The efficacy of papaverine administration by different routes for the treatment of experimental acute cerebral vasospasm

Natural Product-Derived Phytochemicals for Influenza A Virus (H1N1) Prevention and Treatment

Influenza A (H1N1) viruses are prone to antigenic mutations and are more variable than other influenza viruses. Therefore, they have caused continuous harm to human public health since the pandemic in 2009 and in recent times. Influenza A (H1N1) can be prevented and treated in various ways, such as direct inhibition of the virus and regulation of human immunity. Among antiviral drugs, the use of natural products in treating influenza has a long history, and natural medicine has been widely considered the focus of development programs for new, safe anti-influenza drugs. In this paper, we focus on influenza A (H1N1) and summarize the natural product-derived phytochemicals for influenza A virus (H1N1) prevention and treatment, including marine natural products, flavonoids, alkaloids, terpenoids and their derivatives, phenols and their derivatives, polysaccharides, and derivatives of natural products for prevention and treatment of influenza A (H1N1) virus. We further discuss the toxicity and antiviral mechanism against influenza A (H1N1) as well as the druggability of natural products. We hope that this review will facilitate the study of the role of natural products against influenza A (H1N1) activity and provide a promising alternative for further anti-influenza A drug development.

Papaverine: A Miraculous Alkaloid from Opium and Its Multimedicinal Application

The pharmacological actions of benzylisoquinoline alkaloids are quite substantial, and have recently attracted much attention. One of the principle benzylisoquinoline alkaloids has been found in the unripe seed capsules of Papaver somniferum L. Although it lacks analgesic effects and is unrelated to the compounds in the morphine class, it is a peripheral vasodilator and has a direct effect on vessels. It is reported to inhibit the cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) phosphodiesterase in smooth muscles, and it has been observed to increase intracellular levels of cAMP and cGMP. It induces coronary, cerebral, and pulmonary artery dilatation and helps to lower cerebral vascular resistance and enhance cerebral blood flow. Current pharmacological research has revealed that papaverine demonstrates a variety of biological activities, including activity against erectile dysfunction, postoperative vasospasms, and pulmonary vasoconstriction, as well as antiviral, cardioprotective, anti-inflammatory, anticancer, neuroprotective, and gestational actions. It was recently demonstrated that papaverine has the potential to control SARS-CoV-2 by preventing its cytopathic effect. These experiments were carried out both in vitro and in vivo and require an extensive understanding of the mechanisms of action. With its multiple mechanisms, papaverine can be considered as a natural compound that is used to develop therapeutic drugs. To validate its applications, additional research is required into its precise therapeutic mechanisms as well as its acute and chronic toxicities. Therefore, the goal of this review is to discuss the major studies and reported clinical studies looking into the pharmacological effects of papaverine and the mechanisms of action underneath these effects. Additionally, it is recommended to conduct further research via significant pharmacodynamic and pharmacokinetic studies.

Therapeutic Modification of Hypoxia

Regions of reduced oxygenation (hypoxia) are a characteristic feature of virtually all animal and human solid tumours. Numerous preclinical studies, both in vitro and in vivo, have shown that decreasing oxygen concentration induces resistance to radiation. Importantly, hypoxia in human tumours is a negative indicator of radiotherapy outcome. Hypoxia also contributes to resistance to other cancer therapeutics, including immunotherapy, and increases malignant progression as well as cancer cell dissemination. Consequently, substantial effort has been made to detect hypoxia in human tumours and identify realistic approaches to overcome hypoxia and improve cancer therapy outcomes. Hypoxia-targeting strategies include improving oxygen availability, sensitising hypoxic cells to radiation, preferentially killing these cells, locating the hypoxic regions in tumours and increasing the radiation dose to those areas, or applying high energy transfer radiation, which is less affected by hypoxia. Despite numerous clinical studies with each of these hypoxia-modifying approaches, many of which improved both local tumour control and overall survival, hypoxic modification has not been established in routine clinical practice. Here we review the background and significance of hypoxia, how it can be imaged clinically and focus on the various hypoxia-modifying techniques that have undergone, or are currently in, clinical evaluation.

