Background: The phenylpropanoid metabolites are an extremely diverse group of natural products biosynthesized by plants, fungi, and bacteria. Although these compounds are widely used in human health care and nutrition services, their availability is limited by regional variations, and isolation of single compounds from plants is often difficult. Recent advances in synthetic biology and metabolic engineering have enabled artificial production of plant secondary metabolites in microorganisms. Results: We develop an Escherichia coli system containing an artificial biosynthetic pathway that yields phenylpropanoic acids, such as 4-coumaric acid, caffeic acid, and ferulic acid, from simple carbon sources. These artificial biosynthetic pathways contained a codon-optimized tal gene that improved the productivity of 4-coumaric acid and ferulic acid, but not caffeic acid in a minimal salt medium. These heterologous pathways extended in E. coli that had biosynthesis machinery overproducing tyrosine. Finally, the titers of 4-coumaric acid, caffeic acid, and ferulic acid reached 974 mg/L, 150 mg/L, and 196 mg/L, respectively, in shake flasks after 36-hour cultivation. Conclusions: We achieved one gram per liter scale production of 4-coumaric acid. In addition, maximum titers of 150 mg/L of caffeic acid and 196 mg/L of ferulic acid were achieved. Phenylpropanoic acids, such as 4-coumaric acid, caffeic acid, and ferulic acid, have a great potential for pharmaceutical applications and food ingredients. This work forms a basis for further improvement in production and opens the possibility of microbial synthesis of more complex plant secondary metabolites derived from phenylpropanoic acids.

Methylated resveratrol analogs show similar biological activities that are comparable with those of the resveratrol. However, the methylated resveratrol analogs exhibit better bioavailability as they are more easily transported into the cell and more resistant to degradation. Although these compounds are widely used in human health care and in industrial materials, at present they are mainly obtained by extraction from raw plant sources. Accordingly their production can suffer from a variety of economic problems, including low levels of productivity and/or heterogeneous quality. On this backdrop, large-scale production of plant metabolites via microbial approaches is a promising alternative to chemical synthesis and extraction from plant sources. An Escherichia coli system containing an artificial biosynthetic pathway that produces methylated resveratrol analogues, such as pinostilbene (3,4’-dihydroxy-5-methoxystilbene), 3,5-dihydroxy-4’-methoxystilbene, 3,4’-dimethoxy-5-hydroxystilbene, and 3,5,4’-trimethoxystilbene, from simple carbon sources is developed. These artificial biosynthetic pathways contain a series of codon-optimized O-methyltransferase genes from sorghum in addition to the resveratrol biosynthetic genes. The E. coli cells that harbor pET-opTLO1S or pET-opTLO3S produce the one-methyl resveratrol analogues of 3,5-dihydroxy-4’-methoxystilbene and pinostilbene, respectively. Furthermore, the E. coli cells that harbor pET-opTLO13S produce 3,5-dihydroxy-4’-methoxystilbene, bis-methyl resveratrol (3,4’-dimethoxy-5-hydroxystilbene), and tri-methyl resveratrol (3,5,4’-trimethoxystilbene). Our strategy demonstrates the first harness microorganisms for de novo synthesis of methylated resveratrol analogs used a single vector system joined with resveratrol biosynthetic genes and sorghum two resveratrol O-methyltransferase genes. Thus, this is also the first report on the production of the methylated resveratrol compounds bis-methyl and tri-methyl resveratrol (3,4’-dimethoxy-5-hydroxystilbene and 3,5,4’-trimethoxystilbene) in the E. coli culture. Thus, the production of the methylated resveratrol compounds was performed on the simple E. coli medium without precursor feeding in the culture.

Flavonoids are a diverse family of natural phenolic compounds commonly found in fruits and vegetables. Epidemiologic studies showed that flavonoids also reduce the risk of colon cancer. Tectochrysin is one of the major flavonoids of Alpinia oxyphylla Miquel. However, the anti-cancer effects and the molecular mechanisms of tectochrysin in colon cancer cells have not yet been reported. We investigated whether tectochrysin could inhibit colon cancer cell growth at 1, 5, 10 μg/ml. In in vivo study, we injected a tectochrysin treatment dose of 5 mg/kg to each mouse. Tectochrysin suppressed the growth of SW480 and HCT116 human colon cancer cells. The expression of DR3, DR4 and Fas were significantly increased, and pro-apoptotic proteins were also increased. Tectochrysin treatment also inhibited activity of NF-κB. A docking model indicated that tectochrysin binds directly to the p50 unit. In in vivo, tumor weights and volumes in mice were reduced when treated with tectochrysin. Tectochrysin leads to apoptotic cell death in colon cancer cells through activation of death receptors expression via the inhibition of NF-κB. Tectochrysin can be a useful agent for the treatment of colon cancer cell growth as well as an adjuvant agent for chemo-resistant cancer cells growth.

Fructus mume (F. mume) has been used as a traditional medicine for many years in Asian countries. The present study was designed to determine the effect of a 70% ethanol extract of F. mume on white matter and hippocampal damage induced by chronic cerebral hypoperfusion. Permanent bilateral common carotid artery occlusion (BCCAo) was performed on male Wistar rats to induce chronic cerebral hypoperfusion. Daily oral administration of F. mume (200 mg/kg) was initiated 21 days after BCCAo and continued for 42 days. The experimental groups in this study were divided into three groups: a sham-operated group, a BCCAo group, and a BCCAo group that was administered with the F. mume extract. The activation of glial cells, including microglia and astrocytes, and the levels of myelin basic protein (MBP), inflammatory mediators, Toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88), and p38 mitogen-activated protein kinase (MAPK) phosphorylation were measured in brains from rats subjected to chronic BCCAo. Our results revealed that F. mume alleviates the reduction in MBP expression caused by chronic BCCAo in the white matter and the hippocampus and significantly attenuates microglial and astrocytic activation induced by chronic BCCAo in the optic tract of white matter. In addition, F. mume treatment reduced the increased expression of cyclooxygenase-2 (COX-2), interleukin-1β (IL-1β) and interleukin-6 (IL-6), as well as the activation of TLR4/MyD88 and p38 MAPK signaling, in the hippocampus of rats subjected to chronic BCCAo. Taken together, our findings demonstrate that brain injury induced by chronic BCCAo is ameliorated by the anti-inflammatory effects of F. mume via inhibition of MBP degradation, microglial and astrocytic activation, increased inflammatory mediator expression, and activated intracellular signalings, including TLR4 and p38 MAPK, implying that F. mume is potentially an effective therapeutics for the treatment of vascular dementia.