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14 new naphthoquinones were prepared and tested against human cancer cell lines PC-3 (prostate), HCT-116 (colon carcinoma), SNB-19 (glioblastoma), HL-60 (leukemia) and MCF-7 (breast), and a nontumor cell line L929 (murine fibroblasts) to determine cytotoxicity with the MTT assay. 8-OH-β-lapachones (14a, 14c, 14d) presented best results, showing low IC50 values and high selectivity for HCT-116 and HL-60 tumor cells. [ABSTRACT FROM AUTHOR]

Abstract: Two complementary methodologies involving olefin ring-closing metathesis and Knoevenagel-electrocyclization were utilized for the synthesis of α-xyloidones and fused chromene-1,4-naphthoquinones 5f–n and 6. The latter methodology was performed under acid catalysis or microwave irradiation allowing the synthesis of α-xyloidones 5f–j in moderate to good yield, which could not be obtained via the Knoevenagel-electrocyclization method. On the other hand, the lawsone bis-alkylation (C and O) then RCM olefin enabled the preparation of simple xyloidone 5m–n and the oxepin-1,4-naphthoquinones 6. [Copyright &y& Elsevier]

Chagas disease (CD) still represents a serious public health problem in Latin America, even after more than 100 years of its discovery. Clinical treatments (nifurtimox and benznidazole) are considered inadequate, especially because of undesirable side effects and low efficacy in the chronic stages of the disease, highlighting the urgency for discovering new effective and safe drugs. A small library of compounds (1a–i and 2a–j) was designed based on the structural optimization of a Hit compound derived from 1,4-naphthoquinones (C2) previously identified. The biological activity, structure-activity relationship (SAR), and the in silico physicochemical profiles of the naphthoquinone derivatives were analyzed. Most modifications resulted in increased trypanocidal activity but some substitutions also increased toxicity. The data reinforce the importance of the chlorine atom in the thiophenol benzene ring for trypanocidal activity, highlighting 1g, which exhibit a drug-likeness profile, as a promising compound against Trypanosoma cruzi. SAR analysis also revealed 1g as cliff generator in the structure-activity similarity map (SAS maps). However, compounds C2 and 1g were unable to reduce parasite load, and did not prevent mouse mortality in T. cruzi acute infection. Phenotypic screening and computational analysis have provided relevant information to advance the optimization and design of new 1,4-naphthoquinone derivatives with a better pharmacological profile. [ABSTRACT FROM AUTHOR]

The aims of this study were the planning, synthesis and in vitro evaluation of 2-hydroxy-3-phenylsulfanylmethyl-[1,4]-naphthoquinones against Gram-negative and Gram-positive strains, searching for potential lead compounds against bacterial biofilm formation. A series of 12 new analogs of 2-hydroxy-3-phenylsulfanylmethyl-[1,4]-naphthoquinones were synthesized by adding a thiol and different substituents to a ο -quinone methide using microwave irradiation. The compounds were tested against Gram-positive ( Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 25923, S. simulans ATCC 27851, S. epidermidis ATCC 12228 and a hospital Methicillin-resistant S. aureus (MRSA) strain), as well as Gram-negative ( Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, P. aeruginosa ATCC 15442, Proteus mirabilis ATCC 15290, Serratia marcescens ATCC 14756, Klebsiella pneumoniae ATCC 4352 and Enterobacter cloacae ATCC 23355) strains, using the disk diffusion method. Ten compounds showed activity mainly against Gram-negative strains with a minimal inhibitory concentration (MIC = 4–64 μg/mL) within the Clinical and Laboratory Standards Institute (CLSI) levels. The biofilm inhibition data showed compounds, 9e , 9f , 9j and 9k , are anti-biofilm molecules when used in sub-MIC concentrations against P. aeruginosa ATCC 15442 strain. Compound ( 9j ) inhibited biofilm formation up to 63.4% with a better profile than ciprofloxacin, which is not able to prevent biofilm formation effectively. The reduction of P. aeruginosa ATCC 15442 mature biofilms was also observed for 9e and 9k . The structure modification applied in the series resulted in 12 new naphthoquinones with antimicrobial activity against Gram-negative bacteria strains ( E. coli ATCC 25922, P. aeruginosa ATCC 27853 and ATCC 15442). Four compounds decreased P. aeruginosa biofilm formation effectively. [ABSTRACT FROM AUTHOR]

We report herein a straightforward and efficient one-step reaction to prepare new nor-β-lapachone derivatives tethered with phenylthio groups at position 3 of the furan ring. We have screened the compounds on bloodstream trypomastigotes of Trypanosoma cruzi , the causative agent of Chagas disease, aimed at finding a new prototype with high trypanocidal activity. The new compounds possess a broad range of activity (IC 50 /24 h from 9.2 to 182.7 μM), higher than the original quinone (391.5 μM) and four of them higher than standard drug benznidazole (103.6 μM). The most active was compound 13b (9.2 μM), being 11 times active than benznidazole and the less toxic derivative to heart muscle cells. [ABSTRACT FROM AUTHOR]

Abstract: A series of 36 new phenylsulfanylmethyl[1,4]naphthoquinones (7–42) were synthesized by a three-component reaction that involves lawsone, the appropriate aldehyde and thiols with variable substitution patterns. These reactions involve the in situ generation of o-quinone methides (o-QM) via Knoevenagel condensation and 1,4-nucleophilic addition under conventional heating or microwave irradiation. The new naphthoquinones obtained by this methodology were shown to have moderate to good in vitro antimalarial activity against Plasmodium falciparum (3D7). [Copyright &y& Elsevier]