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Boletín de la Sociedad Chilena de Química

versión impresa ISSN 0366-1644

Bol. Soc. Chil. Quím. v.46 n.1 Concepción mar. 2001

http://dx.doi.org/10.4067/S0366-16442001000100005 

STUDIES ON CHILEAN LICHENS XXXI. ADDITIONS TO THE
CHEMISTRY OF PSEUDOCYPHELLARIA.

MARISA PIOVANO, MARIA C. CHAMY AND JUAN A. GARBARINO.*

Departamento de Química, Universidad Técnica Federico Santa María, Casilla 110-V,
Valparaíso, Chile. E-mail : jgarbari@qui.utfsm.cl
(Received: August 25, 2000 - Accepted: September 28, 2000)

ABSTRACT

Five lichens species of the Pseudocyphellaria genus from Puyehue National Park, Southern Chile were studied. Quantitative analysis showed significant differences in the chemical composition by comparison with previously described results performed by TLC.

KEY WORDS: Lichens, Pseudocyphellaria, Lobariaceae, secondary metabolites, depside, depsidones, terpenoids.

RESUMEN

Se estudiaron 5 especies liquénicas del género Pseudocyphellaria del Parque Nacional Puyehue (X Región). Mediante un análisis cuantitativo, se encontraron diferencias significativas en la composición química al comparar con los resultados previamente descritos en literatura y realizados por ccf.

PALABRAS CLAVES: Líquenes, Pseudocyphellaria, Lobariaceae, metabolitos secundarios, dépsido, depsidonas, terpenoides.

INTRODUCTION

Fifty three species of Pseudocyphellaria Vainio are recorded and described from cool-temperated South America, including Chile. They are conspicuous leafy and foliose lichens with richest species diversity in rainforest(1).

Pseudocyphellaria is characterized by a wide chemical diversity. Compounds are produced from all three major pathways of secondary metabolites. The chemistry of the genus has been studied mainly by standardized TLC methods(2), in just few species some compounds were isolated and characterized by spectroscopical means(3-8).

Species of Pseudocyphellaria play an important ecologycal role in the fixation of atmospheric nitrogen in a widely important habitat(9). A possible nitrogen contribution of between 1 and 10 kg N per hectare per year has been suggested to(10). The imput through lichen decomposition could potentially be a further important factor in rainforest nitrogen budgets(11).

In this paper we report a revision of the chemistry of some species of Pseudocyphellaria. The results show differences with the chemical composition previously described for these lichen species(1).

EXPERIMENTAL

Pseudocyphellaria berberina (G. Forster) D. Galloway and P. James, P.divulsa (Taylor) Imshaug, P. exanthematica Lamb, P. meyenii (Trevisan) D. Galloway and P. nitida (Taylor) Malme, were collected in Puyehue National Park, Southern Chile (40° 30’ S) at 400 to 700 m.a.s.l., growing on threes bark.

Voucher specimens are deposited in the herbarium at Santa Maria University, Valparaiso, Chile.

Melting points were determined on a Stuart Scientific SMP3 apparatus. Optical rotation were measured in CHCl3 with a Schmidt-Haensch polarimeter. 1H-NMR spectra were recorded at 60 MHz (Varian T-60) and 400 MHz (Bruker AM) with TMS as internal standard. IR spectra were recorded as KBr pellets (FT-IR Nicolet Impact 420). TLC and CC were performed on Si gel from E.Merck and eluted with mixts of petrol (60-80°) - ethylacetate -formic acid in different polarities (35:10:1; 35:15:1; 20:35:1). The air-dried and ground lichen thalli were extracted successively with dichloromethane and acetone, or acetone, each time for 48 h. At room temperature.

The all known compounds were identified by physical and spectroscopic methods and compared with authentic samples using the Culberson Standardized Solvent Systems(12, 13). Full details of isolation and identification of the compounds are available on request to the senior author.(*)

P. berberina (84 g) was collected at 600 m.a.s.l. Calycin 8 (0.59 g; 0.69 %) pulvinic acid 10 (0.03 g; 0.04 %) and pulvinic dilactone 9 (0.03 g; 0.04 %) were isolated fron the acetone extract (35:15:1).

