mandar profeeeee valp

8/13/2019 Mandar Profeeeee Valp

1/3

Journal o Natural ProductsVol . 53 , NO . , p p ~ 025-1027, Ju I-A u~ 990 1025

STUDIES ON CHILEAN LICHENS, XIV. 2-O-METHYLHIASCICACID,A NEW TRIDEPSIDEIN CATZLLARZA CORYMBOSAC. VI NET,W. QUILHOT,

Escuela de Quimicay Fatmacia, Facultadak Medicina, Uniwsia addeValparaiso, C a d & 92 -V , Valparaiso, Cbilcand J. A . G A R E I A R I N O ~

Departanento de Quhica, Faultad de Ciencia, U n iw r si U Timica F co Santa MariaCasilla 1 1 0-V , Valparaiso, ChileABSTR~CT.-2-O-Methylhiaxic cid 111 new tridepside, w s solated from Catilkariacorymbora,an Antarctic lichen. Its structure w s establishedby spectroscopic da ta.

In the course of our chemotaxonomicsurvey of the lichens of the Chilean flora,the study of Catillaria cotymbosa (Hue)Lamb was undertaken. The chemistry ofCatillaria a lichen genus of the familyLecideaceae, is poorly known. Usnicacid, atranorin, (-)-placodiolic acid,(-)-pseudoplacodiolic acid, fumar-protocetraric acid, and zeorin have beenreported from members of the genus (2).CHCI, and Me,CO lichen extractswere subjected to cc to yield atranorin(3), chloroatranorin (3) and 2-0-methylhiascic acid El] a new tridep

The structure of 2-O-methylhiascicacid 117 was deduced from its spectraldata. The ir spectrum showed two car-bonyl absorptions due to depside esterlinkages at 1720 and 1665cm-. In theH-nmr spectrum signals were exhib-ited corresponding to an isolated one-proton singlet at 6 1.54, assigned to aphenolic function at C-2 associated withan ester group, and a two-proton singletat 6 9.94, assigned to phenolic groups atposition 4 and 5. Aromatic protons at3, 3, 5, and 5 appeared, respectively,as a series of four doublets at 6 6.69,

side. These compounds, derived fromhiascic acid, constitute a limited groupof lichen substances. Elix and co-work-ers isolated 5-0-methylhiascic acid (4)and 4,5-di-O-rnethylhiascic acid (5)from Pamlia h m c e n s and Parmeliapseudofetiscens. Recently, Elix etal. (6)re-ported the structure of 2-0-methylhias-cic acid from Pamlinopsis neodamazianain addition to 5-0-methylhiascic acidand 2 4 5-tri-O-methylhiascic cid.

For Part XIII , see Vinet et al. 1) .

6.66, 6.60, 6.56, all withJ = 2.05 Hz,and a one-proton singlet at 6 6.38, cor-responding to position 3. A methoxylfunction was detected as a singlet at 63.63, and three methyl groups appearedas singlets at 6 2.43, 2.37, and 2.27.The 13C nmr (Table 1) confirmed thepresence of three methyl groups at posi-tions 6, 6, and 6 (21.3, 19.32, and13.28 ppm); one methoxyl group at59.79 ppm, and five non-substitutedaromatic carbons (7,8). The mass spec-trum did not exhibit a molecular ion, in


2/3

1026 Journal of Natural Products [Vol. 53, No. 4TABLE. '3C-nmr Specna Data ofCompound 1 .

Carbonc -1c-2c -3c-4c-5C-6 . . . . . . . . . . . . .c-7C-8 . . . . . . . . . . . . .c-1' . . . . . . . . . . . . .c-2' . . . . . . . . . . . . .c-3'c-4' . . . . . . . . . . . . .c-5' . . . . . . . . . . . . .C-6'c-7 'C-8'2'-OMec-1c-2 . . . . . . . . . . . . .c-3c-4c-5 . . . . . . . . . . . . .C-6c-7C-8 . . . . . . . . . . . . .

109.53153.63'101.76153.77'156.77138.98166.48b21.31'

118.13160.03107. 16d152.21'114.12'137.98165.69b19.32'59.79

118.13140.10107.35d152.03'114.15'138.98170.9013.28'

slues may be interchanged.

agreement with similar results on othertridepsides derived from hiascic acid 4-6), and the principal ion fragments atmlz 168(7), 166(12), 165 ( 5 ) , 151 12),138 (26), 124 (100) corresponded torings formed by rupture of diphenylester linkages (4,5,7,8). The fragmentsdue to ring B mlz 165 and 138) are theonly ones which explain the presence of amethoxyl group. Moreover, the peaks at8 6.66 and 6.56 of the H-nmr spec-trum refer to aromatic protons on 3 and5 , respectively, and are explained by areciprocal meta-type influence. This as-signment is confirmed by comparisonwith the 13C-nmr spectra of othertridepsides with the same B-ring struc-ture (8).Finally, it is well known that allpara-depsides derived biogeneticallyfrom p-orcinol are always methylated atpositions 6 and 6' (9,lO); this leaves the2 -position in ring B as the only plausi-ble site for the methoxy group.

