Biosynthesis of fraxetin from three different substrates using engineered Escherichia coli

Abstract

Fraxetin, which is a simple coumarin, is a phytochemical present in medicinal plants, such as Fraxinus rhynchophylla, and Cortex Fraxini. In plants, it serves as a controller of iron homeostasis. The health-enhancing activities of fraxetin, such as anticancer, neuroprotective and antibacterial activities, are known. Scopoletin 8-hydroxylase (S8H) is a key enzyme involved in the synthesis of fraxetin from scopoletin. Scopoletin can be synthesized either from esculetin by O-methylation or from ferulic acid by feruloyl CoA 6′-hydroxylase (F6′H) and 4-coumaric acid CoA ligase (4CL). To enable fraxetin synthesis, the fraxetin biosynthesis pathway was introduced into Escherichia coli. Three distinct routes, from ferulic acid, esculetin, and scopoletin, were designed for the synthesis of fraxetin. In the first approach, E. coli strain harboring S8H was used and found to synthesize 84.8 μM fraxetin from 100 μM scopoletin. Two E. coli strains were used for the other two approaches because these approaches required at least two enzymatic reactions. Through this approach, 41.4 μM fraxetin was synthesized from 100 μM esculetin, while 33.3 μM fraxetin was synthesized from 100 μM ferulic acid.

Fraxetin attenuates disrupted behavioral and central neurochemical activity in a model of chronic unpredictable stress

“…In this respect, plant-based natural products may provide an alternative solution and one such phytochemical class are the coumarins with recognized therapeutic potentials in multiple neuropsychiatric illnesses through antioxidant, neuroprotective, neuromodulator and antidepressant actions( Skalicka-Woźniak et al, 2016 ; Abu-Aisheh et al, 2019 ; Pruccoli, 2019 ; Daliev et al, 2021 ; Koyiparambath et al, 2021 ; Sharifi-Rad et al, 2021 ; Kılıç, 2022 ). One particular coumarin derivative, fraxetin, is an O -methylated coumarin ( An et al, 2020 ), present in many functional foods as well as several dietary supplements with a documented neuroprotective profile mediated primarily through inhibition of oxidative stress ( Pruccoli, 2019 ; Qin et al, 2019 ; Zhang et al, 2021a ). Although the antioxidant, anti-inflammatory, and neuroprotective activities of fraxetin have been described ( Zhang et al, 2021a ), its effects on stress have not been reported in the literature and remain unknown.…”

Clostridium acetobutylicum atpG-Knockdown Mutants Increase Extracellular pH in Batch Cultures

“…Bacterial Strains, Plasmids, and Culture Conditions E. coli strains and recombinants were grown in Luria-Bertani (LB) broth at 37 °C (An et al, 2020;Lone et al, 2020). C. acetobutylicum ATCC 824 and the engineered strain BEKW and mutants were grown in clostridial growth medium (CGM) or 2X YTG agar in an anaerobic chamber (Forma Scientific, Marietta, OH, United States) under 4% hydrogen and 96% nitrogen at 37 °C (Jang et al, 2012).…”

Combined Microbial Fermentation Converts Bioactive Compounds in Nitraria Tangutorum Bobrov Fruit and Displays its Antidiabetic Potential

“…Esculetin can be converted to scopoletin by an O-methyltransferase, and then scopoletin can be synthesized to fraxetin by scopoletin 8-hydroxylase. Ferulic acid can also be synthesized to scopoletin by E. coli, and then further synthesized to fraxetin [36]. Coumarin was found only in NTJ, not in NTF or NTR, which indicated that coumarin was newly generated through fermentation process.…”