Inactivation of Plasmodium falciparum in whole blood by riboflavin plus irradiation.

BACKGROUND: Malaria parasites are frequently transmitted by unscreened blood transfusions in Africa. Pathogen reduction methods in whole blood would thus greatly improve blood safety. We aimed to determine the efficacy of riboflavin plus irradiation for treatment of whole blood infected with Plasmodium falciparum. STUDY DESIGN AND METHODS: Blood was inoculated with 10(4) or 10(5) parasites/mL and riboflavin treated with or without ultraviolet (UV) irradiation (40-160 J/mL red blood cells [mL(RBCs)]). Parasite genome integrity was assessed by quantitative amplification inhibition assays, and P. falciparum viability was monitored in vitro. RESULTS: Riboflavin alone did not affect parasite genome integrity or parasite viability. Application of UV after riboflavin treatment disrupted parasite genome integrity, reducing polymerase-dependent amplification by up to 2 logs (99%). At 80 J/mL(RBCs), riboflavin plus irradiation prevented recovery of viable parasites in vitro for 2 weeks, whereas untreated controls typically recovered to approximately 2% parasitemia after 4 days of in vitro culture. Exposure of blood to 160 J/mL(RBCs) was not associated with significant hemolysis. CONCLUSIONS: Riboflavin plus irradiation treatment of whole blood damages parasite genomes and drastically reduces P. falciparum viability in vitro. In the absence of suitable malaria screening assays, parasite inactivation should be investigated for prevention of transfusion-transmitted malaria in highly endemic areas

Hydrodynamic chronoamperometry for probing kinetics of anaerobic microbial metabolism : case study of Faecalibacterium prausnitzii

Monitoring in vitro the metabolic activity of microorganisms aids bioprocesses and enables better understanding of microbial metabolism. Redox mediators can be used for this purpose via different electrochemical techniques that are either complex or only provide non-continuous data. Hydrodynamic chronoamperometry using a rotating disc electrode (RDE) can alleviate these issues but was seldom used and is poorly characterized. The kinetics of Faecalibacterium prausnitzii A2-165, a beneficial gut microbe, were determined using a RDE with riboflavin as redox probe. This butyrate producer anaerobically ferments glucose and reduces riboflavin whose continuous monitoring on a RDE provided highly accurate kinetic measurements of its metabolism, even at low cell densities. The metabolic reaction rate increased linearly over a broad range of cell concentrations (9 x 10(4) to 5 x 10(7) cells. mL(-1)). Apparent Michaelis-Menten kinetics was observed with respect to riboflavin (K-M = 6 mu M; k(cat) = 5.3x10(5) s(-1), at 37 degrees C) and glucose (K-M = 6 mu M; k(cat) = 2.4 x 10(5) s(-1)). The short temporal resolution allows continuous monitoring of fast cellular events such as kinetics inhibition with butyrate. Furthermore, we detected for the first time riboflavin reduction by another potential probiotic, Butyricicoccus pullicaecorum. The ability of the RDE for fast, accurate, simple and continuous measurements makes it an ad hoc tool for assessing bioprocesses at high resolution

Real-time detection of riboflavin production by Lactobacillus plantarum strains and tracking of their gastrointestinal survival and functionality in vitro and in vivo using mCherry labeling

Some strains of lactic acid bacteria (LAB) produce riboflavin, a water-soluble vitamin of the B complex, essential for human beings. Here, we have evaluated riboflavin (B2 vitamin) production by five Lactobacillus plantarum strains isolated from chicha, a traditional maize-based fermented alcoholic beverage from north-western Argentina and their isogenic riboflavin-overproducing derivatives previously selected using roseoflavin. A direct fluorescence spectroscopic detection method to quantify riboflavin production in bacterial culture supernatants has been tested. Comparison of the efficiency for riboflavin fluorescence quantification with and without prior HPLC fractionation showed that the developed method is a rapid and easy test for selection of B2 vitamin-producing strains. In addition, it can be used for quantitative detection of the vitamin production in real time during bacterial growth. On the basis of this and previous analyses, the L. plantarum M5MA1-B2 riboflavin overproducer was selected for in vitro and in vivo studies after being fluorescently labeled by transfer of the pRCR12 plasmid, which encodes the mCherry protein. The labeling did not affect negatively the growth, the riboflavin production nor the adhesion of the strain to Caco-2 cells. Thus, L. plantarum M5MA1-B2[pRCR12] was evaluated for its survival under digestive tract stresses in the presence of microbiota in the dynamic multistage BFBL gut model and in a murine model. After exposure to both models, M5MA1-B2[pRCR12] could be recovered and detected by the pink color of the colonies. The results indicated a satisfactory resistance of the strain to gastric and intestinal stress conditions but a low colonization capability observed both in vitro and in vivo. Overall, L. plantarum M5MA1-B2 could be proposed as a probiotic strain for the development of functional foods.Fil: Mohedano, Mari Luz. Consejo Superior de Investigaciones Científicas. Centro de Investigaciones Biológicas; EspañaFil: Hernández Recio, Sara. Consejo Superior de Investigaciones Científicas. Centro de Investigaciones Biológicas; EspañaFil: Yépez, Alba. Universidad de Valencia; EspañaFil: Requena, Teresa. Consejo Superior de Investigaciones Científicas. Instituto de Investigación en Ciencias de la Alimentación; EspañaFil: Martínez Cuesta, M. Carmen. Consejo Superior de Investigaciones Científicas. Instituto de Investigación en Ciencias de la Alimentación; EspañaFil: Peláez, Carmen. Consejo Superior de Investigaciones Científicas. Instituto de Investigación en Ciencias de la Alimentación; EspañaFil: Russo, Pasquale. Università di Foggia; ItaliaFil: Leblanc, Jean Guy Joseph. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Spano, Giuseppe. Università di Foggia; ItaliaFil: Aznar, Rosa. Universidad de Valencia; España. Consejo Superior de Investigaciones Científicas. Instituto de Agroquímica y Tecnología de Alimentos; EspañaFil: López, Paloma. Consejo Superior de Investigaciones Científicas. Centro de Investigaciones Biológicas; Españ

