Review on nitric oxide at the forefront of rapid systemic signaling in mitigation of salinity stress in plants: Crosstalk with calcium and hydrogen peroxide

Soil salinity is a global issue that limits plant growth in agricultural fields and contributes to food crisis. Salt stressors impede plant's ionic, osmotic, and oxidative balance, as well as a variety of physiological functions. Exposure to salinity stress manifest considerable ROS clustering, entailing modification in performance of various organelles. To deal with salinity, plants use a variety of coping strategies, such as osmoregulation, ion-homeostasis, increased antioxidant synthesis, and so on. Nitric oxide (NO) is a pivotal signalling molecule that helps facilitate salt stress-induced physiological plant responses. A variety of evidences point to NO being produced under similar stress conditions and with similar kinetics as hydrogen peroxide (H2O2). The interplay between H2O2 and NO has important functional implications for modulating plant transduction processes. Besides, NO and calcium (Ca2+)-dependent pathways also have some connection in salt stress response mechanisms. Extensive crosstalk between NO and Ca2+ signalling pathways is investigated, and it suggests that almost every type of Ca2+ channel is under the tight control of NO, and NO acts as a Ca2+ mobilising compound and aids in signal reliance. The review provides insights into understanding recent advances regarding NO's, Ca2+ and H2O2 role in salt stress reduction with entwine signaling mechanisms.

Protective role of nitric oxide donors on endothelium in ischemia-reperfusion injury: a meta-analysis of randomized controlled trials

BACKGROUND

Decreased bioavailability of nitric oxide (NO) under hypoxic conditions can lead to endothelial dysfunction. NO supplementation may protect endothelial function in ischemia-reperfusion (IR) injury. Therefore, a meta-analysis of randomized controlled trials (RCTs) was performed to verify the protective effect of NO donors on endothelium in IR injury.

METHODS

Medline, Embase, Cochrane Library, and Web of Science databases were searched from inception to April 1, 2023. The specific inclusion criteria were as follows: (1) RCTs; (2) trials comparing NO donors with placebo control groups; and (3) trials reporting the effects of these interventions on vascular endothelial functional outcomes in IR injury. Random-effects models were used to assess pooled effect sizes, which were expressed as standardized mean differences (SMD).

RESULTS

Seven studies satisfied the inclusion criteria and consisted of a total of 149 participants. NO donors were protective of endothelial function in IR injury (SMD: - 1.60; 95% confidence interval [CI]: - 2.33, - 0.88, P < 0.0001; heterogeneity [I² = 66%, P = 0.001]). Results of the subgroup analysis showed the following: absence of protective effect of NO donor use following ischemia on endothelial function in IR injury - 1.78 (95% CI: - 2.50, - 1.07) and loss of protective effect on endothelial function after prolonged NO donor use - 0.89 (95% CI: - 2.06, 0.28).

CONCLUSION

The short-period use of NO donors before the onset of ischemia can protect endothelial function in IR injury.

Design, synthesis and biological evaluation of novel nitric oxide donors with antioxidative activity

Reactive oxygen species (ROS) are the primary cause of organic nitrate drug tolerance and endothelial dysfunction. In order to scavenge the ROS and maintain the therapeutic effect of nitrates, we designed and synthesized ten new types of dual-acting nitrate molecules by combining NIT-type nitroxides and 5-ISMN. These included two types of novel epimeric nitroxide-nitrate conjugates (15(S) and 15(R)), which had pharmacophore connections. We also synthesized 8 NIT radicals without 5-ISMN in order to compare the activities of these novel nitric oxide donors. Several dual-acting nitroxide-based nitrate conjugates showed the ability to release NO and cause anti-oxidant effects in human umbilical vein endothelial cells. Among these conjugates, 15(S) showed the most prominent pro-vasodilative effect. In angiotensin II infusion-induced hypertensive mice, 15(S) treatment for 4 weeks decreased both the systolic and diastolic blood pressures and ameliorated the vascular endothelial and smooth muscle functions of isolated thoracic aortas. In addition, the vascular structure of the mice was restored and their vascular oxidative stress was decreased. The results suggest that these novel nitric oxide donors can be used as potential drugs in the treatment of vascular diseases. Therefore, the strategy of using a combination of antioxidants and NO-donors can be a promising way to develop novel organic nitrate drugs for future use in combating disease.

