versión On-line ISSN 0717-9707
J. Chil. Chem. Soc. v.50 n.4 Concepción dic. 2005
J. Chil. Chem. Soc., 50, N° 4 (2005), págs: 667-669
SECONDARY PRODUCTS FROM Pannaria tavaresii (LICHENS)
CECILIA RUBIO*1, DAVID J.GALLOWAY2 & WANDA QUILHOT1
1Facultad de Farmacia, Universidad de Valpararaíso, Chile. email@example.com
Pannarin, chloroatranorin, leprolomin, ursolic acid and ergosterol peroxide were isolated from Pannaria tavaresii P.M. Jørg. The results confirm that the chlorinated depsidone pannarin is the most representative compound in this lichen genus.
keywords: Pannaria tavaresii, Chemistry, Secondary Products.
Lichens are well known for their unusual secondary products, rarely encountered elsewhere in nature. The compounds are used extensively in lichen systematics, and even in discussions of origins and relationships (Elix 1992); many of them have biological activities (Huneck & Yoshimura 1998), explaining the increasing interest of the pharmaceutical industry in lichen substances and lichen extracts.
The present communication records for the first time the isolation of secondary compounds in Pannaria tavaresii P.M. Jørg. (Pannariaceae, lichenized Ascomycota) widespread in temperate regions of both northern and southern hemisphere (Jørgensen 2002). The taxon has a very restricted distribution in Chile, from lat. 37º2'S to lat. 38°8'S; where it ranges from 800 to 1000 m altitude, and has been recently collected in our country .
The lichen material (46 g) was collected from bark of Austrocedrus chilensis (D. Don) Pic. Ser. et Bizz. in Conguillio National Park in november 2002. Voucher specimens are deposited in the herbarium of the Facultad de Farmacia, Univesidad de Valparaíso.
Melting points were determinated on a Mettler FP 61 Melting Point Instrument. Optical rotation was measured in CHCl3 with a Carl Zeiss polarimeter. IR spectra was recorded as KBr pellet in a Perkin Elmer model 1605. 1H and 13C-NMR spectra were recorded in a Bruker spectrometer model AVANCE 400; 1H at 400 MHz, and 13C at 100.623 MHz.
Thin-layer chromatography and column chromatography were performed on silica gel from E. Merck.
The lichen sample was dried, ground, and extracted successively with petroleum-ether (60º-80º) and dichloromethane, each time 24 h at room temperature. Both extracts were mixed and fractioned on silica gel columns and eluted with toluene-ethyl acetate- formic acid (139: 83:8).
The compounds were identified by their physical and spectroscopic data and by comparison with authentic samples.
RESULTS AND DISCUSSION
The characteristics of the compound isolated (Fig 1) were as follows:
Pannarin (1) 0.440g, 1.0% dry weight, mp. 215–216 ºC (Lit. mp. 216-217 ºC Jackman & Sargent 1975) 1H-NMR (CDCl3) 2.20, 2.35, 2.60 (s,each ArCH3), 3.80 (3H,s,OCH3), 6.45 (1H,s,H-3'), 10.70 (1H,s,CHO), 12.80 (1H,s,OH). 13C-NMR (CDCl3): C-1: 110.80a, C-2: 161.01b, C-3: 109.03a, C-4: 161.01b, C-5: 117.39, C-6: 150.79, C-7: 163.14, C-8: 193.08, C-9: 19.97, C-1': 143.17, C-2': 126.68, C-3': 114.49, C-4': 155.4, C-5': 120.84, C-6': 142.89, C-7': 9.25, C-8': 17.39, C-4'-OMe: 55.99 (values marked with a, and b may be exchanged). Pannarin has been informed in P. tavaressii (Jørgensen 2000) using the method of spot tests.
Chloroatranorin (2) 0.69g, 1.5% dry weight, mp. 209–210 ºC (Lit. mp. 208-208.5 ºC Culberson 1969). IR (KBr): 720, 759, 805, 834, 902, 939, 988, 1028, 1077, 1108, 1168, 1200, 1270, 1287, 1360, 1380, 1416, 1453, 1584, 1652, 2956, 3335. 1H-NMR (CDCl3): 2.80, 2.40, 2.60, (s, each, ArCH3), 3.80 (3H,s,COOCH3), 6.50 (1H,s,H-5'), 10.42 (1H,s,CHO-8), 12.06, 12.42, 12.61 (3x1H,3xs,3x-OH). 13C-NMR (CDCl3): C-1: 109.03, C-2: 161.90, C-3: 114.49, C-4: 155.40, C-5: 117.39, C-6: 143.17, C-7: 163.14, C-8: 17.39, C-9: 193.08, C-1': 126.68, C-2': 161.01, C-3': 110.80, C-4': 150.80, C-5': 120.84, C-6': 142.88, C-7': 180.95, C-8': 19.98, C-9': 9.25, C-7'-COOMe: 55.90.
