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Metabolic engineering is a powerful tool for the sustainable production of chemicals. Over the years, the exploration of microbial, animal and plant metabolism has generated a wealth of valuable genetic information. The prudent application of this knowledge on cellular metabolism and biochemistry has enabled the construction of novel metabolic pathways that do not exist in nature or enhance existing ones. The hand in hand development of computational technology, protein science and genetic manipulation tools has formed the basis of powerful emerging technologies that make the production of green chemicals and fuels a reality. Microbial production of chemicals is more feasible compared to plant and animal systems, due to simpler genetic make-up and amenable growth rates. Here, we summarize the recent progress in the synthesis of biofuels, value added chemicals, pharmaceuticals and nutraceuticals via metabolic engineering of microbes.

Nutraceuticals are important natural bioactive compounds that confer health-promoting and medical benefits to humans. Globally growing demands for value-added nutraceuticals for prevention and treatment of human diseases have rendered nutraceuticals a multi-billion dollar market. However, supply limitations and extraction difficulties from natural sources such as plants, animals or fungi, restrict the large-scale use of nutraceuticals. Metabolic engineering via microbial production platforms has been advanced as an eco-friendly alternative approach for production of value-added nutraceuticals from simple carbon sources. Microbial platforms like the most widely used Escherichia coli and Saccharomyces cerevisiae have been engineered as versatile cell factories for production of diverse and complex value-added chemicals such as phytochemicals, prebiotics, polysaccaharides and poly amino acids. This review highlights the recent progresses in biological production of value-added nutraceuticals via metabolic engineering approaches.

Chemical investigation of the anti-inflammatory Chinese folk medicine Calophyllum membranaceum has resulted in the isolation and characterization of three new xanthones (1-3), one new biphenyl C-glycoside (4), and one new phenylethanoid glycoside (5) along with 17 known compounds. Their structures were characterized on the basis of spectroscopic and chemical methods. Two xanthones, 2,6-dihydroxy-1,7-dimethoxyxanthone (1) and 3,4-dihydroxyxanthone, were found to exhibit selective inhibitory activity against cyclooxygenase-2 (IC(50)=2.99 and 1.80 microM) in vitro.

We report here, for the first time, the BOP-mediated one-pot macrocyclization that is facilitated and guided by internally placed intramolecular H-bonds to allow for the highly selective formation of five-residue cation-binding macrocycles.

ApUGT, a diterpene glycosyltransferase from Andrographis paniculata, could transfer a glucose to the C-19 hydroxyl moiety of andrograpanin to form neoandrographolide. This glycosyltransferase has a broad substrate scope, and it can glycosylate 26 natural and unnatural compounds of different structural types. This study provides a basis for exploring the glycosylation mechanism of ent-labdane-type diterpenes and plays an important role in diversifying the structures used in drug discovery.