The emergence of new infectious diseases, the resurgence of several infections that appeared to have been controlled and the increase in bacterial resistance have created the necessity for studies directed towards the development of new antimicrobials. Considering the failure to acquire new molecules with antimicrobial properties from microorganisms, the optimization for screening methods used for the identification of antimicrobials from other natural sources is of great importance. The objective of this study was to evaluate technical variants used in screening methods to determine antibacterial activity of natural products. Thus, a varied range of natural products of plant, fungi and lichen origin were tested against two bacterial species, Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922, by two variants of the agar diffusion method (well and disc), two variants of the bioautographic method (direct and indirect) and by microdilution assay. We concluded that the well-variant of the diffusion method was more sensitive than the disc-variant, whilst the direct-variant of the bioautographic method exhibited a greater sensitivity if compared to indirectvariant. Bioautographic and diffusion techniques were found to have similar sensitivity; however the latter technique provided more suitable conditions for the microbial growth. In this study, we also discussed the best conditions for the determination of minimal inhibitory concentration.

IntroductionThere is an increasing interest in phytochemicals as new sources of natural antioxidant and antimicrobial agents. The use of synthetic antioxidants in the food industry is severely restricted as to both application and level (TAWAHA et al., 2007;PENG et al., 2005). Currently, there is a strong debate about the safety aspects of chemical preservatives, since they are considered responsible for many carcinogenic and teratogenic attributes, as well as residual toxicity (MOREIRA et al., 2005).Plant-derived polyphenols receive considerable attention because of their potential antioxidant and antimicrobial properties (MOREIRA et al., 2005;PROESTOS;SERELI;KOMAITIS, 2006). Phenolic compounds exhibit a considerable free-radical scavenging (antioxidant) activity, which is determined by their reactivity as hydrogen-or electron-donating agents, the stability of the resulting antioxidant-derived radical, their reactivity with other antioxidants and, finally, their metal chelating properties (RICE-EVANS; MILLER; PAGANGA, 1997).Rosemary (Rosmarinus officinalis L.) is a spice and medicinal herb widely used around the world. Of the natural antioxidants, rosemary has been widely accepted as one of the spices with the highest antioxidant activity (PENG et al., 2005). Rosemary essential oil is also used as an antibacterial, antifungal (OLUWATUYI; KAATZ;GIBBONS, 2004;FERNÁNDEZ-LÓPEZ et al., 2005;KABOUCHE et al., 2005;REZZOUG;BOUTEKEDJIRET;ALLAF, 2005) and anticancer agent (LEAL et al., 2003). Ouattara et al. (1997) investigated the antibacterial activity of selected essential oils against some food spoilage organisms. They concluded that the essential oils of cinnamon, clove and rosemary were the most active. Similar results were obtained by Valero and Salmeron (2003) for the antibacterial activity of rosemary essential oil against Bacillus cereus strains grown in carrot broth.Many compounds have been isolated from rosemary, including flavones, diterpenes, steroids, and triterpenes. Of these, ResumoExtratos das partes aéreas de alecrim foram obtidos utilizando fluidos supercríticos (FSC) e extrações Sohxlet. Sua composição foi analisada com GC-MS. Os extratos foram analisados com base nos compostos repostados na literatura como tendo atividade antimicrobiana e antioxidante. Os extratos de alecrim foram testados quanto à atividade antioxidante (radicais DPPH e conteúdo total de fenólicos -reagente

The antibacterial activity of coumarin per se and other 45 coumarin derivatives was tested against strains of Bacillus cereus MIP 96016, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, and Staphylococcus aureus ATCC 25923. The inhibitory effects of coumarins were affected by their substitution patterns. Osthenol (44) showed the most effective antibacterial activity against Gram-positive bacteria with MIC values ranging between 125 and 62.5 µg/ml. These results suggested that the prenyl chain of 44 at position 8 and the presence of OH at position 7 of the benzenic ring are required for the antibacterial activity against these strains.

The antifungal activity of 40 coumarins was tested against the fungal strains: Candida albicans (ATCC 14053), Aspergillus fumigatus (ATCC 16913) and Fusarium solani (ATCC 36031), using the broth microdilution method. Osthenol showed the most effective antifungal activity among all the compounds tested, with a MIC value of 125 μg/ml for Fusarium solani and 250 μg/ml for Candida albicans and Aspergillus fumigatus. The antifungal potential of this prenylated coumarin can be related to the presence of an alkyl group at C-8 position.

Cystic fibrosis (CF) is the most common genetic disease among Caucasians and is rare among sub-Saharan Africans. The Brazilian population is not ethnically homogeneous but it is the result of threeway ethnic admixture of Europeans, Africans and Amerindians in varying proportions, depending on the region. In the present study, we investigated 33 patients who had been diagnosed and are currently under treatment for CF at the University Hospital João de Barros Barreto, Belém, Pará State. The molecular analysis for G542X, G551D and R553X mutations was performed by PCR followed by RFLP using BstN I, HincII and MboI, respectively, in polyacrylamide gel eletrophoresis and stained with AgNO 3 . The ∆F508 mutation (a deletion of 3 bp) was only analyzed by polyacrylamide gel electrophoresis and stained with AgNO 3 . Each sample was analyzed for regions of interest in the CFTR gene using amplified by PCR and specific primers. The ∆F508 and G551D mutations presented frequencies of 22.7 and 3%, respectively. In 74.3% of the remaining patients, none of the mutations investigated was found. The present study characterized in a sample of patients with an established clinical diagnosis of CF (asthma, repeated bronchopneumonia, disorders of nutritional status, etc.) the most frequent mutation (∆F508) in the North region of Brazil and is also the first report of the G551D mutation. In spite of the wide spectrum of CF mutations and the heterogeneous ethnic origin of the Amazon population, the molecular diagnosis is a helpful additional tool for the diagnosis and treatment of CF patients. Correspondence

Blood lipid levels are determined by a combination of genetic and environmental factors. Higher than average values of high-density lipoprotein cholesterol (HDL-cholesterol) have been observed in people of Japanese ethnicity. The aim of this study was to investigate whether Japanese immigrants to Brazil and subsequent generations maintain the protective benefits associated with higher levels of HDL-cholesterol, and to examine the potential associations between HDL-cholesterol and a variety of other blood lipids, anthropometric and lifestyle factors. Healthy men and women aged 35 years and older who were Native Japanese (n = 198) or Japanese-Brazilians (JB) living in São Paulo, Brazil (n = 198) and in some Japanese cities (n = 246) were investigated. Anthropometric variables, blood lipids including HDL-cholesterol, and lifestyle factors were assessed. Serum HDL-cholesterol was observed to be lower for JB in São Paulo (both women and men) compared with Natives and JB in Japan. Among the groups, triglycerides, waist circumference, LDL-cholesterol, meat intake, stress, and smoking were observed to be independently negatively associated with HDL-cholesterol, whereas total cholesterol, fish intake, and physical activity were positively associated. Lower levels of HDL-cholesterol among both men and women of JB in São Paulo compared with both other groups were confirmed even after lifestyle adjustments. Our findings highlight the significantly lower levels of HDL-cholesterol among Japanese-Brazilians living in São Paulo city compared to Japanese-Brazilians and Native Japanese residing in Japan. Although several lifestyle factors were found to be significantly associated with HDL-cholesterol, they cannot adequately explain the role of the Brazilian cultural environment on HDL-cholesterol levels.