Chemical characterization, antioxidant and antimicrobial activity of propolis obtained from Melipona quadrifasciata quadrifasciata and Tetragonisca angustula stingless bees

<div><p>In this study, we investigated the chemical composition, and antioxidant and antibacterial properties of ethanolic extracts of propolis (EEP) from Melipona quadrifasciata quadrifasciata and Tetragonisca angustula. Chemical composition of EEP was determined by colorimetry and chromatographic (HPLC-DAD and UPLC-Q/TOF-MS/MS) analysis. Antimicrobial activity of EEP was evaluated against gram-positive (S. aureus, methicillin-resistant S. aureus, E. faecalis) and gram-negative (E. coli and K. pneumoniae) bacteria by the minimal inhibitory concentration (MIC) test using the microdilution method. Furthermore, the growth curve and integrity of cell membrane of S. aureus and E. coli were investigated using standard microbiological methods. HPLC-DAD analysis showed that the EEP of M. quadrifasciata quadrifasciata has a more complex chemical composition than the EEP of T. angustula. Moreover, UPLC-MS analyses of M. quadrifasciata quadrifascita indicated flavonoids and terpenes as major constituents. The bactericidal activity of both EEPs was higher against gram-positive bacteria than for gram-negative bacteria. The EEP from M. quadrifasciata quadrifasciata presented MIC values lower than the EEP from T. angustula for all tested bacteria. The EEP from M. quadrifasciata quadrifasciata caused lysis of the bacterial wall and release of intracellular components from both E. coli and S. aureus. Our findings indicate that the chemical composition of propolis from stingless bees is complex and depends on the species. The extract from M. quadrifasciata quadrifascita was more effective against gram-positive than gram-negative strains, especially against S. aureus and methicillin-resistant S. aureus compared to T. angustula extract, by a mechanism that involves disturbance of the bacterial cell membrane integrity.</p></div

Valor nutritivo de cultivares de capim-elefante (Pennisetum purpureum Schum.) sob condições de pastejo Elephant grass (Pennisetum purpureum, Schum.) cultivars nutritive value under grazing conditions

Com objetivo de avaliar as cultivares (cvs.) de capim-eletante: Merckeron Pinda, Mercker-86-México, Porto Rico e Cameroon sob pastejo, conduziu-se este experimento em Santa Maria-RS. Para avaliação, foram Utilizadas novilhas e vacas em lactação da raça Holandês em pastejo rotativo. O valor nutritivo foi estimado a partir dos teores de proteína bruta (PB) e coeficientes de digestibilidade in vitro da matéria orgânica (DIVMO) determinados sobre amostras da parte aérea das plantas, colmos, tolhas e extrato da forragem paste jada. As cvs. apresentaram valor nutritivo bastante equilibrado, diferindo quanto aos teores de PB das folhas e DIVMO destas e do extrato da forragem pastejada: obtendo os melhores resultados com as cvs. Merckeron Pinda e Mercker-86-México.<br>To evaluate four different elephant grass cultivars (cvs.): Merckeron Pinda, Mercker-86-Mexico, Porto Rico and Cameroon, under grazing conditions. Holstem heiters and cows were used in a rotational grazing system. This work was undertaken at the experimental area of the Animal Science Department, Federal University Campus, Santa Maria-RS. Nutritivo value was estimated through crude protein (PB) and in vitro organic matter digestibility (DIVMO) coefficients from samples of the aerial part of plants, stalks and leaves, and an extract of the area being pasteured, collected by hand, simulating grazing. The cvs. have shown very similar nutritivo values, but there were differences in PB for leaves and DIVMO for leaves and for the extract of the simulated grazing; Merckeron Pinda and Mercker-86-Mexico were the best