Search Results (1,088)

Bone is the most frequent site of distant metastasis in advanced prostate cancer (PCa), contributing substantially to patient morbidity and mortality. Hypoxia, a defining feature of the solid tumour microenvironment, plays a pivotal role in driving bone-tropic progression by promoting epithelial-to-mesenchymal transition (EMT), cancer stemness, extracellular matrix (ECM) remodelling, and activation of key signalling pathways such as Wingless/Integrated (Wnt) Wnt/β-catenin and PI3K/Akt. Hypoxia also enhances the secretion of extracellular vesicles (EVs), enriched with pro-metastatic cargos, and upregulates bone-homing molecules including CXCR4, integrins, and PIM kinases, fostering pre-metastatic niche formation and skeletal colonisation. In this review, we analysed current evidence on how hypoxia orchestrates PCa dissemination to bone, focusing on the molecular crosstalk between HIF signalling, Wnt activation, EV-mediated communication, and cellular plasticity. We further explore therapeutic strategies targeting hypoxia-related pathways, such as HIF inhibitors, hypoxia-activated prodrugs, and Wnt antagonists, with an emphasis on overcoming therapy resistance in castration-resistant PCa (CRPC). By examining the mechanistic underpinnings of hypoxia-driven bone metastasis, we highlight promising translational avenues for improving patient outcomes in advanced PCa. Full article

In the preceding and early stages of cancer progression, local drug delivery to pre-cancerous and cancerous skin lesions may be applied as an alternative or supplementary therapy. At present, 5-Fluorouracil, imiquimod, and tirbanibulin creams and ointments have established their place in practice, while several other active pharmaceutical ingredients (APIs) (e.g., calcipotriol, tretinoin, diclofenac) have been repurposed, used off-label, or are currently being investigated in mono- or combined chemotherapies of skin cancers. Apart from them, dozens to hundreds of therapeutics of natural and synthetic origin are proven to possess anti-tumor activity against melanoma, squamous cell carcinoma (SCC), and other skin cancer types in in vitro studies. Their clinical introduction is most often limited by low skin permeability, challenged targeted drug delivery, insufficient chemical stability, non-selective cytotoxicity, or insufficient safety data. A variety of prodrug and nanotechnological approaches, including vesicular systems, micro- and nanoemulsions, solid lipid nanoparticles, nanostructured lipid carriers, polymeric nanoparticles, and others, offer versatile solutions for overcoming the biophysical barrier function of the skin and the undesirable physicochemical nature of some drug molecules. This review aims to present the most significant aspects and latest achievements on the subject. Full article

Background/Objectives: Hepatocellular carcinoma (HCC) is the predominant form of liver cancer and currently is the second-leading cause of cancer-related mortality globally. Current front-line systemic therapies for advanced HCC offer only modest improvements in patient overall survival. HCC is a sexually dimorphic disease, and cancer progression is driven in part by AR activity. Here, we present novel niclosamide pro-drugs for use in advanced HCC based upon niclosamide’s known anti-AR activity and additional anti-cancer pathway efficacy. Methods: Niclosamide analogs were evaluated for their impacts on the AR protein in two HCC cell lines with different AR phenotypes. Amino acid conjugates of niclosamide were developed, and pharmacokinetic (PK) analyses were conducted to determine improvements in clearance and oral exposure. Finally, niclosamide analogs and amino acid conjugates were evaluated in an in vivo model of HCC. Results: Niclosamide analogs maintained anti-AR properties in HCC. Valine-conjugated niclosamide showed improved oral exposure, positioning it as a potential therapeutic in advanced HCC. Conclusions: Valine–niclosamide improves upon niclosamide’s poor solubility and oral bioavailability, increasing its utility for a variety of therapeutic uses. Further study of valine–niclosamide in advanced HCC and in other cancers or diseases is warranted. Full article

