The aqueous ethanolic extract of Russula emetica contains at least six fluorescent compounds. A description is given of the isolation and some properties of r us s u l a r h o d i n, the red dye from Russula emetica

D. Cerar

K. Balenović

V. Škarić

Z. Pučar

English

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AR H I V Z A K E M I JU 27 (1955) 15 The Chemistry of Higher Fungi. nr. Contribution to the Chemistry of the Genus Russula K. Balenovic, D. Cerar, Z. Puear and V . Skaric Chemical Institute, Faculty of Science, University of Zagreb, Strossmayerov trg 14, · Zagreb, Croatia, Yugoslavia Received February 4, 1955 The aqueous ethanolic extract of Russula emetica contains at least six fluorescent compounds. A description is given of the isolation and some properties of r us s u 1 a r hod i n, the red dye from Russula emetica. From the botanical point of view the genus Russula is the most difficult of the family Agaricaceael. Some characteristic representatives of this genus have been the subject of earlier chemical investigations·. Thus Bertrand and Bourquelot2 discovered the presence of tyrosinase in Russula nigricans, and it was subse-quently shown that in certain species of this genus oxidases can be found in comparatively large quantities, and can be isolated in pure form3. From the work of Bourquelot4 it is evident that certain species of the genus Russula contain 10-20 times as much mannitol as other higher fungi. • Russula integra L., for example, contains 19-20°/o of mannitol (of the weight of dry material)S. Qualitative descriptions of the coloring matters of this genus have been given by Weiss6, Schroter7 and Bachmann8**, who extracted the red dye from Russula integra L., R. emetica Fr., R. alutacea Per s ., and R. aurata Wit h. with cold water, and after having preci-pitated proteins and other substances with alcohol, obtained an amorphous red mixture of dyes. This showed a blue to blue-greeI). fluorescence, if .isolated from Russula integra L. On addition of very small quantities of mineral acids the fluorescence disappeared. Careful neutralization !festored the fluorescence, which again disaippeared at the slightest excess of alkali. This dye is also present in Russula nitida P er s ., R. chameleontina Fr., R. nauseosa Pers., and R. rubra (D C)lO. In several of these SiPecies a yellow dye was also reported. Acco-rding to Kobertu, in Russula emetica basic substances are al:so present, such as cho-line and, probably, muscarine. Later, the chemistry of pigments was investigated, al:so qualitatively, by Gautier12 ; the findings of earlier aut_hors were confirmed, but no new data given. The l>Pecies of the genus Russula which · occur in Croatia have been described by Schulzer13, Gjurasin14, Vouk and Pevalek15, 16, Skoric17 and Blagai(:18. These are:*** Russula adusta (Pers.) Fr.17, R. aeruginea Fr.16,11, R. aeruginosa P.13, R. atropurpurea Krom b h.13, R. aurora Krom b h. var. mitis Sc h 1 :i . 13, R. bifida (B u 11.) Sc h r 6 t.17, R. cruentata S c h 1 z. et Q u e 1.13, R. cyanoxantha (Schaf f.) F r.14, rn, R. delica F r .13, R. deliciosa (Va i 11.) Sc h r 6 t.1s, 16, 11, R. depallens (Pers.) F r16, 11, R. diabolica Sc h 1 z.13, R. emetica (Schaf f.) F !f,14, 16, 11, 18, R. fragilis (P er •s.) F r.13, 14, 16, 11, 18, R. fragilis Bresadolae S c h 1 z.13, R. foetens p er s,13, rn,18, R. f'Ulvo-alba Sc h 1 z.13, R. furca Per s.18, R. galorheiformis S c h 1 z.13, R. grise·a Per s.18, R. incarnata Q u e 1. var. livida B re s a d.13, R. incerta S c h [ z.13, R. integra (L.) F r .1•, rn, R .. lactea Per s.1•. 