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The purpose of this study was to assess the in vitro antimicrobial activity of alkaloid-enriched extracts from Prosopis juliflora (Fabaceae) pods in order to evaluate them as feed additives for ruminants. As only the basic chloroformic extract (BCE), whose main constituents were juliprosopine (juliflorine), prosoflorine and juliprosine, showed Gram-positive antibacterial activity against Micrococcus luteus (MIC = 25 μg/mL), Staphylococcus aureus (MIC = 50 μg/mL) and Streptococcus mutans (MIC = 50 μg/mL), its influence on ruminal digestion was evaluated using a semi-automated in vitro gas production technique, with monensin as the positive control. Results showed that BCE has decreased gas production as efficiently as monensin after 36 h of fermentation, revealing its positive influence on gas production during ruminal digestion. Since P. juliflora is a very affordable plant, this study points out this alkaloid enriched extract from the pods of Prosopis juliflora as a potential feed additive to decrease gas production during ruminal digestion.

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Os óleos essenciais das folhas, flores e frutos de Myrcia myrtifolia DC foram coletados ao longo dos anos de 2002 e 2003 e foram analisados utilizando CG-DIC e CG-EM. No total foram identificados 28 componentes sendo que o α-pineno foi a substância predominante em todas as amostras analisadas apresentando-se em concentrações que variaram entre 61.5 e 90.9%. As propriedades antimicrobianas do óleo essencial das folhas coletadas em outubro de 2002 foram avaliadas contra seis bactérias, duas leveduras e cinco fungos filamentosos sendo mais fortemente ativo contra Microsporum canis e Trichophyton rubrum, ativo contra Staphylococcus aureus, Staphylococcus aureus resistente à meticilina, Candida albicans, Cryptococcus neoformans e Aspergillus fumigatus. O óleo ainda mostrou uma toxicidade moderada, LC 50 of 479,16 μg mL -1 , contra Artemia salina.This work reports the seasonal variation of the composition of leaf volatile oils and the composition of volatile oils from flowers and fruits of Myrcia myrtifolia DC harvested in the sand dunes of Salvador, Bahia, northeastern region of Brazil between 2002 and 2003. The oils were analyzed by GC-FID and GC-MS so that 28 components were identified. α-Pinene was predominant in a range from 61.5 to 90.9% in all samples analyzed. The leaf oil collected in October 2002 had their antimicrobial properties tested against six bacteria, two yeasts and five filamentous fungi being active against Staphylococcus aureus, methicilin-resistant Staphylococcus aureus, Candida albicans, Cryptococcus neoformans and Aspergillus fumigatus, and showed strongest activity against Microsporum canis and Trichophyton rubrum. The oil displayed moderate toxicity against Artemia salina showing a LC 50 of 479.16 μg mL -1 .Keywords: Myrtaceae, Myrcia myrtifolia, essential oil, monoterpene, sesquiterpene, antimicrobial activity IntroductionAromatic plants have been used since ancient times as antiseptics and anti-infectious agents, as aroma in perfumes and cosmetics as well as preservative and flavour ingredients in food and beverages. Their biological properties are directly related with their chemical compositions, which can be affected by environmental, geographical, seasonal and circadian variations.The family Myrtaceae is constituted by 140 genera with about 3000 species, which are widely distributed in America and Australia. 1 The genus Myrcia comprises more than 300 species that grow in all Brazilian territory. Indigenous tribes and traditional Brazilian communities have used several species of this genus as astringent, against diabetes and diarrhea, as diuretic, to stanch hemorrhages, against the hypertension and ulcers of the mouth. 2 Some works were published regarding the chemistry and the biological properties of Myrcia species. From M. citriofolia, the occurrence of a C-methylated flavone, eucalyptin, was related, 3 from the methanolic extract of M. multiflora were isolated flavonol, flavanone and acetophenone glucosides along with myricitrin, mearnssitin, quercitrin, desmanthin-1 and guaijaverin...