Peroxisome proliferator-activated receptor alpha (PPARα) is a key regulator of lipid metabolism, making its agonists valuable therapeutic targets for various diseases, including chronic peripheral neuropathy. Existing PPARα agonists face limitations such as poor selectivity, sub-optimal bioavailability, and safety concerns. We previously demonstrated that A190, a novel, potent, and selective PPARα agonist, effectively alleviates chemotherapy-induced peripheral neuropathy and CFA-induced inflammatory pain as a non-opioid therapeutic agent. However, A190 alone has solubility and permeability issues that limits its oral delivery. To overcome this challenge, in this study, four new-generation ester prodrugs of A190; A190-PD-9 (methyl ester), A190-PD-14 (ethyl ester), A190-PD-154 (isopropyl ester), and A190-PD-60 (cyclic carbonate) were synthesized and evaluated for their enzymatic bioconversion and chemical stability. The lead candidate, A190-PD-60, was further formulated as a microemulsion (A190-PD-60-ME) and optimized via Box–Behnken design. A190-PD-60-ME featured nano-sized droplets (~120 nm), low polydispersity (PDI < 0.3), and high drug loading (>90%) with significant improvement in artificial membrane permeability. Crucially, pharmacokinetic evaluation in rats demonstrated that A190-PD-60-ME reached a 16.6-fold higher Cmax (439 ng/mL) and a 5.9-fold increase in relative oral bioavailability compared with an A190-PD-60 dispersion. These findings support the combined prodrug-microemulsion approach as a promising strategy to overcome oral bioavailability challenges and advance PPARα-targeted therapies. Full article

Cancer has remained one of the leading causes of death worldwide throughout history despite significant advancements in drug development, radiation therapy, and surgery. Traditional chemotherapeutic small molecules are often hindered by narrow therapeutic indices and limited specificity, leading to suboptimal clinical outcomes. On the other hand, more advanced approaches, such as antibody–drug conjugates (ADCs), frequently encounter obstacles, including poor tumor penetration and prohibitive production costs. The tumor-forming and metastatic capacity of cancer further challenges currently available cancer therapies by creating a biochemical milieu known as the tumor microenvironment (TME). Although solid tumor development presents significant obstacles, it also opens new avenues for innovative therapeutic approaches. It is well-documented that as tumors grow beyond 1–2 mm³ in size, they undergo profound changes in their microenvironment, including alterations in oxygen levels, pH, enzymatic activity, surface antigen expression, and the cellular composition of the stroma. These changes create unique opportunities that can be exploited to develop novel and innovative therapeutics. Currently, numerous ADCs, small-molecule–drug conjugates (SMDCs), and prodrugs are being developed to target specific aspects of these microenvironmental changes. In this review, we explore five TME parameters in detail, with a focus on their relevance to specific cancer types, phenotypic identifiers, and preferred methods of therapeutic targeting. Additionally, we examine the chemical moieties available to target these changes, providing a framework for design strategies that exploit the dynamics of the tumor microenvironment. Full article

Gaultherin [methyl salicylate 2-O-β-D-xylopyranosyl-(1→6)-β-D-glucopyranoside] is a natural salicylate found in some plant species belonging primarily to the Ericaceae and Rosaceae families. Biological studies conducted since the beginning of the 21st century have suggested the potential use of gaultherin in treating various diseases related to inflammation and oxidative stress, including rheumatoid arthritis, sciatica, neuralgia, and muscular pain. The accumulated results indicated a targeted range of biological effects, particularly anti-inflammatory, antipyretic, and anti-rheumatic properties associated with reduced adverse outcomes. The molecular mechanisms involve the influence on several signalling pathways, including NF-κB, MAPK, and potentially AMPK, as well as the inhibition of critical pro-inflammatory enzymes, such as COX-2. This inhibition is achieved without affecting the COX-1 isoform, thereby preventing side effects such as bleeding ulcers or intracranial haemorrhage. This overview summarises the current knowledge about pharmacokinetics, molecular mechanisms, pharmacology, and biocompatibility of gaultherin. Additionally, four methods for isolating gaultherin from plant material and its distribution within the plant kingdom were the focal points of review and discussion. The paper also describes significant differences between synthetic aspirin and natural gaultherin in their biological potential and side effects, resulting from their different mechanisms of action. As a prodrug of salicylic acid, gaultherin releases salicylic acid gradually through enzymatic hydrolysis in the gastrointestinal tract. This controlled release minimises direct gastric irritation and accounts for its superior gastrointestinal safety profile compared to aspirin. Unlike aspirin, which irreversibly inhibits COX-1 and can lead to serious side effects with chronic use, gaultherin selectively inhibits COX-2 while sparing COX-1. These properties position gaultherin as a compelling natural alternative for patients requiring long-term anti-inflammatory therapy with reduced risk of gastrointestinal or bleeding complications. Full article

