Kanae Sakai

Agelamadins A and B, dimeric bromopyrrole alkaloids from a marine sponge Agelas sp.

Two structurally unique dimeric bromopyrrole alkaloids, agelamadins A (1) and B (2), were isolated from a marine sponge Agelas sp. Agelamadins A (1) and B (2) have a structure consisting of an agelastatin-like tetracyclic moiety and an oroidin-like linear moiety in common. The structures of 1 and 2 were elucidated on the basis of spectroscopic analysis. The antimicrobial activity and cytotoxicity of agelamadins A (1) and B (2) were evaluated.

Agelamadins C-E, bromopyrrole alkaloids comprising oroidin and 3-hydroxykynurenine from a marine sponge Agelas sp.

Three structurally unique bromopyrrole alkaloids, agelamadins C-E (1-3), were isolated from a marine sponge Agelas sp. Agelamadin C (1) possesses a hybrid structure of oroidin and 3-hydroxykynurenine connected through a dihydro-1,4-oxazine moiety. Agelamadins D (2) and E (3) are a C-9/C-10 diastereomer and a 10-epimer of 1, respectively. The structures of 1-3 were elucidated on the basis of spectroscopic analysis as well as application of a PGME method and a TDDFT ECD calculation. Antimicrobial activity of 1-3 was evaluated.

Genome sequence comparison of Aspergillus fumigatus strains isolated from patients with pulmonary aspergilloma and chronic necrotizing pulmonary aspergillosis

Aspergillus fumigatus is the Aspergillus species most commonly associated with aspergillosis. Of the various presentations of aspergillosis, one of the most frequently observed in cases involving A. fumigatus pulmonary infections is aspergilloma (PA). In such infections one finds a fungus ball composed of fungal hyphae, inflammatory cells, fibrin, mucus, and tissue debris. Chronic necrotizing pulmonary aspergillosis (CNPA), also known as semi-invasive or invasive aspergillosis, is locally invasive and predominantly seen in patients with mild immunodeficiency or with a chronic lung disease. In the present study, with the aid of a next-generation sequencer, we conducted whole genome sequence (WGS) analyses of 17 strains isolated from patients in Japan with PA and CNPA. A total of 99,088 SNPs were identified by mapping the reads to A. fumigatus genome reference strain Af293, and according to genome-wide phylogenetic analysis, there were no correlations between the whole genome sequence typing results and pathologic conditions of patients. Here, we conducted the first multi-genome WGS study to focus on the A. fumigatus strains isolated from patients with PA and CNPA, and comprehensively characterized genetic variations of strains. WGS approach will help in better understanding of molecular mechanisms of aspergillosis cases caused by A. fumigatus.

Prenylated Benzophenones from Triadenum japonicum

Six new prenylated benzophenones, (-)-nemorosonol (1) and trijapins A-E (2-6), were isolated from the aerial parts of Triadenum japonicum. (-)-Nemorosonol (1) and trijapins A-C (2-4) have a common tricyclo[4.3.1.0(3,7)]decane skeleton, while 1 is an enantiomer of (+)-nemorosonol previously isolated from Clusia nemorosa. The absolute configuration of (-)-nemorosonol (1) was assigned by ECD spectroscopy. Trijapins A-C (2-4) are analogues of 1 possessing an additional tetrahydrofuran ring. Trijapins D (5) and E (6) are prenylated benzophenones with a 1,2-dioxane moiety and a hydroperoxy group, respectively. (-)-Nemorosonol (1) exhibited antimicrobial activity against Escherichia coli (MIC, 8 μg/mL), Staphylococcus aureus (MIC, 16 μg/mL), Bacillus subtilis (MIC, 16 μg/mL), Micrococcus luteus (MIC, 32 μg/mL), Aspergillus niger (IC50, 16 μg/mL), Trichophyton mentagrophytes (IC50, 8 μg/mL), and Candida albicans (IC50, 32 μg/mL), while trijapin D (5) showed antimicrobial activity against C. albicans (IC50, 8 μg/mL).

