Chemical Constituents of the lichen Stereocaulon tomentosum

A phytochemical investigation on the lichen Stereocaulon tomentosum has been conducted. Three compounds namely Atranorin (1), Glutinol (2) and Vulpinic acid (3) were isolated from the ethyl acetate extract of the plants. The structures of 1-3 were determined by NMR studies including from H, C, APT spectral data.


INTRODUCTION
Lichens are the symbiotic organisms of fungi (mycobionts) and algae (photobionts) distributed worldwide [Huneck 1999].Lichen Saccumulate large concentrations of products, particularly aromatic phenolic compounds, sometimes exceeding 20% of dry weight.The majority of these compounds originate from them ycobiont.The general resistance of lichens toinsects and microbial attack is attributed to the presence of lichen compounds (Lawrey 1986).The cortical presence of yellow-coloured compounds, such as pulvinic acid derivatives in lichens play a defensive role against the non-visually oriented small invertebrate herbivores (Rundel 1978).A lichen is not a single organism the way most other living things are, but rather it is a combination of two organisms which live together intimately.Most of the lichen is composed of fungal filaments, but living among the filaments are algal cells, usually from a green alga or a bacterium.In many cases the fungus and the alga which together make the lichen may each be found living in nature without its partner, but many other lichens include a fungus which cannot survive on its own --it has become dependent on its algal partner for survival.

MATERIALS AND METHODS
TLC and preparative TLC were performed using per coated aluminum and glass plates with silica gel 60 F 254 , where as column chromatography was carried out on silica gels 230-400 mesh.Spots and bands for compounds on TLC were detected using UV light.UV spectra were recorded on a UV-1650PC spectrophotometer.Xray structure determination was carried out by Bruker SMART APEX and the accompanying SHELXTL programming suite. 1 H NMR (400 MHz) and 13 C NMR (100 MHz) spectra were recorded on JEOL and chemical shifts in ppm were referenced to internal acetone-d6 and CDCl 3 , respectively. 1 H-1 H COSY and NOESY spectra were acquired using the standard JOEL software.

Plant material:
The Stereocaulon tomentosum were collected from a UKM forest.A voucher specimen had been deposited at the Herbarium of UKM.
Compound 3; was obtained as yellow needles, which determined by EIMS, 1 H and 13 C NMR.The molecular formula of compound 3 was established by EIMS as C 19 H 14 O 5 which indicated 13 degree of instauration, (M + , m/z 322), melting point 150-152 o C, and showed strong absorption in its UV spectrum.Suitable structure for X-ray analysis is in figure 2. The 1 H NMR displayed aromatic.

CONCLUSION
The isolation and identification of Atranorin (1), Glutinol (2) and vulpinicacid (3) from the lichen Stereocaulon tomentosum was the first ever to be done on this plant.The work was carried out by means of various physical (solvent extraction, column chromatography, radial chromatography, preparative TLC, malting points and R f value) and spectral techniques.