A novel reductive amination method with isotopic formaldehydes for the preparation of internal standard and standards for determining organosulfur compounds in garlic

Quantification of derivatized phenylalanine and tyrosine in dried blood spots using liquid chromatography with tandem spectrometry for newborn screening of phenylketonuria

Phenylketonuria (PKU) is an autosomal genetic disorder caused by a deficiency of the phenylalanine hydroxylase (PAH) enzyme. The lack of PAH results in the inability of phenylalanine (PHE) to transform into tyrosine (TYR). Consequently, this leads to the accumulation of PHE in the blood samples of newborns causing metabolic diseases such as irreversible neurological problems. An analysis was required for determining the values of PHE and TYR in blood samples from newborn babies. In this study, therefore, we developed a derivatized method to monitor PHE and TYR in plasma samples using liquid phase chromatography linked with quadrupole mass spectrometry. Accessible formaldehyde isotopes and cyanoborohydride were used to react with PHE and TYR amino groups to generate h2-formaldehyde-modified PHE and TYR (as standards) and d2-formaldehyde-modified PHE and TYR (as internal standards). We used tandem mass spectrometry for multiple reaction monitoring. We demonstrated a derivatized method suitable for the PKU screening of newborns. The recoveries for PHE and TYR were 85% and 90%, respectively. Furthermore, we compared the values of PHE and TYR in different human plasma sample storage methods, including direct plasma and dried blood spots, and the results showed no significant difference.

Assisted Reductive Amination for Quantitation of Tryptophan, 5-Hydroxytryptophan, and Serotonin by Ultraperformance Liquid Chromatography Coupled with Tandem Mass Spectrometry

Herein, we used isotopic formaldehyde and sodium cyanoborohydride via reductive amination to label two methyl groups on primary amine to arrange the standards (h₂-formaldehyde-modified) and internal standards (ISs, d₂-formaldehyde-modified) of tryptophan and its metabolites, such as serotonin (5-hydroxytryptamine) and 5-hydroxytryptophan. These derivatized reactions with a high yield are very satisfactory for manufacturing standards and ISs. This strategy will generate one or two methyl groups on amine to create different mass unit shifts with 14 vs. 16 or 28 vs. 32 in individual compounds for biomolecules with amine groups. In other words, multiples of two mass units shift are created using this derivatized method with isotopic formaldehyde. Serotonin, 5-hydroxytryptophan, and tryptophan were used as examples to demonstrate isotopic formaldehyde-generating standards and ISs. h₂-formaldehyde-modified serotonin, 5-hydroxytryptophan, and tryptophan are standards to construct calibration curves, and d₂-formaldehyde-modified analogs such as ISs spike into samples to normalize the signal of each detection. We utilized multiple reaction monitoring modes and triple quadrupole mass spectrometry to demonstrate the derivatized method suitable for these three nervous biomolecules. The derivatized method demonstrated a linearity range of the coefficient of determinations between 0.9938 to 0.9969. The limits of detection and quantification ranged from 1.39 to 15.36 ng/mL.

S-Allyl cysteine in garlic (Allium sativum): Formation, biofunction, and resistance to food processing for value-added product development

S-allyl cysteine (SAC), which is the most abundant bioactive compound in black garlic (BG; Allium sativum), has been shown to have antioxidant, anti-apoptotic, anti-inflammatory, anti-obesity, cardioprotective, neuroprotective, and hepatoprotective activities. Sulfur compounds are the most distinctive bioactive elements in garlic. Previous studies have provided evidence that the concentration of SAC in fresh garlic is in the range of 19.0-1736.3 μg/g. Meanwhile, for processed garlic, such as frozen and thawed garlic, pickled garlic, fermented garlic extract, and BG, the SAC content increased to up to 8021.2 μg/g. BG is an SAC-containing product, with heat treatment being used in nearly all methods of BG production. Therefore, strategies to increase the SAC level in garlic are of great interest; however, further knowledge is required about the effect of processing factors and mechanistic changes. This review explains the formation of SAC in garlic, introduces its biological effects, and summarizes the recent advances in processing methods that can affect SAC levels in garlic, including heat treatment, enzymatic treatment, freezing, fermentation, ultrasonic treatment, and high hydrostatic pressure. Thus, the aim of this review was to summarize the outcomes of treatment aimed at maintaining or increasing SAC levels in BG. Therefore, publications from scientific databases in this field of study were examined. The effects of processing methods on SAC compounds were evaluated on the basis of the SAC content. This review provides information on the processing approaches that can assist food manufacturers in the development of value-added garlic products.