Fluorescent sensing for some nitric oxide donors in dosage forms and biological matrices

New fluorescent sensing of some nitric oxide donors, nitroglycerin and isosorbide dinitrate was developed in our laboratories. Two fluorescent reagents, 2-(2-hydroxyethylamino)-4,6-dimethylpyridine-3-carbonitrile, 3a and 2-(3-chloro-phenylamino)-4,6-dimethylpyridine-3-carbonitrile, 3b were synthesized in our laboratories and a comparative study was performed between them from the point of fluorescence intensity. The fluorophore, 3a, was selected for the analytical study as it exhibit higher quantum yield value. The interaction between the selected drugs and the fluorophore was noticed to be quenching. The mechanism of quenching was studied and it was supposed to be collisional quenching through photo induced electron transfer process. The proposed sensing method was applied successfully for the analysis of nitroglycerin and isosorbide dinitrate in dosage forms within concentration range of (0.05-0.5 µg/mL) with percentage recoveries of 99.9 ± 0.5 and 99.9 ± 0.7 respectively. The studied drugs, nitroglycerin and isosorbide dinitrate, were also probed in spiked biological matrices such as plasma samples with percentage recoveries of 99.1 ± 1.97 and 100.7 ± 1.96 and urine samples with percentage recoveries of 100.4 ± 1.8 and 100.3 ± 1.7 respectively. In vivo analysis of both drugs in real plasma was also investigated. The sensing method exhibit well intra-day and inter day precision with %RSD < 2%.

Advances in inorganic-based colloidal nanovehicles functionalized for nitric oxide delivery

Nitric oxide (NO) is an important pharmaceutical agent of considerable therapeutic interest ascribed to its vasodilative, tumoricidal and antibacterial effects. Rapid development of functional nanomaterials has provided opportunities for us to achieve controllable exogenous delivery of NO. In the current review, a variety of functionalized colloidal nanovehicles that have been developed to date for nitric oxide delivery are reported. Specifically, we focus on inorganic nanomaterials such as semiconductor quantum dots, silica nanoparticles, upconversion nanomaterials, carbon/graphene nanodots, gold nanoparticles, iron oxide nanoparticles as the functional or/and supporting materials to carry NO donors. N-diazeniumdiolates, S-nitrosothiols, nitrosyl metal complexes and organic nitrates as main types of NO donors have their own unique properties and molecular structures. Conjugating the NO donors of different forms with appropriate nanomaterials results in NO delivery nanovehicles capable of releasing NO in a dose-controllable or/and on-demand manner. We also consider the therapeutic applications of those NO delivery nanovehicles, especially their applications for cancer therapy. In the end, we discuss possible future directions for developing exogenous NO delivery systems with more desired structure and improved performance. This review aims to offer the readers an overall view of the advances in functionalized colloidal nanovehicles for NO delivery. It will be attractive to scientists and researchers in the areas of material science, nanotechnology, biomedical engineering, chemical biology, etc.

Human cationic amino acid transporters are not affected by direct nitros(yl)ation

A direct inhibiting effect of NO on the function of CAT-1 and -2A has been postulated to occur via nitrosylation of cysteine residues in the transporters. Neither the NO donor SNAP nor a mixture of SIN-1 and Spermine NONOate, that generates the strong nitrosating agent N₂O₃, reduced CAT-mediated L-arginine transport. Direct nitros(yl)ation does either not occur in CATs or does not affect their transport function. A regulatory effect of NO or nitrosating agents on CAT-mediated transport under physiological conditions seems, therefore, unlikely.

