Penicillium meliponae, a recently described and rare species, was isolated as an endophytic fungus from the Amazonian plant Duguetia sthelechantha, and has been proven to be a pigment producer. Considering the high productivity of this species and the lack of data on its chemical composition, the present study aimed to characterize the chemical profile of P. meliponae and evaluate the influence of agitation and the use of different culture media. For this purpose, liquid chromatography coupled with mass spectrometry (LC-MS/MS) and molecular networking were used, allowing the identification of 17 azaphilone molecules with sclerotiorin-like skeletons, becoming the first chemical report of this species. In addition, the different production patterns in the tested culture media were indicative that this species is sensitive to changes in the composition of the carbon source and to the presence of agitation. Furthermore, this work contributes to the fragmentation mechanisms of the different possible structural arrangements for azaphilones of the sclerotiorin type and serves as a repository of information on the gas-phase behavior of this type of metabolite in mass spectrometry experiments and will assist future studies aimed at the discovery of azaphilones.

Mari-mari (Cassia leiandra Benth.) is an Amazonian native fruit that is highly appreciated in the northern region of Brazil, but there are few studies regarding its chemical composition and/or biological properties. A phytochemical study was conducted on the extracts of the pulp, peel and seeds; and their antioxidant, cytotoxic and antimicrobial potential were also determined. Methanol and acetone extracts from different fruit parts were subjected to total phenolic, 2,2-diphenyl-1 picrylhydrazyl (DPPH) radical scavenging and FeIII reducing capacity (FRAP) assays. From the peel extracts, the engeletin and astilbin could also be isolated and characterized based on nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry. A quantification using ultra-fast liquid chromatography of acetone dry crude extracts (DCE) of the peel showed that engeletin was the main compound (532.77 mg g-1 DCE). Astilbin content was also determined (131.53 mg g-1 DCE). The antibacterial and antiproliferative activities were evaluated and the methanol extract of the peel showed higher growth inhibition activity against all tested bacteria. Engeletin showed a relevant antimicrobial effect against Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli. Acetone and methanol peel extracts exhibited a relevant inhibitory effect on the proliferation of breast carcinoma cells (MCF-7), with no toxicity to the normal cell line (NIH/3T3).

The genus Penicillium is among the most promising alkaloid-producing fungal and therefore plays an important role in terms of producing molecules with biotechnological potential. Thus, in order to identify alkaloid-producing fungi, 25 endophytic Penicillium strains previously isolated from Amazon medicinal plants were subject to an integrative approach based on direct infusion positive electrospray ionization mass spectrometry (ESI-MS) and principal component analysis (PCA). The multivariate analysis pointed paxiline (1), glandicoline B (2), roquefortine C (3), and oxaline (5) as responsible for the segregation of three promising alkaloid-producing groups, been these groups constituted for P. chrysogenum, P. oxalicum, P. paxilli, and P. rubens strains. These alkaloids and the glandicoline A (4) were tentatively identified by multiple-stage mass spectrometry. In addition, compounds 1 and 2 were isolated and confirmed by using 1D and 2D nuclear magnetic resonance (NMR) spectroscopy. Overall, the chemical profile analysis by ESI-MS along with PCA provided a simple and effective approach to screening alkaloid-producing Penicillium strains for biotechnological applications.

Endopleura uchi (Huber) Cuatrec. is an Amazonian medicinal plant with restricted distribution to the North Region of Brazil. Its bark is commonly used as natural medicines for the treatment of many diseases. Although widely investigated from the phytochemical viewpoint, the knowledge regarding the phenolic content remains unexplored. In order to access the phenolic composition of E. uchi bark, an integrative approach based on simplex-centroid design, direct infusion electrospray ionization mass spectrometry (ESI-MS) and chemometric analysis was adopted. In addition, the extracts were evaluated to total phenolic content and antioxidant activity. The multivariate analysis pointed to the ethanol-based extracts as the most representative for phenolic compounds, with 3,5-di-O-galloylquinic acid (2), gallic acid (4), 5-galloylquinic acid (5) and gallocatechin gallate (6) tentatively identified by MS analysis, all described for the first time in E. uchi. Besides, pure ethanol extract presented highest total phenolic content (TPC = 133.61 ± 0.3 mg GAE 100 g-1) and antioxidant activity (half maximal inhibitory concentration, IC50 = 9.32 ± 0.15). The integrative approach proposed to this work provided an effective way to assess the phenolic compounds of E. uchi bark, therefore, improving the knowledge regarding phenolic content in this Amazonian medicinal plant.