Transcription factor Afmac1 controls copper import machinery in Aspergillus fumigatus

Copper (Cu) is an essential metal for all living organisms, although it is toxic in excess. Filamentous fungus must acquire copper from its environment for growth. Despite its essentiality for growth, the mechanisms that maintain copper homeostasis are not fully understood in filamentous fungus. To gain insights into copper homeostasis, we investigated the roles of a copper transcription factor Afmac1 in the life-threatening fungus Aspergillus fumigatus, a homolog of the yeast MAC1. We observed that the Afmac1 deletion mutant exhibited not only significantly slower growth, but also incomplete conidiation including a short chain of conidia and defective melanin. Moreover, the expressions of the copper transporters, ctrA1, ctrA2, and ctrC, and metalloreductases, Afu8g01310 and fre7, were repressed in ∆Afmac1 cells, while those expressions were induced under copper depletion conditions in wild-type. The expressions of pksP and wetA, which are, respectively, involved in biosynthesis of conidia-specific melanin and the late stage of conidiogenesis, were decreased in the ∆Afmac1 strain under minimal media condition. Taken together, these results indicate that copper acquisition through AfMac1 functions in growth as well as conidiation.

Amphidinins C–F, Amphidinolide Q Analogues from Marine Dinoflagellate Amphidinium sp.

Four new polyketides, amphidinins C-F (1-4), have been isolated from the culture broth of symbiotic dinoflagellate Amphidinium sp. The analysis of their spectral data revealed that amphidinins C-F (1-4) were 4,5-seco-analogues of amphidinolide Q (5). The absolute configurations of the new compounds were elucidated by the combination of J-based configuration analysis, modified Moshers method, and chemical derivatization. Amphidinins D (2) and F (4) are the first glycosides related to amphidinolides. Amphidinins C-F (1-4) showed antimicrobial activity against bacteria and/or fungi.

Hyrtinadines C and D, New Azepinoindole-Type Alkaloids from a Marine Sponge Hyrtios sp.

New bisindole alkaloids, hyrtinadines C (1) and D (2), have been isolated from an Okinawan marine sponge Hyrtios sp. The structures of hyrtinadines C (1) and D (2) were elucidated based on analyses of the spectral data. Hyrtinadines C (1) and D (2) were the relatively rare alkaloids possessing a 3,4-fused azepinoindole skeleton. Hyrtinadines C (1) and D (2) showed antimicrobial activity.

Visual analysis of DNA microarray data for accurate molecular identification of non-albicans Candida isolates from patients with candidemia episodes.

ABSTRACT The performance of a visual slide-based DNA microarray for the identification of non-albicans Candida spp. was evaluated. Among 167 isolates that had previously been identified by Vitek 2, the agreement between DNA microarray and sequencing results was 97.6%. This DNA microarray platform showed excellent performance.

Identification and Functional Analysis of the Nocardithiocin Gene Cluster in Nocardia pseudobrasiliensis

Nocardithiocin is a thiopeptide compound isolated from the opportunistic pathogen Nocardia pseudobrasiliensis. It shows a strong activity against acid-fast bacteria and is also active against rifampicin-resistant Mycobacterium tuberculosis. Here, we report the identification of the nocardithiocin gene cluster in N. pseudobrasiliensis IFM 0761 based on conserved thiopeptide biosynthesis gene sequence and the whole genome sequence. The predicted gene cluster was confirmed by gene disruption and complementation. As expected, strains containing the disrupted gene did not produce nocardithiocin while gene complementation restored nocardithiocin production in these strains. The predicted cluster was further analyzed using RNA-seq which showed that the nocardithiocin gene cluster contains 12 genes within a 15.2-kb region. This finding will promote the improvement of nocardithiocin productivity and its derivatives production.

Hikiokoshins A-I, diterpenes from the leaves of Isodon japonicus.

Diterpenes, hikiokoshins A-I, and twelve known diterpenes were isolated from the leaves of Isodon japonicus (Burm. f.) H. Hara (Lamiaceae). The hikiokoshins A-I possess various skeletons such as ternifonane {hikiokoshin A}, ent-6,7:8,15-diseco-6,8-cyclokauran-7,20-olide {hikiokoshin B}, ent-6,7-secokauran-7,20-olide {hikiokoshin C}, and ent-7,20-epoxykaurane {hikiokoshins D-I}. Their structures were elucidated on the basis of spectroscopic analysis. Antimicrobial activities of hikiokoshins A and B were evaluated.