Flavonoid C-glucosides, which are found in several plant families, are characterized by several biological properties, including antioxidant, anticancer, anti-inflammatory, neuroprotective, hepatoprotective, cardioprotective, antibacterial, antihyperalgesic, antiviral, and antinociceptive activities. The biosynthetic pathway of flavonoid C-glucosides in plants has been elucidated. In the present study, a pathway was introduced to Escherichia coli to synthesize four flavonoid C-glucosides, namely, isovitexin, vitexin, kaempferol 6-C-glucoside, and kaempferol 8-C-glucoside. A five- or six-step metabolic pathway for synthesizing flavonoid aglycones from tyrosine was constructed and two regioselective flavonoid C-glycosyltransferases from Wasabia japonica (WjGT1) and Trollius chinensis (TcCGT) were used. Additionally, the best shikimate gene module construct was selected to maximize the titer of each C-glucoside flavonoid. Isovitexin (30.2 mg/L), vitexin (93.9 mg/L), kaempferol 6-C-glucoside (14.4 mg/L), and kaempferol 8-C-glucoside (38.6 mg/L) were synthesized using these approaches. The flavonoid C-glucosides synthesized in this study provide a basis for investigating and unraveling their novel biological properties.

Alkyl-4-quinolones (AQs) are natural compounds synthesized by bacteria. Members of this group are known quorum-sensing molecules. Other biological functions, such as anti-bacterial, anti-algal, antifungal, and anti-malaria activities have also been reported. The synthetic pathways of AQs have been validated in Pseudomonas aeruginosa. Five genes (pqsA–E) are involved in the synthesis of 2-heptyl-4(1H)-quinolone (HHQ). To synthesize HHQ in a microbial system, pqsA–E genes were introduced into Escherichia coli and HHQ and 2-methyl-4(1H)-quinolone (MHQ) were synthesized. After the copy number, construct promoters, and substrate supplements were optimized, 141.3 mg/L MHQ and 242.8 mg/L HHQ were synthesized.