PROTAC derivatization of natural products for target identification and drug discovery: Design of evodiamine-based PROTACs as novel REXO4 degraders.

INTRODUCTION: Natural products (NPs) play a crucial role in the development of therapeutic drugs. However, it is still highly challenging to identify the targets of NPs. Besides, NPs usually exert their pharmacological activities via acting on multiple targets or pathways, which also poses great difficulties for the target identification of NPs. OBJECTIVES: Inspired by our continuous efforts in designing drug-like protein degraders, this study introduced a successful example for the target identification and drug discovery of natural products evodiamine by employing PROTAC technology. METHODS: Taking advantages of proteolysis targeting chimera (PROTAC), herein an integrated strategy combining PROTAC derivatization, quantitative proteomic analysis and binding affinity validation was developed for target identification and drug discovery of antitumor NP evodiamine. RESULTS: In this study, both highly potent PROTACs and negative controls were designed for quantitative proteomic analysis. Furthermore, REXO4 was confirmed as a direct target of 3-fluoro-10-hydroxylevodiamine, which induced cell death through ROS. In addition, the PROTAC 13c effectively degraded REXO4 both in vitro and in vivo, leading to potent antitumor activities and reduced toxic side effects. CONCLUSION: In summary, we developed an integrated strategy for the target identification and drug discovery of NPs, which was successfully applied to the PROTAC derivatization and target characterization of evodiamine. This proof-of-concept study highlighted the superiority of PROTAC technology in target identification of NPs and accelerated the process of NPs-based drug discovery, exhibiting broad application in NP-based drug development.

Discovery of Highly Potent Nicotinamide Phosphoribosyltransferase Degraders for Efficient Treatment of Ovarian Cancer.

Nicotinamide phosphoribosyltransferase (NAMPT) is identified as a promising target for cancer therapy. However, known NAMPT inhibitors are characterized by weak clinical efficacy and dose-dependent toxicity. There is an urgent need to develop new NAMPT intervention strategies. Using the proteolysis-targeting chimera (PROTAC) technology, we designed and synthesized a series of new von Hippel-Lindau (VHL)-recruiting NAMPT-targeting PROTACs. A highly potent NAMPT degrader (B3) was successfully identified, which displayed excellent degradation activity (DC50 < 0.17 nM, Dmax > 90%) and antiproliferative potency against A2780 cells (IC50 = 1.5 nM). PROTAC B3 induced NAMPT depletion in a concentration- and time-dependent manner through the ubiquitin-proteasome system. Particularly, PROTAC B3 achieved good plasma exposure levels via intravenous injection, gained potent tumor growth inhibition (TGI = 88.1%, 2 µM/kg) in the xenograft model, and demonstrated good biosafety without undesired toxicities. This study provides a highly potent VHL-recruiting NAMPT degrader for the treatment of ovarian cancer.

Anaerobic Co-Digestion of Pig Manure and Rice Straw: Optimization of Process Parameters for Enhancing Biogas Production and System Stability.

The objective of this study was to optimize the process parameters of the anaerobic co-digestion of pig manure and rice straw to maximize methane production and system stability. In this study, batch experiments were conducted with different mixing ratios of pig manure and rice straw (1:0, 1:1, 1:5, 1:10, and 0:1), total solid concentrations (6%, 8%, 10%, 12%, and 14%), and inoculum accounts (5%, 10%, 15%, 20%, and 25%). The results show that a 1:5 mixing ratio of pig manure to rice straw, a 12% total solid content, and a 15% inoculum account yielded biogas up to 553.79 mL/g VS, which was a result of co-digestion increasing the cooperative index (CPI > 1). Likewise, the evolution of the pH and VFAs indicated that the co-digestion system was well-buffered and not easily inhibited by acidification or ammonia nitrogen. Moreover, the results of the Gompertz model's fitting showed that the cumulative methane production, delay period, effective methane production time, and methane production rate under optimal conditions were significantly superior compared to the other groups employed.

Water-soluble derivatives of evodiamine: Discovery of evodiamine-10-phosphate as an orally active antitumor lead compound.

10-Hydroxyevodiamine is a multitargeting antitumor lead compound with excellent in vitro activity. However, its in vivo antitumor potency is rather limited, which has hampered its further clinical development. To overcome this obstacle, a series of novel water-soluble derivatives of 10-hydroxyevodiamine were designed and synthesized. Most of them exhibited good to excellent antitumor activities against several cancer cell lines. In particular, phosphate derivative 9 was orally active and showed improved in vivo antitumor efficacy in HCT116 xenograft models. Further antitumor mechanism studies indicated that compound 9 acted by triple Top1/Top2/tubulin inhibition and induced apoptosis with G2/M cell cycle arrest. Taken together, this study extended the structure-activity relationship of evodiamine and identified phosphate derivative 9 as a promising antitumor lead compound.

Synthesis and structure-activity relationships of guaiane-type sesquiterpene lactone derivatives with respect to inhibiting NO production in lipopolysaccharide-induced RAW 264.7 macrophages.

A guaiane framework was scaffolded by photochemical rearrangement reactions using α-santonin 1 as a starting material. Then, using a series of reactions, we synthesized the guaiane-type sesquiterpene lactone 5 in high yield. The inhibitory activities of compound 5 and of a series of derivatives on nitric oxide (NO) release were evaluated in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. Compounds 6g, 7h, 7i, 7k and 8g, exhibited significant inhibitory effects on NO production, with IC50 values of 14.8, 22.3, 18.3, 17.4 and 7.0 µM, respectively. Their cytotoxicities were also estimated using an MTT assay. The structure-activity relationships of these compounds were also discussed.

Construction of 2-substituted-3-functionalized benzofurans via intramolecular Heck coupling: application to enantioselective total synthesis of daphnodorin B.

A novel approach was developed for the synthesis of 2-substituted-3-functionalized benzofurans, using an intramolecular Heck reaction which was further applied in the first enantioselective total synthesis of Daphnodorin B.