Onychopetalum is an Amazonian botanical genus close-related with Bocageopsis and Unonopsis, whose species are used in traditional medicine. Although these genera are widely investigated from the phytochemical viewpoint, the knowledge about Onychopetalum remains almost unexplored. In order to perform a comprehensive characterization of isoquinoline-derived alkaloids from Onychopetalum amazonicum, an integrative approach based on the alkaloid profile analysis by leaf spray mass spectrometry (LS-MS), followed by a robust dereplication through high-performance liquid chromatography coupled with diode array detector and atmospheric pressure chemical ionization tandem mass spectrometry, (HPLC-DAD-APCI-MS/MS) and nuclear magnetic resonance (NMR) analysis was adopted. LS-MS allowed the tentative identification of reticuline, norjuziphine, nornuciferine, O-methylisopiline, nuciferine, N-methyl-O-methylisopiline, anonaine, and N-methylanonaine. HPLC-DAD-MS/MS analysis supported the tentative identification of N-methylasimilobine, asimilobine, norushinsunine, N-methylisopiline, isopiline, liriodenine, and lysicamine. Moreover, the integration of MS and NMR data allowed the additional identification of stepholidine and isocorypalmine. The applied integrative approach proposed herein enabled a comprehensive analysis of the alkaloid content from the O. amazonicum, showing to be a useful strategy for the dereplication of isoquinoline-derived alkaloids.

Bertholletia excelsa Bonpl. (Lecythidaceae) is a South American tree worldwide known for providing the Brazil nuts. In the Amazon Region, B. excelsa is found in monocultures, integrating agroforestries and providing raw materials for food and timber industries. Through the application of an integrative analysis based on high-performance liquid chromatography coupled with diode array detector and tandem mass spectrometry (HPLC-DAD-MS/MS) and nuclear magnetic resonance (NMR) techniques, the present study showed that B. excelsa bark biomass residues contain large quantities of ellagic acid (EA) and its derivatives. Qualitatively, five compounds were characterized for the first time in this species. Quantitations were carried out to determine the total amount of these compounds in outer and inner bark tissues. A total of 4.96 and 44.09 g of EA derivatives per kg of dry residues was determined for the outer and inner barks, respectively. Among the EA derivatives, eschweilenol C, ellagic acid and valoneic acid dilactone were the main compounds. These results pointed B. excelsa barks as a valuable biomass residue with potential to be source of health-promoting compounds. Therefore, a potential raw material as source of valuable bioactive phenolic compounds is described herein.

In this study, we investigated the chemical compositions and antioxidant and antimicrobial activities of propolis produced by the stingless bee Frieseomelitta longipes and the honeybee Apis mellifera collected from colonies in North Brazil. In terms of volatile composition, both mono- and sesquiterpenes were detected in the propolis of F. longipes while only sesquiterpenes were detected in that of A. mellifera. Out of 50 volatiles identified in all samples, 26 were found exclusively in F. longipes propolis and 8 were found exclusively in A. mellifera propolis. The chemical profiles of the propolis extracts were determined by atmospheric pressure chemical ionization-mass spectrometry and liquid chromatography-electrospray ionization-tandem mass spectrometry allowed to identify several prenylated benzophenones. A. mellifera extracts exhibited major antioxidant activity as assessed by the 2,2-diphenyl-1-picrylhydrazyl method and all extracts exhibited antioxidant activity as assessed by the β-carotene/linoleic acid method. The ethanolic extracts of the propolis showed promisor activity against all tested microorganisms.

The continuous search for biologically active compound candidates pushes the pursuit of new substances produced by diverse organisms. Endophytic fungi are known as a promising source of metabolites with several biological activities. Based on the rich Amazonian biodiversity and the chemical potential of microbial sources, three Talaromyces strains, all major endophytes from their respective host plants, were studied aiming at the isolation of biologically active secondary metabolites. Through classical chromatographic approaches, 13 compounds were isolated from the antimicrobial extracts of the studied strains. From these, polyketides, steroids, anhydrides, and phenolic compounds were identified. Among them, two previously undescribed compounds were elucidated based on spectroscopic and spectrometric methods, a homodimer chromanone and a maleic anhydride methyl ester. The antimicrobial activity against a panel of pathogenic microorganisms from extracts, fractions, and isolated compounds was evaluated.

