicate-derived fungi, novel sesquiterpenoids, named JBIR-27 (1) and -28 (2), together with known sporogen-AO1 and phomenone, were isolated from the culture broth of Penicillium sp. SS080624SCf1. The structures of 1 and 2 were determined to be eremophilane analogs on the basis of extensive NMR and MS analyses. Sporogen-AO1, phomenone and 2 showed cytotoxicity against human cervical carcinoma cell line HeLa at IC50 values of 8.3, 19 and 92 μM, respectively, whereas 1 was inactive at a concentration of 80 μM.

New Aureothin Derivative, Alloaureothin, from Streptomyces sp. MM23

A new polypropionate alloaureothin (1) possessing a nitro group, together with a known polypropionate aureothin (2), was isolated from mycelium of Streptomyces sp. MM23. The structure was determined on the basis of spectroscopic data. 1 exhibited growth inhibitory effect against human fibrosarcoma HT1080 cells with an IC50 value of 30 μM.

JBIR-37 and -38, Novel Glycosyl Benzenediols, Isolated from the Sponge-Derived Fungus, Acremonium sp. SpF080624G1f01

In the course of our chemical screening program for new secondary metabolites, we isolated new compounds JBIR-37 (1) and -38 (2) from a culture broth of the marine sponge-derived fungus, Acremonium sp. SpF080624G1f01. The structures of 1 and 2 were determined to be di- and mono-O-β-D-glucopyranosyloxy-4-(1,1-dimethyl-2-propenyl)benzene on the basis of extensive NMR and MS spectroscopic data, respectively.

Anti-Influenza Virus Compound from Streptomyces sp. RI18

Screening for anti-influenza virus activity in compounds isolated from Streptomyces sp. RI18, which was isolated using the membrane filter method, uncovered a novel compound, JBIR-68 (1), which contains a unique skeleton. Its structure was established by extensive NMR and MS analyses. In addition, 1 was synthesized to confirm the configuration of its sugar moiety. Compound 1 inhibited influenza virus growth in plaque assays.

A Novel Antimycin-like Compound, JBIR-06, from Streptomyces sp. ML55

A novel compound of antimycin family, JBIR-06 (1), was isolated from Streptomyces sp. ML55. The structure of 1 was established as a twelve-membered macrocyclic skeleton with a 3-(formylamino)-2-hydroxybenzamide based on the spectroscopic data. Compound 1 inhibited the expression of GRP78 induced by 2-deoxyglucose at the IC50 value of 250 nM.

Streptomyces aomiensis sp. nov., isolated from a soil sample using the membrane-filter method

A Gram-positive actinobacterium, designated M24DS4(T), was isolated from a soil sample collected from Aomi, Tokyo, Japan, using the membrane-filter method. Strain M24DS4(T) exhibited low 16S rRNA gene sequence similarity (96.1 %) with Streptomyces scabrisporus NBRC 100760(T). Cell hydrolysates contained the ll-isomer of diaminopimelic acid and the predominant quinones were MK-9(H(8)) and MK-9(H(6)). The genomic DNA G+C content was 75 mol%. Comparison of the characteristics of strain M24DS4(T) and related members of the genus Streptomyces with validly published names showed that the strain represents a novel species of the genus, for which the name Streptomyces aomiensis sp. nov. is proposed. The type strain is M24DS4(T) ( = NBRC 106164(T)  = KACC 14925(T)).

New angucycline C -glycosides from Streptomyces sp. RI33

In the course of our screening program for anticancer agents from natural sources, five new angucyclines, JBIR-90 (1), -116 (2), -91 (3), -92 (4) and -93 (5), were isolated from the fermentation broth of Streptomyces sp. RI33. The structures of 1–5 were elucidated on the basis of 1D and 2D NMR spectroscopy and MS analyses. Compounds 2–4 showed cytotoxic activities against malignant pleural mesothelioma cells at IC50 values of 20–50 μM.

Novel 24-membered macrolides, JBIR-19 and -20 isolated from Metarhizium sp. fE61

In the course of our screening program for active compounds that induce cell morphological changes of Saccharomyces cerevisiae, the culture broth of an entomopathogenic fungus Metarhizium sp. fE61 exhibited a unique morphological phenotype. We conducted an activity-guided isolation from the fermentation broth of Metarhizium sp. fE61 to yield two new macrolide compounds named JBIR-19 (1) and -20 (2) as active substances. Their structures were determined to be 24-membered macrolide analogs containing a 2-aminoethyl phosphate ester on the basis of NMR and other spectroscopic data. Compounds 1 and 2 induced striking elongated morphology of S. cerevisiae at concentrations of 3.1 and 13 μM, but showed weak antiyeast activity at MICs of 200 and >200 μM, respectively.

