Discovery of Novel Allopurinol Derivatives with Anticancer Activity and Attenuated Xanthine Oxidase Inhibition

Hydrotrope assisted green synthesis of dicoumarols and in silico and in vitro antibacterial, antioxidant and xanthine oxidase inhibition studies

Aqueous hydrotrope has been employed for the first time to synthesize heteroaryl dicoumarols by condensation of 4-hydroxycoumarin and different heterocyclic aldehydes. This method is highly efficient and green, and the same aqueous hydrotropic solution can be used up to five times without any considerable loss of yield in the product. The synthesized compounds showed good antibacterial potential against Gram-positive (Staphylococcus aureus/NTCC 0997 and B. oceanisediminis) and Gram-negative (Escherichia coli/D0157:H7 and E. coli rosetta) bacterial strains using the Resazurin microtiter plate visual method. The MIC value of 312 µg/ml for compounds 3b, 3k and 3l for S. aureus while 39 µg/ml for compounds 3a, 3b and 3k for E. coli and 625 µg/ml for 3a and 3b for B. oceanisediminis was observed. The compounds were screened via computational methods like molecular docking studies and molecular dynamic simulations with PDB Id's 2W9S and 2EX6. Antioxidant activity was assessed using DPPH and H2O2 assays. Five compounds with the best binding score in molecular docking with XO (PDB ID: 1FIQ) have been tested in an in-vitro study using an enzyme inhibition assay. Novel compound 3b gave the IC50 value of 0.28 µg/ml, comparable to the standard drug Allopurinol.Communicated by Ramaswamy H. Sarma.

Friend or Foe? An Unrecognized Role of Uric Acid in Cancer Development and the Potential Anticancer Effects of Uric Acid-lowering Drugs

In recent years, metabolic syndrome (Mets) has been a hot topic among medical scientists. Mets has an intimate relationship with the incidence and development of various cancers. As a contributory factor of Mets, hyperuricemia actually plays an inseparable role in the formation of various metabolic disorders. Although uric acid is classically considered an antioxidant with beneficial effects, mounting evidence indicates that a high serum uric acid (SUA) level may serve as a pro-oxidant to generate inflammatory reactions and oxidative stress. In this review, we describe the unrecognized role of hyperuricemia in cancer development and summarize major mechanisms linking uric acid to carcinogenesis. Furthermore, we also discuss the potential mechanism of liver metastasis of cancer and list some types of uric acid-lowering agents, which may exert anticancer effects.

High Serum Uric Acid Levels Could Be a Risk Factor of Hepatocellular Carcinoma Recurrences

BACKGROUND

The Apolipoprotein-related MORtality RISk (AMORIS) study in Sweden revealed that serum uric acid (SUA) was significantly associated with hepatobiliary cancer occurrence. However, the association with postoperative hepatocellular carcinoma (HCC) recurrence has not been reported.

METHODS

A total of 256 surgically resected HCC patients were included (from January 2003 to December 2017) in this study. Comparisons in terms of clinicopathologic factors and long-term outcomes were made between patients with high SUA (>6.1 mg/dl) at the time of hepatectomy and low SUA. Besides, SUA data at one postoperative year (1POY) of the same cohort were collected and analyzed in the same manner.

RESULTS

About 88.8% of tumor relapse sites were the remnant liver. High SUA levels were associated with male and well-differentiated HCCs. Recurrence-free survival (RFS) of high SUA patients was significantly inferior to low SUA patients [median survival time (MST): 22.7 vs. 28.5 mo, P = 0.033], whereas no difference was observed in overall survival (MST: both not reached, P = 0.771). RFS of high SUA patients at 1POY also showed significantly poorer outcomes than low SUA patients (MST: 29.3 vs. 57.0 mo, P = 0.049).

CONCLUSIONS

High SUA implies a significant risk factor of activating hepatocarcinogenesis. Keeping the SUA level low may be recommended after HCC resections.

