Aims:  To evaluate the antibacterial and free‐radical scavenging (FRS) activities of propolis collected from three different areas of Sonoran Desert in northwestern Mexico [Pueblo de Alamos (PAP), Ures (UP) and Caborca (CP)]. Methods and Results:  The antibacterial and FRS activities of Sonoran propolis were determined by the broth microdilution method and the DPPH (1,1‐diphenyl‐2‐picrylhydracyl) assay, respectively. Propolis samples had antibacterial activity against only Gram‐positive bacteria. The UP sample showed the highest antibacterial activity against Staphylococcus aureus [minimal inhibitory concentration (MIC) 100 μg ml−1] in a concentration‐dependent manner (UP > CP > PAP). Caffeic acid phenethyl ester (CAPE), a UP propolis constituent, had very high growth‐inhibitory activity towards Gram‐positive bacteria, particularly against S. aureus (MIC 0·1 mmol l−1). To our knowledge, this is the first study showing a strong antibacterial activity of CAPE against S. aureus. Additionally, propolis CP exhibited high FRS activity (86% ± 0·3 at 100 μg ml−1) comparable with those of the reference antioxidants vitamin C (87·4% ± 1·7 at 70 μmol l−1) and BHT (66·07% ± 0·76 at 140 μmol l−1). The propolis compounds CAPE and rutin showed high FRS activity (90·4% ± 0·2 and 88·5% ± 0·8 at 70 μmol l−1, respectively). Conclusions:  Sonoran propolis UP and CAPE had strong antibacterial activity against S. aureus. In addition, propolis CP showed potent FRS activity comparable with those of vitamin C and BHT. Significance and Impact of the study:  The strong antibacterial and antioxidant properties of Sonoran propolis and some of its constituents support further studies on the clinical applications of this natural bee product against S. aureus and several oxidative damage‐related diseases.

Butyrate is a short-chain fatty acid extensively used in animal nutrition since it promotes increases in body weight and other multiple beneficial effects on the intestinal tract. Although such effects have been demonstrated in several species, very few studies have assessed them in fish. On the other hand, little is known about the metabolic processes underlying these effects. In the present work, growth parameters and changes in more than 80 intestinal metabolites (nucleotides, amino acids and derivatives, glycolytic intermediates, redox coenzymes and lipid metabolism coenzymes) have been quantified in juvenile sea bream fed a butyrate-supplemented diet. Results showed a significant increase in the weight of fish receiving butyrate, while metabolomics provided some clues on the suggested effects of this feed additive. It seems that butyrate increased the availability of several essential amino acids and nucleotide derivatives. Also, the energy provision for enteric cells might have been enhanced by a decrease in glucose and amino acid oxidation related to the use of butyrate as fuel. Additionally, butyrate might have increased transmethylation activity. This work represents an advance in the knowledge of the metabolic consequences of using butyrate as an additive in fish diets.

No abstract

No abstract

Postlarvae of tiger shrimp, Penaeus monodon (Fabricius), were fed semipurified diets supplemented with various levels of astaxanthin (AX) and ascorbic acid-polyphosphate (ApP): three groups were fed 230 mg AX kg -1 diet combined with 100, 1700 and 3400 mg ascorbic acid (AA) kg -1 diet, respectively; two diets contained 810 mg AX kg -1 mixed with 200 and 1700 mg AA kg -1 , respectively. Each treatment was run in four replicates. Incorporated levels of AA and AX, production output, and physiological condition were recorded after 4 weeks of feeding. Whole-body AA (21-47 µg g -1 ) and AX concentrations (19-35 µg g -1 ) were linked to dietary ApP and AX supply, respectively, although not significantly for the latter. The biomass of the group receiving the lower dietary ApP-AX combination was significantly lower than for all other treatments, i.e. 3.1 versus 3.9 g, respectively. In the groups fed 230 mg AX kg -1 diet, significant differences in stress resistance were observed according to the dietary ApP level, i.e. raising the vitamin C content in the feed from 100 to 3400 mg AA kg -1 resulted in a concomitant drop in mortality after an osmotic shock. For the treatments receiving 810 mg AX kg -1 diet, the beneficial effect of extra dietary vitamin C was not significant. An increase in the dietary AX for shrimp fed comparable ApP levels resulted in a significant drop of the stress index from 56 to 33 (cumulative