Kazuyoshi Ohashi

Sesamin suppresses activation of microglia and p44/42 MAPK pathway, which confers neuroprotection in rat intracerebral hemorrhage.

Thrombin plays important roles in the pathology of intracerebral hemorrhage (ICH). The recruitment of activated microglia, accompanied by thrombin-induced phosphorylation of the mitogen-activated protein kinase (MAPK) family, contributes to ICH-associated neuron loss. Here we investigated the possibility that sesamin, a lignan of sesame seed oil, is a natural candidate as an inhibitor of microglial activation and MAPK pathways under ICH insults. Sesamin (30-100 μM) suppressed thrombin-induced nitric oxide (NO) production by primary-cultured rat microglia via inhibition of inducible NO synthase (iNOS) protein expression, independently of the antioxidative effect. Sesamin selectively inhibited p44/42 MAPK phosphorylation in the MAPK family (p38 and p44/42) involved in iNOS protein expression in primary-cultured rat microglia. An in vivo rat ICH model was prepared by intrastriatal injection of 0.20U collagenase type IV unilaterally. ICH evoked the phosphorylation of p44/42 MAPK, microglial proliferation with morphological change into the activated ameboid form, and neuron loss. The phosphorylation of p44/42 MAPK was inhibited by intracerebroventricular administration of 30-nmol sesamin. Sesamin prevented ICH-induced increase of microglial cells in the perihematomal area. Notably, ramified microglia, the resting morphology, were observed in brain sections of the animals administrated sesamin. Sesamin furthermore achieved neuroprotection in the perihematomal area but not in the hematomal center. These results suggest that sesamin is a promising natural product as a novel therapeutic strategy based on the regulation of microglial activities accompanied by the activated p44/42 MAPK pathway in ICH.

Composition of the endophytic filamentous fungi isolated from the tea plant Camellia sinensis

It has been found by ribosomal DNA analysis that the endophytic filamentous fungi isolated from the tea plant Camellia sinensis (Theaceae) are composed of six groups; one Fusarium sp., one Penicillium sp., two Schizophyllum sp., and two Diaporthe sp..

Ability of endophytic filamentous fungi associated with Cinchona ledgeriana to produce Cinchona alkaloids

We have investigated the ability of endophytic filamentous fungi associated with Cinchona ledgeriana (Rubiaceae) to produce Cinchona alkaloids on potato dextrose agar medium and in a synthetic liquid medium. It was found that all twenty-one endophytic fungi produce Cinchona alkaloids, despite their genetic differences.

Composition of endophytic fungi living in Cinchona ledgeriana (Rubiaceae).

A total of 21 endophytic filamentous fungi were isolated from the young stems of Cinchona ledgeriana (Rubiaceae) cultivated in West Java, Indonesia. They were classified into six genera, namely nine Phomopsis spp., six Diaporthe spp., two Schizophyllum spp., two Penicillium spp., one Fomitopsis sp., and one Arthrinium sp. by using nucleotide sequence analysis of the internal transcribed spacers (ITS1 and ITS2) including 5.8S ribosomal DNA region and phylogenetic analysis.

A complex of perseitol and K+ ion from Scurrula fusca (Loranthaceae)

A complex of perseitol (d-glycero-d-galacto-heptitol) and K+ ions in a molar ratio of 20:1 was isolated from the leaves of Scurrula fusca (Loranthaceae). The stereochemical structure of the complex was determined using several kinds of NMR techniques.

Artemisioside, a new monoterpene glucoside from the aerial parts of Artemisia ordosica (Asteraceae)

A new monoterpene glucoside, artemisioside, was isolated from the aerial parts of Artemisia ordosica Krasch. (Asteraceae). The chemical structure was elucidated from physicochemical data and by the application of Klyne’s rule.

Comparison of Curcuma sp. in Yakushima with C. aeruginosa and C. zedoaria in Java by trnK gene sequence, RAPD pattern and essential oil component

As the result of a comparison of Curcuma sp. (Gajutsu in Japanese) in Yakushima Island, Japan, with Curcuma aeruginosa and C. zedoaria in Java, Indonesia, by trnK gene sequence, random amplified polymorphic DNA (RAPD) pattern and essential oil component, it is indicated that Curcuma sp. in Yakushima is more closely related to C. aeruginosa than to C. zedoaria.

Composition of the endophytic filamentous fungi associated with Cinchona ledgeriana seeds and production of Cinchona alkaloids

Four kinds of endophytic filamentous fungi (code names: CLS-1, CLS-2, CLS-3, and CLS-4) associated with the seeds of Cinchona ledgeriana (Rubiaceae) from West Java, Indonesia, were isolated. All of the isolates were classified into Diaporthe spp. based on phylogenetic analysis of the nucleotide sequences of the internal transcribed spacers (ITS1 and ITS2) including the 5.8S ribosomal DNA region. All four of these endophytic fungi produce Cinchona alkaloids, mainly quinine and quinidine, in synthetic liquid medium.

Bioproduction of bile acids and the glycine conjugates by Penicillium fungus

It has been found that the Penicillium endophytic filamentous fungus with the young stems of Scurrula atroprupurea (Loranthaceae) produces cholic acid, deoxycholic acid and the glycine conjugates.

Curcuma sp.‐derived dehydrocurdione induces heme oxygenase‐1 through a Michael reaction between its α, β‐unsaturated carbonyl and Keap1

To elucidate the anti‐inflammatory mechanism of Curcuma sp., we investigated whether dehydrocurdione, a sesquiterpene contained in Curcuma sp., induces heme oxygenase (HO)‐1, an antioxidative enzyme, in RAW 264.7 macrophages. Dehydrocurdione was extracted from the rhizome of Curcuma sp., and its purity was verified by high performance liquid chromatography. Treatment with 10–100 μM dehydrocurdione transiently and concentration‐dependently increased HO‐1 mRNA and protein levels. Docking simulation suggested the presence of the Michael reaction between dehydrocurdione and Kelch‐like ECH‐associated protein (Keap)1 keeping nuclear factor‐erythroid2‐related‐factor (Nrf)2, a transcription factor, in the cytoplasm. Nrf2 that was definitely free from Keap1 was detected in the nuclei after dehydrocurdione treatment. Subsequently, the HO‐1 E2 enhancer, a target of Nrf2, was activated, resulting in HO‐1 expression. Also, an investigation using 6‐shogaol and 6‐gingerol supported the concept that the α, β‐unsaturated carbonyl structure plays an important role in the interaction with Keap1. Dehydrocurdione suppressed lipopolysaccharide‐induced NO release, a marker of inflammation. Clarification of the HO‐1 synthesis increase mechanism revealed in this study will help contribute to the development of novel phytotherapeutic strategies against inflammation‐associated diseases.