The synthesis of 1,4-naphthoquinone derivatives is of great interest since these compounds exhibit strong activity as antimalarial, antibacterial, antifungal and anticancer agents. A series of 50 naphthoquinone derivatives was synthesized and evaluated for antibacterial and antifungal activity against Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis, Staphylococcus aureus, Candida krusei, Candida parapsilosis and Cryptococcus neoformans using the broth microdilution method. The Candida species were the most susceptible microorganisms. Halogen derivatives of 1,4-naphthoquinone presented strong activity, e.g., 2-bromo-5-hydroxy-1,4-naphthoquinone, which exhibited inhibition at an MIC of 16 µg/mL in S. aureus, and 2-chloro-5,8-dihydroxy-1,4-naphthoquinone, with an MIC of 2 µg/mL in C. krusei. These compounds showed higher activity against fungi, but the antibacterial activities were very low. The study of structure–activity relationships is very important in the search for new antimicrobial drugs due to the limited therapeutic arsenal.

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Synthesis, antibacterial and antifungal activities of naphthoquinone derivatives: a structure–activity relationship study

Synthesis and SAR study of novel anticancer and antimicrobial naphthoquinone amide derivatives

Natural compounds from plants, including essential oils, resins, and biopolymers, possess various biological effects such as antibacterial, antimalarial, antifungal, and antioxidant activity as well as pleasant odor. Their medicinal properties are due to the presence of phenolics, terpenoids, and alkaloids, which are the lead constituents of many pharmacologically active compounds. These benefits can be applied on textiles to prepare various cosmetic or medical products to provide protection, therapeutic, or wellness properties. There is a relationship between the chemical structure of plant-based compounds and their biological function. This chapter provides a review of antimicrobial natural compounds and polymers with detailed discussions about their chemical structures, properties, and applications.

Plant-based compounds for antimicrobial textiles

Twenty-one substituted 1,4-naphthoquinones and five 8-quinolinols and copper(II) chelates were tested for antifungal activity against Candida albicans and Trichophyton mentagrophytes. Compounds con...

Fungitoxicity of 1,4-naphthoquinones to Candida albicans and Trichophyton mentagrophytes.

The palladium-catalyzed efficient cross-couplings of mono-, di- and tetra- bromo-1,4-quinones with triarylbismuth reagents were developed, involving threefold arylation. This first time study which is demonstrated with a wide variety of substrates possesses high synthetic utility and furnished a plethora of arylated 1,4-quinones in a one-pot operation.

Pd-catalyzed threefold arylations of mono, di and tetra-bromoquinones using triarylbismuth reagents

1. New halogenated 1,4-naphthoquinones were synthesized and together with other known 1,4-naphthoquinones, were screened for antibacterial activity by a turbidimetric method, and for antifungal activity by the diffusion method on agar plates.

2. The half-wave potentials and the influence on the oxidative phosphorylation of some of these compounds were determined.

3. 2-chloro-3,2′-chloro-ethyl-1,4-naphthoquinone (half-wave potential=-187 mV) was the most active compound, completely inhibiting cell respiration.

4. While the natural active naphthoquinones, vitamin K and ubiquinones, possess, as substituent, the electron repelling methyl group, the microbiologically active 1,4-naphthoquinones are substituted, in the quinone moiety, with electron attracting groups such as OH or Cl.

5. The half-wave potentials can give only an initial indication of the activity of the compounds studied; a good correlation, on the contrary, can be found between the ultraviolet spectra of such compounds and their activity which seems to depend on the ability of active compounds to exist in an extensively conjugated structure and to form hydrogen bonds.

M. Di Somma

Papers

Studies on the antibacterial and antifungal properties of 1,4-naphthoquinones.