- Synthesis of a tyrosinase inhibitor by consecutive ethenolysis and cross-metathesis of crude cashew nutshell liquid
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A convenient and sustainable three-step synthesis of the tyrosinase inhibitor 2-hydroxy-6-tridecylbenzoic acid was developed that starts directly from the anacardic acid component of natural cashew nutshell liquid (CNSL). Natural CNSL contains 60-70% of anacardic acid as a mixture of several double bond isomers. The anacardic acid component was converted into a uniform starting material by ethenolysis of the entire mixture and subsequent selective precipitation of 6-(ω-nonenyl)salicylic acid from cold pentane. The olefinic side chain of this intermediate was elongated by its cross-metathesis with 1-hexene using a first generation Hoveyda-Grubbs catalyst, which was reused as precatalyst in a subsequent hydrogenation step. Overall, the target compound was obtained in an overall yield of 61% based on the unsaturated anacardic acid content and 34% based on the crude CNSL.
- Pollini, Jacqueline,Bragoni, Valentina,Goo?en, Lukas J.
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- Synthesis and Evaluation of Ginkgolic Acid Derivatives as SUMOylation Inhibitors
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SUMOylation has emerged as an important post-translational modification that has been shown to modulate protein activity associated with various signaling pathways, and consequently, it has emerged as an important therapeutic target. While several natural products have been shown to inhibit enzymes involved in the SUMOylation process, there has been little progress toward the development of more selective and potent SUMOylation inhibitors. Ginkgolic acid was one of the first natural products discovered to inhibit the SUMO E1 enzyme. Despite its use to mechanistically investigate the SUMOylation process, ginkgolic acid also modulates other pathways as well. In this Letter, preliminary structure-activity relationships for ginkgolic acid as a SUMOylation inhibitor are presented.
- Brackett, Christopher M.,García-Casas, Ana,Castillo-Lluva, Sonia,Blagg, Brian S. J.
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p. 2221 - 2226
(2020/12/17)
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- Novel chemical synthesis of ginkgolic acid (13:0) and evaluation of its tyrosinase inhibitory activity
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A novel efficient synthesis of ginkgolic acid (13:0) from abundant 2,6-dihydroxybenzoic acid was successfully developed through a state-of-the-art palladium-catalyzed cross-coupling reaction and catalytic hydrogenation with an overall yield of 34% in five steps. The identity of the synthesized ginkgolic acid (13:0) was confirmed by nuclear magnetic resonance, mass spectrometry, infrared, and high-performance liquid chromatography. The reaction sequence of this method can be readily extended to the synthesis of other ginkgolic acids. The synthesized ginkgolic acid (13:0) exhibited promising anti-tyrosinase activity (IC50 = 2.8 mg/mL) that was not correlated to antioxidant activity as probed by 1,1-diphenyl-2-picrylhydrazyl, 2,2′-azino-bis(3- ethylbenzothiazoline-6-sulfonic acid), ferric reducing ability of plasma, and oxygen radical absorbance capacity assays. The synthetic strategy developed in this work will significantly facilitate biological studies of ginkgolic acids that have great potential applications in food and pharmaceuticals.
- Fu, Yuanqing,Hong, Shan,Li, Duo,Liu, Songbai
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p. 5347 - 5352
(2013/07/27)
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- Synthesis of Anacardic Acids
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The anacardic acids 1-11, isolated from various plants, were synthesized by a new general method.Reaction of the methyl alkynoates 12-18 with 1-methoxy-1,4-cyclohexadiene at 200 deg C afforded directly the methyl 2-methoxybenzoates 19-25 with long chain substituents in 6-position in 74-85percent yield.The dienophiles 12-16 were prepared by pyrolysis of the corresponding acylphosphoranes 26-30, the dienophiles 17 and 18 by methoxycarbonylation of the corresponding alkynes 31 and 32 via the hydroxy esters 33 and 34.Demethylation of 19-23 with AlI3 gave the methyl salicylates 35-39 which could be hydrolized to the anacardic acids 1-4 and 7.Hydrolysis of 24 and 25 provided the hydroxy acids 40 and 41, which were converted by treatment with CBr4/PPh3 into the acids 42 and 43 bearing bromoalkyl side chains.These were transformed into 44-47 by reaction with 1-hexynyllithium and 1-octynyllithium.Stereoselective hydrogenation of 44-47 gave 48-51 with (Z)-alkene side chains.In a similar approach 42 was converted into 52 and then into 53, which gave upon treatment with 1-pentynylmagnesium bromide or 1-heptynylmagnesium bromide the acids 54 and 55 with alkadiyne side chains.Stereoselective hydrogenation provided 56 and 57 with (Z,Z)-alkadiene side chains.The 2-methoxy group in 48-51, 56, 57 was demethylated by treatment with AlI3 to give the anacardic acids 5, 6, 8-11. - Keywords: Anacardic acids; Benzoates, methyl 6-alkyl-2-methoxy-; 2-Alkynoates, methyl; Aluminium triiodide, demethylation by treatment with
- Zehnter, Reinhard,Gerlach, Hans
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p. 2209 - 2220
(2007/10/03)
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