The effects of extended nitric oxide release on responses of the human non-pregnant myometrium to endothelin-1 or vasopressin

BACKGROUND

Uterotonic mediators: endothelin-1 (ET-1), arginine vasopressin (AVP), and nitric oxide (NO) play important roles in the regulation of uterine contractility. We hypothesize that NO affects both ET-1 or AVP. Therefore, this study investigated the involvement of extended exogenous NO release in the regulation of responses of the human non-pregnant myometrium to ET-1 and AVP.

METHODS

Specimens were obtained from 10 premenopausal women, undergoing hysterectomy for benign gynecological disorders. Responses of the myometrial strips to ET-1 or AVP in the absence and presence of an exogenous NO donor (diethylenetriamine; DETA/NO; 10-4 mol/L) were recorded under isometric conditions. To inhibit endogenous NO, a competitive inhibitor of NO synthase, L-NG-nitroarginine (L-NNA) was added to the organ bath.

RESULTS

ET-1 enhanced the spontaneous contractile activity of the myometrium more powerfully (p < 0.01) than AVP. Preincubation with exogenous NO weakened ET-1- or AVP-induced increases in this contractile activity (p < 0.05). However, unexpected results were obtained after preincubation with L-NNA and with DETA/NO then added. Both ET-1 and AVP induced augmented contractile effects in almost all concentrations compared with the responses to these peptides alone or after NOS synthase inhibition (both p < 0.01).

CONCLUSIONS

This study demonstrated for the first time that extended incubation with a NO donor influences the uterine muscle response evoked by ET-1 and AVP. Both endogenous and exogenous NO is involved in the control of the uterine responses to ET-1 or AVP of non-pregnant myometrium. Furthermore, both peptides stimulate increased uterine contractility when the local imbalance between the constrictive and relaxing mediators takes place.

Nitric oxide-donor/PARP-inhibitor combination: A new approach for sensitization to ionizing radiation

Recently, clinical development of PARP inhibitors (PARPi) expanded from using them as a single agent to combining them with DNA-damaging therapy to derive additional therapeutic benefit from stimulated DNA damage. Furthermore, inhibiting PARP in cancers with BRCA1/2 mutations has been shown to be an effective synthetic lethality approach either as a single agent or in combination with the different DNA damaging agents: chemotherapy or ionizing radiation (IR). However, inherited BRCA1/2 mutations account only for 5–10% of breast cancers, 10–15% of ovarian cancers, and lesser for the other cancers. Hence, for most of the cancer patients with BRCA1/2-proficient tumors, sensitization to DNA-damaging agents with PARPi is significantly less effective. We recently demonstrated that moderate, non-toxic concentrations of NO-donors inhibited BRCA1 expression, with subsequent inhibition of error-free HRR and increase of error-prone non-homologous end joining (NHEJ). We also demonstrated that the effect of NO-dependent block of BRCA1 expression can only be achieved in the presence of oxidative stress, a condition that characterizes the tumor microenvironment and is also a potential effect of IR. Hence, NO-donors in combination with PARPi, with effects limited by tumor microenvironment and irradiated area, suggest a precise tumor-targeted approach for radio-sensitization of BRCA1/2-proficient tumors. The combination with NO-donors allows PARPi to be successfully applied to a wider variety of tumors. The present work demonstrates a new drug combination (NO-donors and PARP-inhibitors) which demonstrated a high potency in sensitization of wide variety of tumors to ionizing radiation treatment.

Microvesicles Secreted by Nitric Oxide-Primed Mesenchymal Stromal Cells Boost the Engraftment Potential of Hematopoietic Stem Cells

