The Application of Microwaves, Ultrasounds, and Their Combination in the Synthesis of Nitrogen-Containing Bicyclic Heterocycles.

The use of alternative energy sources, such as microwaves (MW) or ultrasounds (US), and their mutual cross-combination have been widely described in the literature in the development of new synthetic methodologies in organic and medicinal chemistry. In this review, our attention is focused on representative examples, reported in the literature in the year range 2013-2023 of selected N-containing bicyclic heterocycles, with the aim to highlight the advantages of microwave- and ultrasound-assisted organic synthesis.

Paracetamol-Galactose Conjugate: A Novel Prodrug for an Old Analgesic Drug.

Paracetamol has been one of the most commonly used and prescribed analgesic drugs for more than a hundred years. Despite being generally well tolerated, it can result in high liver toxicity when administered in specific conditions, such as overdose, or in vulnerable individuals. We have synthesized and characterized a paracetamol galactosylated prodrug (PARgal) with the aim of improving both the pharmacodynamic and pharmacological profile of paracetamol. PARgal shows a range of physicochemical properties, solubility, lipophilicity, and chemical stability at differing physiological pH values and in human serum. PARgal could still be preclinically detected 2 h after administration, meaning that it displays reduced hepatic metabolism compared to paracetamol. In overdose conditions, PARgal has not shown any cytotoxic effect in in vitro analyses performed on human liver cells. Furthermore, when tested in an animal pain model, PARgal demonstrated a sustained analgesic effect up to the 12th hour after oral administration. These findings support the use of galactose as a suitable carrier in the development of prodrugs for analgesic treatment.

Galactosylated Pro-Drug of Ursodeoxycholic Acid: Design, Synthesis, Characterization, and Pharmacological Effects in a Rat Model of Estrogen-Induced Cholestasis.

Ursodeoxycholic acid (UDCA) is considered the first-choice therapy for cholestatic disorders. To enhance solubility and exploit specific transporters in liver, we synthesized a new galactosyl pro-drug of UDCA (UDCAgal). Ethinylestradiol (EE)-induced cholestasis was used to study and compare the effects of UDCAgal with UDCA on bile flow, hepatic canalicular efflux transporter expression, and inflammation. UDCAgal resulted quite stable both at pH 7.4 and 1.2 and regenerated the parent drug after incubation in human plasma. Its solubility, higher than UDCA, was pH- and temperature-independent. UDCAgal displayed a higher cell permeation compared to UDCA in liver HepG2 cells. Moreover, in cholestatic rats, UDCAgal showed a higher potency compared to UDCA in reducing serum biomarkers (AST, ALT, and ALP) and cytokines (TNF-α and IL-1ß). The higher effect of UDCAgal on the increase in bile salt export pump and multidrug resistance-associated protein 2 transcription indicated an improved spillover of bile acids from the liver. UDCAgal showed a reduction in CCL2, as well as TNF-α, IL-1ß, and cyclooxygeanse-2 mRNAs, indicating a reduction in hepatic neutrophil accumulation and inflammation. Moreover, UDCAgal, similarly to UDCA, heightens bile flow and modulates biliary acids secretion. These results indicate that UDCAgal has a potential in the treatment of cholestatic disease.

Aceclofenac-Galactose Conjugate: Design, Synthesis, Characterization, and Pharmacological and Toxicological Evaluations.

Aceclofenac is a popular analgesic, antipyretic, and nonsteroidal anti-inflammatory drug (NSAID) used for prolonged treatment (at least three months) in musculoskeletal disorders. It is characterized by several limitations such as poor water solubility and low oral bioavailability. The main side-effect of aceclofenac, as well as all NSAIDs, is the gastrotoxicity; among other adverse effects, there is the risk of bleeding since aceclofenac reversibly inhibits platelet aggregation. With the aim to reduce these drawbacks, we have designed, synthesized, and characterized, both in vitro and in vivo, an orally administrable pro-drug of aceclofenac (ACEgal). ACEgal was obtained by conjugating carboxyl group with the 6-OH group of d-galactose; its structure was confirmed by X-ray powder diffractometry. The pro-drug was shown to be stable at 37 °C in simulated gastric fluid (SGF-without pepsin, pH = 1.2) and moderately stable in phosphate buffered saline (PBS, pH = 7.4). However, it hydrolyzed in human serum with a half-life ( t1/2) of 36 min, producing aceclofenac. Furthermore, if compared to its parent drug, ACEgal was four-times more soluble in SGF. To predict human intestinal absorption, cell permeability in a Caco-2 model of aceclofenac and ACEgal was determined. Anti-inflammatory, analgesic, and ulcerogenic activities have been investigated in vivo. In addition, oxidative stress parameters (thiobarbituric acid reactive substances, TBARS, and glutathione, GSH) and platelet antiaggregatory activity both of parent drug and pro-drug were evaluated. Results clearly showed that the conjugation of aceclofenac to a galactose molecule improves physicochemical, toxicological (at gastric and blood level), and pharmacological profile of aceclofenac itself without changing intestinal permeability and antiplatelet activity (in spite the new sugar moiety).