Novel Papaverine Metal Complexes with Potential Anticancer Activities

Cancer is one of the leading causes of death worldwide. Although several potential therapeutic agents have been developed to efficiently treat cancer, some side effects can occur simultaneously. Papaverine, a non-narcotic opium alkaloid, is a potential anticancer drug that showed selective antitumor activity in various tumor cells. Recent studies have demonstrated that metal complexes improve the biological activity of the parent bioactive ligands. Based on those facts, herein we describe the synthesis of novel papaverine–vanadium(III), ruthenium(III) and gold(III) metal complexes aiming at enhancing the biological activity of papaverine drug. The structures of the synthesized complexes were characterized by various spectroscopic methods (IR, UV–Vis, NMR, TGA, XRD, SEM). The anticancer activity of synthesized metal complexes was evaluated in vitro against two types of cancer cell lines: human breast cancer MCF-7 cells and hepatocellular carcinoma HepG-2 cells. The results revealed that papaverine-Au(III) complex, among the synthesized complexes, possess potential antimicrobial and anticancer activities. Interestingly, the anticancer activity of papaverine–Au(III) complex against the examined cancer cell lines was higher than that of the papaverine alone, which indicates that Au-metal complexation improved the anticancer activity of the parent drug. Additionally, the Au complex showed anticancer activity against the breast cancer MCF-7 cells better than that of cisplatin. The biocompatibility experiments showed that Au complex is less toxic than the papaverine drug alone with IC₅₀ ≈ 111µg/mL. These results indicate that papaverine–Au(III) complex is a promising anticancer complex-drug which would make it a suitable candidate for further in vivo investigations.

Emerging strategies to target cancer metabolism and improve radiation therapy outcomes

Cancer-specific metabolic changes support the anabolic needs of the rapidly growing tumor, maintain a favorable redox balance, and help cells adapt to microenvironmental stresses like hypoxia and nutrient deprivation. Radiation is extensively applied in a large number of cancer treatment protocols but despite its curative potential, radiation resistance and treatment failures pose a serious problem. Metabolic control of DNA integrity and genomic stability can occur through multiple processes, encompassing cell cycle regulation, nucleotide synthesis, epigenetic regulation of gene activity, and antioxidant defenses. Given the important role of metabolic pathways in oxidative damage responses, it is necessary to assess the potential for tumor-specific radiosensitization by novel metabolism-targeted therapies. Additionally, there are opportunities to identify molecular and functional biomarkers of vulnerabilities to combination treatments, which could then inform clinical decisions. Here, we present a curated list of metabolic pathways in the context of ionizing radiation responses. Glutamine metabolism influences DNA damage responses by mechanisms such as synthesis of nucleotides for DNA repair or of glutathione for ROS detoxification. Repurposed oxygen consumption inhibitors have shown promising radiosensitizing activity against murine model tumors and are now in clinical trials. Production of 2-hydroxy glutarate by isocitrate dehydrogenase1/2 neomorphic oncogenic mutants interferes with the function of α-ketoglutarate-dependent enzymes and modulates Ataxia Telangiectasia Mutated (ATM) signaling and glutathione pools. Radiation-induced oxidative damage to membrane phospholipids promotes ferroptotic cell loss and cooperates with immunotherapies to improve tumor control. In summary, there are opportunities to enhance the efficacy of radiotherapy by exploiting cell-inherent vulnerabilities and dynamic microenvironmental components of the tumor.

Anticancer effects of a non-narcotic opium alkaloid medicine, papaverine, in human glioblastoma cells

The interaction between high-mobility group box 1 protein (HMGB1) and receptor for advanced glycation end products (RAGE) is important for tumor cell growth. We investigated the tumor biological effects of HMGB1 and RAGE interaction. Previously, we identified an inhibitor of HMGB1/RAGE interaction, papaverine (a non-narcotic opium alkaloid), using a unique drug design system and drug repositioning approach. In the present study, we examined the anticancer effects of papaverine in human glioblastoma (GBM) temozolomide (TMZ; as a first-line anticancer medicine)-sensitive U87MG and TMZ-resistant T98G cells. HMGB1 supplementation in the culture medium promoted tumor cell growth in T98G cells, and this effect was canceled by papaverine. In addition, papaverine in T98G cells suppressed cancer cell migration. As an HMGB1/RAGE inhibitor, papaverine also significantly inhibited cell proliferation in U87MG and T98G cells. The effects of papaverine were evaluated in vivo in a U87MG xenograft mouse model by determining tumor growth delay. The results indicate that papaverine, a smooth muscle relaxant, is a potential anticancer drug that may be useful in GBM chemotherapy.

Papaverine and its derivatives radiosensitize solid tumors by inhibiting mitochondrial metabolism

Tumor hypoxia reduces the effectiveness of radiation therapy by limiting the biologically effective dose. An acute increase in tumor oxygenation before radiation treatment should therefore significantly improve the tumor cell kill after radiation. Efforts to increase oxygen delivery to the tumor have not shown positive clinical results. Here we show that targeting mitochondrial respiration results in a significant reduction of the tumor cells' demand for oxygen, leading to increased tumor oxygenation and radiation response. We identified an activity of the FDA-approved drug papaverine as an inhibitor of mitochondrial complex I. We also provide genetic evidence that papaverine's complex I inhibition is directly responsible for increased oxygenation and enhanced radiation response. Furthermore, we describe derivatives of papaverine that have the potential to become clinical radiosensitizers with potentially fewer side effects. Importantly, this radiosensitizing strategy will not sensitize well-oxygenated normal tissue, thereby increasing the therapeutic index of radiotherapy.

