Microbiological Assay Methods for Vitamins

A robust method for simultaneous determination of eight B vitamins in human serum by liquid chromatography tandem mass spectrometry

The level of vitamin B group in human serum is an important index of human health. Among B vitamins, cyanocobalamin in serum is unstable and its content is extremely low. Rapid and simultaneous detection of multiple B vitamins including cyanocobalamin is a challenge. Herein, we have developed a rapid and stable method that can realize the determination of thiamine, riboflavin, nicotinamide, pantothenic acid, pyridoxic acid, biotin, 5-methyltetrahydrofolate, and cyanocobalamin simultaneously in 6 min. The method was established based on protein precipitation with methanol and then chromatographic separation was achieved using Waters acquity ultra-high-performance liquid chromatography high strength silica T3 column, which was stable and sensitive especially for cyanocobalamin. Limit of quantification, precision, trueness, and matrix effect were validated according to the European Medicines Agency and United States Food and Drug guidelines and Clinical and Laboratory Standards Institute guidelines on bioanalytical method. The limit of quantification for thiamine, riboflavin, nicotinamide, pantothenic acid, pyridoxic acid, biotin, 5-methyltetrahydrofolate, and cyanocobalamin was 0.4, 0.4, 0.8, 2.0, 0.4, 0.1, 0.4, and 0.04 ng/mL separately, respectively. Intra- and interday precisions were 1.1%-12.4% and 2.0%-13.5%, respectively. The relative errors were between 0.3% and 13.3%, and the matrix effects were between 2.6% and 10.4%.

Development and validation of a dried blood spot test for thiamine deficiency among infants by HPLC-fluorimetry

Thiamine deficiency, if detected early in infancy, can be treated with thiamine supplementation and can prevent seizures, other disabilities and death. The dried blood spot (DBS) sampling technique is an attractive sample collection technique for infants. The present study reports the development and validation of a highly sensitive and precise method for quantification of thiamine diphosphate from DBS. The method utilizes full-spot analysis of a volumetrically deposited 40 μl DBS. The analyte was extracted from the DBS using 50% methanol and then derivatized using potassium ferricyanide to thiochrome. Separation was achieved with the help of an Inertsil ODS C₁₈ column (5.0 μm, 250 × 4.6 mm) using 150 mm phosphate buffer pH 7-acetonitrile (90:10, % v/v) as the mobile phase. The use of a fluorimetric detector gave a good response to the thiochrome derivative offering good sensitivity for the method. The excitation and emission wavelengths were 367 and 435 nm, respectively. The limit of detection and lower limit of quantification were 5 and 10 ng/ml, respectively. Linearity was demonstrated from 10 to 1000 ng/ml, and precision (CV) was <12.08%, at all tested quality control levels. The method accuracy was 89.34-118.89% with recoveries >80%. Bland-Altman analysis of DBS sampling vs. whole blood demonstrated a mean bias of only 1.16 ng/ml, with a majority of the 60 investigated patient samples lying within 7.2% of the corresponding concentration measured in blood, thereby meeting the clinical desirable biological specification criterion and showing that the two methods are comparable.

Quantification of B-vitamins from different fresh milk samples using ultra-high performance liquid chromatography mass spectrometry/selected reaction monitoring methods

Absolute quantification of B-vitamins in milk is becoming imperative to correlate its impact on child/human health. In today's world of changing food habits and environmental pollution, there is concern if milk is what we think it to be. In the present work, ultra-high performance liquid chromatography mass spectrometry/selected reaction monitoring (UPHPLC-MS/SRM) methods have been developed and validated for quantitative estimation of 21 different B-vitamins [B1-3, B2-3, B3-2, B5-1, B6-5, B8-1, B9-2 vitamins, total choline (betaine, choline and acetylcholine)] from a drop (50 µL) and B12 from 500 µL of milk. These two methods qualify all essential bio-analytical parameters (recovery >80%, accuracy <±15%, variation <±10%) and are highly reproducible. By using these developed methods, B-vitamins in different fresh milk samples from cow, goat, buffalo and pasteurized cow milk (each 10 and total n = 40) were analysed. Total choline is the highest (6.5-10.5 µg/mL) and vitamin B8 is the lowest (16.1-32.9 ng/mL) in all milk samples. Inverse correlation between vitamin B2 and B5 was observed in milk samples. The ratio of vitamin B5/B2 was checked in all milk samples, it is higher in cow (2.64), equal in goat (1.04) and lower in buffalo (0.42) milk. Total B-vitamin content in cow milk is higher (10.5 µg/mL) compared to other three (goat-7.2, buffalo-6.5, pasteurized-8.8 µg/mL). Vitamin B12 is higher in cow milk (3.6 ng/mL) compared to other two fresh milk samples. Different isomers for vitamin B6 were noticed in the fresh milk samples. The complete profile of water soluble vitamins and the ratio of two abundant B vitamins (B5/B2) in milk will be useful to check the nutritional quality and to differentiate the kind of animal milk.

