142 H. Raistrick Experimental methods The general plan of the work was the investigation of the products of metabolism of pure cultures of species and strains of moulds when grown under controlled conditions on simple, reproducible and chemically defined culture media. We have used almost exclusively one or other of the two folio whig media: Czapek-Dox medium Raulin-Thom medium glucose 50 g. glucose 75 g.
Bakerian Lecture 143 KOJIC ACID, PATULIN, 2-HYDRO XYMETHYL-5-FURANE CARBOXYLIC ACID AND TERREIN ,CHOH HOHC^ ^CHOH "CH HOHC- -CHOH HOHC. .CHoOH HOHC AACH.CHOH.CH2OH glucopyranose glucofuranose 0 A HCII ---------CIIH HOCII/ CH AA HOOC.C C.CH20H AA HC C.CH20H IV hi 2 -hy d roxymethyl- 5 - furane kojic acid carboxylic acid I0 HOHC| ----------CI=0 Hj(r X=CH HW H AA HjC CH.C<f° CH.CH=CH.
Bakerian Lecture 145 Ascorbic acid (XV) was identified along with much larger amounts of citric acid by Geiger-Huber & Galli in 1945 from cultures of Aspergillus It is surely more than a coincidence that these two substances are also present together in the juice of citrus fruits.
146 H. Raistriek Caperatic acid is a monomethyl ester of nor-caperatic acid (XXI), but it is not mown at present which of the three carboxyl groups is esterified in caperatic acid itself. It was described as a constituent of the lichen Parmelia by Hesse in 1898(41), and the structure of nor-caperatic acid, which is clearly a tetradecyl-citric acid, was established by Asano & Ohta(42, 43).
Bakerian Lecture 147 Before leaving the aliphatic mould metabolites there is a matter of some structural significance to which I wish to draw your attention. In the course of the investiga tion of their molecular constitution it has been found that a number of products from moulds, higher fungi and lichens give rise to substituted succinic acids on degradation. These are summarized in table 2. Thus tetrahydroterrein gives »-propylsuccinic acid (22). Palitantin, C14H2204, a metabolite of Penicillium palitans, is a complex unsaturated dihydroxyaldehyde of at present unsettled molecular constitution (45). Its reduction product, tetrahydropalitantin, yields w-heptyl- succinie acid on oxidation. The long side-chains in the substituted succinic acids obtained by the breakdown of minioluteic(39), nor-caperatic (43) and agaricic(43) acids contain respectively 10, 14 and 16 carbon atoms.
Bakerian Lecture 149 Simple benzene compounds with one carbon chain My colleague, Dr J. H. Birkinshaw, and Dr W. P. K. Findlay, of the Forest Products Research Laboratory, Princes Risborough, have recently been engaged in a study of the biochemistry of the wood-rotting fungi. They have isolated from some of these higher fungi a number of interesting metabolic products. In particular, they have shown that laboratory cultures of and lepideus, both of which have characteristic aromatic odours, contain the series of four simple benzenoid compounds, XXXII, XXXIII, XXXIV, XXXV, which are clearly closely related to each other structurally; Cultures of Trametes suaveolens owe their odour to anisaldehyde (XXXII) and methyl anisate (XXXIII) (56), and those of Lentinus lepideus to the methyl esters of cinnamic acid (XXXIV) and p-methoxycinnamic acid (XXXV) (57). It will be seen that all four metabolites contain either a methyl ether or a methyl ester grouping or both.
150 H. Raistrick 3:5-dihydroxyphthalic acid (XXXIX) from brevi-compactum and ustic acid (62,63), (XL) from Aspergillus ustus 6-Hydroxy-2-methylbenzoic acid is clearly related (64). to mellein (XLI) from A. melleus(65, and from ockmceus and is, in fact, 66) i . (67, 68), produced from it by potash fusion. Mellein itself is the lactone of the acid given in OH OH OH (^^\coon c^\cOOH cS^’^^NiCOOH % ^ CH3 HO COOH HO CHOH.CO.CHj OCH3 XXXVIII xxxijc XL 6-hydroxy-2-methyl- 3:5-dihydroxy- ustic acid benzoic acid phthalic acid / 0AH CO OH 7XOOH t^^hCOOH JCH.CH2.CH3 CHOH.CH2.CH3 HO CHj.COlCHj XLI XLII mellein CioHio05 OH OH (?^\COOH tf^NiCOOH HO CHOH.CO.CH3 CO. CO. CHa+H2 O XLII1 XUV CI0H10O6 C.oH.oO, brackets. 3:5-Dihydroxyphthalic acid is also clearly related to the other metabolic products of Penicillium brevi-compactum, namely, the acids C10H10O5 (XLII), Ci0Hi0Oe (XLIII) and C10H10O7 (XLIV) Each of these three compounds, (62, 69, 70). as well as mellein and ustic acid, has a side-chain of three carbon atoms in varying degrees of oxidation. Ustic acid itself may be regarded as the methoxy derivative of C10H10O6, although it is not yet established with certainty in which of the possible tautomeric forms the three carbon side-chain is present.