Simultaneous determination of retinol acetate, retinol palmitate, cholecalciferol, α-tocopherol acetate and alphacalcidol in capsules by non-aqueous reversed-phase HPLC and column backflushing

Summary A very simple non-aqueous reversed-phase HPLC method has been developed for analysis of retinol acetate, retinol palmitate, cholecalciferol, α-tocopherol acetate and alphacalcidol in capsules without the need for saponification. A reversed-phase (LiChrospher C8, 4.6 mm i.d.) column is used with acetonitrile-methanol, 95∶5 (v/v) as mobile phase at flow rate of 1 mL min⁻¹. Sample treatment consists only in dilution of the capsule contents withn-hexane and methanol. This method is suitable for routine quantification in the industrial quality-assurance laboratory.     

超高效液相色谱-串联质谱法测定蛋白胨中9种B族维生素

建立了能够同时测定蛋白胨中9种B族维生素的超高效液相色谱-串联质谱法（UPLC-MS/MS）。样品经水溶解后,滤液经Syncronis C₁₈色谱柱分离,采用电喷雾电离源,正离子、多反应监测模式进行检测,分析时间8 min,外标法定量。结果表明,9种B族维生素在各自质量浓度范围内线性良好,相关系数（R²）均大于0.999,方法的检出限为0.09~1.67 μg/L,方法的相对标准偏差均<3%（n=6）;9种B族维生素不同添加水平下的平均回收率为80.2%~103.9%。该方法简便、准确,灵敏度高,适用于蛋白胨中B族维生素的测定。     

The Hydrogenobyric Acid Structure Reveals the Corrin Ligand as an Entatic State Module Empowering B12 Cofactors for Catalysis

The B₁₂ cofactors instill a natural curiosity regarding the primordial selection and evolution of their corrin ligand. Surprisingly, this important natural macrocycle has evaded molecular scrutiny, and its specific role in predisposing the incarcerated cobalt ion for organometallic catalysis has remained obscure. Herein, we report the biosynthesis of the cobalt‐free B₁₂ corrin moiety, hydrogenobyric acid ( Hby ), a compound crafted through pathway redesign. Detailed insights from single‐crystal X‐ray and solution structures of Hby have revealed a distorted helical cavity, redefining the pattern for binding cobalt ions. Consequently, the corrin ligand coordinates cobalt ions in desymmetrized “entatic” states, thereby promoting the activation of B₁₂‐cofactors for their challenging chemical transitions. The availability of Hby also provides a route to the synthesis of transition metal analogues of B₁₂.     

Natural Dietary Compounds in the Treatment of Arsenic Toxicity

Chronic exposure to arsenic (As) compounds leads to its accumulation in the body, with skin lesions and cancer being the most typical outcomes. Treating As-induced diseases continues to be challenging as there is no specific, safe, and efficacious therapeutic management. Therapeutic and preventive measures available to combat As toxicity refer to chelation therapy, antioxidant therapy, and the intake of natural dietary compounds. Although chelation therapy is the most commonly used method for detoxifying As, it has several side effects resulting in various toxicities such as hepatotoxicity, neurotoxicity, and other adverse consequences. Drugs of plant origin and natural dietary compounds show efficient and progressive relief from As-mediated toxicity without any particular side effects. These natural compounds have also been found to aid the elimination of As from the body and, therefore, can be more effective than conventional therapeutic agents in ameliorating As toxicity. This review provides an overview of the recently updated knowledge on treating As poisoning through natural dietary compounds. This updated information may serve as a basis for defining novel prophylactic and therapeutic formulations.     

Transients and cooperative action of β-carotene, vitamin E and C in biological systems in vitro under irradiation

Using N^•₃ species as specific electron acceptor a defined ascorbate radical: AH^•↔A^•−+H⁺ (λ_max=360 nm, =3400 dm³ mol⁻¹ cm⁻¹) is observed. The attack of DMSO^•+ on vit.E results in a vit.E^• radical (k=1×10⁹ dm³ mol⁻¹ s⁻¹; λ_max=425 nm, =2400 dm³ mol⁻¹ cm⁻¹; 2k=4.7×10⁸ dm³ mol⁻¹ s⁻¹). Vit.E-acetate leads to the formation of a radical cation (vit.E-ac^•+). β-carotene reacts also with DMSO^•+ forming a radical cation, β-car^•+ (k=1.75×10⁸ dm³ mol⁻¹ s⁻¹; λ_max=942 nm, =14 600 dm³ mol⁻¹ cm⁻¹), which probably leads to the formation of a dimer radical cation, (β-car)^•+₂ (k=2.5×10⁷ dm³ mol⁻¹ s⁻¹).

Using E.coli bacteria (AB1157) as a model system in vitro it was found that all three vitamins are rather efficient radiation protecting agents. They can also increase the activity of cytostatica, e.g., mitomycin C (MMC), by electron transfer process. The mixture of vit.E-ac and β-car acts contradictory, but adding vit.C to it a strong cooperative enhancement of the MMC activity is observed once again. A relationship between the pulse radiolysis and the radiation biological data is found and discussed. A possible explanation of the previously reported trials concerning the role of vit.E and β-car on the increased occurence of lung and other types of cancer in smokers and drinkers is presented.     

反相高效液相色谱法同时测定食品和多维片中8种水溶性维生素

建立了以0．05mol/L KH2PO4-甲醇为流动相的梯度洗脱反相高效液相色谱同时测定水溶性维生素C,B1,B2,B6,B12,烟酸,烟酰胺和叶酸的分析方法,方法检出限为1．4－0．76ng,用该法测定了奶粉,玉米粉,饮料及复合维生素片中水溶性维生素,相对标准偏差为2．8％－8．8％,加标回收率为74．7％－112．5％。     

Functionalization of polyesters with multiple B vitamins

A method to covalently attach combinations of six different B vitamins provided an avenue to new functional thermosets without multi‐step coupling reactions. The melt polymerization strategy required no organic solvent and facilitated covalent attachment of OH (B₁, B₂, B₅, B₆) or COOH (B₇, B₉) groups on B vitamins via Fischer esterification. Characterization of model reactions with LC/MS, FTIR, and GPC confirmed covalent attachment. Based on control experiments, B vitamins demonstrated unexpected thermal stability and appreciable solubility in the melt polymerization. This approach was demonstrated with citric acid and diglycerol, but has wide‐ranging potential for other polar monomers with negative octanol–water partition coefficients (LogP). © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3308–3316     

Organometallic B12–DNA Conjugate: Synthesis,Structure Analysis,and Studies of Binding to Human B12‐Transporter Proteins

Design, synthesis, and structural characterization of a B₁₂‐octadecanucleotide are presented herein, a new organometallic B₁₂–DNA conjugate. In such covalent conjugates, the natural B₁₂ moiety may be a versatile vector for controlled in vivo delivery of oligonucleotides to cellular targets in humans and animals, through the endogenous B₁₂ transport systems. Binding of the organometallic B₁₂ octadecanucleotide to the three important human proteins of B₁₂ transport was studied, to examine its structural suitability for the task of eventual in vivo oligonucleotide delivery. Binding was efficient with transcobalamin (TC), but not so efficient with the homologous glycoproteins intrinsic factor and haptocorrin. Binding of the B₁₂ octadecanucleotide to TC suggests the capacity of the B₁₂ moiety to serve as a natural vector for specific transport of single stranded, organometallic oligonucleotide loads from the blood stream into cells.