From Xanthine Oxidase Inhibition to In Vivo Hypouricemic Effect: An Integrated Overview of In Vitro and In Vivo Studies with Focus on Natural Molecules and Analogues

Hyperuricemia is characterized by elevated uric acid (UA) levels on blood, which can lead to gout, a common pathology. These high UA levels are associated with increased purine ingestion and metabolization and/or its decreased excretion. In this field, xanthine oxidase (XO), by converting hypoxanthine and xanthine to UA, plays an important role in hyperuricemia control. Based on limitations and adverse effects associated with the use of allopurinol and febuxostat, the most known approved drugs with XO inhibitory effect, the search for new molecules with XO activity is growing. However, despite the high number of studies, it was found that the majority of tested products with relevant XO inhibition were left out, and no further pharmacological evaluation was performed. Thus, in the present review, available information published in the past six years concerning isolated molecules with in vitro XO inhibition complemented with cytotoxicity evaluation as well as other relevant studies, including in vivo hypouricemic effect, and pharmacokinetic/pharmacodynamic profile was compiled. Interestingly, the analysis of data collected demonstrated that molecules from natural sources or their mimetics and semisynthetic derivatives constitute the majority of compounds being explored at the moment by means of in vitro and in vivo animal studies. Therefore, several of these molecules can be useful as lead compounds and some of them can even have the potential to be considered in the future clinical candidates for the treatment of hyperuricemia.

Combination Therapy of Allopurinol and Dantrolene and Its Role In The Prevention of Experimental Ischemia Reperfusion Injury Of The Small Intestine

BACKGROUND

The effect of different drugs on ischemia and reperfusion (I/R; induced oxygen free radical damage) was examined in small bowel tissue because the intestine is extremely sensitive to this pathology. Different drugs (allopurinol and dantrolene) can remove oxygen free radicals or inhibit the mechanisms leading to their generation, thus reducing mucosal lesions. We investigated the protective potential of combination therapy in the intestine against I/R damage.

METHODS

Forty-eight male Wistar rats were separated into 8 groups: one sham (control), one I/R (ischemia 60 min + reperfusion at 24 h), and 6 groups treated with allopurinol, dantrolene, or combination therapy. The grade of injury in the small bowel was established by the lipid peroxidation (MDA) and antioxidant enzymatic activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in tissue samples. Moreover, the collected samples were subjected to histological study.

RESULTS

Combination therapy preserved normal enzymatic levels compared to the I/R groups (p < 0.05) for all parameters studied. The animals treated with combination therapy showed less severe small bowel damage than I/R group in accordance with the histological results.

CONCLUSIONS

Results obtained in the experimental process indicate that the administration of antioxidants protects against intestinal damage by I/R. Overall, combination therapy may protect intestinal tissue from I/R injury.

Neuroprotection with hypothermia and allopurinol in an animal model of hypoxic-ischemic injury: Is it a gender question?

BACKGROUND

Hypoxic-ischemic encephalopathy (HIE) is one of the most important causes of neonatal brain injury. Therapeutic hypothermia (TH) is the standard treatment for term newborns after perinatal hypoxic ischemic injury (HI). Despite this, TH does not provide complete neuroprotection. Allopurinol seems to be a good neuroprotector in several animal studies, but it has never been tested in combination with hypothermia. Clinical findings show that male infants with (HI) fare more poorly than matched females in cognitive outcomes. However, there are few studies about neuroprotection taking gender into account in the results. The aim of the present study was to evaluate the potential additive neuroprotective effect of allopurinol when administrated in association with TH in a rodent model of moderate HI. Gender differences in neuroprotection were also evaluated.

METHODS

P10 male and female rat pups were subjected to HI (Vannucci model) and randomized into five groups: sham intervention (Control), no treatment (HI), hypothermia (HIH), allopurinol (HIA), and dual therapy (hypothermia and allopurinol) (HIHA). To evaluate a treatment's neuroprotective efficiency, 24 hours after the HI event caspase3 activation was measured. Damaged area and hippocampal volume were also measured 72 hours after the HI event. Negative geotaxis test was performed to evaluate early neurobehavioral reflexes. Learning and spatial memory were assessed via Morris Water Maze (MWM) test at 25 days of life.

RESULTS

Damaged area and hippocampal volume were different among treatment groups (p = 0.001). The largest tissue lesion was observed in the HI group, followed by HIA. There were no differences between control, HIH, and HIHA. When learning process was analyzed, no differences were found. Females from the HIA group had similar results to the HIH and HIHA groups. Cleaved caspase 3 expression was increased in both HI and HIA. Despite this, in females cleaved caspase-3 was only differently increased in the HI group. All treated animals present an improvement in short-term (Negative geotaxis) and long-term (WMT) functional tests. Despite this, treated females present better long-term outcome. In short-term outcome no sex differences were observed.

CONCLUSIONS

Our results suggest that dual therapy confers great neuroprotection after an HI event. There were functional, histological, and molecular improvements in all treated groups. These differences were more important in females than in males. No statistically significant differences were found between HIHA and HIH; both of them present a great improvement. Our results support the idea of different regulation mechanisms and pathways of cell death, depending on gender.