The essential oils of Piper cernuum and Piper regnellii leaves were analyzed by gas chromatography-mass spectrometry (GC-MS) and the results were compared to that obtained by means of a program designed to analyse (13)C-NMR data of complex mixtures. Bicyclogermacrene (21.88 %)/beta-caryophyllene (20.69 %) and myrcene (52.60 %)/linalool (15.89 %) were the major constituents in essential oil from leaves of P. cernuum and P. regnellii, respectively. Both essential oils presented growth inhibitory activities against Staphylococcus aureus and Candida albicans.

Dermatological disorders related to pigmentation result in tenuous hyper or hypopigmentation Cosmetic and pharmaceutical products containing depigmenting substances are used in the treatment of patients who have high pigmentation disorders, such as melasma or chloasma, post-inflammatory hyperpigmentation, senile lentigo and ephelides. Skin lightening agents are not yet totally effective or safe and therefore intensive research for the discovery of new agents is continuous. Enzyme inhibitors involved in melanogenesis, such as tyrosinase, have been discovered in Asian countries, including those isolated from plant extracts. The Brazilian flora has the highest species diversity in the world, and the chemical, pharmacological and cosmetic potential for the discovery of new skin whitening agents is in proportion with this biodiversity. For these reasons, 25 aqueous and 24 organic extracts obtained from 19 plants native to the Amazon rain forest and to the Atlantic forest, belonging to 11 different families, were evaluated as tyrosinase inhibitors. Nine out of 49 extracts showed inhibitory activity in the screening process. The 50% inhibitory activity (IA 50 ) was calculated, revealing that the most active extracts were the organic extracts from the leaves and stem of Ruprechtia sp. (IA 50 33.76 mg.mL -1 ) and the organic extract from the aerial organs of Rapanea parviflora (IA 50 64.19 mg.mL -1 ).Uniterms: Tyrosinase. Melanin. Plant extract/in vitro evaluation. Skin lightening agents. Amazonian plants/evaluation/dermatological use.Problemas dermatológicos relacionados com a pigmentação resultam em hiperpigmentações ou hipopigmentação cutâneas. Produtos cosméticos e farmacêuticos com atividade despigmentante são utilizados para o tratamento de pacientes que apresentam distúrbios de hiperpigmentação, tais como melasma ou cloasma, hiperpigmentação pós-inflamatória, lentigem senil e efélides. Os despigmentantes atualmente utilizados não são totalmente eficazes ou seguros, razão pela qual há intensa pesquisa, principalmente em países asiáticos, com a finalidade de se obter novos agentes com esta ação, em especial inibidores de enzimas envolvidas na melanogênese, como a tirosinase. Considerando-se que algumas substâncias obtidas de plantas apresentam essa atividade, a flora brasileira constitui-se uma fonte potencial de obtenção de novos despigmentantes. Por essa razão, 25 extratos aquosos e 24 orgânicos obtidos de 19 plantas da Floresta Amazônica e Mata Atlântica, provenientes de 11 diferentes famílias, foram avaliados quanto à atividade de inibição da tirosinase. Do total de 49 extratos testados, 9 mostraram atividade. Os valores de concentração da atividade inibitória 50% (AI 50%), foram calculados e o mais ativo foi o extrato orgânico das folhas e caule de Ruprechtia sp. (AI 50 33,76 mg.mL -1 ) seguido do extrato orgânico dos órgãos aéreos de Rapanea parviflora (AI 50 64,19 mg.mL -1 ).Unitermos: Tirosinase. Melanina. Extrato de plantas/avaliação in vitro. Despigmentantes. Plantas amazônicas/avaliação/uso dermatológico.

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The volatile oils from the leaves and stem barks of Cedrela fissilis were submitted to GC-MS analysis and separation by adsorption chromatography. The fractions were analysed by GC, 1 H-and 13 C-NMR as well as GC-MS. The major components found in the leaf oil were β β β β β-caryophyllene (26.3%) and bicyclogermacrene (34.6%), while in the stem bark oil the major compounds were β β β β β-bisabolene (10.9%) and globulol (10.9%). In an antibacterial assay, only the leaf oil was able to inhibit growth of Staphylococcus aureus and Eschorichia coli.