P. divulsa (125 g) was collected at 700 m.a.s.l. The dichloromethane extract afforded 7b-acetoxy-22-hydroxyhopane 12 (5.10 g; 4.08 %), zeorin 11 (0.51 g; 0.41 %) and ergosterol peroxide 14 (0.39 g; 0.31%). (35:15:1). From the acetone extract, tenuiorin 7 (2.40 g; 1.92 %), constictic acid 5 (0.05 g; 0.04%) and cryptostictic acid 6(0.08 g; 0.06%) were obtained (20:35:1).

P. exanthematica (217 g) was collected at 600 m.a.s.l. 7b-acetoxy-22-hydroxyhopane 12 (1.60 g; 0.74%), zeorin 11 (0.50 g; 0.23 %) and ergosterol peroxide 14 (0.07 g; 0.03 %) were isolated from the dichloromethane extract (35:15:1); Norstictic acid 2 (0.17 g; 0.08%), hyposalazinic acid 3 (0.18 g; 0.08%), stictic acid 1 (0.57 g; 0.26%) and hypostictic acid 4 (0.13 g; 0.06 %) from the acetone extract (35:15:1).

P. meyenii (55 g) was collected at 400 m.a.s.l. Tenuiorin 7 (0.10 g; 0.18%), 7b-acetoxy-22-hydroxyhopane 12 (0.25 g; 0.45%); leucotylin 13 (0.02 g; 0.03 %) and ergosterol peroxide 14 (0.04 g; 0.06 %) were isolated from the dichloromethane and acetone combined extracts (35:10:1).

P. nitida (298 g) was collected at 600 m.a.s.l. Tenuiorin 7(0.30 g; 0.10 %), 7b-acetoxy-22-hydroxyhopane 12 (0.20 g; 0.07 %), zeorin 11 (0.10 g; 0.03 %), ergosterol peroxide 14 (0.40 g; 0.13 %) and stictic acid 1 (0.05 g; 0.02 %) were isolated from the combined extracts (35:10:1).

RESULTS AND DISCUSSION

Results obtained from the revision of five taxa of Pseudocyphellaria and which are shown in Table I, Fig. 1 differ from those reported previously(1). From P. berberina which is characterized by the accumulation of metabolites derived from the shikimic acid pathway, calycin 8, pulvinic dilactone 9 and pulvinic acid 10, were isolated; this last one was not informed previoulsy. Triterpenes were not detected in this study.

For P. divulsa and P. exanthematica methylgyrophorate, methyllecanorate, methylevernate , and 7b-22-dihydroxyhopane were reported; however these compounds were not found in the analysed material.

The largest differences were observed in P. meyenii and P. nitida. For P. meyenii, the only compounds common to the lichen material analysed by TLC include tenuiorin 7 and 7b-acetoxy-22-hydroxyhopane 12. Didepsides previously informed were not founded. P. nitida is a species with white medulla and pseudocyphellae which indicates the absence of coloured compounds derived from shikimic acid. For this species calycin 8 and pulvinic dilactone 9 were informed among other compunds(14). The chemical differences observed (Table 1 and 2) in these species of Pseudocyphellaria might be a consequence of the presence of chemical races which are frecuent among lichens(15), of the erroneus taxonomic determination of P. divulsa or of the sensivility of microchemical method used (TLC).




ACKNOWLEDGEMENTS

This work was supoorted by Grant 991321 from D.G.I.P., Universidad Técnica Federico Santa María. We are grateful to Corporación Nacional Forestal (CONAF), X Región, Chile, for logistic assistance.

REFERENCES

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9. D. J. Galloway. Studies in Pseudocyphellaria (lichens) I. The New Zealand species. Bull. Br. Mus. Nat. Hist. (Bot.) 17:1-267 (1988).        [ Links ]

10. T. G.A. Green. J. Horstmann, H. Bonnett, A. L. Wilkins and W. B. Silvester. New Phytol. 84:339-348 (1980).        [ Links ]

11. G. Guzmán, W. Quilhot and D. J. Galloway. Lichenologist 22: 325-331.        [ Links ]

12. C.F. Culberson, W. L. Culberson and A. Johnson. Bryologist 84:16-29 (1981).        [ Links ]

13. F. Culberson and A. Johnson. J. Chromatogr. 238: 483-487 (1982).        [ Links ]

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