Antigenotoxicity of Depsidones Isolated from Brazilian Lichens

Although phenolic compounds produced by lichens have been widely investigated in antitumor assays, only a small number have been evaluated for mutagenicity and genotoxicity. This study evaluated protocetraric, hypostictic, psoromic, and salazinic acids for their potential genotoxic or antigenotoxic activity against somatic cells of Drosophila melanogaster. These compounds were isolated from the lichens Parmotrema dilatatum, Pseudoparmelia sphaerosphora, Usnea jamaicensis, and Parmotrema cetratum, respectively, collected from the Brazilian Cerrado biome. The compounds were evaluated at 0.75, 1.5, 3.0, and 6.0 mmol L–1 using the SMART test, employing standard and high-bioactivation crosses of Drosophila melanogaster. Doxorubicin (DXR) was the positive control. Psoromic and salazinic acids proved toxic at 6.0 mM. None of the compounds evaluated exhibited mutagenicity, but each of them significantly reduced genetic damage caused by DXR, proving antigenotoxic when tested on somatic cells of D. melanogaster. DOI: http://dx.doi.org/10.17807/orbital.v9i1.89

Herbicidal and Plant-growth Stimulating Effects of Phenolic Compounds Isolated from Lichens

The depsides atranorin (7) and diffractaic acid (1), the depsidones hypostictic (2) protocetraric (3), salazinic (4) acids, the xanthone secalonic acid (5), and usnic acid (6) were evaluated for their phytotoxic potentials against the target species Allium cepa cv. Baia periforme (onion, Monocotyledoneae). The bioassays, carried out under laboratory conditions, revealed that diffractaic (1) and hypostictic (2) acids stimulated plant growth; secalonic acid (5) stimulated seed germination and radicle growth, while reducing coleoptile length. Usnic acid (6) promoted seed germination and stronger inhibition of radicle and coleoptile growth. Protocetraric (3) and salazinic (4) acids and atranorin (7) exhibited a herbicidal effect, inhibiting seed germination and reducing radicle and coleoptile growth—features that suggest their utility as natural herbicides. These results invite further investigation to elucidate the mode of action of these compounds and to synthesize them for field experiments. DOI: http://dx.doi.org/10.17807/orbital.v7i3.75

Parmotrema screminiae (Parmeliaceae), a Novel Lichen Species from Brazil with Potent Antimicrobial Activity

Parmotrema is a genus of major interest in the lichen flora of Mato Grosso do Sul state, Brazil, since many of its species are sources of important bioactive compounds. Parmotrema screminiae Spielmann & Canêz, a novel species, is a noteworthy source of norlobaridone (a depsidone), protolichesterinic acid and atranorin (a depside). Extract composition was determined by TLC and NMR techniques (1H, 13C, and DEPT-135). The acetone extract was evaluated for antibiotic activity against Gram-negative (Escherichia coli, ATCC 25922) and Gram-positive bacteria (Staphylococcus aureus, ATCC 25923 and clinical strains), Enterococcus faecalis (ATCC 51299), and E. faecium (vancomycin-resistant clinical strain). Highly promising results were obtained, since the extract proved active against Gram-positive bacteria alone (MIC = 31.25 μg/mL for E. faecalis, 15.6 μg/mL for both E. faecium and clinical-strain S. aureus, and 7.8 μg/mL for standard S. aureus). Bioautography showed norlobaridone and protolichesterinic acid to be responsible for the antibiotic activity. DOI: http://dx.doi.org/10.17807/orbital.v8i6.87

Gas Chromatography-Mass Spectrometry (GC-MS) and evaluation of antioxidant and antimicrobial activities of essential oil of Campomanesia adamantium (Cambess.) O. Berg (Guavira)

The essential oils from Campomanesia adamantium (Cambess.) O. Berg leaves, collected in the reproductive (flowering and fruit-bearing) and vegetative stages, were characterized by GC-MS (Gas Chromatography-Mass Spectrometry). A total of 95 compounds of the essential oils were identified. In the reproductive stage (flowering) the major constituents were monoterpenes (limonene, α-pinene and β-pinene) while during the vegetative stage the major constituents were the sesquiterpenes (bicyclogermacrene and globulol). The essential oil of the reproductive stage shows high antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans, and all show moderate activity against Escherichia coli. The essential oils were also evaluated for their radical-scavenging activity by DPPH. The chemogeographical variations of the oil composition from the four distinct localities studied all contained α-pinene, β-pinene, limonene, linalool, β-caryophyllene, germacrene D and bicyclogermacrene, however the samples from Jardim city contained neither limonene nor linalool.Os óleos essenciais obtidos das folhas de Campomanesia adamantium foram caracterizados através da combinação de CG-EM e índice de retenção, sendo identificado um total de 95 compostos. Na floração as substâncias majoritárias foram monoterpenos (limoneno, α-pineno e β-pineno) e durante o estágio vegetativo as substâncias majoritárias foram sesquiterpenos (biciclogermacreno e globulol). Os óleos essenciais obtidos da floração e frutificação mostraram alta atividade contra Staphylococcus aureus, Pseudomonas aeruginosa e Candida albicans e moderada contra Escherichia coli em todos os estágios. Foi avaliada a atividade antioxidante dos óleos essenciais usando o método do DPPH. O óleo essencial das 4 cidades mostrou a presença de α-pineno, β-pineno, limoneno, linalol, β-cariofileno, germacreno D e biciclogermacreno, mas a amostra da cidade de Jardim não apresentou limoneno e linalol