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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.

beta-Glucans of Agaricus brasiliensis fruiting bodies in different stages of maturity were isolated and characterized by FTIR and NMR. These fractions had greater amount of (1-->6)-beta-glucan and the (1-->3)-beta-glucan increased with fruiting bodies maturation. Yields of beta-glucans increased from 42 mg beta-glucans g(-1) fruiting bodies (dry wt) in immature stage to 43 mg g(-1) in mature stage with immature spores, and decreased to 40 mg g(-1) in mature stage with spore maturation. Mature fruiting bodies, which included these glucans, have potential therapeutical benefits for use in nutraceutical products.

Recebido em 20/3/12; aceito em 26/7/12; publicado na web em 7/12/12Aloysia gratissima (Gill. et Hook) Tronc. (Verbenaceae) is native to South America with folk therapeutic applications for a wide range of diseases. The polyphenolic and carotenoid profile, toxicity, and antioxidant activity of aqueous extract of Aloysia gratissima were investigated. HPLC analyses showed high amounts of ferulic acid, trans-cinnamic acid and p-coumaric acid, and also transb-carotene and lutein which fluctuated throughout the seasons. Furthermore, the extract investigated not only exerted antioxidant activity but also inhibited lipid peroxidation. Toxicity was achieved only at the highest dose tested. Therefore, A. gratissima is a potential species for medicinal purposes.Keywords: Aloysia gratissima; Verbenaceae; antioxidant activity. INTRODUCTIONAloysia gratissima (Gill. et Hook) Tronc. (Verbenaceae) is an aromatic native plant widely distributed in subtropical regions of South America, particularly Brazil, Paraguay, and Argentina. In Brazil, its folk name is "erva-santa", popularly named by local communities that use its aqueous extract to which they attribute several therapeutic benefits. In traditional medicine, it is thought to be a remedy to alleviate and help treat symptoms associated with headaches, bronchitis, and nervous system disorders 1 including depression 2 and also to treat digestive system disorders. 3 However, there are no published studies investigating Aloysia gratissima's toxicity while scientific articles about its chemical composition or antioxidant action are scarce, with those available focusing mainly on aqueous extract. Thus, while the chemical composition and some biological activities 4 of Aloysia gratissima's essential oil have been investigated, information on the bioactive compounds belonging to the aqueous extract, to the best of our knowledge, has not yet been described. Furthermore, there is a lack of information about the seasonal phytochemical profile of Aloysia gratissima's aqueous extract.The methanolic extract of A. gratissima has shown the presence of kauranes, flavonoids and phenylethanoids 5 in addition to α-bisabolol, triterpenes such as α-amirin, the acids betulinic, oleanolic and ursolic, flavonoids such as genkwanin, 5-hydroxy-7,4'-dimethoxyapigenin, 5-hydroxy-7,3',4'-trimethoxyluteolin, and rutin, which exhibited antibacterial, antiedematogenic, and antioxidant properties. 6 Recently, Zeni et al. 7 demonstrated that Aloysia gratissima's aqueous extract has both antidepressant-like and neuroprotective effects in mice.Polyphenols and carotenoids have been studied as factors responsible for treating several cardiovascular and neurodegenerative diseases and cancer. 8 The aim of this study was to determine the polyphenolic and carotenoid composition of the plant throughout the seasons; to select the aqueous extract with the highest level of those compounds, and to investigate the toxicity and antioxidant activity of the aqueous extract containing the highest level of bioactive compounds an...

Chitosan has recently shown potential for the control of plant diseases and can act as an elicitor in the induction of defence mechanisms. This study was made to assess the effect of chitosan on bacterial spot control caused by Xanthomonas gardneri in tomato plants. The chitosans used were commercial (Ccom), low molecular weight (Clmw) and medium molecular weight (Cmmw). Chitosans provided disease protection of up to 56%, with best results from Clmw at 3 mg⁄ml, applied 3 days prior to bacterial inoculation. The spectrophotometric profile of tomato plants that were treated with Clmw showed an increase of absorbance between wavelengths 280 and 300 mm, indicating that the polysaccharide may have induced the plants into synthesizing different compounds as a response to X. gardneri. The analysis of total phenolic compounds and flavonoids supported the results obtained in spectrophotometric scanning, showing a significant increase of those metabolites 3 days after inoculation. Therefore, chitosan has the capability of controlling bacterial spot in tomato plants, which is thought to be attributable to the induction of defence mechanisms in the plant.