(3,3'-Methylene)bis-2-hydroxy-1,4-naphthoquinones induce cytotoxicity against DU145 and PC3 cancer cells by inhibiting cell viability and promoting cell cycle arrest.

We developed a novel method for the synthesis of bis-naphthoquinones (BNQ), which are hybrids of lawsone (2-hydroxy-1,4-naphthoquinone) and 3-hydroxy-juglone (3,5-dihydroxy-1,4-naphthoquinone). The anticancer activity of three synthesized compounds, named 4 (RC10), 5 (RCDFC), and 6 (RCDOH) was evaluated in vitro against two metastatic prostate cancer (PCa) cell lines, DU145 and PC3, using MTT assays. We found that 4 (RC10) and 5 (RCDFC) induced cytotoxicity against DU145 and PC3 cells. Flow cytometry analysis revealed that these two compounds promoted cell cycle arrest in G1/S and G2/M phases, increased Sub-G1 peak and induced inhibition in cell viability. We also showed that these effects are cell-type context dependent and more selective for these tested PCa cells than for HUVEC non-tumor cells. The two BNQ compounds 4 (RC10) and 5 (RCDFC) displayed promising anticancer activity against the two tested metastatic PCa cell lines, DU145 and PC3. Their effects are mainly associated with inhibition of cell viability, possibly through apoptotic cell death, besides altering the SubG1, G1/S and G2/M phases of cell cycle. 5 (RCDFC) compound was found to be more selective than 4 (RC10), when comparing their cytotoxic effects in relation to HUVEC non-tumoral cells. Future work should also test these compounds in combination with other chemotherapeutic drugs to evaluate their effects on further sensitizing drug-resistant metastatic PCa cells.

Selective and Sensitive Pull Down of Amyloid Fibrils Produced in Vitro and in Vivo by the Use of Pentameric-Thiophene-Coupled Resins.

Protein aggregation is a hallmark of several degenerative diseases, including Alzheimer's disease, Parkinson's disease and familial amyloidosis (Finnish type) (FAF). A method to isolate and detect amyloids is desired for the diagnosis of amyloid diseases. Here, we report the synthesis of pentameric thiophene amyloid ligand (p-FTAA) linked to agarose resin for selective purification of amyloid aggregates produced in vitro and in vivo. Using amyloid fibrils produced in vitro from α-synuclein, gelsolin, and Aß1-40 and gelsolin amyloid aggregates extracted from tissue homogenates of a mouse model of FAF, we observed that p-FTAA resin was able to pull down amyloid aggregates. The functionalized resin was also able to pull down oligomers produced in vitro from the A30P variant of α-synuclein. The methodology described here can be useful for the diagnosis of amyloidogenic disease and also can be used to purify amyloid fibrils from biological samples, rendering the fibrils available for more accurate structural and biochemical characterization.

Antibacterial naphthoquinone derivatives targeting resistant strain Gram-negative bacteria in biofilms.

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.