Canthin‐6‐one alkaloids, which are present in plants of the genus Simaba, are natural compounds that are capable of acting as fluorescent probes. However, the chemical composition and fluorescent properties of most species of this genus have not been analyzed. The objective of this study was to characterize the fluorescent properties of an extract of S. bahiensis and identify the chemical entities responsible for these properties. In addition, the cell‐labeling properties of the fluorescent dye from A and of the isolated compounds were characterized by confocal fluorescence microscopy and flow cytometry. One quassinoid and three fluorescent alkaloids were isolated from S. bahiensis, all compounds were identified by using NMR spectroscopy and high‐resolution mass spectrometry. Staining experiments and HPLC‐FL analysis shown that canthin‐6‐one alkaloids are the main green fluorescent compounds in the analyzed dyes. All compounds evaluated showed a cytoplasmic marker with a residence time of 24 h. The present study is the first to describe the presence of canthin‐6‐one alkaloids in S. bahiensis, in addition to demonstrating promising cell‐labeling properties of fluorescent compounds from S. bahiensis with broad emission wavelengths.

Graphical Abstract Abstract.Alkaloids of the canthi-6-one type have been reported in differents natural sources. These alkaloids have showed a wide range of pharmacological properties including cytotoxic, antibacterial, antifungal, antiparasict, antiviral, anti-inflammatory and beside it, some of them show excellent photophysical properties that gives an interesting use as fluorescent dye probe in florescent cellular microscopy. Because it, new studies have been carrying out in an attempt to identify new alkaloids with pharmacological properties. Some researchers have been trying to synthesize new derivatives or identify new compounds in natural sources. Among the >60 canthin-6-one alkaloids already reported in natural sources, more the half are present in plants of the family Simaroubaceae. In the Simaba genus, up to the present, only eighteen alkaloids was described in seven species, but other plants of the genus that occur in the brazilian's flora haven't been studied yet. In this work we describe the first phytochemical study of the specie Simaba bahiensis (Simaroubaceae), collected at the city of Camaçari, Bahia State, Brazil. Also, it's related complete structural determination using differents NMR experiments and HRMS of a new canthin-6-one alkaloid in addition to two others already known MOL2NET, 2017, 3, doi:10.3390/mol2net-03-xxxx IntroductionCanthi-6-one alkaloids occur in plants from families Rutaceae, Simaroubareace, Amaranthaceae, Caryophyllaceae and Zygophylaceae [1][2][3]. More than 60 members of this type of alkaloid were isolated from natural sources since first report in 1952 [4]. These alkaloids have shown a wide range of pharmacological properties including cytotoxic, antibacterial, antifungal, antiparasict, antiviral, antiinflammatory and beside it, some of them show interesting photophysical properties that gives an interesting use the fluorescent dye probe in florescent cellular microscopy. New studies have been carring out in an attempt to identify new alkaloids with pharmacological properties by synthesis or isolation from different natural sources [2]. In family Simaroubaceae more than 30 canthi-6-one alkaloids have already been described with different substitution patterns and it shows that the investigation of new alkaloids in this family it's an important way to search new chemical entities [2,3]. In this work we describe the first phytochemical study of Simaba bahiensis (Simaroubaceae), collected at the city of Camaçari, Bahia State, Brazil. Also, it's related complete structural determination using differents NMR experiments and HRMS of a new canthin-6-one alkaloid and two others already known.