EXPERIMENTALGENERAL METHODS.-M~'S were deter-

mined on a Kotler hot plate and are uncorrected.'H- and I3C-nmr spectra were recorded inDMSO-$ on a Varian =-loo spectrometeroperating at 100 MHz and 25.15 MHz, respec-tively, with TMS as internal standard. The chem-ical shift values are reported in ppm and the cou-pling constants in Hz. Eims were obtained by di-rect inlet with 70 eV using a Varian MAT CH-7instrument. Ir spectra were recorded using KBrpellets (Perkin Elmer model 683). Si gel G(Merck) and Si gel 60 F-254 (Merck) were used forcc and tlc (0.25 mm), respectively.

P U N T MATERIAL.&. CW) mboJc2 Was COl-lected on soil and rocks at Caleta Copper Mine,Robert Island, Antarctica, in February 1987.Voucher specimens are deposited at the her-barium of the School of Chemistry and Pharmacy,Univenidad de Valparaiso, Chile.

EXTRACTIONAND rSOLATION.--The air-dried lichen thalli (730g were triturated and ex-tracted with CHCI, (1.5 liten X 2) at room tem-perature for 24 h. Evaporation of the solvent gavethe crude extract (12.8 g that was chromato-graphed on a column of Si gel. Elution was con-ducted with mixtures of C6H6 and EtOAc of in-creasing polarity, affording three compoundsmonitored by tlc on Si gel with toluene-EtOAc-HCOOH (35:5:1) as the eluent. A similarMe,CO extract (13 g , worked up in the sameway, afforded the same compounds, atranorin andchloroatranorin, which were identified by directcomparison (mp, tlc, and 'H nmr), and 2'-0-methylhiascic acid El].

lized from Me,CO as colorless prisms: mp 207-209'; ir v max 3300, 2920, 2880, 1720, 1665,1600, 1250, 840, 795 cm-'; 'H-nmr 6 10.54( lH , s 2-OH), 9.94 (2H, s 4-OH, 5-OH), 6.69]=2.05 Hz, H-3'), 6.60 ( lH, d,]=2.05 Hz,( lH , s H-3h 3.63 (3H, s 2'-OMe), 2.43 (3H,s 6-Me), 2.37 (3H, s 6 -Me), 2.27 (3H, s 6'-Me); eims d z rel. int.) 168 (7), 166 (12), 165(5), 151 (12), 138(26), 135 (lo) , 124(100), 123(68), 111 (17), 107 (12), 95 (27), 94 (1 ), 78(58), 63 (72).

2'-O-METHYLHIMCIC ACID [ l ] . z r y S t d -

( lH , d, j =2 . 05 Ht, H-3 ), 6 .66 ( lH , d,H-5 ), 6.56 (l H, d,]=2.05 Ht , H-5'), 6.38

ACKNOWLEDGMENTSWe acknowledge the support of a grant from

the Instituto Antdrtico Chileno, INACH. We aregrateful to Professor M. Nicoletti, Univenitd LaSapienza, Rome, for recording the 'H-nmr spec-trum, Professor P.J.Nathan, Instituto Poli tk-nico Nacional, Mexico, and Dr. B. Didyk, Re-fineria Petr6leo Con-Con, Chile, for the massSpectrum.


3/3

Jul-Aug 199 1 Vinet etal. : New Tridepside 1027LITERATURE CITED

1. C. Vinet, W. Quilhot, V. Gambaro andJ.A. Garbarino, J Nut. Prod., 53 500(1990).D.J. Galloway, in: Flora ofNew Zealand:Lichens. Ed. by P.D. Hasselberg, Gov-ernment Prints, Wellington, New Zea-land, 1985, p. 110.Ch. F. Culberson, Chemical and BotanicalGuide t o Lichen Products, The Universityof North Carolina Press, Chapel Hill,1969, p. 85 .J.A. Elix and V.K. Jayanthi, Aust. J .Chon. , 29 1029 (1976).J.A. Elix and U . Engkaninan, A u t J .

2.

3 .

4.5.

C h . , 9 2701 (1976).6. J.A. Elix, V.K. Jayanthi, and J.H .

Wardlaw, A u t . J C h . , 42 1423(1989).7. G. Nicollier, M. Rebetez, and R. Tabac-chi, Helv. Chim. Acta, 62 7 11 (1979).8. S Huneck, K. Schreiber, and G. Sund-holm, Phytochemistry, 19 885 (1980).

9. V. Ahmadjian and M. Hale, TheLichens, Academic Press, New York,C. Vicente, Fisiologia de las sustanciasliqdnicas, Alhambra, Madrid, 1976, p.76.

1973, p . 530.10.

Received 25 Junuuiy 1990

mandar profeeeee valp

Documents