Chemical composition and antioxidant activity of the essential oil of Renealmia alpinia (Rottb.) Maas.

Renealmia alpinia (Rottb.) Maas was collected in Serra do Tepequém, municipality of Amajari, state of Roraima, Brazil. The essential oil was obtained from the fresh leaves by hydrodistillation using a Clevenger apparatus and analysed using GC-FID and GC-MS. The oil provided a yield of 0.6% (w/w), which, in the analysis of its contents, presented a higher concentration of sesquiterpenes, with α-phellandrene (23.10%), 16-oxo-8(17),12(E)-labdadien-15-oic acid (17.05%), ß-caryophyllene (10.28%), valencene (5.27%) and allo-aromadendrene (3.52%) being the most abundant. The antioxidant activity of the essential oil was determined using two methods, and indicated significant activity by both. Using the DPPH method, the essential oil presented an IC50 of 1.470 ± 0.0264 mg.L1 and an inhibition of the ß-carotene/linoleic acid oxidation system of 76.43 ± 0.80%.

Molecular network-guided chemical profile and mass spectrometry, volatile compounds, and antimicrobial activity of Scaptotrigona depilis propolis.

RATIONALE: Propolis has a great diversity in its composition due to numerous factors; therefore, each study is an important contribution to the knoFwledge of its composition and biological action. The objective of this study was to determine the chemical profile and biological activity of propolis produced by Scaptotrigona depilis. METHODS: Extracts with 70% ethanol (EPE70) and with cereal alcohol (CAPE) were elaborated, and then characterized using UHPLC-ESI(+)-MS/MS. Volatile compounds were extracted and then characterized using gas chromatography mass spectrometry (GC-MS). In addition, antimicrobial activities were verified against resistant strains. RESULTS: The volatile compounds of propolis predominantly consist of sesquiterpenes. Using the exploratory metabolomic approach, compounds of different classes were putatively identified in the ethanolic extracts, of which the most representative were terpenes, and some of the sesquiterpenes identified among the volatiles were also detected. The extracts were shown to be active against Escherichia coli and Staphylococcus aureus bacteria with a minimum inhibitory concentration (MIC) of 0.5 and 1.0 mg mL-1 , respectively. CONCLUSIONS: The molecular network approach proved to be determining the chemical profile of S. depilis propolis rapidly and accurately, and led to the identification of lipophilic compounds. The identification of compounds using GC-MS and UHPLC-ESI(+)-MS/MS is complementary and useful for the characterization of propolis.

Ultra-high-performance liquid chromatography combined with electrospray ionization quadrupole time-of-flight mass spectrometry and molecular networking analysis to investigate the chemodiversity of bioactive extracts of Annona jahnii Saff. fungi from the Brazilian Amazon.

RATIONALE: Annona species are of interest for the isolation of bioactive molecules; however, studies of Annona jahnii Saff. are limited. The exploration of bioactive metabolites of endophytes isolated from this species is unprecedented and allows the preservation of the host plant, in addition to enabling the discovery of compounds with promising biological activities. METHODS: Ethyl acetate extracts from the cultured media of five fungi were obtained. The antioxidant capacity of the extracts was measured using the 1,1-diphenyl-2-picrylhydrazyl free radical method. Antimicrobial activity was determined using the microdilution method in broth in 96-well plates. The exploration of the metabolic profile of the extracts and dereplication of the compounds were performed using ultra-high-performance liquid chromatography/electrospray ionization/tandem mass spectrometry (UHPLC/ESI-MS/MS) combined with analysis using molecular networking (MN). RESULTS: A total of 1818 MS features were detected in the five selected extracts, of which 39 compounds were putatively identified. The secondary metabolites with the highest abundance were alkaloids, naphthopyrons, and cytochalasins. Other secondary metabolites include fumonisins, coumarin, and a meroterpenoid. Most of these compounds are related to specific biological properties such as antioxidant, anti-inflammatory, antimicrobial, antiviral, and antitumor activities. Extracts F398 and F403 showed inhibitory activity of the four pathogens tested. Extracts F475 and F506 did not inhibit the growth of Staphylococcus aureus, and F407 did not inhibit the growth of Escherichia coli in addition to having potent antioxidant activity, with IC50 values of 10 µg/mL or less. CONCLUSIONS: The use of UHPLC/ESI-MS/MS data combined with MN proved useful in the dereplication of bioactive molecules of complex extracts that are still unexplored. These initial investigations should significantly assist in further research and increase the efficiency and speed in the discovery of new sources of secondary metabolites and new natural products.

Identification of lipophylic constituents of the nest of Frieseomelitta silvestrii (FRIESE, 1902).

Bees are becoming more and more valued for the extremely important role they play in ecological communities, especially for their pollinating action. The state of Roraima, Brazil has areas of native vegetation and variety of stingless bees, and this potential is still untapped. The objective of this study was to determine the chemical composition of materials collected from the nests of Frieseomelitta silvestrii (FRIESE, 1902), identified in São Luiz, in Roraima state, Brazil. The chemical composition of the collected material was determined by gas chromatography coupled to mass spectrometry (GC-MS). The dichloromethane extracts of propolis, cerumen threads and resin present in the stingless bee nest presented differentiated profiles with the occurrence of low polarity compounds.