16, 11, R. lilacea Q u.14, 18, R. Linnaei F r .13, 16, R. livida (P er s.) Sc h r 6 t.rn, R. lutea Hu d s.14, R. macella m. var. valida Sc h 1 z.13, R. media Sc h 1 z.13, R. nigricans B u 11.16, ·R. nivea P ,13, R . ochraceo-alba Brit z.16, * Paper II, K. Balenovic, N. Bregant a nd T. Galijan, Arhiv kem. 26 (1954) 233. ** A very valuable review on the chemistry of higher fungi was given in 1906 by ZellnerD. *** 'These botanical data could be of value for further work in this field. 16 K. BALENOVIC, D. CERAR, Z. PUCAR AND V. SKARIC R. ochroleuca (Pers.) F r.16, R. olivacea (Schaf f.) F r.16, 11, R. pectinata (B u 11.) F r.13, 16, 11, R. palumbina Q u e 1.13, R. purpurea Schaf f.16, R. purpurina Q u e 1. et Sc h 1 z.13, R. Queletii Sc h 1 z.13, R. rosacea (B u 11.) F r.12, 16, R. rubra (DC) F r.14, 16, . R. sanguinea (B u 11.) F r15, R. Sardonia F r17, R. vesca F r.16, R. veternosa F r.13, R. violacea Q u.14, R. virescens (Sc ha.ff.) F r.13, 16, 1s, R. xeramP,elina Schaf f .1a. We have included Rus:sulae in our investigations of the. chemistry of higher fungi for many reaisons, but especially becaUJSe this interesting genus has not been investigated for half a · century with newer chemical techniques In a preparative manner we started our work with R. e~etica Fr. The ethanolic extracts of this speeies showed a marked fluorescence; a cross-section of the fresh mushroom showed also an intensive fluorescence in the ultraviolet (355 mµ). We selected some ten species of Russulae and found that all of them displayed a marked fluorescence (Fig. 1). Other genera (Amanita, Boletus, Lacta-rius, etc.) showed no fluorescence. This distribution of fluorescent compounds according to Fig. 1 is highly characteristic of all the hitherto investigated Rus:sulae. Fig. 1. - Cross-section through a Russu!a specimen in ultraviolet light: A , Red pigment layer {russularhodin) shows no fluorescence, but a strong absorption. B, zone immediately next to pigment layer (cca. 0,5 mm.), intensive blue fluorescence, c, D, pi!eus, lame!!ae and stipes all show an intensive yellow fluorescence. Further investigation of the ethanolic-aqueous solution of these fluorescent coloring matters have shown that Ru:ssulae, especially R. errietica, produce a series of very stable, fluorescent pigments and colorless compounds. By paiper chromatograiphy of the ethanolk extract, using butainol-wa!ter and phenol-water, as well as by electrophoresis on paper, at least six fluorescent compounds could be detected, · with red, yellow, blue, violet, and purple fluorescence. We car,ried out paper chromatography and electrophoresis of ethanolic extracts of ten selected Ru:ssulae and found that some of the fluorescent compounds are common to all the selected specimens, while some are specific for a given species. It is, therefore, probable that paper chromatograms and electrophero-grams could be a valuable aid in the . identification of Rus1su1ae. From Russula emetica we isolated 14.5°/o of mannitol (based on the weight of dry mushroom). The red dye from the pilei of Russula emetica was also isolated from the ethainolic extract by adsorp.tion on cellulose.