Edulinic acid

Natural sesquiterpene pyridine alkaloid formation needs two precursors, one for the pyridinium moiety and another for the sesquiterpene moiety. The a for formation of the pyridinium moiety is nicotinic acid, which reacts with isoleucine and, by oxidative reaction, produces evoninic acid, wilfordic acid or edulinic acids, a for the sesquiterpene moiety is still open to question, but E, E-famesyl cation has been suggested as one possibility and hedycarylol as a second. This moiety is dihydroagarofuran. Therefore, a for the sesquiterpene pyridine alkaloids is nicotinic acid and E, E-famesyl cation and, controversially, hedycaryol. The /3 is amacrocycling ring formation substance (two moieties), from which the alkaloid forms (Figure 62). 

Ac, Acetic Nic, nicotinic Bzo, benzoic HyBu, 2-hydroxyisobutyric MGall. tri-O-methylgaliic Evon, evoninic Cath, cathic Edul, edulinic acid. 

The edulinic acid residue found in K17 and K19 may share a similar bio-genetic origin to evoninic acid. Both may be viewed as products of coupling of (at a different oxidation level) nicotinic acid (or quinolinic acid) at C-2 with C-4 or C-5 of isoleucine as in 63. The absolute configuration at C-3 of isoleucine is the same as at C-8 of evoninic acid, but that of edulinic acid is not yet known. 

Cathedulins -K17, -K19, and -K20 have been isolated from C. edulis, and their structures determined using FABMS, and one- and two-dimensional and NMR [169]. Cathedulins -K17 and -K19 each contain edulinic acid (B) as the acid component of the macrocyclic dilactone. The absolute configuration of B derived from cathedulin -K19 was established by synthesis of the (5)-dialcohol C from methyl (R)-3-hydroxy-2-methylpropionate. The product (C) was identical to the compound produced by UAIH4 reduction of cathedulin -K19, in sign of optical rotation, IR, H and NMR spectra [170]. 

Edrophonium, 206-207 Edulinate, 127 Eduline, 158 Edulinic acids, 152 Edulitine, 158... 

The acids which esterify the core were isolated as esters from the alcoholysis. Both cathic (38) and edulinic (37) acids were new acids, and their structures were determined from chemical and spectroscopic studies evoninic acid was already known from previous work on celastraceous alkaloids. Simpler acids were identified and quantified by NMR and GLC means. 2-Hydroxyisobutyric acid had not been found previously as an esterifying acid in celastraceous alkaloids, and its high water solubility and steam volatility made it difficult to isolate an added difficulty was its tendency to react by a B l2 mechanism in alcoholysis, giving the free acid when the ester was expected. 

This type of polyester sesquiterpenes, is a family of macrolactones that contain a pyridine dicarboxylic acid, such as, evoninic, isoevoninic, wilfordic, isowilfordic, hydrox ilfordic, cassinic, edulinic or cathaic Fig. (11), which bridge the positions C3-C13 of the highly functionalized sesquiterpenoid cores evoninol, euonyminol and isoeounyminol. Fig. (12). 

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