Effect of low-dosage vitamin A and riboflavin on iron-folate supplementation in anaemic pregnant women

A double-blind, placebo, controlled trial was conducted in Banyudono subdistrict, Boyolali regency, Central Java province, Indonesia. The aim of the study was to determine whether adding low-dosage vitamin A and riboflavin can enhance the effect of iron-folate supplementation in anaemic pregnant women. From July to November 2000, 202 pregnant women were screened for anaemia (haemoglobin <11.0 g/dL). One hundred and three pregnant women (51%) were found to be anaemic and were then allocated alternately into four groups. Over a period of 60 days, group IF (n = 29) received iron-folate tablets (200 mg FeSO4 and 250 µg folic acid) + 5 mg glucose; group IFR (n = 22) received iron-folate tablets + 5 mg riboflavin; group IFA (n = 29) received iron-folate tablets + 2.75 mg retinyl palmitate (equal to 5000 IU vitamin A); and group IFRA (n = 23) received iron-folate tablets + 5 mg riboflavin + 2.75 mg retinyl palmitate. At the end of the study 19 pregnant women (18.4%) were excluded from the analysis because of various reasons. Statistical analysis was based on 84 women (81.5%): group IF, n = 25; group IFR, n = 22; group IFA, n = 18; and group IFRA, n = 19. Haemoglobin measurements were carried out using the Technicon H1* (cyanmethaemoglobin method). All groups showed a significant increase in haemoglobin concentration (P 0.05), with the highest increment being in group IFR. Multiple comparisons only showed significant differences between group IFR and group IFA (P < 0.05). It can be concluded that iron-folate supplementation can increase haemoglobin concentrations in anaemic pregnant women. Adding riboflavin tends to enhance the effect of iron- folate supplementation, but this is not the case with adding vitamin A. Key words: anaemic pregnant women, iron-folate, low-dosage vitamin A, riboflavin

Femtosecond dynamics of flavoproteins: Charge separation and recombination in riboflavine (vitamin B_2)-binding protein and in glucose oxidase enzyme

Flavoproteins can function as hydrophobic sites for vitamin B_2 (riboflavin) or, in other structures, with cofactors for catalytic reactions such as glucose oxidation. In this contribution, we report direct observation of charge separation and recombination in two flavoproteins: riboflavin-binding protein and glucose oxidase. With femtosecond resolution, we observed the ultrafast electron transfer from tryptophan(s) to riboflavin in the riboflavin-binding protein, with two reaction times: approx 100 fs (86% component) and 700 fs (14%). The charge recombination was observed to take place in 8 ps, as probed by the decay of the charge-separated state and the recovery of the ground state. The time scale for charge separation and recombination indicates the local structural tightness for the dynamics to occur that fast and with efficiency of more than 99%. In contrast, in glucose oxidase, electron transfer between flavin-adenine-dinucleotide and tryptophan(s)/tyrosine(s) takes much longer times, 1.8 ps (75%) and 10 ps (25%); the corresponding charge recombination occurs on two time scales, 30 ps and nanoseconds, and the efficiency is still more than 97%. The contrast in time scales for the two structurally different proteins (of the same family) correlates with the distinction in function: hydrophobic recognition of the vitamin in the former requires a tightly bound structure (ultrafast dynamics), and oxidation-reduction reactions in the latter prefer the formation of a charge-separated state that lives long enough for chemistry to occur efficiently. Finally, we also studied the influence on the dynamics of protein conformations at different ionic strengths and denaturant concentrations and observed the sharp collapse of the hydrophobic cleft and, in contrast, the gradual change of glucose oxidase

Women in resource-poor settings are at risk of inadequate intakes of multiple micronutrients.