Metabolites from invasive pests inhibit mitochondrial complex II: A potential strategy for the treatment of human ovarian carcinoma?

The red pigment caulerpin, a secondary metabolite from the marine invasive green algae Caulerpa cylindracea can be accumulated and transferred along the trophic chain, with detrimental consequences on biodiversity and ecosystem functioning. Despite increasing research efforts to understand how caulerpin modifies fish physiology, little is known on the effects of algal metabolites on mammalian cells. Here we report for the first time the mitochondrial targeting activity of both caulerpin, and its closely related derivative caulerpinic acid, by using as experimental model rat liver mitochondria, a system in which bioenergetics mechanisms are not altered. Mitochondrial function was tested by polarographic and spectrophotometric methods. Both compounds were found to selectively inhibit respiratory complex II activity, while complexes I, III, and IV remained functional. These results led us to hypothesize that both algal metabolites could be used as antitumor agents in cell lines with defects in mitochondrial complex I. Ovarian cancer cisplatin-resistant cells are a good example of cell lines with a defective complex I function on which these molecules seem to have a toxic effect on proliferation. This provided novel insight toward the potential use of metabolites from invasive Caulerpa species for the treatment of human ovarian carcinoma cisplatin-resistant cells.

Galactose: A Versatile Vector Unveiling the Potentials in Drug Delivery, Diagnostics, and Theranostics.

D-galactose, a simple natural compound, has been investigated as a powerful scaffold for drug delivery, diagnostics, and theranostics due to its distinctive properties and interactions with specific cell receptors. In the field of drug delivery, galactose functions as a ligand to selectively target cells expressing galactose receptors, such as hepatocytes, macrophages, and specific cancer cells. The direct attachment of galactose to the main drug or to drug-loaded nanoparticles or liposomes enhances cellular uptake, thereby improving drug delivery to the intended target cells. Galactose has also been found to be useful in diagnostics. Specifically, diagnostic tests based on galactose, such as the galactose elimination capacity test, are utilized to evaluate liver function and assess liver disease as well as hepatic functional reserve. Additionally, galactose-based theranostic agents can be designed by combining drug delivery and diagnostic capabilities. This review is an update of our previous review concerning the broad spectrum of possibilities for exploiting D-galactose as a vector for prodrug design and the synthetic strategies that allow its realization, jointly in diagnostics and theranostics, to highlight the versatility of this interesting vector.

Isothiocyanate-Corticosteroid Conjugates against asthma: Unity makes strength.

Asthma is a major noncommunicable disease, affecting both children and adults, and represents one of the major causes leading to high health care costs due to the need for chronic pharmacological treatments. The standard gold therapy of inflammation in asthmatic patients involves the use of glucocorticoids even if their chronic use is often related to serious adverse effects. Growing evidence suggests the biological relevance of hydrogen sulfide (H2S) in the pathogenesis of airway diseases. Hence, aiming to associate the beneficial effects of steroidal anti-inflammatory drugs (SAIDs) to H2S biological activity, we designed and synthesized novel multi-target molecules by chemically combining a group of glucocorticoids, usually employed in asthma treatment, with an isothiocyanate moiety, well-known for its H2S releasing properties. Firstly, the synthesized compounds have been screened for their H2S-releasing profile using an amperometric approach and for their in vitro effects on the degranulation process, using RBL-2H3 cell line. The physicochemical profile, in terms of solubility, chemical and enzymatic stability of the newly hybrid molecules, has been assessed at different physiological pH values and in esterase-rich medium (bovine serum albumin, BSA). The selected compound 5c, through both its corticosteroid and H2S releasing component, has been evaluated in vivo in experimental model of asthma. The compound 5c inhibited in vivo all asthma features with a significative effect on the restoration of pulmonary structure and reduction of lung inflammation.

