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Natural products have long been recognized as a rich source of potent therapeutics but further development is often limited by high structural complexity and high molecular weight. In contrast, at the core of the thujaplicins is a lead-like tropolone scaffold characterized by relatively low molecular weight, ample sites for diversification, and metal-binding functionality poised for targeting a range of metalloenzyme drug targets. Here, we describe the development of this underutilized scaffold for the discovery of tropolone derivatives that function as isozyme-selective inhibitors of the validated anticancer drug target, histone deacetylase (HDAC). Several monosubstituted tropolones display remarkable levels of selectivity for HDAC2 and potently inhibit the growth of T-cell lymphocyte cell lines. The tropolones represent a new chemotype of isozyme-selective HDAC inhibitors. KEYWORDS: Tropolone, HDAC, isozyme-selectivity, thujaplicin, metalloenzyme, T-lymphocyte cancer cell lines N atural products have long served as a rich source of drugs for a variety of indications ranging from anticancer to antimicrobial to neurological disorders. Typically these natural products are characterized by high molecular weight and potency as well as high levels of structural complexity with limited sites for diversification. In contrast, thujaplicins, members of the tropolone family of natural products, can be regarded as lead-like natural products. β-Thujaplicin (also known as hinokitiol) is characterized by low molecular weight (MW = 164) and a relatively lower level of complexity that allows more extensive structural modification. Thujaplicins are monoterpene natural products isolated from the heartwood of trees in the Cupressaceae family 1 that are associated with antiproliferative activity.2−4 There have been few attempts to utilize these lead-like compounds in drug discovery, perhaps exacerbated by limited synthetic accessibility to these nonbenzenoid aromatics.The tropolone functionality is uniquely disposed to strongly chelate metal ions, which may be a hallmark of the biological activity of these compounds.3 Substituted tropolones are a compelling and distinct chemotype for the development of inhibitors of metalloenzyme drug targets. Herein, we describe our efforts to use β-thujaplicin as a lead-like natural product to develop a novel class of inhibitors of histone deacetylase, a validated target in the treatment of cancer. 5,6 Of the 18 HDAC isoforms, 11 are metalloenzymes that use zinc to remove a terminal acetyl group from lysine residues present in histones and other client proteins. The reversible acetylation and hydrolysis of the ε-acetamide in histones is associated with regulation of gene expression. Interestingly, there are a variety of natural products that inhibit HDACs such as trichostatin A (TSA; Figure 1), romidepsin, and trapoxin. Both romidepsin and vorinostat were approved by the FDA for the treatment of cutaneous T-cell lymphoma; the latter possesses a zinc-targeting hydroxamate, similar to TS...

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In this work, spent coffee grounds (SCG) were treated using sulfuric acid hydrolysis in order to isolate the sulfuric acid lignin (SAL). The reactivity of SAL was improved through phenolation and acetylation. Spectroscopic analysis showed that the isolated lignin is composed of GHS type and it was characterized by a high amount of (C–C) and β-O-4 bonds. The thermal analysis showed that the phenolated sulfuric acid lignin (Ph-SAL) present higher thermal stability compared to SAL and acetylated sulfuric acid lignin. In addition, the phenolic hydroxyl group content increases from 2.99 to 9.49 mmol/g after phenolation. Moreover, a methylene blue (MB) adsorption test was established in order to find out the sorption capacity of different samples. The study showed that the adsorbed amount of dye increase after the chemical modification of SAL, especially after phenolation. The removal efficiency was enhanced after modification to reach 99.62% for Ph-SAL. The evaluation of the adsorption experimental data with the theoretical models of Langmuir and Freundlich showed that the best fitting was expressed by the Langmuir model for all samples. Finally, this study showed that lignin isolated from SCG can be simply and easily chemical modified and exhibits excellent adsorption ability towards cationic dyes (MB) in aqueous solutions. As a renewable, low-cost, and natural biomass material, lignin from SCG shows a promising practical and economical application of biomass in the field of wastewater purification.