RESUMEN
Here, we report a bienzymatic cascade to produce ß-amino acids as an intermediate for the synthesis of the leading oral antidiabetic drug, sitagliptin. A whole-cell biotransformation using recombinant Escherichia coli coexpressing a esterase and transaminase were developed, wherein the desired expression level of each enzyme was achieved by promotor engineering. The small-scale reactions (30 ml) performed under optimized conditions at varying amounts of substrate (100-300 mM) resulted in excellent conversions of 82%-95% for the desired product. Finally, a kilogram-scale enzymatic reaction (250 mM substrate, 220 L) was carried out to produce ß-amino acid (229 mM). Sitagliptin phosphate was chemically synthesized from ß-amino acids with 82% yield and > 99% purity.
Asunto(s)
Escherichia coli , Esterasas , Ingeniería Genética , Microorganismos Modificados Genéticamente , Regiones Promotoras Genéticas , Fosfato de Sitagliptina/metabolismo , Transaminasas , Escherichia coli/genética , Escherichia coli/metabolismo , Esterasas/genética , Esterasas/metabolismo , Microorganismos Modificados Genéticamente/genética , Microorganismos Modificados Genéticamente/metabolismo , Transaminasas/genética , Transaminasas/metabolismoRESUMEN
BACKGROUND: Evidence of ginseng for reducing blood pressure (BP) in hypertensive patients is controversial. This systematic review updated the previous reviews and evidence for it. METHODS: Ten databases were searched from their inception through October 2016, without language restriction. Randomized clinical trials (RCTs) were included if any types of ginseng were tested as the sole treatment or as an adjunct to other treatments for pre-hypertension or hypertension. The risk of bias (ROB) was assessed with Cochrane ROB tools by two independent reviewers. RESULTS: We found 528 potentially relevant articles, of which 9 RCTs met our inclusion criteria. Two studies reported positive effects of Korean red ginseng (KRG) on acute reduction of systolic BP (SBP: n=54, mean differences (MD), -6.52; P=0.0002; I2=0%) and diastolic BP DBP: MD, -5.21; P=0.0001; I2=0%), while two other trials failed to do so with north American ginseng (NAG) in both SBP and DBP. Five RCTs assessed the long-term effects of ginseng (KRG or NAG) on SBP and DBP. Two studies showed positive effects of KRG on reducing SBP and DBP compared with placebo (SBP: n = 183, MD, -2.92, P=0.04; I2 = 0%; DBP: MD, -3.19, P=0.008; I2 = 0%). CONCLUSION: This systematic review provides positive evidence for the efficacy of KRG on reducing blood pressure in patients with pre-hypertension and hypertension in acute and long-term. Future RCTs appear to be warranted.
