Phytochemical screening of Ocotea delicata (Lauracaeae)

The Ocotea is the largest genus of Lauraceae family, being one of the genera with greater occurrence in the Amazon rainforest flora.1,2 Though it’s economic importance, with several species being exploited by their outstanding bioactivity (such as antioxidant, antirheumatic, insecticidal and antifungal),3 it had being poorly scientific explored. Approximately only 12% of its species presents any level of chemical description. Therefore, the present work aimed to provide the first chemical description of the Ocotea delicata Vicent., a chemically unexplored endemic specie of Amazon.4 Leaves of O. delicata had being collected in a protected forest fragment of the Biological Dynamics of Forest Fragments Project, 60 km north of Manaus-Amazonas. Samples were air-dried, grounded and submitted to an ultrasound assisted extraction with ethanol 70% as the extracting solvent. The extracts were evaporated to dryness and fractionated by liquid-liquid partition using hexane, ethyl acetate and methanol. Phytochemical screening was performed with the ethyl acetate fraction using reversed phase Ultra High Performance Liquid Chromatography coupled to high resolution mass spectrometry. Biological replicates provided two distinct chemical profile in positive-ion ionization mode and three different profiles in the negative-ion ionization mode. Technical replicates presented coefficients of variance of the peaks areas and retention time were lower than 20% and 2%, proving the analytical method precision. Chemical profiles were mainly composed by phenolic compounds and aporphine alkaloids. Most of phenolic substance were putatively identified as derivates of kaempferol, apigenin and quercetin with glycosylated monomeric units, such as rhamnoside and glucoside. The major peak at negative-ion mode was apigenin-8-C-glucoside. Among the aporphine alkaloids putatively identify it was present compounds such as coridine, predicentrine, coclaurine, corituberine, isoboldine, norisoboldine and dehydronantenine, which was the major peak at the positive-ion mode. Those substances characterize the species as a possible source for the development of bioactive products, since most of the identified compounds were previously reported by their bioactivity. Despite those substances are usually described in Ocotea and Lauraceae species,2,5 this is the first report of O. delicata, which can be further applied on the chemotaxonomy study of the genus and improve the chemical knowledge of such a complex genus as Ocotea.

References:
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2. H. ter Steege, R. W. Vaessen, D. Cárdenas-López, D. Sabatier, A. Antonelli, S. M. de Oliveira, N. C. A. A. Pitman, P. M. Jørgensen and R. P. Salomão, Sci. Rep., 2016, 6, 29549.
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4. H. van der Werff and A. Vicentini, Novon, 2000, 10, 264–297.
5. M. M. R. Silva Teles, A. A. Vieira Pinheiro, C. Da Silva Dias, J. Fechine Tavares, J. M. Barbosa Filho and E. V. Leitão Da Cunha, in Alkaloids: Chemistry and Biology, 2019, pp. 147–304.