Multiple drug-delivery strategies to enhance the pharmacological and toxicological properties of Mefenamic acid.

OBJECTIVE: To improve the biological and toxicological properties of Mefenamic acid (MA), the galactosylated prodrug of MA named MefeGAL was included in polymeric solid dispersions (PSs) composed of poly(glycerol adipate) (PGA) and Pluronic® F68 (MefeGAL-PS). MefeGAL-PS was compared with polymeric solid formulations of MA (MA-PS) or a mixture of equal ratio of MefeGAL/MA (Mix-PS). METHODS: The in vitro and in vivo pharmacological and toxicological profiles of PSs have been investigated. In detail, we evaluated the anti-inflammatory (carrageenan-induced paw edema test), analgesic (acetic acid-induced writhing test) and ulcerogenic activity in mice after oral treatment. Additionally, the antiproliferative activity of PSs was assessed on in vitro models of colorectal and non-small cell lung cancer. RESULTS: When the PSs were resuspended in water, MefeGAL's, MA's and their mixture's apparent solubilities improved due to the interaction with the polymeric formulation. By comparing the in-vivo biological performance of MefeGAL-PS with that of MA, MefeGAL and MA-PS, it was seen that MefeGAL-PS exhibited the same sustained and delayed analgesic and anti-inflammatory profile as MefeGAL but did not cause gastrointestinal irritation. The pharmacological effect of Mix-PS was present from the first hours after administration, lasting about 44 hours with only slight gastric mucosa irritation. In-vitro evaluation indicated that Mix-PS had statistically significant higher cytotoxicity than MA-PS and MefeGAL-PS. CONCLUSIONS: These preliminary data are promising evidence that the galactosylated prodrug approach in tandem with a polymer-drug solid dispersion formulation strategy could represent a new drug delivery route to improve the solubility and biological activity of NSAIDs.

Quantitative determination of BPA, BPB, BPF and BPS levels in canned legumes from Italian market.

The levels of bisphenol A (BPA), bisphenol B (BPB), bisphenol F (BPF) and bisphenol S (BPS) were monitored in twenty-three samples of canned legumes from popular brands marketed in Italy. BPB, BPS and BPF were not detected in any samples, while BPA was found in 91 % of the samples in the concentration range 1.51-21.22 ng/mL. The risk associated with the human exposure to BPA was categorized using the Rapid Assessment of Contaminant Exposure (RACE) tool promoted by the European Food Safety Authority (EFSA). The results showed that there is no risk for any of the population groups when the current TDI value for BPA of 4 µg/kg bw/day was used as toxicological reference point. In contrast, using the new TDI value for BPA of 0.04 ng/kg bw/day, proposed by EFSA in December 2021, the existing risk was found to be real for all population groups.

Cross-reactivity of commercial immunoassays for screening of new amphetamine designer drugs. A review.

The chemical modification of the molecular structure of psychoactive substances is a very common practice in the illicit drugs market, to by-pass current regulations; this lead to the production of compounds, known as "designer drugs", with the same or greater pharmacological effects of the parent drug. The phenomenon is also favored by the fact that the new synthetic compounds are not considered illegal by existing legislation. Amphetamine derivatives represent one of the largest classes of designer drugs. Generally, in toxicological laboratories, rapid screening tests are used for a first monitoring of drugs abuse. However, the available immunoassays for this class of substances are designed for amphetamine, methamphetamine and methylenedioxymethamphetamine, and generally they are unable to detect various amphetamine analogues. This can constitute a disadvantage because it can generate a great number of false-negative results. The present review aims to provide an overview of the cross-reactivity studies carried out on commercially available immunoassays to identify the presence of amphetamine derivatives in biological samples. The knowledge of cross-reactivity data makes it easier to interpret analytical results by demonstrating that a negative result does not always indicate the non-consumption of an amphetamine derivative. This review highlights the great need for more comprehensive screening immunoassays to use when analyzing biological matrices for drugs of abuse search, specifically for the more recent designer drugs..