· When adsorbed on cellu}ose, and at pH 7, the dye showed an orange fluorescence. It was eluted from -the cellulose powder or filter-paper with aqueous 50/o acetic acid. Aqueous solutions of the eluted dye showed no fluorescence at pH 7, nor at any other pH. It is of a bright pink color when adsorbed on paper, showing an orange fluorescence in . the ultraviolet; it is identical with the characte-ristic red color of the pilei of fresh Russula emetica. In future, we will refer to this dye as to r us s u 1 a r h o d i n. On basifying the aqueous solution of THE CHEMISTRY OF HIGHER FUNGI 17 :russularhodin and subsequently neutralizing, the red color reappeared. After a ::prolonged boiling of an aqueous solution of russularhodin with hydrochloric acid, the red color disappeared. Neither was a reaction with an aqueous ferric chloride solution· observed, nor with a ninhydrin solution. Ru:ssularhodin is soluble in water and glacial acetic acid, but is sparingly soluble in ethanol and other "()rganic solvents. Hydrolysis with hydrochloric acid yielded no products with .:a positive ninhydrin reaction, neither did the hydrolysate show the presence -Df carbohydrates. Using Cra1ig's procedure of countercurrent distribution, we attempted to -separate, on a preparative scale, the ethanolic extract into its components. 'The r esults are given in Fig. 2. Russularhodin is found in tubes No 42-58 :Fig. 2, section c), together with the main quantity of mannitol. From a solvent mixture butanol-acetic acid-water we failed to separate russularhodin from ·mannitol. Acknowledgment. We are indebted to Mr. V. Stetic, State Department of :Forestry, Zagreb, for his kind interest in this work, and for his advice and sug-' _-gestions for the collecting, of biological material. We are further indebted ·to Prof. M. :StaniC, who made available to us some of the original papers cited in the references, .:and to L. Butula and D. Sucic for assistance in earlier stages of this work. EXPERIMENT AL Russula emetica was collected in autumn 1953 in oak woods of the neighbor-:410od of Zagreb. Fresh mushrooms (36.2 kg.) were peeled, and the red peelings, not ihioker than 2 mm. (5.6 kg) were minced and kept with two parts of 96°/o ethanol for a fortnight, at 5-100. The ethanol was then decanted off, replaced with fresh -solvent and the same procedure repeated. The first and second extracts were com-bined, the fungi thoroughly pressed in a tincture press, and the filtra te added to ·the extracts. The ethanol was evaporated under r educed pressure at a tempera--ture below 500, and the fat removed by ether extraction. After further evaporation <Of the ethanolic-aque.ous solution, mannitol (140 g.) could be isolated. The dark red :Syrupy residue was evaporated to dryness and used for further exper iments <{Extract A). The peeled fungi (30.5 kg.) were minced and extracted in the same manner, :and 452 g. of mannitol were isolated. By prnceeding in the same manner as for -extract A, 383 g. of ethanolic extract (Extract B) were obtained. From 36.2 kg. <Of fresh mushroom 1,630/o of mannitol could be isolated. -Craig Countercurrent Distributio.n The general methods outlined by Craig19 were used in the attempt to separate -the fluorescent compounds from the extract A. The distTibution was carried out in a Z.00 - tube modification of Craig's all-glass appnratus20, at 210, using 9.22 g. of -the ethanolic extract A of Russula emetica, in the solvent system n-butanol --acetic acid - water (16 : 5 : 20 by volume) , and in 187 transfers. All solvents were <distilled before use, and equilibrated in separatory funnels. In preparing the m~· chine for fractionation 25 ml. of the lower phase were added to each- of the tubes. The extract A was dis.solved in the lower phase, and added to tubes 4-8 . . About six transfers were made per hour. The tube ~ractions were concentrated io dryness by vacuum distillation. The contents of the tubes were weighed. The peak •concentrations were found in tubes 18, 37, and 42. after 187 transfers (Fig. 2). Electro-:pherograms of the fractions from those tubes in which the purest substance was expected showed two or more components. Russularhodin and mannitol - have ::practically the same partition coefficients in the solvent system used (Fig. 2, .section c). 