Photodynamic inactivation (aPDI) involves the interaction of three components: non-toxic photosensitizer molecules (PS), low-intensity visible light, and molecular oxygen. This interaction leads to the generation of toxic reactive oxygen species. The present work demonstrated the efficacy of light-induced antimicrobial photodynamic inactivation against Pseudomonas aeruginosa and Pseudomonas putida using 5-aminolevulinic acid (5-ALA) as a prodrug to produce the photosensitizer protoporphyrin IX. The photoeradication efficiency of these pathogens under blue (405 nm; 45 mW cm⁻²) and red (635 nm; 53 mW cm⁻²) light was investigated. Results showed that at least 30 min of blue light irradiation was necessary to achieve a 99.999% reduction of P. aeruginosa, whereas red light was less effective. P. putida exhibited limited susceptibility under similar conditions. To enhance aPDI efficiency, exogenous glucose was added alongside 5-ALA, which significantly increased the photodynamic efficacy—particularly against P. aeruginosa—leading to complete eradication after just 5 min of exposure. Spectroscopic analyses confirmed that glucose increased the levels of protoporphyrin IX, which correlated with enhanced photodynamic efficacy. Furthermore, multiple aPDI exposure reduced key virulence factors, including alkaline protease activity, biofilm formation, and swarming motility (in P. aeruginosa). These findings suggest that 5-ALA-mediated photodynamic inactivation offers a promising strategy to improve efficacy against resistant Gram-negative pathogens. Full article

Depression in cancer survivors is commonly treated with serotonin and norepinephrine reuptake inhibitors (SNRIs), such as venlafaxine. These drugs alleviate depressive symptoms by inhibiting the reuptake of serotonin and norepinephrine. However, a novel approach has emerged with the development of trans-2-phenylcyclopropylamine (PCPA)–drug conjugates that inhibit lysine-specific demethylase 1 (LSD1), which is a biomarker and molecular target for cancer therapy. LSD1 inhibition can effectively suppress cancer cell proliferation. Nuc01 is a novel PCPA–drug conjugate designed as a prodrug of venlafaxine. In vivo studies showed that Nuc01 dose-dependently reduced immobility time in the tail suspension test in mice, outperforming desmethylvenlafaxine. This suggests that Nuc01 may act as a potent triple reuptake inhibitor, potentially offering enhanced efficacy in the treatment of depression. Additionally, in vitro studies demonstrated that Nuc01 effectively occupies the PCPA binding site within LSD1 (IC₅₀ = 530 nm) and inhibits the proliferation of MDA-MB-231 cancer cells (IC₅₀ = 1130 nm). These findings suggest that Nuc01 may function as an LSD1 inhibitor with potential anticancer properties. Collectively, the data indicate that Nuc01 appears to exhibit dual functional characteristics: acting as a triple reuptake inhibitor potentially applicable for depression treatment and as an LSD1 inhibitor demonstrating anticancer potential. Full article

Although it is more than a century since it was first marketed, acetaminophen remains one of the most popular analgesic agents. In addition, acetaminophen has recently been applied to multimodal analgesia in combination with non-steroidal anti-inflammatory drugs, and its consumption significantly increased during the pandemic of coronavirus disease 2019 as well as diclofenac and ibuprofen. However, the detailed mode of analgesic action of acetaminophen is still unclear. In the present study, we comprehensively discuss conventional, recognized, and postulated mechanisms of analgesic acetaminophen and highlight the current mechanistic concepts while comparing with diclofenac and ibuprofen. Acetaminophen inhibits cyclooxygenase with selectivity for cyclooxygenase-2, which is higher than that of ibuprofen but lower than that of diclofenac. In contrast to diclofenac and ibuprofen, however, anti-inflammatory effects of acetaminophen depend on the extracellular conditions of inflamed tissues. Since the discovery of cyclooxygenase-3 in the canine brain, acetaminophen had been hypothesized to inhibit such a cyclooxygenase-1 variant selectively. However, this hypothesis was abandoned because cyclooxygenase-3 was revealed not to be physiologically and clinically relevant to humans. Recent studies suggest that acetaminophen is deacetylated to 4-aminophenol in the liver and after crossing the blood–brain barrier, it is metabolically converted into N-(4-hydroxyphenyl)arachidonoylamide. This metabolite exhibits bioactivities by targeting transient receptor potential vanilloid 1 channel, cannabinoid receptor 1, Cav3.2 calcium channel, anandamide, and cyclooxygenase, mediating acetaminophen analgesia. These targets may be partly associated with diclofenac and ibuprofen. The perspective of acetaminophen as a prodrug will be crucial for a future strategy to develop analgesics with higher tolerability and activity. Full article

