Junhong Liu

The metabolism and biotechnological application of betaine in microorganism

Glycine betaine (betaine) is widely distributed in nature and can be found in many microorganisms, including bacteria, archaea, and fungi. Due to its particular functions, many microorganisms utilize betaine as a functional chemical and have evolved different metabolic pathways for the biosynthesis and catabolism of betaine. As in animals and plants, the principle role of betaine is to protect microbial cells against drought, osmotic stress, and temperature stress. In addition, the role of betaine in methyl group metabolism has been observed in a variety of microorganisms. Recent studies have shown that betaine supplementation can improve the performance of microbial strains used for the fermentation of lactate, ethanol, lysine, pyruvate, and vitamin B12, during which betaine can act as stress protectant or methyl donor for the biosynthesis of structurally complex compounds. In this review, we summarize the transport, synthesis, catabolism, and functions of betaine in microorganisms and discuss potential engineering strategies that employ betaine as a methyl donor for the biosynthesis of complex secondary metabolites such as a variety of vitamins, coenzymes, and antibiotics. In conclusion, the biocompatibility, C/N ratio, abundance, and comprehensive metabolic information of betaine collectively indicate that this molecule has great potential for broad applications in microbial biotechnology.

Single-dose bioequivalence assessment of two formulations of polysaccharide iron complex capsules in healthy adult male Chinese volunteers: A sequence-randomized, double-blind, two-way crossover study

BACKGROUND Iron deficiency anemia (IDA) is a common nutritional disease worldwide. Iron supplementation is an efficient method for treating patients with IDA. Polysaccharide iron complex is an oral iron supplement that is associated with generally good tolerability and good bioavailability. OBJECTIVE The aim of this study was to evaluate the bioequivalence of 2 branded formulations of polysaccharide iron complex in healthy adult male Chinese volunteers by determining the pharmacokinetic parameters after single-dose oral admi ni strati on. METHODS This sequence-randomized, double-blind, 2-way crossover study was carried out in the Affiliated Hospital, Institute of Medical Sciences of Qingdao University, Qingdao, China. Healthy adult male Chinese volunteers were enrolled and evenly randomized to receive 1 of 2 formulations on day 1. Subjects received an oral dose of 150 mg (1 capsule) of polysaccharide iron complex with 150 mL of warm water in the morning. Capsules were of similar size, shape, and color to ensure blinding. Four hours after administration, the subjects were given standardized meals. After a 1-week washout period, the subjects were crossed over to receive the other formulation in a similar manner. The serum iron concentration 12 hours after study drug administration was determined using atomic-absorption spectrometry. The pharmacokinetic parameters Cmax, Tmax, AUC0-t, and AUC0-∞ were obtained and analyzed using the Schuir mann 2 one-sided t test. The 2 formulations were considered bioequi valent if the test/reference ratios of Cmax, AUC0-t, and their 90% CIs were within the range of 70% to 143% for Cmax and within 80% to 125% for AUC0-t. Tolerability was monitored by inquiring whether the subjects had experienced adverse events (AEs), with a focus on gastrointestinal AEs, during the clinic visits during the 24-hour period after drag administration and subsequently via telephone throughout the study. RESULTS Thirty adult male Chinese volunteers were assessed for inclusion. Twenty healthy male volunteers (10 in each group) (mean [SD] age, 21.5 [2.9] years [range, 19-23 years]; weight, 66.2 [5-8] kg [range, 56-80 kg]; height, 172.5 [5.1] cm [range, 162-180 cm]) were enrolled and completed the study. The pharmacokinetic parameters of the test and reference formulations were as follows: AUCO-t, 6.58 (2.09) and 6.58 (1.91) μg/mL · h(-1); Cmax, 1.10 (0.28) and 1.07 (0.25) μg/mL; Tmax, 3.93 (0.37) and 3-93 (0.37) hours; t½, 8.33 (0.36) and 8.38 (0.41) hours; and AUC0-∞, 6.93 (2.23) and 6.95 (2.13) μg/mL · h(-1), respectively. There were no statistically significant differences in AUC0-∞ or Tmax by formulation, period, or subject between the test and reference formulations. Similarly, there were no statistically significant differences in Cmax by period; however, a significant difference was found in Cmax by formulation (P = 0.012). No clinically significant AEs were reported with either formulation. CONCLUSIONS In these healthy adult male Chinese volunteers, the test formulation of polysaccharide iron complex was found to be bioequivalent to the reference formulation according to the Chinese regulatory definition. A significant difference by formulation was found in Cmax. The sample size was smaller than that recommended by the US Food and Drug Administration for a bioequivalence study, and additional studies with larger sample sizes are needed.