JBIR-12, a novel antioxidative agent from Penicillium sp. NBRC 103941

In the course of our screening program for active compounds from fungal metabolites, we isolated JBIR-12 (1) as a free radical scavenger from the culture broth of Penicillium sp. NBRC 103941. Structure elucidation of 1 was carried out using methylated and/or acetylated derivatives of 1. As a consequence, the structure of 1 was determined to be a novel highly oxygenated tetrahydronaphthalene species attached to an acyl chain moiety on the basis of NMR and other spectroscopic data. It was interesting that 1 was spontaneously methylated when left in methanol. Furthermore, isomerization or rearrangements could occur during the derivatization of 1. Compound 1 exhibited potent radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl radical with an IC50 value of 75 μM.

JBIR-137 and JBIR-138, new secondary metabolites from Aspergillus sp. fA75.

Natural products are considered to be good sources for the screening of lead compounds of clinical drugs. We performed many drug screenings employing a variety of assay systems with crude extracts of microbial cultures as a traditional natural product library. In some assay systems, effective application of our crude extract library was difficult without making some improvements. From this viewpoint, we started to construct a purified natural compounds library from cultures of microorganisms. To achieve this, we established the highthroughput detection system for microbial secondary metabolites using UPLC-UV-evaporative light-scattering (ELS)-MS system, and more than 1000 compounds, which we have already isolated, were analyzed by the common analytic method and in our database. The registered compounds in microbial cultures are automatically identified with our system, which allows us easily to pick up unregistered compounds. The unregistered compounds are isolated from the cultures and store in our library. Because Aspergillus species are known to produce more than 950 documented bioactive compounds such as mevinolin, aflatoxin and citrinin,1 their secondary metabolites are an important source to obtain various bioactive compounds. Therefore, we attempted to obtain secondary metabolites from cultures of Aspergillus. During chemical screening based on our analytic system, we isolated a new janthitrem derivative named JBIR137 (1) and a novel metabolite JBIR-138 (2), together with the known compounds, a tremorgenic agent janthitrem B2 and 6-hydroxycyclopiamine B3 from the culture of Aspergillus sp. fA75 (Figure 1). This paper describes the fermentation, isolation, structural elucidation, and briefly, biological activity of 1 and 2. Aspergillus sp. fA75 was isolated from a soil sample collected in the forest at Noda, Chiba Prefecture, Japan. The strain was cultivated in 50-ml test tubes, each containing 15 ml potato dextrose medium (24 g l–1; BD Biosciences, San Jose, CA, USA). The test tubes were shaken reciprocally (320 r.p.m.) at 27 1C for 2 days. Aliquots (4 ml) of the culture were transferred to 500-ml Erlenmeyer flasks containing brown rice 15 g (Akitakomachi, Yamagata, Japan), bacto–yeast extract 30 mg (BD Biosciences), sodium tartarate 15 mg, K2HPO4 15 mg and water 45 ml. The flasks were incubated statically at 27 1C for 14 days. The culture (10 flasks) was extracted with 80% aq. Me2CO (200 ml per flask), and the extract was filtered. After concentration in vacuo, the aqueous residue was extracted with EtOAc (600 ml 3). The EtOAc layer was dried over anhydrous Na2SO4 and evaporated in vacuo, yielding a dark brown gum (815 mg). The extract was fractionated using normal-phase medium-pressure liquid chromatography (Purif-Pack SI-30, Shoko Scientific Co., Yokohama, Japan) with a gradient system of n-hexane–EtOAc (0–25% EtOAc) followed by the stepwise solvent system of CHCl3–MeOH (0, 2, 5, 10, 20, 30 and 100% MeOH) to obtain five fractions (5% fraction-1, 5% fraction-2, 5% fraction-3, 10 and 20–30%). The fractions were monitored by UPLC-UV-ELS-MS system. Compound 1 was isolated from the 5% MeOH fraction-1 (26.5 mg) by reversed-phase HPLC using a CAPCELL PAK C18 MG II column (5.0mm, 20 i.d. 150 mm; Shiseido, Tokyo, Japan) with 85% aq. MeOH containing 0.1% formic acid (flow rate 10 ml min–1, Retention time (Rt)1⁄4 11.6 min). From the 5% MeOH fraction-2 (89.1 mg), janthitrem B2 (5.0 mg) was isolated by HPLC preparation. The 5% MeOH fraction-3 (45.6 mg) was applied to gel filtration chromatography (Sephadex LH-20, GE Healthcare BioSciences AB, Uppsala, Sweden) eluting with CHCl3–MeOH (1:1) to yield crude 2 (45.6 mg). The obtained material was further purified by the HPLC (40% aq. MeOH containing 0.1% formic acid, Rt1⁄4 17.3 min) to yield pure 2 (9.9 mg). The 6-hydroxycyclopiamine B3 (3.7 mg) was purified from the 20–30% MeOH fraction (124.7 mg) using LH-20 column chromatography and HPLC. JBIR-137 (1) was obtained as a colorless amorphous solid: [a]22-66 (MeOH; c 0.13); UV lmax nm (e): 281 (30 300), 290 (32 200) and 374 (5800) in MeOH; IR (nmax): 3400 (hydroxy), 1618, 1455, 1371 (aromatic and pyrrole) cm 1. Its molecular formula was determined