Antioxidant survey to assess antagonism to redox stress using a prokaryotic and an eukaryotic system

Using a prokaryote (Escherichia coli) and a metazoa-resembling eukaryote (Ochromonas danica), we surveyed antioxidants which might overcome redox stress imposed by menadione sodium bisulphite (MD) and buthionine sulphoximine (BSO). BSO oxidant stress was evident only in O. danica; MD oxidant stress was evident in both organisms. Glutathione, its precursors, e.g. cysteine, homocysteine, and 2-oxo-4-thiazolidine carboxylic acid, and red blood cells, emerged as prime antioxidants for relieving BSO and MD oxidant stress. BSO and MD oxidant activity and antioxidant-annulling effect in O. danica were judged comparable to those found in animal cells whereas the results E. coli were not entirely equivalent. The O. danica system emerged as a practical, rapid, and useful system for pinpointing oxidant stressors and antioxidants, and shows promise for studies with mammalian systems.

Holotranscobalamins in B12 and non B12 requiring prokaryotes and eukaryotes

Transcobalamins, vitamin B12 binding proteins, deliver B12 to cell surface receptors which then permit B12 to cross cell membranes for metabolic use. There is little documentation concerning B12 binding proteins in bacteria and protists. We found that prokaryotes and eukaryotes requiring B12, as well as those protists synthesizing B12, also produce several transcobalamins for functionally transporting B12 similar to humans.

Biocidal action of chlorhexidine is annulled by nicotinic acid

An analytical system comprising a bacterium and a protozoan was used to pinpoint the metabolic lesion whereby chlorhexidine (CLX) produced cell death. Nicotinic acid but not nicotinamide annulled the biocidal action of CLX. The results suggest that CLX may not permit bioconversion of nicotinamide to nicotinic acid to annul the growth inhibition induced by CLX.

Teratogenic effects of maternal biotin deficiency on mouse embryos examined at midgestation

Pregnant mice were fed a basal diet that not only did not contain biotin, but also contained the spray-dried egg white including avidin that caused the biotin deficiency. The effects of maternal biotin deficiency on craniofacial and limb development in embryos were examined at two stages of midgestation. On day 12.6 of gestation, male and female embryos weighted less and digit development was retarded in the biotin-deficient group. On day 15.6 of gestation (dg), the embryos also weighted less and external malformations, such as micrognathia (94.8%), micromelia (41.4%), and exencephaly (11.4%), were observed. The inhibition of palatal and digit formation by biotin deficiency at midgestation is responsible for later formation of cleft palate and micromelia. On dg 12.6 the liver biotin level of biotin-deficient dams was reduced to 20% of control values. Interestingly, the biotin content of the whole embryonic body was about ninefold greater than liver biotin levels in their dams.

Determination of metabolically active B12 and inactive B12 analog titers in human blood using several microbial reagents and a radiodilution assay

Metabolically active B12 analogs and inactive B12 analogs were measured in plasma, red blood cells (RBC), and pooled pernicious anemia serum. B12 values by Lactobacillus leichmannii, Escherichia coli, Euglena gracilis, and radioisotope dilution method (RIDA) as assays for total B12 (active analogs + inactive analogs) were compared to Ochromonas malhamensis values as index of only metabolically active B12. B12 values above those with O malhamensis distinguished inactive analogs from active B12. Inactive analogs contribute 85, 97, 135, and 163% above active B12 activity in normal plasma when E gracilis, L leichmannii, RIDA, and E coli, respectively, were used for B12 analysis. RIDA B12 determinations for active B12 in plasma showed that 44% of the B12 measured was still due to inactive analogs when compared to O malhamensis B12 activity. Inactive B12 analogs contributed 21, 151, and 224% above O malhamensis active B12 in RBC when E gracilis, L leichmannii, and E coli, respectively, were used.

The measurement of serum pyridoxal by a microbiological assay using Lactobacillus casei

A new method has been developed for the assay of serum pyridoxal using L. casei. Bound pyridoxal phosphate in serum is converted by acid hydrolysis to pyridoxal for which this organism is specific. This method proved to be considerably more sensitive than other methods so far reported in the literature. Serum pyridoxal concentrations were measured in 151 control subjects aged 17 to 80 years. The range of concentrations found was 1.5 to 13.5 ng/ml which compared well with values obtained by most workers measuring pyridoxal phosphate by enzymatic methods. A marked fall with age was confirmed, and levels in women of childbearing age were lower than in men of comparable age. Subnormal serum pyridoxal concentrations were found in 62% of patients with sideroblastic anaemia and in the majority of patients with rheumatoid arthritis, Crohn's disease, coeliac disease, and in pregnant women at term.

INFLUENCE OF METHOD FOR REMOVAL OF SESTON ON THE DISSOLVED ORGANIC MATTER. II. COBALAMINS

Comparisons of the 3 previously used methods (continuous flow centrifugation, Millipore®filtration, and biodialysis) for making water samples seston-free before analysis for cobalamins point to several likely sources of error: (a) unpredictable occlusion of pores in Millipore®membranes during filtration; (b) irreversible adsorption of cobalamins by Millipore®membranes; (c) probable cell injury and leakage by centrifugation. Some water samples gave good agreement on soluble vitamin B12 by all 3 methods, while other samples had appreciable discrepancies. The validity of total vs. sestonic cobalamin determinations therefore is questioned. One lake had time-dependent fluctuation in soluble cobalamin.

Blood thiamine and nicotinic acid levels in alcoholism and confusional states

It has been routine psychiatric practice in recent years to prescribe vitamins in alcoholism and confusional states and sometimes in other organic psychoses. The doses given are massive, varying from about ten to twenty times those strictly necessary in deficiency states. This empirical therapy is supported neither by controlled trials nor by direct evidence of vitamin deficiency.