The fruiting bodies of Isaria fungi have been traditionally used in Korea to treat cancer. An apoptosis-inducing compound, 4-acetyl-12,13-epoxyl-9-trichothecene-3,15-diol, was isolated from the methanol extract of fruiting bodies of Isaria japonica YASUDA by bioassay-guided fractionation. The apoptosis of the human leukemia cells (HL-60) by the compound was accessed by propidium iodide-staining flow cytometric analysis, and apoptosis-inducing activity at IC 50 concentration (10 nmol/l) was further confirmed by a nuclear morphological change, a ladder pattern of internucleosomal DNA fragmentation, and an activation of caspase-3.Key words Isaria japonica YASUDA; human HL-60 leukemia cell; 4-acetyl-12,13-epoxyl-9-trichothecene-3,15-diol; apoptosis japonica were inoculated into potato dextrose agar, and incubated at 25°C until the fungal colony grow to 5 cm in diameter. It usually took 10 d, and the colony turned gray. The cultures were then refrigerated at approximately 4°C, and used as stock cultures. In the second culture, a 1 l flask, containing 500 ml of culture medium, which had been sterilized at 121°C for 20 min and then cooled to 15°C, was inoculated with four 5-mm agar plugs taken from stock cultures. The flask culture was aerated by agitation on an orbital shaker at 140 rpm for a period of 3 d at 25°C, then at 160 ppm for 4 d. The culture medium consists of potato (200 g/l) and sugars (30 g/l). All cultures were conducted in the dark room. The third fermentation was carried out in the pupae of the silkworm (100 g). The fermentation media were autoclaved at 121°C for 40 min. After the media had cooled to 15°C, they were inoculated with 5 ml of spore inoculum and incubated for 8 d at 25°C in the dark room. After 8 d of cultivation, the culture condition was changed to 60% humidity for 10 d in the dark room, then 80% humidity at 20°C in 2000 lux of brightness for 30 d. After incubation, the fruiting bodies of the fungi were harvested, and extracted with MeOH for further chemical and biological investigations.Isolation and Structure Determination of 4-Acetyl-12,13-epoxy-9-trichothecene-3,15-diol The air-dried fruiting bodies (226 g) from the fermentation of I. japonica were extracted with methanol (MeOH) for 48 h. The MeOH extract was concentrated, suspended in H 2 O, and sequentially partitioned with n-hexane, CH 2 Cl 2 , and ethyl acetate (EtOAc). The EtOAc-soluble fraction (247.5 mg) was subjected to C18 flash column chromatography with a stepwise gradient of 30 to 100% (v/v) MeOH in H 2 O. The fractions eluting at 30% and 40% MeOH in H 2 O (36.8 mg) were combined, and subjected to preparative reversed-phase HPLC using a gradient from 15 to 35% CH 3 CN in H 2 O over 40 min, then 100% CH 3 CN for 10 min (Alltech HS Hyperprep 100 BDS C 18 (1.0ϫ25 cm; 8-mm particle size; 2 ml/min; UV detection at 210 nm)) to yield compound 1 (12.3 mg). The structure of compound 1 was identified as 4-acetyl-12,13-epoxy-9-trichothecene-3,15-diol (AEDT) by the comparison of MS and NMR data with those reported in the literature ...

(3R,6R)-4-methyl-6-(1-methylethyl)-3-phenylmethylperhydro-1,4-oxazine-2,5-dione (1) was isolated from the fruiting bodies of Isaria japonica as an apoptosis-inducing agent. The complete structural assignment of the compound was accomplished on the basis of spectroscopic methods and chemical transformations. Compound 1 induced apoptotic cell death of the human leukemia cells (HL-60) in a dose-dependent manner, ranging from 5.0 microg/ml to 100.0 microg/ml.

We studied the effect of 4-acetyl-12,13-epoxyl-9-trichothecene-3, 15-diol (AETD) isolated from Isaria japonica, one of the most popular Chinese fungal medicines, on the induction of apoptosis in rat bladder carcinoma NBT-II cells. AETD was cytotoxic to NBT-II cells, and this cytotoxic effect appears to be attributed to its induction of apoptotic cell death, as AETD induced nuclear morphological changes and internucleosomal DNA fragmentation, and increased the proportion of hypodiploid cells and activity of caspase-3. AETD treatment also decreased the expression of the anti-apoptotic protein Bcl-2 and increased the expression of the pro-apoptotic protein Bax. These results provide important information in understanding the mechanism(s) of AETD-induced apoptosis.