Highly flexible and rapidly degradable papaverine-loaded electrospun fibrous membranes for preventing vasospasm and repairing vascular tissue

Vasospasm is a common post-operative complication after vascular anastomosis. Currently, the main treatment is a local injection of antispasmodic drugs. However, this method has a high rate of relapse and is subject to a large degree of individual variation, and repeated injections cause additional pain for patients. In this study, we developed highly flexible and rapidly degradable papaverine-loaded electrospun fibrous membranes to be wrapped around vascular suturing to prevent vasospasm. Poly-l-lactic acid/polyethylene glycol (PLLA/PEG) electrospun fibers containing papaverine maintained a high degree of flexibility and could withstand any folding, and are therefore suitable for wrapping vascular suturing. A rapid release of papaverine, between 2 and 7 days, was achieved by adjusting the proportions of PEG and PLLA. PLLA electrospun fibers containing 40% PEG (PLLA-40%) could control drug release and polymer degradation most effectively during the first 2 weeks post-operation. Testing using an in vivo rabbit model showed that PLLA-40% fibrous membranes produced significant antispasmodic effect without observable inflammation or hyperplasia, and the fibrous membranes were ideally biodegradable, with no impact on regional blood flow, pressure, vessel diameter or surrounding tissue hyperplasia. Therefore, papaverine-loaded electrospun fibrous membranes show the potential to greatly reduce post-operative vasospasm and maintain regular vascular morphology during antispasmodic therapy.

Synthesis, acoustic stability, and pharmacologic activities of papaverine-loaded echogenic liposomes for ultrasound controlled drug delivery

BACKGROUND

development of encapsulated therapeutics that could be released upon ultrasound exposure has strong implications for enhancing drug effects at the target site. We have developed echogenic liposomes (ELIP) suitable for ultrasound imaging of blood flow and ultrasound-mediated intravascular drug release. Papaverine was chosen as the test drug because its clinical application requires high concentration in the target vascular bed but low concentration in the systemic circulation.

METHODS

the procedure for preparation of standard ELIP was modified by including Papaverine hydrochloride in the lipid hydration solution, followed by three freeze-thaw cycles to increase encapsulation of the drug. Sizing and encapsulation pharmacokinetics were performed using a Coulter counter and a phosphodiesterase activity assay. Stability of Papaverine-loaded ELIP (PELIP) was monitored with a clinical diagnostic ultrasound scanner equipped with a linear array transducer at a center frequency of 4.5 MHz by assessing the mean digital intensity within a region of interest over time. The stability of PELIP was compared to those of standard ELIP and Optison.

RESULTS

relative to standard ELIP, PELIP were larger (median diameter = 1.88 +/- 0.10 microm for PELIP vs 1.08 +/- 0.15 microm for ELIP) and had lower Mean Gray Scale Values (MGSV) (92 +/- 24.8 for PELIP compared to 142.3 +/- 10.7 for ELIP at lipid concentrations of 50 microg/ml). The maximum loading efficiency and mean encapsulated concentration were 24% +/- 7% and 2.1 +/- 0.7 mg/ml, respectively. Papaverine retained its phosphodiesterase inhibitory activity when associated with PELIP. Furthermore, a fraction of this activity remained latent until released by dissolution of liposomal membranes with detergent. The stability of both PELIP and standard ELIP were similar, but both are greater than that of Optison.

CONCLUSIONS

our results suggest that PELIP have desirable physical, biochemical, biological, and acoustic characteristics for potential in vivo administration and ultrasound-controlled drug delivery.

Peri-operative measures for treatment and prevention of cerebral vasospasm following subarachnoid hemorrhage

OBJECTIVE

Aneurysmal subarachnoid hemorrhage (aSAH) is associated with high early mortality rates. Cerebral vasospasm remains the major source of morbidity after aSAH. Angiographic evidence of vasospasm is apparent in 70% of patients, while clinical manifestation of vasospasm is present in one third of patients. Early or existing vasospasm at the time of presentation poses an additional challenge in the management of the patient, and forms the basis for this review.

METHODS

Treatment modalities for management of ruptured aneurysms in the setting of vasospasm, including timing of aneurysm surgery and peri-operative management, are reviewed. Intraoperative measures aimed at treatment of existing vasospasm and at the prevention of vasopasm are discussed.

RESULTS

Operative/endovascular means to secure the ruptured aneurysm should be performed as soon as possible to facilitate treatment of the vasospasm. Surgery performed in the presence of angiographic/symptomatic vasospasm can be associated with good outcome. Operative measures to decrease the incidence of vasospasm include clot removal, intracisternal injection of thrombolytics, fenestration of the lamina terminalis and local application of vasodilatory agents. Post-operative measures include early intra-arterial injection of vasodilators (verapamil or nicardipine), percutaneous angioplasty, triple-H therapy and CSF drainage.

DISCUSSION

The utilization of a multimodality approach to treat patients with aneurysmal subarachnoid hemorrhage presenting with existing vasospasm can result in good outcome.