Quantitative Determination of Bisphenol A and Its Congeners in Plant-Based Beverages by Liquid Chromatography Coupled to Tandem Mass Spectrometry.

The consumption of plant-based beverages as an alternative to cow's milk has recently gained vast attention worldwide. The aim of this work is to monitor the intake of Bisphenol A (BPA), Bisphenol B (BPB) and Bisphenol S (BPS) in the Italian population through the consumption of these foodstuffs. Specifically, the development and validation of an analytical procedure for the quantitative determination of the analytes by liquid chromatography coupled to tandem mass spectrometry was reported. Thirty-four samples of plant-based beverages (soya, coconut, almond, oats and rice) of popular brands marketed in Italy were analyzed. BPA was found in 32% of the samples, while BPB was found in 3% of the samples. The risk assessment using the Rapid Assessment of Contaminant Exposure (RACE) tool demonstrated that there was no risk for all population groups, when using the current Tolerable Daily Intake (TDI) of 4 ng/kg body weight (bw)/day as a toxicological reference point. In contrast, using the new temporary TDI of 0.04 ng/kg bw/day, the existing risk was found to be real for all population groups. If this value were to become final, even more attention would have to be paid to the possible presence of BPA in food to protect consumer health.

Galactosylated Prodrugs: A Strategy to Improve the Profile of Nonsteroidal Anti-Inflammatory Drugs.

Carbohydrates are one of the most abundant and important classes of biomolecules. The variety in their structures makes them valuable carriers that can improve the pharmaceutical phase, pharmacokinetics and pharmacodynamics of well-known drugs. D-galactose is a simple, naturally occurring monosaccharide sugar that has been extensively studied for use as a carrier and has proven to be valuable in this role. With the aim of validating the galactose-prodrug approach, we have investigated the galactosylated prodrugs ibuprofen, ketoprofen, flurbiprofen and indomethacin, which we have named IbuGAL, OkyGAL, FluGAL and IndoGAL, respectively. Their physicochemical profiles in terms of lipophilicity, solubility and chemical stability have been evaluated at different physiological pH values, as have human serum stability and serum protein binding. Ex vivo intestinal permeation experiments were performed to provide preliminary insights into the oral bioavailability of the galactosylated prodrugs. Finally, their anti-inflammatory, analgesic and ulcerogenic activities were investigated in vivo in mice after oral treatment. The present results, taken together with those of previous studies, undoubtedly validate the galactosylated prodrug strategy as a problem-solving technique that can overcome the disadvantages of NSAIDs.

H2S donating corticosteroids: Design, synthesis and biological evaluation in a murine model of asthma.

Introduction: Hydrogen sulfide (H2S) is a fundamental biological endogenous gas-mediator in the respiratory system. It regulates pivotal patho-physiological processes such as oxidative stress, pulmonary circulation, airway tone and inflammation. Objectives: We herein describe the design and synthesis of molecular hybrids obtained by the condensation of several corticosteroids with different hydrogen sulfide releasing moieties. Methods: All the molecules are characterized for their ability to release H2S both via amperometric approach and using a fluorescent probe. The chemical stability of the newly synthesized hybrid molecules has been investigated at differing pH values and in human serum. Results: Prednisone-TBZ hybrid (compound 7) was selected for further evaluations. The obtained results from the in vitro and in vivo studies clearly show evidence in favor of the anti-inflammatory properties of the released H2S. Conclusions: The protective effect on airway remodeling makes the hybrid Prednisone-TBZ (compound 7) as a promising therapeutic option in reducing allergic asthma symptoms and exacerbations.

Ketogal Safety Profile in Human Primary Colonic Epithelial Cells and in Mice.

