Functional vitamin B12 deficiency: Improving methylmalonic acid reference intervals in urine.

BACKGROUND-AIM: Most laboratory requests focus on the detection of possible vitamin B12 deficiency. In this context, methylmalonic acid (MMA) is reported as the best biomarker. The aim of our study was to establish the biological reference interval for MMA in urine, and assess the influence of age, sex, and vitamin B12 status on MMA concentrations. METHODS: This is a prospective observational study considering individuals with normal results for blood count and liver and kidney function. Individuals who presented supplementation, any pathology or treatment that could cause cobalamin metabolism disorders, and pregnant women were excluded. Likewise, individuals whose vitamin B12 result presented antibody-mediated interference were excluded. Individuals were grouped by age-group and sex. Reference intervals were determined by non-parametric calculation (percentiles 1-99). RESULTS: It was established a single reference interval [0.52 (CI90%: 0.50-0.54) - 5.75 (CI90%: 5.57-6.17) mmolMMA/mol creatinine], with 100 % of individuals with MMA above the upper limit of reference presenting a total vitamin B12 concentration ≤ 238 pmol/L. CONCLUSION: The establishment of optimal reference intervals for methylmalonic acid excretion in urine is crucial in individuals with a suspicion of functional vitamin B12 deficiency. However, the possibility of establishing a cut-off value for total vitamin B12 suggesting subclinical deficiency remains a challenge for this magnitude.

One-pot organocatalytic/multicomponent approach for the preparation of novel enantioenriched non-natural selenium-based peptoids and peptide-peptoid conjugates.

A combined organocatalytic and multicomponent synthetic approach was designed for the preparation of selenium-based peptoids and peptide-peptoid conjugates. This single-step synthetic protocol comprises the organocatalytic asymmetric insertion of phenylselenium in the aldehyde moiety followed by the Ugi four-component reaction which results in obtaining the desired compounds in good-to-moderate yields and with good-to-excellent levels of stereoselectivity.

Occurrence and Chemical Synthesis of Apocarotenoids from Mucorales: A Review.

Apocarotenoids are metabolites originated by degradation of carotenes through the loss of carbon atoms placed at the side chain of their structure as consequence of oxydative reactions. We present here the first review of apocarotenoids in the fungi mucorales Phycomyces blakesleeanus, Blakeslea trispora and Mucor mucedo. This review is divided into two parts: the first one presents their structures and sources, whereas the second part is dedicated to their chemical synthesis.

Synthesis of Stilbene Derivatives: A Comparative Study of their Antioxidant Activities.

A series of structurally simple compounds belonging to thestilbene family were synthesized by means of a Ti(III)-mediated methodology that allows access, in an efficient manner, to derivatives of dihydrostilbene, E-stilbene, and stilbene oxide, with high yields. The antioxidant activity of these compounds has been evaluated by means of two electrochemical assays, which provide complementary information, showing that the majority of these stilbene analogs exhibit significant antioxidant activity dependent on the electronic structure and functionalization of the molecule in each case.