A systematic review was conducted to identify all studies that were published between 1988 and 2008 reporting micronutrient intakes of women in resource-poor settings. Inclusion criteria were study location (resource-poor), dietary assessment method (24-h recall, estimated/weighed record, or locally validated FFQ), energy and 1 or more micronutrient intakes reported (vitamin A, vitamin B-6, vitamin B-12, vitamin C, thiamin, riboflavin, niacin, folate, iron, or zinc), age range (15-50 y), sample size (≥30), and sex (female). Of the 1560 papers identified, 52 papers were included. Results showed that, except for vitamin A (29%), vitamin C (34%), and niacin (34%), the reported mean/median intakes in over 50% of studies were below the Estimated Average Requirement (EAR). Folate intake was most often below EAR (91% of studies). Regional differences were apparent for intakes of vitamins A, C, and B-6 and riboflavin; mean/median intakes in Latin America exceeded the EAR, whereas in Asia, reported mean/median intakes of vitamin C, vitamin A, and riboflavin were below the EAR in 47, 50, and 77% of the studies, respectively, as was the case for vitamin B-6 in 75% of the studies in Africa. These results suggest that inadequate intakes of multiple micronutrients are common among women living in resource-poor settings and emphasize the need for increased attention to the quality of women's diets. There is a need for more high-quality studies of women's micronutrient intakes

Riboflavin: The Health Benefits of a Forgotten Natural Vitamin

Riboflavin (RF) is a water-soluble member of the B-vitamin family. Sufficient dietary and supplemental RF intake appears to have a protective effect on various medical conditions such as sepsis, ischemia etc., while it also contributes to the reduction in the risk of some forms of cancer in humans. These biological effects of RF have been widely studied for their anti-oxidant, anti-aging, anti-inflammatory, anti-nociceptive and anti-cancer properties. Moreover, the combination of RF and other compounds or drugs can have a wide variety of effects and protective properties, and diminish the toxic effect of drugs in several treatments. Research has been done in order to review the latest findings about the link between RF and different clinical aberrations. Since further studies have been published in this field, it is appropriate to consider a re-evaluation of the importance of RF in terms of its beneficial properties

Lactococcus lactis is capable of improving the riboflavin status in deficient rats

Lactococcus lactis is a commonly used starter strain that can be converted from a vitamin B2 consumer into a vitamin B2 'factory' by over-expressing its riboflavin biosynthesis genes. The present study was conducted to assess in a rat bioassay the response of riboflavin produced by GM or native lactic acid bacteria (LAB). The riboflavin-producing strains were able to eliminate most physiological manifestations of ariboflavinosis such as stunted growth, elevated erythrocyte glutathione reductase activation coefficient values and hepatomegalia that were observed using a riboflavin depletion–repletion model. Riboflavin status and growth rates were greatly improved when the depleted rats were fed with cultures of L. lactis that overproduced this vitamin whereas the native strain did not show the same effect. The present study is the first animal trial with food containing living bacteria that were engineered to overproduce riboflavin. These results pave the way for analysing the effect of similar riboflavin-overproducing LAB in human trials

Supplementation of iron alone and combined with vitamins improves haematological status, erythrocyte membrane fluidity and oxidative stress in anaemic pregnant women

Pregnancy is a condition exhibiting increased susceptibility to oxidative stress, and Fe plays a central role in generating harmful oxygen species. The objective of the present study is to investigate the changes in haematological status, oxidative stress and erythrocyte membrane fluidity in anaemic pregnant women after Fe supplementation with and without combined vitamins. The study was a 2 months double-blind, randomised trial. Pregnant women (n 164) were allocated to four groups: group C was the placebo control group; group I was supplemented daily with 60 mg Fe (ferrous sulphate) daily; group IF was supplemented daily with Fe plus 400 µg folic acid; group IM was supplemented daily with Fe plus 2 mg retinol and 1 mg riboflavin, respectively. After the 2-month trial, Hb significantly increased by 15·8, 17·3 and 21·8 g/l, and ferritin by 2·8, 3·6 and 11·0 µg/l, in the I, IF and IM groups compared with placebo. Polarisation (¿) and microviscosity (¿) decreased significantly in other groups compared with placebo, indicating an increase in membrane fluidity. Significant decreases of ¿ and ¿ values compared with group C were 0·033 and 0·959 for group I, 0·037 and 1·074 for group IF and 0·064 and 1·865 for group IM, respectively. In addition, significant increases of glutathione peroxidase activities and decreases of malondialdehyde were shown in all treated groups, as well as increases of plasma retinol and urine riboflavin in group IM. The findings show that supplementation with Fe and particularly in combination with vitamins could improve the haematological status as well as oxidative stress and erythrocyte membrane fluidit