Leprolomin (3) 0.100g, 0.12% dry weight, mp. 237–238 ºC (mp. 238–239 ºC Elix et al. 1978). 1H-NMR (CDCl3): 1.95, 2.35, 2.68, 2.70 (4x3H, 4xs,4xMe-), 3.65, 3.80, (2x3H,2xs,2x-OMe) 5.70 (1H,s,H-3), 9.50, 13.60, 13.92 (3x1H,3xs,3x-OH). 13C-NMR (CDCl3): C-1: 107.88, C-2: 163.34, C-3: 88.85, C-4: 162.67, C-5: 110.24, C-6: 159.55, C-7: 203.86a, C-8: 31.32b, C-9: 7.43c, C-1': 109.43, C-2': 158.51, C-3': 105.97, C-4': 155.07, C-5': 125.35, C-6': 154.97, C-7': 203.96a, C-8': 32.89b, C-9': 8.94c (values marked with a, b and c may be exchanged).
Ursolic acid (4) 0.030g, 0.006% dry weight, mp. 285–290 º, [a]D20+68 (MeOH) C (Lit. mp. 284.5-285 ºC, [a]D20+62.5 to 68 (MeOH) Glasby 1982). 1H-NMR (CDCl3): 0.80, 0.86, 0.87, 0.95, 1.01, 1.05, 1.09 (21H, 7xs, 7x-Me), 1.83 (1H,bd, H-18), 3.25 (1H, bt,H-3), 5.75 (1H, bt, H-12). 13C-NMR (CDCl3): C-1: 36.72, C-2: 27.82, C-3: 78.30, C-4: 39.37, C-5: 41.83, C-6: 22.65, C-7: 29.35, C-8: 39.00, C-9: 52.99, C-10 30.39, C-11: 22.94, C-12: 125.43, C-13: 138.29, C-14: 39.04, C-15: 29.34, C-16: 26.48, C-17: 55.33, C-18: 38.58, C-19: 32.92, C-20: 36.69, C-21: 27.34, C-22: 38.42, C-23: 14.95, C-24: 14.59, C-25: 18.06, C-26: 16.41, C-27: 23.93, C-28: 178.00, C-29: 20.15, C-30: 16.22.
Ergosterol peroxide (5) (0.95g, 0.037% dry weight). mp. 183–184 ºC. [a]D20-30 (CHCl3) ( Lit. mp.178-180, [a]D20-25 (CHCl3) González et al. 1983) 1H-NMR (CDCl3): 0.79, 0.83, 0.88, 0.97, 1.07 (18H, 6 Me), 3.94 (1H, m, H-3), 5.24 (2H, m, H-22 and H-23), 6.29 (1H, d, J=8.7 Hz, H-7) and 6.55 (1H, d, J= 8.7 Hz, H-6).
With the exception of chloroatranorin, an orcinol depside, the compounds isolated from P. tavaressii were found to be present in a number of species in Pannaria, being the chlorinated depsidone pannarin the main substance found (Jørgensen & Galloway 1992). Leprolomin, a biphenyl-ether apparently derived from phenolic coupling of two methylphloroacetophenone units (Elix et al. 1984), is rarely found in Pannaria (Jørgensen and Galloway 1992). The triterpenoid ursolic acid is frequent in taxa of this genus (Jørgensen and Galloway 1992). Ergosterol peroxide is a phytosterol widely occurring in lichens (Hill et al. 1991).
In P. hookeri, from Antarctica, atranorin and erogosterol peroxide were isolated, no pannarin-like compounds were found (Quilhot et al 1989).
Ursolic acid and ergosterol peroxide are considered accessory compounds. Such accessory substances have no correlation with any morphological or distributional variations and therefore are given no taxonomic significance (Elix 1992).
From a chemical viewpoint, Pannaria agree with other genera of Pannariaceae characterized by the synthesis of chlorinated depsidones. Compounds of this series have been isolated from taxa of Erioderma (Quilhot et al. 1983; Elix et al. 1986), Fuscoderma (Jørgensen & Galloway 1992) Leioderma (Piovano et al. 1995), Psoroma (Elix et al. 1982; Quilhot et al. 1989b) and Siphulastrum (Jørgensen & Galloway 1992). In Degelia (Quilhot et al. 1995) no chlorinted depsidones-like compounds were found.
ACKNOWLEGMENTS: - The research was supported by a grant DIPUV from Dirección de Investigación y Postgrado, Universidad de Valparaíso. We would like to thank Corporacíon Nacional Forestal (CONAF XI Región) for logistic assistance.
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