Helicoma ambiens

Trapoxin (Fig. 16) is a fimgal metahohte isolated from Helicoma ambiens. It is an irreversihle HDAC inhihitor with nanomolar potency (Tahle 10) similar to chlamydocin and toxins. Trapoxin also has the ability to act on v-5 5-transformed N1H3T3 cells and reverse them into their normal cells. 

Trapoxins were discovered by Itazaki et al. in 1990, from the flingas Helicoma ambiens RF-1023. These compounds exhibit detransformation activity against v-sis oncogene-transformed NIH3T3 cells. Trapoxin A has no effect on human red blood cells, even at a concentration of 250pg/ml and incubation at 37 °C for 2 days Trapoxins are known to inhibit histone deacetylase (HDACl) activity" and trapoxin B has no effect on the stability of HDAC6-PP1 complexes or on tubulin acetylation ... 

Discovery Trapoxins A and B (1 and 2) were isolated as antitnmor agents from the culture broth of Helicoma ambiens RF-1023 [1]. The structures were determined by x-ray analysis, mass spectrometry, NMR, and chemical studies [1,2]. 

Mr 602.73, needles, mp. 173-174°C, [o]d -63.7° (CH3OH). Cyclopeptide antibiotic from cultures of the fungus Helicoma ambiens, which shows antitumor activity. 

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