Biofilm formation significantly contributes to microbial survival in hostile environments and it is currently considered a key virulence factor for pathogens responsible for serious chronic ...infections. In the last decade many efforts have been made to identify new agents able to modulate bacterial biofilm life cycle, and many compounds have shown interesting activities in inhibiting biofilm formation or in dispersing pre-formed biofilms. However, only a few of these compounds were tested using in vivo models for their clinical significance.
Contrary to conventional antibiotics, most of the anti-biofilm compounds act as anti-virulence agents as they do not affect bacterial growth.
In this review we selected the most relevant literature of the last decade, focusing on the development of synthetic small molecules able to prevent bacterial biofilm formation or to eradicate pre-existing biofilms of clinically relevant Gram-positive and Gram-negative pathogens.
In addition, we provide a comprehensive list of the possible targets to counteract biofilm formation and development, as well as a detailed discussion the advantages and disadvantages of the different current biofilm-targeting strategies.
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•Biofilm formation significantly contributes to microbial survival.•Most of the anti-biofilm compounds act as anti-virulence agents.•Disabling quorum-sensing system is a potential therapeutic strategy to prevent bacterial pathogenicity.•Second messenger are key mediators of biofilm formation.•SrtA plays a critical role in Gram-positive bacterial pathogenesis.
Methicillin‐resistant Staphylococcus aureus (MRSA) has emerged as one of the leading causes of persistent human infections. This pathogen is widespread and is able to colonize asymptomatically about ...a third of the population, causing moderate to severe infections. It is currently considered the most common cause of nosocomial infections and one of the main causes of death in hospitalized patients. Due to its high morbidity and mortality rate and its ability to resist most antibiotics on the market, it has been termed a “superbug”. Its ability to form biofilms on biotic and abiotic surfaces seems to be the primarily means of MRSA antibiotic resistance and pervasiveness. Importantly, more than 80 % of bacterial infections are biofilm‐mediated. Biofilm formation on indwelling catheters, prosthetic devices and implants is recognized as the cause of serious chronic infections in hospital environments. In this review we discuss the most relevant literature of the last five years concerning the development of synthetic small molecules able to inhibit biofilm formation or to eradicate or disperse pre‐formed biofilms in the fight against MRSA diseases. The aim is to provide guidelines for the development of new anti‐virulence strategies based on the knowledge so far acquired, and, to identify the main flaws of this research field, which have hindered the generation of new market‐approved anti‐MRSA drugs that are able to act against biofilm‐associated infections
Various steps involved in methicillin‐resistant Staphylococcus aureus (MRSA) biofilm production can be considered valuable targets for the development of new anti‐virulence strategies. Herein we discuss efforts over the past five years to develop small‐molecule inhibitors of biofilm formation in the fight against MRSA. The aim is to provide guidelines for the development of new anti‐virulence strategies based on the knowledge so far acquired and to identify aspects that have hindered the generation of new drugs that are able to act against biofilm‐associated infections.
Infectious diseases caused by antimicrobial-resistant strains have become a serious threat to global health, with a high social and economic impact. Multi-resistant bacteria exhibit various ...mechanisms at both the cellular and microbial community levels. Among the different strategies proposed to fight antibiotic resistance, we reckon that the inhibition of bacterial adhesion to host surfaces represents one of the most valid approaches, since it hampers bacterial virulence without affecting cell viability. Many different structures and biomolecules involved in the adhesion of Gram-positive and Gram-negative pathogens can be considered valuable targets for the development of promising tools to enrich our arsenal against pathogens.
Anti-virulence strategy is currently considered a promising approach to overcome the global threat of the antibiotic resistance. Among different bacterial virulence factors, the biofilm formation is ...recognized as one of the most relevant. Considering the high and growing percentage of multi-drug resistant infections that are biofilm-mediated, new therapeutic agents capable of counteracting the formation of biofilms are urgently required. In this scenario, a new series of 18 thiazole derivatives was efficiently synthesized and evaluated for its ability to inhibit biofilm formation against the Gram-positive bacterial reference strains
ATCC 25923 and
ATCC 6538 and the Gram-negative strain
ATCC 15442. Most of the new compounds showed a marked selectivity against the Gram-positive strains. Remarkably, five compounds exhibited BIC
values against
ATCC 25923 ranging from 1.0 to 9.1 µM. The new compounds, affecting the biofilm formation without any interference on microbial growth, can be considered promising lead compounds for the development of a new class of anti-virulence agents.
New analogs of nortopsentin, a natural 2,4-bis(3'-indolyl)imidazole alkaloid, in which the central imidazole ring of the natural lead was replaced by a 1,2,4-oxadiazole moiety, and in which a ...7-azaindole portion substituted the original indole moiety, were efficiently synthesized. Among all derivatives, prescreened against the HCT-116 colon rectal carcinoma cell line, the two most active compounds were selected and further investigated in different human tumor cells showing IC
values in the micromolar and submicromolar range. Flow cytometric analysis of propidium iodide-stained MCF-7 cells demonstrated that both the active derivatives caused cell cycle arrest in the G0⁻G1 phase. The cell death mechanism induced by the compounds was considered to be apoptotic by measuring the exposure of phosphatidylserine to the outer membrane and observed morphological evaluation using acridine orange/ethidium bromide double staining. Moreover, further tested on intestinal normal-like differentiated Caco-2 cell line, they exhibited preferential toxicity towards cancer cells.
Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal form of cancer characterized by drug resistance, urging new therapeutic strategies. In recent years, protein kinases have emerged as ...promising pharmacological targets for the treatment of several solid and hematological tumors. Interestingly, cyclin-dependent kinase 1 (CDK1) is overexpressed in PDAC tissues and has been correlated to the aggressive nature of these tumors because of its key role in cell cycle progression and resistance to the induction of apoptosis. For these reasons, CDK1 is one of the main causes of chemoresistance, representing a promising pharmacological target. In this study, we report the synthesis of new 1,2,4-oxadiazole compounds and evaluate their ability to inhibit the cell growth of PATU-T, Hs766T, and HPAF-II cell lines and a primary PDAC cell culture (PDAC3). Compound
was the most active compound, with IC
values ranging from 5.7 to 10.7 µM. Molecular docking of
into the active site of CDK1 showed the ability of the compound to interact effectively with the adenosine triphosphate binding pocket. Therefore, we assessed its ability to induce apoptosis (which increased 1.5- and 2-fold in PATU-T and PDAC3 cells, respectively) and to inhibit CDK1 expression, which was reduced to 45% in Hs766T. Lastly, compound
passed the ADME prediction, showing good pharmacokinetic parameters. These data demonstrate that
displays cytotoxic activity, induces apoptosis, and targets CDK1, supporting further studies for the development of similar compounds against PDAC.
Pyruvate dehydrogenase kinases (PDKs) are serine/threonine kinases, that are directly involved in altered cancer cell metabolism, resulting in cancer aggressiveness and resistance. Dichloroacetic ...acid (DCA) is the first PDK inhibitor that has entered phase II clinical; however, several side effects associated with weak anticancer activity and excessive drug dose (100 mg/kg) have led to its limitation in clinical application. Building upon a molecular hybridization approach, a small library of 3-amino-1,2,4-triazine derivatives has been designed, synthesized, and characterized for their PDK inhibitory activity using in silico, in vitro, and in vivo assays. Biochemical screenings showed that all synthesized compounds are potent and subtype-selective inhibitors of PDK. Accordingly, molecular modeling studies revealed that a lot of ligands can be properly placed inside the ATP-binding site of PDK1. Interestingly, 2D and 3D cell studies revealed their ability to induce cancer cell death at low micromolar doses, being extremely effective against human pancreatic KRAS mutated cancer cells. Cellular mechanistic studies confirm their ability to hamper the PDK/PDH axis, thus leading to metabolic/redox cellular impairment, and to ultimately trigger apoptotic cancer cell death. Remarkably, preliminary in vivo studies performed on a highly aggressive and metastatic Kras-mutant solid tumor model confirm the ability of the most representative compound
to target the PDH/PDK axis in vivo and highlighted its equal efficacy and better tolerability profile with respect to those elicited by the reference FDA approved drugs, cisplatin and gemcitabine. Collectively, the data highlights the promising anticancer potential of these novel PDK-targeting derivatives toward obtaining clinical candidates for combatting highly aggressive KRAS-mutant pancreatic ductal adenocarcinomas.
A new series of imidazo2,1-b1,3,4thiadiazole derivatives was efficiently synthesized and screened for their in vitro antiproliferative activity on a panel of pancreatic ductal adenocarcinoma (PDAC) ...cells, including SUIT-2, Capan-1 and Panc-1. Compounds 9c and 9l, showed relevant in vitro antiproliferative activity on all three pre-clinical models with half maximal inhibitory concentration (IC50) ranging from 5.11 to 10.8 µM, while the compounds 9e and 9n were active in at least one cell line. In addition, compound 9c significantly inhibited the migration rate of SUIT-2 and Capan-1 cells in the scratch wound-healing assay. In conclusion, our results will support further studies to increase the library of imidazo 2,1-b1,3,4 thiadiazole derivatives for deeper understanding of the relationship between biological activity of the compounds and their structures in the development of new antitumor compounds against pancreatic diseases.
The marine environment is an excellent source of molecules that have a wide structural diversity and a variety of biological activities. Many marine natural products (MNPs) have been established as ...leads for anticancer drug discovery. Most of these compounds are alkaloids, including several chemical subclasses. In this review, we focus on the bis-indolyl alkaloid Nortopsentins and their derivatives with antiproliferative properties. Nortopsentins A–C were found to exhibit in vitro cytotoxicity against the P388 murine leukaemia cell line. Their structural manipulation provided a wide range of derivatives with significant anti-tumour activity against human cell lines derived from different cancer types (bladder, colon, gastric, CNS, liver, lung, breast, melanoma, ovarian, pancreatic, prostate, pleural mesothelioma, renal, sarcoma, and uterus). In vivo assays on animal models also proved that Nortopsentins and related bis-indolyl compounds have potent anti-inflammatory activity. These remarks set the foundation for future investigations into the development of new Nortopsentin derivatives as new anticancer and anti-inflammatory agents.
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