Ken-ichi Kawai

Studies on fungal products. Part 8. Isolation and structure of emestrin, a novel antifungal macrocyclic epidithiodioxopiperazine from Emericella striata. X-Ray molecular structure of emestrin

Together with ergosterol, sterigmatocystin, and emericellin, a new compound designated emestrin (1), C27H22H2O10S2, was isolated from the mycelial extract of Emericella striata. Violaceic acid (6) was also isolated from the culture filtrate. The structure of emestrin (1), including the absolute configuration, was determined on the basis of a spectroscopic investigation of some derivatives and X-ray crystallography of emestrin methanol solvate. Emestrin is a new macrocyclic epidithiodioxopiperazine, derived from two molecules of phenylalanine and one molecule of benzoic acid, and has strong antifungal activity.

Penicillide and dehydroisopenicillide from Talaromyces derxii

Abstract Penicillide and dehydroisopenicillide were isolated from Talaromyces derxii cultivated on rice. The structure of dehydroisopenicillide was determined by spectroscopic methods, and the absolute configuration of penicillide was confirmed by the ‘partial resolution’ method of Horeau.

New penicillide derivatives isolated from Penicillium simplicissimum

Two new penicillide derivatives, secopenicillides A (3) and B (4), were isolated along with penicillide (1) and purpactin A (2), and altenusin (5) and dehydroaltenusin (6), the antifungal substances of this fungus, from the extract of Penicillium simplicissimum IFM 53375. The absolute structures of 3 and 4 were determined by spectroscopic investigation and chemical correlation to penicillide (1). The absolute configuration of purpactin A (2) was determined by the chemical method.

Isolation of a new potent cytotoxic pigment along with indigotin from the pathogenic basidiomycetous fungus Schizophyllum commune

An indole derivative, schizocommunin, was isolated along with indigotin (indigo), indirubin, isatin, and tryptanthrin, from the liquid culture medium in which a culture of Schizophyllum commune, isolated from the bronchus of a human patient with allergic bronchopulmonary mycosis, had been grown. The structure of schizocommunin was established by spectroscopic investigation. Schizocommunin showed the strong cytotoxicity against murine lymphoma cells. The assignments of the 1H- and 13C-NMR signals of indigotin were also listed.

Indoloditerpenes related to tremorgenic mycotoxins, penitrems, from Penicillium crustosum

Abstract Recently the minor metabolises, PC-M5′and PC-M6, were isolated along with the tremorgenic mycotoxins, penitrems A–F, from the mycelium of Pencillium crustosum , which was found contaminating bread intended for school lunches in Tokyo city. Two new indoloditerpenes, PC-M4 and PC-M5, were also isolated from the above fungus. The structures of these two compounds were determined on the basis of spectroscopic investigations. PC-M4 has the same carbon number as the penitrems but a different cyclic ring system. PC-M5 might be a biosynthetic precursor of penitrems and PC-M4 as may also PC-M5′ and PC-M6.

New Vermistatin Derivatives Isolated from Penicillium simplicissimum

Four new vermistatin derivatives, dihydrovermistatin (1), acetoxydihydrovermistatin (2), hydroxydihydrovermistatin (3), and penisimplicissin (4) were isolated along with vermistatin (5), penicillide, and funicone from theextract of Penicillium simplicissimum IFM 53375. The structures of 1 - 4 were determined by spectroscopic and chemical methods.

A dioxopiperazine derivative from Penicillium megasporum

Abstract Megasporizine, a new dioxopiperazine derivative, has been isolated from Penicillium megasporum NHL 2977, together with physcion (parietin), 7-hydroxy-4,6-dimethylphthalide, asperphenamate, and phyllostine. Megasporizine was also isolated from the strains NRRL 2232 and ATCC 48997 along with physcion, asperphenamate, and penicillic acid. The structure of megasporizine has been investigated by spectroscopic means. Megasporizine is a dioxopiperazine which has a methoxy group at the α-carbon of an amino acid residue.

A new indoloditerpene derivative, penijanthine A, isolated from Penicillium janthinellum

In a screen searching for new bioactive agents, a new indoloditerpene, penijanthine A (1), was isolated from Penicillium janthinellum IFM 55557. The structure of 1 was established on the basis of spectroscopic and chemical investigation, as well as detailed comparison with the spectroscopic and physico-chemical data of paxilline (2), which was isolated along with 1.

Antifungal cyclic depsipeptide, eujavanicin A, isolated from Eupenicillium javanicum.

In the course of searching for new antifungal agents, a new cyclic depsipeptide, eujavanicin A (1), was isolated from Eupenicillium javanicum as an antifungal agent against the human pathogenic filamentous fungus Aspergillus fumigatus. The structure of 1 was established by spectroscopic and chemical investigations. The absolute stereochemistry was elucidated by Marfeys method and by chiral HPLC analysis.

Three pyrrolyloctatetraenyl-α-pyrones from Auxarthron conjugatum

The red pigments, auxarconjugatins A, B and C, were isolated from mycelia of Auxarthron conjugatum, an ascomycetous fungus belonging to the Onygenaceae, in which the causative fungi of severe mycoses also belong. The structures of auxarconjugatins A, B and C, including the stereochemistry of the conjugated tetraene, were established by spectroscopic analyses. These compounds were in equilibrium with a few double bond stereoisomers of the double bonds when dissolved in MeOH or MeCN.