Identification of a new eicosanoid from in vitro biosynthetic experiments with clavularia viridis. Implications for the biosynthesis of clavulones.
✍ Scribed by E.J. Corey; Peter T. Lansbury Jr.; Yasuji Yamada
- Publisher
- Elsevier Science
- Year
- 1985
- Tongue
- French
- Weight
- 303 KB
- Volume
- 26
- Category
- Article
- ISSN
- 0040-4039
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✦ Synopsis
A cell-free homogenate of Clavularia viridis converts tritiated arachidonic acid into a new eicosanoid identified as 5 (free acid) by chemical and chromatographic studies in comparison with synthetic substances. The isolation of 4, suggests a novel, non-prostanoid type pathway for the biosynthesis of the clavulones. The clavulones, isolated from Clavularia viridis and exemplified by clavulone I (L ), together with the more recently studied 'punaglandins"2 represent a new series of marine derived eicosanoids which are of considerable biological interest. 3 Although there are structural similarities between these eicosanoids and the prostaglandins, the pathways of biosynthesis are likely to differ significantly. 4 In this paper we report on the enzymatic transformation of arachidonic acid (the obvious predecessor of the clavulones) by a cell-free extract from the stolonifer Clavularia viridis to a new metabolite. The structure of this substance, obtained in tritiated form on sub-nanomolar scale, suggests that it is probably a precursor of the clavulones. From this structure an interesting new possibility can be deduced for the biosynthesis of the clavulones (and punaglandins). Structural identification of the metabolite, designated herein as pre-clavulone A (PC-A), was carried out by a radio tracer chemical study using high performance liquid chromatography (HPLC) analysis and comparison with synthetic compounds of known structure.
Clavularia viridis at -7805 was placed in pH 8, 0.05 MTris buffer containing 1. OM sodium chloride at 0" @. 1 g of coral in 10 ml of buffer) and homogenized in a blender. To the cold filtered homogenate (10 ml) was added 5,6,8,9,11,12,14, 15-[3H]-arachidonic acid (87 Ci/mMole) tc give a concentration of 6 nM. Aerobic incubation was carried out at 23" for 50 min after which the mixture was extracted with hexane, 6 acidified with citric acid and extracted thoroughly with ethyl acetate. The ethyl acetate extracts contained a mixture of carboxylic acids as was shown by tic analysis before and after treatment with diazomethane. The major component @. 5 % yield) was isolated, after esterification of the mixture with