Green Chemistry最新文献

Plant-derived oleanolic and ursolic acids are sought-after triterpenoid sapogenins used in modern curative and preventive medicines. Several plant species have been overexploited for triterpenoid sapogenin extraction. In this study, we reconfigured the metabolic fingerprints of Ganoderma lucidum and produced oleanolic and ursolic acids, ganoderic acids, and meroterpenoids. Oleanolic and ursolic acids were first synthesized in the medicinal mushroom by expressing amyrin-synthases and beta-amyrin 28-monooxygenase from plants. The production of sapogenin precursors (2,3-oxidosqualene) and ganoderic acid was enhanced by reconstructing the mushroom terpenoid biosynthetic pathway using a new terpenoid gene cluster recovered from the mycelium. Overexpression of the VeA–VelB velvet and LaeA proteins upregulated secondary metabolism and stimulated the hyperproduction of a renoprotective meroterpenoid. The VeA–VelB velvet and LaeA protein variants developed a radically distinctive yellow phenotype that has not yet been reported in any of the mushroom mycelial variants. CRISPR-AsCpf1-based lanosterol synthase editing repressed the competing ganoderic acid pathway and further enhanced 2,3-oxidosqualene accumulation and triterpenoid sapogenin biosynthesis. The oleanolic and ursolic acid titer reached 1.478 g L⁻¹ and 0.87 g L⁻¹, respectively, when the fermentation conditions were optimized in a 5 L lab bioreactor. This study presents fascinating metabolic engineering strategies that remodel Ganoderma's metabolic route and produce oleanolic acid, ursolic acid, ganoderic acids, and meroterpenoids. These new strains could replace wild plant species as a green source of triterpenoid sapogenins.

Biomass is a promising feedstock for reducing greenhouse gas emissions in the chemical industry. Biomass availability, however, is limited. Still, many bio-based processes focus on producing a single product. Thereby, valuable feedstock potential is often lost with undesired co-products. In this study, we assess the environmental and economic potential of bio-based multi-product systems and provide insights on the sustainability benefits of co-producing hydrogen and high-value acids from bio-alcohols compared to fossil and green alternatives. We select dehydrogenation as a promising early-stage technology for producing hydrogen and four co-product candidates: formic acid, acetic acid, lactic acid, and succinic acid. All investigated dehydrogenation multi-product systems show the potential to reduce climate impacts and to become profitable. A higher carbon tax can improve the economic potential. Acetic acid is the most promising co-product compared to both fossil and green benchmarks with potential benefits in various environmental impact categories. In contrast, co-producing lactic acid shows substantial trade-offs compared to the benchmark technologies. Expected eutrophication impacts associated with biomass use occur in all dehydrogenation routes. Our analysis highlights that multi-product systems can increase benefits compared to single-product systems from both environmental and economic perspectives.

Nucleophilic addition to pyridiniums, metal-catalyzed hydrogenation, and cycloadditions constitute a valuable toolbox of modern pyridine dearomatization strategies. Though, in recent years, there have been notable improvements and variations of the canonical Birch reduction to address its notorious safety hazards and poor chemoselectivity, it remains an unexplored mode of reactivity for controlled pyridine dearomatization. Here, we report a simple and safe protocol for the electrochemical Birch carboxylation of pyridines utilizing a sustainable approach and CO₂ as a green C1 building block. This reaction is highly selective for pyridine reduction in the presence of several functional groups incompatible with the canonical Birch reduction and enables direct access to decorated piperidine scaffolds.

The electrosynthesis of H₂O₂via the two-electron oxygen reduction reaction (2e⁻-ORR) is a promising alternative method due to its cost-effectiveness and environmentally friendly nature. Atomically dispersed Co single atoms are considered as the active catalyst for the 2e⁻-ORR, but they still suffer from the strong adsorption of the intermediate *OOH resulting in low selectivity for H₂O₂. Herein, we propose an inter-atomic synergistic strategy by constructing a heteronuclear diatomic catalyst (Co/ZnPc-S-C₃N₄) to optimize the adsorption of *OOH and enhance the performance of H₂O₂ electrosynthesis. In Co/ZnPc-S-C₃N₄, synthesized by a supramolecular strategy through π–π stacking between MPc (M = Co or Zn) and a S-doped C₃N₄ substrate, the incorporation of Zn induces electron transfer from cobalt to zinc constructing an electron-deficient cobalt center, which inhibits the cleavage of the O–O bond in adsorbed *OOH and favors the two-electron ORR pathway. Thus, Co/ZnPc-S-C₃N₄ exhibits more than 95% H₂O₂ selectivity and nearly 100% Faraday efficiency as well as long-term stability in both alkaline and neutral electrolytes, with H₂O₂ yields of 5.35 and 5.45 mol g_cat⁻¹ h⁻¹, respectively, outperforming the reported analogous catalysts. This work provides an effective strategy for the design of heteronuclear diatomic catalysts, making them promising candidates for the 2e⁻-ORR.