18 K. BALENOVIC, D. CERAR, Z. PUCAR AND V. SKARIC no 100 " E t 140 ] 120 ·= 1 '.E I 180 ,,[ :f © : @) i Q) ~·O.Z89 ~ : ~ . :~o.l__..o--o--<.>-i-o--Q-'""'ioo 60 10 eo 50 100 110 izo 1JO ,40 ,,o 150 uo Tubo number Fig. 2. - Craig Countercurrent Distribution. Solvent system n-butanol-acetic acid-water-(16 : 5 : 20), 187 transfers, 9.2 g. of Extract A. Plot: dry residue weight in milligrams of 10 ml. lower and 10 ml. upper phase versus tube number. Fluorescence of tube contents in the-ultravlolet: (a) violet ; (b) green; (c) red; (d) light blue; (e) pale yellow ; (f) yellow; (g) violet ;. (h) green; (i) no fluorescence ; (j) violet. Paper Chromatography Paper chromatography was carrie<l out on Whatman paper No. 1, at 19°, using phenol-water as mobile phase, during 24 hours. A series of fluorescent spots appeare<l, with RF values between 0,52 and 0.70. The S[>Ot due to :riussularhodin appeared as. an adsorption comet, a phenomenon often encountered with dyes21. Paper Electrophoresis Paper electrophoresis was carried out on Munktell Paper 20/150; the strip·· was 30Xl.5 cm.; the buffer was HaBOa-NaOH-Na-acetate, pH 8.60, ionic strength· 0.0482. Voltage on the electrodes 140 V, current density in the strip was 0.22. mA/cm-at the beginning, and 0.45 mA/cm. at the end of the electrophoresis. The duration of the electrophoresis was 20 hours (see Fig. 3). Strip I on Fig. 3 represents the· results obtained with the ethanolic aqueous extract (2 : 1) of fresh peelings after-five days' extraction. Strip II was obtaine<l using the second extract after a month:. of extraction at 100. Russularhodin i:s contained in section 2 of the strips. , , lt!Il~~ [J] ~ ~;]~~@~ I g @ I 11 ir~ ~~ t~] till! ~~ ~ 1· .5 io 5 10 15 20cm Fig. 3. - Electropherogram of aqueous ethanolic extract of Russula emetica peelings. Strip I~ first aqueous ethanolic extract (1 : 2) (after five days' extraction). Strip II, second extract: (after a month of extraction) . Fluorescence in the ultraviolet: (1) orange-red; (2) russularhodin ;. (3) yellow ; (4) crimson; (5) blue ; (6) green; (7) blue; (8) violet. Isolation of Russularhodin A solution of Extract A (8 g.) in disstille<l water (150 ml.) was passe<l through. a column of cellulose powder (17 X i 2' cm., 16 g., Whatman, Standard Grade, B .. Quality). The column was prepared by slurring the cellulose powder with distilled water in to a gla.Ss column .. The adsorbent was thornughly agitated to ensure re-moval of siuspende<l air bubbles, and to produce a fine dispersion. The russularhodin was adsorbed at t.he top of the column. The column was washed with distilled: CHEMISTRY OF HIGHER FUNGI 19 water (1200---<1500 ml.) untH the completely colorless washings showed no more fluorescence in the ultravio1et. The russularhodin was eluted with 50/o acetic acid (800--1000 ml.), and the column remained faintly colored. The acetic acid solution was evaporated under reduced pressure at a temperature below 300, and rus-sularhodin remained as a dark red, semicrystalline solid. Yield 200 mg. of rus-sularhodin from the peelings of 36 kg. of fresh fungi. Russularhodin gives no reaction with a 10/o methanolic FeCls solution, nor with a ninhydrin solution. When treated with hydrogen in statu nascendi (Zn + HCl) at room