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The effect of lichen extracts obtained from Cladonia substellata and its main constituent, on the germination and growth of onion (Allium cepa L.) seedlings was investigated. No significant inhibitory effect of the lichen extracts and usnic acid on germination was found, except of usnic acid at the concentration of 726.7 mM. Growth inhibition of the radicle and of the hypocotyl of the seedlings was found for the total extract and for usnic acid in concentrations of 290.6 mM and 726.7 mM.
Secalonic acid A, a yellow pigment from fungal metabolism, was isolated from the lichens Pseudoparmelia sphaerospora and P. hypomilta. From P. sphaerospora was also isolated the depsidone hypostictic acid. The structure of these compounds was determined by spectroscopic methods and comparison with literature data.
Field and herbarium studies of the lichen family Cladoniaceae in the states of Paraíba, Pernambuco and Sergipe, Northeast Brazil, yielded 22 species, many of them being new reports for the region. The phenolic compounds identified in each species are reported. Cladonia clathrata Ahti & Xavier Filho, Cladonia polita Ahti, Cladonia polyscypha Ahti & Xavier Filho, and Cladonia rugicaulis Ahti are described as new. C. clathrata, C. rhodoleuca Vainio, C. rugicaulis, C. salzmannii Nyl., and C. subminiata Stenroos appear to represent an element confined to northeastern Brazil.