The continuous search for antimicrobial candidates pushes the pursuit of compounds in the most diverse organisms. Amphibians are known as a prolific source of antibacterial peptides. Based on the rich biodiversity of the Amazon region the unexplored green-tree frog (Hypsiboas cinerascens) was studied for its skin secretion peptide content. Chromatographic separations and established tandem mass spectrometry (MS/MS) methods were used for sequencing the primary structures of the purified compounds. De novo sequencing lead to the identification of five new peptides related to hylaseptin P1, displaying an aminated C-terminal. Sequencing of the complementary deoxyribonucleic acid (cDNA) analysis allowed the disambiguation of isobaric amino-acids for C-01. Matrix assisted laser desorption ionization (MALDI) was carried out, demonstrating the in situ co-occurrence of the identified peptides in the dorsal skin. The major peptide C-01 was synthesized and assayed against a selection of microorganisms displaying minimal inhibitory concentrations (MICs) ranging from 4 to 16 µM.

DgCr22.1b, um isolado endofítico de Talaromyces sp., foi coletado na Floresta Amazônica a partir da planta medicinal Duguetia stelechantha. Do fracionamento do extrato metanólico de sua massa micelial, foi isolada uma nova xantona dimérica talaroxantona. A estrutura deste novo composto foi elucidada com base em análises espectroscópicas incluindo experimentos de ressonância magnética nuclear (RMN) 2D.

DgCr22.1b, an endophytic isolate of Talaromyces sp., was collected in the Amazonian Rainforest from the medicinal plant Duguetia stelechantha. From the fractionation of the methanolic mycelial extract, a new xanthone dimer talaroxanthone was isolated. The structure of this new compound was elucidated based on spectroscopic analyses including 2D nuclear magnetic resonance (NMR) experiments.

In vitro evaluation of alkaloidal fractions of twigs, barks and leaves from two Unonopsis species, Unonopsis guatterioides R.E. Fr. and Unonopsis duckei R.E. Fr., Annonaceae, against promastigote forms of Leishmania amazonensis revealed these species as sources of substances with promising leishmanicidal potential. All alkaloidal fractions from twigs, barks and leaves of U. guatterioides were classified as highly active, with IC50 1.07, 1.90, and 2.79 mg/mL, respectively. Only the alkaloidal fraction from the twigs of U. duckei was classified as inactive.

Mauritia flexuosa L. f., Arecaceae, is an endemic species of South America. This species was studied with the intent to isolate the constituents of its roots. After the fractionation of the n-hexane and methanolic extracts from the roots of M. flexuosa, six triterpenes were obtained: friedelin, taraxerone, lupenyl acetate, lupenone, betulin and betulinic acid, along with three flavonoids: rutin, quercitrin and quercetin. All the compounds were identified by analysis of NMR and MS data and comparison with the literature. All those compounds are been reported for the first time in Mauritia, and the chemosystematic significance of the flavonoids isolated in this genus is discussed.

O presente trabalho descreve o isolamento, a partir do caule de Annona amazonica, do ácido acantóico, um diterpeno do tipo pimaradieno que possui várias e importantes atividades biológicas descritas na literatura. Neste estudo foi verificado que este composto apresenta significante atividade tripanocida contra as formas epimastigotas de Trypanosoma cruzi. Também foi constatado que este diterpeno é o constituinte majoritário da planta, encontrado em cerca de 65% do extrato hexânico, demonstrando que A. amazonica é uma nova fonte natural renovável desta substância. Além do ácido acantóico, a investigação química resultou no isolamento dos alcalóides liriodenina e cassiticina, entre outros compostos, tais como terpenos, esteróides e ácidos graxos. Adicionalmente, é descrita a completa e inequívoca atribuição dos deslocamentos químicos de RMN de ¹H e 13C da cassiticina.

The present work reports the isolation of acanthoic acid, a promising pimaradiene-type diterpene with several important biological activities described in the literature, from the stems of Annona amazonica. We found that acanthoic acid has significant trypanocidal activity against the epimastigote forms of Trypanosoma cruzi. This diterpene is the major constituent of the plant, comprising at least 65% of the hexane extract, demonstrating that A. amazonica is a new renewable natural source for this compound. The chemical investigation also resulted in the isolation of the alkaloids liriodenine and cassythicine, and other compounds including terpenes, sterols, and fatty acids. Additionally, the complete and unequivocal ¹H and 13C NMR chemical shift assignments for cassythicine are provided.