In our previous studies, a ketorolac-galactose conjugate (ketogal) showed prolonged anti-inflammatory and analgesic activity, causing less gastric ulcerogenic effect and renal toxicity than its parent drug ketorolac. In order to demonstrate the safer profile of ketogal compared to ketorolac, histopathological changes in the small intestine and liver using three staining techniques before and after repeated oral administration in mice with ketorolac or an equimolecular dose of its galactosylated prodrug ketogal were assessed. Cytotoxicity and oxidative stress parameters were evaluated and compared in ketorolac- and ketogal-treated Human Primary Colonic Epithelial cells at different concentrations and incubation times. Evidence of mitochondrial oxidative stress was found after ketorolac treatment; this was attributable to altered mitochondrial membrane depolarization and oxidative stress parameters. No mitochondrial damage was observed after ketogal treatment. In ketorolac-treated mice, severe subepithelial vacuolation and erosion with inflammatory infiltrates and edematous area in the intestinal tissues were noted, as well as alterations in sinusoidal spaces and hepatocytes with foamy cytoplasm. In contrast, treatment with ketogal provided a significant improvement in the morphology of both organs. The prodrug clearly demonstrated a safer profile than its parent drug both in vitro and ex vivo, confirming that ketogal is a strategic alternative to ketorolac.

Galactosyl derivative of N(omega)-nitro-L-arginine: study of antiproliferative activity on human thyroid follicular carcinoma cells.

The methyl ester prodrug of N(omega)-nitro-L-arginine (L-NAME) has been reported to exert anticancer effects against several human tumors, including thyroid carcinoma, by inhibiting nitric oxide synthase (NOS). However, chronic administration of L-NAME has often led to adverse events causing cardiovascular alterations due to its potential toxic effect. Here we report for the first time the synthesis of the galactosyl ester prodrug of N(omega)-nitro-L-arginine, NAGAL, a prodrug capable of inhibiting NOS more efficiently and with fewer adverse events than its parent drug. For this purpose RO82-W-1, a thyroid cell line derived from human follicular carcinoma, was used. MTT test results showed that NAGAL affected cell viability to a significantly greater extent than did L-NAME. Moreover, fluorescence activated cell sorter (FACS) analyses revealed that NAGAL, compared to L-NAME, was able to reduce nitric oxide (NO) production as well as increase the percentage of apoptotic thyreocytes. Western blot further confirmed the reduction in NOS-II expression by NAGAL. Finally, by using the LC-MS technique, we found that NAGAL elicited a higher increase in N(omega)-nitro-L-arginine (NA) concentration than did L-NAME. Thus, this study suggests that NAGAL could be considered a potential therapeutic tool for those pathologies involving an overproduction of NO, including thyroid carcinoma.

T-type channel blocking properties and antiabsence activity of two imidazo[1,2-b]pyridazine derivatives structurally related to indomethacin.

It is presently unclear whether the antiseizure effects exerted by NSAIDs are totally dependent on COX inhibition or not. To clarify this point we investigated whether 7-methyl-2-phenylimidazo[1,2-b]pyridazine-3-carboxylic acid (DM1) and 6-methoxy-2-phenylimidazo[1,2-b]pyridazine-3-carboxylic acid (DM2), two imidazo[1,2-b]pyridazines structurally related to indomethacin (IDM) but ineffective in blocking COXs, retain IDM antiabsence activity. When administered by intraperitoneal injection in WAG/Rij rats, a rat strain which spontaneously develops SWDs, both DM1 and DM2 dose-dependently suppressed the occurrence of these seizures. Importantly, these compounds were both more potent in suppressing SWD occurrence than IDM. As T-type channel blockade is considered a mechanism of action common to many antiabsence drugs we explored by whole cell patch clamp electrophysiology in stably transfected HEK-293 the effect of DM1 and DM2 on Ca(V)3.1 channels, the T-type channel subtype preferentially expressed in ventrobasal thalamic nuclei. Both these compounds dose-dependently suppressed the currents elicited by membrane depolarization in these cells. A similar T-type blocking effect was also observed when the cells were exposed to IDM. In conclusion, DM1 and DM2 whilst inactive on COXs, are potent antiabsence drugs. This suggests that compounds with structural features typical of NSAIDs may exert antiepileptic activity independently from COX inhibition and possibly by a direct interaction with T-type voltage-dependent Ca(2+) channels.

Chitosan/TPP and chitosan/TPP-hyaluronic acid nanoparticles: systematic optimisation of the preparative process and preliminary biological evaluation.