Objectives: Colorectal cancer (CRC) is a leading cause of cancer-related mortality, driven by chronic inflammation, gut microbiota dysbiosis, and complex tumor microenvironment interactions. Current therapies are limited by systemic toxicity and poor tumor accumulation. This study aimed to develop a ROS/enzyme dual-responsive oral drug delivery system, KGM-CUR/PSM microspheres, to achieve precise drug release in CRC and enhance tumor-specific drug accumulation, which leverages high ROS levels in CRC and the β-mannanase overexpression in colorectal tissues. Methods: In this study, we synthesized a ROS-responsive prodrug polymer (PSM) by conjugating polyethylene glycol monomethyl ether (mPEG) and mesalazine (MSL) via a thioether bond. CUR was then encapsulated into PSM using thin-film hydration to form tumor microenvironment-responsive micelles (CUR/PSM). Subsequently, konjac glucomannan (KGM) was employed to fabricate KGM-CUR/PSM microspheres, enabling targeted delivery for colorectal cancer therapy. The ROS/enzyme dual-response properties were confirmed through in vitro drug release studies. Cytotoxicity, cellular uptake, and cell migration were assessed in SW480 cells. In vivo efficacy was evaluated in AOM/DSS-induced CRC mice, monitoring tumor growth, inflammatory markers (TNF-α, IL-1β, IL-6, MPO), and gut microbiota composition. Results: In vitro drug release studies demonstrated that KGM-CUR/PSM microspheres exhibited ROS/enzyme-responsive release profiles. CUR/PSM micelles demonstrated significant anti-CRC efficacy in cytotoxicity assays, cellular uptake studies, and cell migration assays. In AOM/DSS-induced CRC mice, KGM-CUR/PSM microspheres significantly improved survival and inhibited CRC tumor growth, and effectively reduced the expression of inflammatory cytokines (TNF-α, IL-1β, IL-6) and myeloperoxidase (MPO). Histopathological and microbiological analyses revealed near-normal colon architecture and microbial diversity in the KGM-CUR/PSM group, confirming the system’s ability to disrupt the “inflammation-microbiota-tumor” axis. Conclusions: The KGM-CUR/PSM microspheres demonstrated a synergistic enhancement of anti-tumor efficacy by inducing apoptosis, alleviating inflammation, and modulating the intestinal microbiota, which offers a promising stimuli-responsive drug delivery system for future clinical treatment of CRC. Full article

Efficient adventitious root formation is crucial for Lavandula angustifolia Mill. propagation. This study evaluated the effects of continuous and short-duration pulse applications (1 min, 1 h, and 1 day) of the auxin dichlorprop (DCP) and its prodrug dichlorprop-2-ethylhexyl ester (DCPE) at varying concentrations on adventitious rooting and callus formation. DCPE generally proved more effective than DCP in promoting rooting, especially at lower concentrations, with continuous application of 0.1 µM DCPE yielding the highest number of adventitious roots. Notably, a brief 1 min pulse of 2.5 µM DCPE induced superior rooting, including high root number and weight, while minimizing callus formation compared to longer exposures. In contrast, 1 h pulse treatments showed a positive correlation between auxin concentration and root number but led to substantial callus development. These findings highlight DCPE’s potential as an efficient auxin source for lavender propagation, likely due to its rapid hydrolysis to active DCP within plant tissues, facilitating systemic distribution. The enhanced rooting achieved with short pulse treatments offers significant implications for optimizing commercial propagation for this economically important aromatic plant. Full article

