Kuehneromycins A and B, Two New Biological Active Compounds from a Tasmanian Kuehneromyces sp. (Strophariaceae, Basidiomycetes) Gerhard Erkel3, Kirsten Lorenzen3, Timm Ankea, Robert Veltenb, Alberto Gimenezb, and Wolfgang Steglichb a Lehrbereich Biotechnologie der Universität. Paul-Ehrlich-Str. 23, 67663 Kaiserslautern, Bundesrepublik Deutschland b Institut für Organische Chemie der Ludwig-Maximilians-Universität, Karlstr. 23, 80333 München, Bundesrepublik Deutschland Z. Naturforsch. 50c, 1-10 (1995); received October 5, 1994 Kuehneromyces sp., Basidiomycetes, Sesquiterpenoids, Drimanes, Nordrimanes In a search for new inhibitors of RNA-directed DNA-polymerases kuehneromycin A (1) was isolated from fermentations of a Tasmanian Kuehneromyces species. Its structure was elucidated by spectroscopic methods. Kuehneromycin A (1) is a non-competitive inhibitor of avian myeloblastosis virus (Kj 200 ^i m ) and moloney murine leukemia virus (K; 40 (.i m ) reverse transcriptases. The second compound, kuehneromycin B (2) is a strong inhibitor of platelet aggregation stimulated with different inducers. In addition, both compounds exhibit cytotoxic and antimicrobial activities. Introduction Lambda 16; CD, Jobin Yvon CD 6 . Optical rota­ Basidiomycetes provide an interesting source of tions were recorded with a Dichrograph Mark IV novel secondary metabolites with a variety of bio­ polarimeter. For TLC aluminum foils coated with logical activities. A screening of some 400 strains silica gel Merck 60 F 254 were used. All solvents for the production of inhibitors of avian myelo­ were distilled prior to use. blastosis virus (AMV)- reverse transcriptase so far resulted in the isolation of podoscyphic acid Kuehneromyces sp. strain 8758 (Erkel et al., 1991) from a Tasmanian Podoscypha Mycelial cultures were obtained from tissue species, clavicoronic acid (Erkel et al., 1992) from plugs of fruiting bodies growing on buried wood Clavicorona pyxidata and hyphodontal (Erkel in the Hartz Mountains, Tasmania. The specimen et al., 1994) from a Hyphodontia species. show the characteristics of the genus as described In the following we describe the fermentation, by Singer (1986). The species, however, could not isolation, structural elucidation, and biological be identified. Voucher specimen and cultures are characterization of two new inhibitors from Kueh­ deposited in the collection of the Lehrbereich Bio­ neromyces sp. strain 8758. technologie, University of Kaiserslautern. Materials and Methods Fermentation General For maintenance and production of kuehnero­ Spectral data were recorded on the following mycins A (1) and B (2) the fungus was cultivated instruments: ’H and 13C NMR, Bruker AM-400 in YMG medium composed of: yeast extract 0.4%, and AMX-600; EI-MS, Finnigan MAT 90 and malt extract 1%, glucose 0.4% and agar 1.5% for 95 Q; FT-IR, Bruker IFS 48; UV, Perkin-Elmer solid media. A well grown seed culture of K ueh­ neromyces sp. 8758 (200 ml) in YMG was used to inoculate 20 1 of YMG medium in a Biolafitte C 6 Abbreviations: AMV, avian myeloblastosis virus; MMuLV, Moloney murine leukemia virus; RT, reverse fermentation apparatus. The fermenter was incu­ transcriptase. bated at 22 °C with an aeration rate of 3 1 air/min Reprint requests to Dr. G. Erkel or Prof. Dr. W. Steglich. and agitation (130 rpm). Larger batches were Telefax: 0631/205 2999 grown in a 150-liter tank (Deutsche Metrohm, 0939-5075/95/0100-0001 $ 06.00 © 1995 Verlag der Zeitschrift für Naturforschung. All rights reserved. 2 G. Erkel et al. ■ Kuehneromycins A and B from a Tasmanian Kuehneromyces sp. Stuttgart) containing 100 1 of YMG medium (in­ (+0.80), 287 (+1.18), 380 (0); IR (KBr) cm 1 3420, oculum 10%, 100 rpm, 15 1 air/min, 22 °C). The 2958, 2931, 1706, 1678, 1646, 1371, 1166; 'H and production of kuehneromycin A was followed by 13C NMR spectra in benzene-d 6 see Table I; JH estimating the inhibitory effect of 2.5 jil of a crude NMR (600 MHz, CDC13) 6 1.04 (3H, s, 13-H), 1.14 extract (concentrated 10 0 times as compared to (3H, s, 14-H), 1.63 (1H, ddd. J = 12.8, 11.5 and 4.5 the culture fluid) in the standard assay of AMV Hz, 5-H), 1.64 (1H, ddd, J = 14.8, 13.5 and 4.5 Hz, RT. 3a-H ), 1.77 (1H, ddd, J = 13.5, 