PURPOSE: Chitosan is one of the most sought-after components for designing nanoparticles for drug delivery applications. However, despite the large number of studies, reproducibility is often an issue; generally more attention should be focused on purity and precise characterization of the starting material, as well as on the development of robust preparative procedures. METHODS: Using a rational experimental design, we have studied the influence of a number of orthogonal factors (pH, concentrations, ratios of components, different methods of mixing) in the preparation of chitosan/triphosphate (TPP) nanoparticles and in their coating with hyaluronic acid (HA), aiming at the minimisation of size polydispersity, the maximisation of zeta potential and long-term stability, and at the control over average nanoparticle size. RESULTS AND CONCLUSION: Three optimised nanoparticles have been developed (two uncoated and one HA-coated) and their toxicity on fibroblasts and macrophages has been evaluated: experiments showed the beneficial character of HA-coating in the reduction of toxicity (IC50 raised from 0.7-0.8 mg/mL to 1.8 mg/mL) and suggested that the uncoated chitosan/TPP nanoparticles had toxic effects following internalisation rather than membrane disruption.

A method to determine BPA, BPB, and BPF levels in fruit juices by liquid chromatography coupled to tandem mass spectrometry.

The monitoring of the contamination levels of bisphenol A (BPA) and its congeners bisphenol B (BPB) and bisphenol F (BPF) in foodstuffs is a necessary process for assessment of consumers' risk. After development and validation of a method using Strata® C18-E cartridge cleanup with detection by liquid chromatography coupled to tandem mass spectrometry, forty-six samples of fruit juices, sold on Italian markets, have been analysed to assess the concentration of BPA, BPB and BPF. BPB and BPF were not detected in any samples, BPA was found in 33 % of the samples. The observed levels ranged from 0.50 ng mL-1 to 2.85 ng mL-1. Potential Daily Intakes (PDI) of BPA for Italian populations were calculated by the budget method model. PDIs ranged from 0.012 to 0.285 µg kg-1 bw day-1. None of the calculated values exceeded the current temporary TDI of 4 µg kg-1 bw day-1.

Galactosyl derivatives of L-arginine and D-arginine: synthesis, stability, cell permeation, and nitric oxide production in pituitary GH3 cells.

Nitric oxide (NO) is critical for the normal physiological regulation of the nervous system and other tissues. L-Arginine, but not D-arginine, is the natural substrate for nitric oxide synthase (NOS), for it is enzymatically converted to NO and L-citrulline. However, recent evidence suggests that D-arginine can also produce NO and NO-derivatives via a different pathway. The aim of the present paper was to raise NO levels in the cells by increasing the cell permeation of its precursors. To this aim, two galactosyl prodrugs, L-arginine-D-galactos-6'-yl ester (L-ArgGal) and D-arginine-D-galactos-6'-yl ester (D-ArgGal) were synthesized. Remarkably, using the HPLC-ESI/MS technique, we found that L-ArgGal and D-ArgGal prodrugs both increased the concentration levels of L- and D-arginine and their derivatives in pituitary GH3 cells. Furthermore, we found that D-ArgGal (1) penetrated cell membranes more rapidly than its precursor D-arginine, (2) released arginine more slowly and in greater amounts than L-ArgGal, and (3) produced much higher levels of DAF-2 monitored NO and nitrite than did L-ArgGal under the same experimental conditions. In conclusion, these results indicate that an increase in the cell permeation of L- and D-arginine by L-ArgGal and D-ArgGal can lead to an increase in NO levels.

2-(Benzimidazol-2-yl)quinoxalines: a novel class of selective antagonists at human A(1) and A(3) adenosine receptors designed by 3D database searching.

The Cambridge Structural Database (CSD) was searched through two 3D queries based on substructures shared by well-known antagonists at the A(1) and A(3) adenosine receptors (ARs). Among the resulting 557 hits found in the CSD, we selected five compounds to purchase, synthesize, or translate synthetically into analogues better tailored to interact with the biological targets. Binding experiments using human ARs showed that four out of five tested compounds turned out to be antagonists at the A(1)AR or A(3)AR with K(i) values between 50 and 440 nM. Lead optimizations of 2-(benzimidazol-2-yl)quinoxalines (BIQs, 3) gave the best results in terms of potency and selectivity at the A(1) and A(3) ARs. Particularly, 2-(4-ethylthiobenzimidazol-2-yl)quinoxaline (3e) exhibited K(i) values at the A(1)AR, A(2A)AR, and A(3)AR of 0.5, 3440, and 955 nM, respectively, whereas 2-(4-methylbenzimidazol-2-yl)quinoxaline (3b) displayed at the same ARs K(i) values of 8000, 833, and 26 nM, respectively.