temperature, rus-sularhodin was reduced and discolored in a short time. Acid Hydrolysis of Russularhodin Russularhodin (5 mg.) was refluxed with 1 N hydrochloric acid (5 ml.). After two hours the red colo-r disappeared. The refluxing was continued for ten mme hours, and the reaction mixture was chromatographed on paper after the second, fifth, tenth and twelfth hour of refluxing. In every instance this was carried out on Whatman No. 1 paper, at 190, and with phenol-water as mobile phase. The paper strLps were developed with a ninhydrin solution, and also with an aniline phthalate solution22. The results were negative in both cases, and t herefore the hydrolysis of russularhodin, under the described conditions, yielded neither amino acids nor ca11bohydrates. Determination of Muscarine-Like Activity of Extract B. The determination of muscarine-like activity was carried out according to Ki:igl2S on Rana esculenta. Six determinations were made, and Extract B showed an activity of S-10 Muscarine Units2s for 1 g. of extract. REFERENCES 1. Cf e. g. R. K ii h n er and H. Rom a g n e s i, Flore analytique des champignons su:perieur s, Paris, 1953, Masson et Cie., p. 436---471. 2. E. Bourque 1 o t and G. B e rt rand, Compt. rend. sac. biol. 47 (1895) 582. 3. H. R. D a 1 ton and I . M. Ne 1 son, J . Am. Chem. Soc. 61 (1939) 2946. 4. E. B o u r q u e 1 o t, Bul. sac. mycologique de France 18 (1892) 13. 5. W. Th i:i r n er, Berliner Berichte 11 (1878) 533; 12 (1879) 1630. 6. Weiss, Beitriige zur Biologie, 1, 116, cit. from9, p. 153. 7. Sc h r i:i t er, Wiener Akademieberichte 91 (1885) 446. 8. B a chm an n , cit. from9, rp. 153. 9. J . Z e 11 n er, Chemie der hoheren Pilze, Leirpzig, 1907. HJ. T. L. Phi p son, Chem. N ews 46 (1882) 199 ; cit. from Chem. Zentr. 1882, 803. 11. Kober t , Chem. Zentr. 1892, II, 929. 12. C. Gautier, Compt. rend. sac. biol. 82 (1918) 72 ; cit. from Chem Zentr. 1919, I, 958. 13. S. S c h u 1 z er, Pilze aus Slavo111,ien, Manuscript Sign. R 3574, University L i-brary, Zagreb, (1869-1886). 14. S. G ju r as in, Nastavni vjesnik 6 (1898) 50. 15. V. Vo u 'k and I. P e_v a 1 e k , Prirodoslovna istrazivanja jugoslavenske akade-mije, Zagreb, 6 (1915) 17. 16. V. Vo u k and I. P e v a 1 e k, Prirodoslovna istrazivanja jugoslavenske akade-mije, Zagreb, 8 (1917) 18. 17. V. S k o rii c, Glasnik hrv.atskog prirodoslovnog drustva, Zagreb, 49-50, (1928) 97. 18. K. B 1 a g a i c, Gljive nasih krajeva, Zagreb, 1931. 19. L. C. Craig and D. Craig, Techniques of Organic Chemistry, Vol. III, In-terscience Publishers, New York, 1950, p . 171. 20. L. C. C r a i g, Anal. Chem. 22 (1950) 1346 21. H. Z ah n, Textil Praxis 6 (1951) 127; cf. E. and M. Led erer, Chromatography, Elsevier Publishing Company, Amsterdam, 1953, p. 78. 22. S. M. Partridge, Nature 164 (1949) 443; L. Hough, J . K. N. Jones and W. H. Wadman, J. Chem. Soc. 1950, 1702. 23. F. K i:i g 1, H. Duis berg and H. Er x 1 e be n, Ann. 489 (1931) 156 20 K. BALENOVIC, D. CERAR, Z. PUCAR AND V. SKARIC IZVOD Kemija visih gljiva. III. Prilog kemiji Russula K. Baienovic, D. Cerar, Z. Puear and V. Skaric P okazano je, da vodeno-etanolni ekstrakt Russuia emetica sadrzi najmanje ~est fluorescentnih spojeva. Opisana je izolacij a i neka svojstva rusularodina, karakteristicne crvene boje Russuia emetica. KEMIJSKI INSTITUT PRIRODOSLOVNO-MATEMA TICK! F AKUL TET . ZAGREB i . INSTITUT »RUDER BOSKOVIC« BIOKEMIJSKI ODJEL ZAGREB Primljeno 4. februara 1955. 

The Chemistry of Higher Fungi III. Contribution to the Chemistry of the Genus Russula

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