6.0 and 2.5 Hz, 3ß-H), 2.32 (1H, dddd, J = 19.5, 11.5, 3.8 and Isolation of kuehneromycins A (1) and B (2) 2.5 Hz, 6 ß-H), 2.38 (1H, ddd, J = 14.8, 4.5 and 2.5 Hz, 2a-H), 2.50 (1H, dddd, J = 19.5, 6.0, 4.5 During purification, kuehneromycin A (1) was and 2.0 Hz, 6 a-H), 2.51 (1H, ddd, J = 14.8, 14.8 detected using the standard assay for AMV RT. and 6.0 Hz. 2ß-H), 2.85 (1H, dd, J = 12.8 and After removal of the mycelia by filtration, 10.0 Hz, 10-H), 3.80 (1H, ddddd, J = 10.0, 3.8, 2.5, kuehneromycin A was extracted from the culture 2.0 and 2.0 Hz, 9-H), 6.98 (1H, ddd, J = 6.0, 2.5 filtrate (90 1) with EtOAc (two times 15 1). Evap­ and 2.5 Hz, 7-H), 9.33 (1H, s, 12-H), 10.32 (1H, d, oration of the organic phase yielded a crude J = 2.0 Hz, 11-H); H R EI-M S (70 eV; DI 85 °C) extract (7.5 g), which was purified by repeated m /z (relative intensity %) 234.1227 (0.4, M+, cald chromatography on silica gel (Merck 60; elution for C 14H 180 3 234.1256), 206 (45, C 13H 180 2), 173 with cyclohexane - EtOAc 75 : 15) resulting in (4, C 12H 130), 150 (15, C 9H 10O 2), 137 (16, 170 mg of an enriched product. This was further C8H 90 2), 132 (85, C 9H sO), 108 (23, C 7H sO), 107 purified by preparative HPLC (LiChrosorb Si60, (30, C7H 70), 91 (28, C 7H7), 79 (43, C 6H 7), 77 (44, column 2,5 x 25 cm, elution with cyclohexane - C6H5), 56 (47), 55 (100), 53 (47). 2-propanol (78 : 22) to yield 120 mg of kuehnero­ mycin A (1). In some batches rechromatography Conversion of kuehneromycin B (2) into panudial of the product obtained after this step on LiChro­ (4) and vice versa sorb CN (column 2,5 x 25 cm, elution with cyclo­ hexane - tert-butyl methyl ether 22 : 78) resulted To a stirred solution of 2 in T H F (3 ml) was in the separation of a second compound, kuehne­ added l,8-diazabicyclo[5.4.0]undec-7-ene (DBU). romycin B (2). Yield: 40 mg from a 100 1 fer­ After stirring for 2 h at 20 °C, the reaction mixture m entation. was diluted with Et20 (15 ml) and washed succes­ sively with 0.1 n HC1 (3 x 10 ml), saturated aque­ Kuehneromycin A (1) ous N a H C 0 3 (10 ml) and brine (10 ml). Evap­ oration of the dried organic layer (Na 2S 0 4) Colorless oil, R{ 0.75 (toluene/acetone/acetic in vacuo yielded a residue, which consisted of a acid = 70:30:1); [a ]D21 -55 (c 0.20, EtOH); UV 4 : 1 mixture of 2 and 4 according to the 'H NMR (MeOH) A.max 229 nm (log e 4.01); CD (EtOH) spectrum (600 MHz; CDC13). Diagnostic aldehyde Xmax 223 nm (Ae -4.96), 247 (0), 257 (+0.23, sh), signals appeared at 6 9.33 (4/5H, s, 12-H of 2), 9.53 296 (+1.16), 380 (0); IR (KBr) cm 1 3440, 2957, (1/5H, s, 12-H of 4), 9.62 (1/5H, s, 11-H of 4), and 2930, 1712, 1683, 1653, 1370, 1157; ]H and 13C 10.32 (4/5H, d, J = 2 Hz, 11-H of 2). NMR spectra see Table I; HREI-MS (70 eV; DI Under the same conditions panudial ( 4) yielded 180 °C) m /z (relative intensity %) 278.1163 (0.2, a 1 : 10 mixture of 2 and 4. Longer reaction times M+, cald for C 15H 180 5 278.1154), 234 (1, led to decomposition in both cases. C 14H 180 3), 206 (51, C 13H 180 2), 132 (80), 107 (25), 77 (41), 55 (100). Biological assays Antimicrobial spectra, cytotoxicity and macro- Kuehneromycin B (2) molecular syntheses in whole L 1210 cells (lym­ Colorless oil, R f 0.75 (toluene/acetone/acetic phocytic leukemia, mouse ATCC CCL 219) were acid = 70:30:1); [a ] D21 -108 (c 0.25, EtOH); UV measured as described previously (Weber et al., (M eO H ) Xmax 229 nm (log e 3.79); CD (MeCN) 1990). HeLa cells (ATCC CCL 2.2) and Ehrlich Xmax 216 nm (Ae -5.50), 231 (0), 243 (+3.04), 266 ascites carcinoma cells (H. Probst, University of G. Erkel et al. ■ Kuehneromycins A and B from a Tasmanian Kuehneromyces sp. 3 Tübingen) were grown in Ham’s F 12 medium, 8 mM MgCl2 30 mM KC1, 10 mM DTT, 200 [ig/ml BH K 21 (ATCC CCL 10) in G-M EM , 3T3/MMSV BSA, 10 |iM dTTP, dATP, dGTP. dCTP, 1 jiCi [3H]- cells (Moloney murine sarcoma virus transformed) dTTP (3.34 pmol), and 20 U/ml HIV RT. The reac­ and H U T 78 cells, (ATCC TIB-161) in RPM I 1640 tion mixture (50 jil) was incubated for 60 min at supplemented with 1 0 % fetal calf serum and 37 °C and the radioactivity in the acid-insoluble 65 (J-g/ml penicillin G and 100 |ig/ml streptomycin fractions were determined as described above.