Quantification of the β2-Adrenergic Feed Additives Ractopamine and Salbutamol by Reductive Amination-Assisted Modification

HIGHLIGHTS

A reductive amination-assisted method was used to synthesize standards and internal standards of ractopamine and salbutamol. Standard and internal standard analogs were fabricated by isotopic formaldehydes and sodium cyanoborohydride. A quantitative method of modified ractopamine and salbutamol was successfully validated. The reductive amination-assisted method enhances the signal for MS detection.

Reductive amination assistance for quantification of oseltamivir phosphate and oseltamivir carboxylate by HPLC-MS/MS

Oseltamivir phosphate (OP) is the first line therapy for influenza, and its primary metabolite oseltamivir carboxylate (OC) is the active agent via inhibition of neuraminidase of influenza virus. Dosages of OP and OC might affect human causing nausea and vomiting and it is therefore necessary to evaluate their toxicity and safety. The separation system: liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a powerful technique to monitor OP and OC. However, quantification of OP and OC needs isotopic analogs as internal standards to monitor the stability of the sample pretreatment procedures and instruments. In this study, we demonstrated a modified method (i.e., reductive amination) to synthesize OP and OC deuterated and hydrogenated analogs as internal standards (ISs) and for illustration of calibration curves, respectively. This modification allowed to overcome ISs selection and to enhance the signal intensities via high yield reductive amination in MS detection. We utilized the multiple reaction monitoring (MRM) mode to target m/z values of precursor and product ions. N-dimethylated OP and N-dimethylated OC showed linearity ranging from 1 to 1000 ng/mL with coefficient of determination (R²) values of 0.9995 and 0.9999, respectively. Additionally, the relative standard deviations (RSD) of intra-day ranged from 0.3% to 5.2%, and the RSD of inter-day ranged from 2.0% to 18.8%, respectively. This quantitative method utilized spiked OP and OC at low (20 ng/mL), intermediate (100 ng/mL), and high (500 ng/mL) concentrations in human serum samples. The average recoveries for OP and OC were 84.6%-107.7% and 94.9%-98.5%, respectively.

Reductive amination derivatization for the quantification of garlic components by isotope dilution analysis

In this work, we synthesized internal standards for four garlic organosulfur compounds (OSCs) by reductive amination with ¹³C, D₂-formaldehyde, and developed an isotope dilution analysis method to quantitate these organosulfur components in garlic samples. Internal standards were synthesized for internal absolute quantification of S-allylcysteine (SAC), S-allylcysteine sulfoxide (alliin), S-methylcysteine (SMC), and S-ethylcysteine (SEC). We used a multiple reaction monitoring (MRM) to detect ¹³C, D₂-formaldehyde-modified OSCs by ultrahigh-performance liquid phase chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) and obtained MS spectra showing different ratios of ¹³C, D₂-formaldehyde-modified and H₂-formaldehyde-modified compounds. The resulting labeled and unlabeled OSCs were exhibited correlation coefficient (R²) ranged from 0.9989 to 0.9994, respectively. The average recoveries for four OSCs at three concentration levels ranged from 89% to 105%. By ¹³C, D₂-formaldehyde and sodium cyanoborohydride, the reductive amination-based method can be utilized to generate novel internal standard for isotope dilution and to extend the quantitative application.

Therapeutic Role of Functional Components in Alliums for Preventive Chronic Disease in Human Being

Objectives. Functional components in alliums have long been maintained to play a key role in modifying the major risk factors for chronic disease. To obtain a better understanding of alliums for chronic disease prevention, we conducted a systematic review for risk factors and prevention strategies for chronic disease of functional components in alliums, based on a comprehensive English literature search that was conducted using various electronic search databases, especially the PubMed, ISI Web of Science, and CNKI for the period 2007-2016. Allium genus especially garlic, onion, and Chinese chive is rich in organosulfur compounds, quercetin, flavonoids, saponins, and others, which have anticancer, preventive cardiovascular and heart diseases, anti-inflammation, antiobesity, antidiabetes, antioxidants, antimicrobial activity, neuroprotective and immunological effects, and so on. These results support Allium genus; garlic and onion especially may be the promising dietotherapeutic vegetables and organopolysulfides as well as quercetin mechanism in the treatment of chronic diseases. This review may be used as scientific basis for the development of functional food, nutraceuticals, and alternative drugs to improve the chronic diseases.