The emergence of antifungal-resistant Aspergillus fumigatus (A. fumigatus) became a serious public health concern, underscoring the need for new effective antifungal agents. Here, we present a strategy based on the in situ generation of radical species that are toxic to the pathogen. The synthesis of an alkoxyamine linked to a peptide substrate recognized by A. fumigatus-secreted dipeptidyl peptidase is described. Kinetic experiments show a stable prodrug prior to enzymatic activation. Ensuing peptide cleavage and spontaneous homolysis resulted in the generation of a stable nitroxide and a reactive alkyl radical moiety. Next, the exposure of A. fumigatus spores to the prodrug lead to pathogen growth inhibition in a compound concentration-dependent fashion (e.g., 42% inhibition at 10 µg/L). Importantly, the designed alkoxyamine inhibited not only the growth of a clinical voriconazole-susceptible A. fumigatus strain, but also the growth of a strain resistant to this azole. To determine the antifungal importance of the reactive alkyl radical, its substitution with a non-radical structure did not prevent A. fumigatus growth. Furthermore, the introduction of succinic group in the peptide substrate resulted in the loss of alkoxyamine antifungal properties. Our work reports a novel chemical strategy for antifungal therapy against A. fumigatus based on the pathogen enzyme-mediated generation of toxic radicals. Significantly, these findings are timely since they could overcome the emerged resistance to conventional drugs that are known to target defined pathogen biologic mechanisms such as ergosterol synthesis. Full article

Background: Remdesivir (RDV) is a broad-spectrum antiviral prodrug, which is rapidly metabolized in vivo within cells to the pharmacologically active triphosphate metabolite, GS-443902. On the other hand, the dephosphorylated metabolite GS-441524 is the main form detected in plasma. RDV acts against RNA viruses, and it was the first antiviral drug to receive EMA and FDA approval for treating COVID-19. Nevertheless, its intracellular pharmacokinetics in real life are poorly explored, particularly due to technical challenges. Methods: The aim of this study was to validate an HPLC-MS/MS method for the direct quantification of GS-443902 in peripheral blood mononuclear cells (PBMCs) with a chromatographic separation of 15 min. Results: The method was validated following EMA and FDA guidelines in terms of sensitivity, specificity, accuracy, precision, matrix effect, recovery, carryover, and stability, and then applied to PBMC isolates from a small cohort of patients with severe COVID-19 who received RDV. Conclusions: This work represents the first method for the direct quantification of GS-443902 in PBMCs, with possible future application to intracellular pharmacokinetic studies in different scenarios, such as new oral prodrugs or drug–drug interaction studies. Full article

Background: Quercetin is a flavonoid found in various dietary sources. It is a prodrug converted by overexpressed tyrosinase in melanoma into an active o-quinone that suppresses tumour growth. However, injected quercetin is rapidly cleared from the tumour site. Method: Our study aimed to enhance quercetin’s efficacy through nanoencapsulation using biodegradable nanocapsules, which were tested in both mouse and human melanoma cell lines in 2D and 3D models. Results: Nanoencapsulation achieved sustained release and improved bioavailability. In mouse 2D cultures, quercetin nanocapsules (Q-nanos) reduced cell viability to 28%, compared with 46% for free quercetin (Q-only) (p < 0.05). In 3D cultures simulating in vivo conditions, Q-nanos reduced viability to 43%, showing significant anti-melanoma activity, while Q-only resulted in 72% viability (p > 0.05 vs. control). A similar trend was observed in human melanotic melanoma, where both Q-nanos and Q-only were effective compared with the controls, with Q-nanos demonstrating superior tumour inhibition (p < 0.05). Conclusions: These findings show the superior efficacy of nanoencapsulated quercetin over free quercetin. Nanoencapsulation prolonged quercetin’s bioavailability, enhanced tumour regression, and addressed limitations associated with the rapid clearance of free quercetin. Full article

The utilization of platinum complexes in medicine continues to be a prevalent treatment modality for diverse tumour types. However, it should be noted that certain platinum complexes are characterized by a high degree of toxicity. In recent years, there has been a focus among scientists on synthesizing “non-classic” platinum complexes, such as those with a trans-configuration, Pt(IV) complexes, and mixed ammine/amine platinum complexes, with the aim of reducing the toxic side effects of certain platinum complexes, including cisplatin. For instance, newly synthesized platinum complexes with a trans-configuration exhibited substantial cytotoxic activity which was comparable to that of the corresponding cis-isomers and cisplatin. This finding challenged the prevailing cis-geometry paradigm and prompted a re-evaluation of the structural activity relationships (SARs) of antitumour platinum complexes. It is widely accepted that Pt(IV) complexes act as prodrugs and release the active Pt(II) species. This property renders them promising candidates as anticancer drugs. Furthermore, it has been established that mixed ammine/amine platinum complexes are less toxic than cisplatin. In addition, compared to cisplatin, they have been observed to have equivalent or greater cytotoxic activity. Full article