Patients with leukemia, lymphoma, severe aplastic anemia, etc. are frequently the targets of bone marrow transplantation, the success of which critically depends on efficient engraftment by transplanted hematopoietic cells (HSCs). Ex vivo manipulation of HSCs to improve their engraftment ability becomes necessary when the number or quality of donor HSCs is a limiting factor. Due to their hematopoiesis-supportive ability, bone marrow-derived mesenchymal stromal cells (MSCs) have been traditionally used as feeder layers for ex vivo expansion of HSCs. MSCs form a special HSC-niche in vivo, implying that signaling mechanisms operative in them would affect HSC fate. We have recently demonstrated that AKT signaling prevailing in the MSCs affect the HSC functionality. Here we show that MSCs primed with nitric oxide donor, Sodium nitroprusside (SNP), significantly boost the engraftment potential of the HSCs co-cultured with them via intercellular transfer of microvesicles (MVs) harboring mRNAs encoding HSC-supportive genes. Our data suggest that these MVs could be used as HSC-priming agents to improve transplantation efficacy. Since both, nitric oxide donors and MSCs are already in clinical use; their application in clinical settings may be relatively straight forward. This approach could also be applied in regenerative medicine protocols. Stem Cells 2019;37:128-138.

Nitric oxide-donating compounds for IOP lowering in glaucoma

INTRODUCTION

An elevated intraocular pressure (IOP) remains the main risk factor for progression of glaucoma upon which we can efficiently act. Pharmacological strategies to reduce IOP are directed towards the reduction of aqueous humour (AH) production and/or the increase in AH drainage through the uveoscleral pathway. However, there are no drugs currently available as first-line treatment to increase AH outflow primarily via the conventional route. Ocular nitric oxide (NO) production takes place in AH outflow pathways and in the ciliary muscle, modulating the cellular response to elevated IOP.

METHODS

This review describes the mechanism of action of endogenous NO and NO-donating compounds that are under research. It includes information regarding pre-clinical and clinical studies previously conducted with these compounds, discussing their role and therapeutic potential in the pharmacological treatment of ocular hypertension in glaucoma.

RESULTS

The topical ocular administration of NO-donating compounds significantly lowered IOP and maintained it in animal models of glaucoma and subjects with ocular hypertension.

CONCLUSIONS

The mechanism of action of these compounds is novel and scientific evidence that shows promising results. However, there is a need for more comprehensive studies to assess long-term safety and tolerability in order to properly evaluate their use in chronic therapies.

Targeting Schlemm's Canal in the Medical Therapy of Glaucoma: Current and Future Considerations

Schlemm’s canal (SC) is a unique, complex vascular structure responsible for maintaining fluid homeostasis within the anterior segment of the eye by draining the excess of aqueous humour. In glaucoma, a heterogeneous group of eye disorders afflicting approximately 60 million individuals worldwide, the normal outflow of aqueous humour into SC is progressively hindered, leading to a gradual increase in outflow resistance, which gradually results in elevated intraocular pressure (IOP). By and large available antiglaucoma therapies do not target the site of the pathology (SC), but rather aim to decrease IOP by other mechanisms, either reducing aqueous production or by diverting aqueous flow through the unconventional outflow system. The present review first outlines our current understanding on the functional anatomy of SC. It then summarizes existing research on SC cell properties; first in the context of their role in glaucoma development/progression and then as a target of novel and emerging antiglaucoma therapies. Evidence from ongoing research efforts to develop effective antiglaucoma therapies targeting SC suggests that this could become a promising site of future therapeutic interventions.

Dispersal of human and plant pathogens biofilms via nitric oxide donors at 4 °C

Recent studies suggest that nitric oxide donors capable of manipulating nitric oxide-mediated signaling in bacteria could induce dispersal of biofilms. Encased in extracellular polymeric substances, human and plant pathogens within biofilms are significantly more resistant to sanitizers. This is particularly a problem in refrigerated environments where food is processed. In an exercise aimed to study the potential of nitric oxide donors as biofilm dispersal in refrigerated conditions, we compared the ability of different nitric oxide donors (SNAP, NO-aspirin and Noc-5) to dislodge biofilms formed by foodborne, human and plant pathogens treated at 4 °C. The donors SNAP and Noc-5 were efficient in dispersing biofilms formed by Salmonella enterica, pathogenic Escherichia coli and Listeria innocua. The biomasses were decreased up to 30 % when compared with the untreated controls. When the plant pathogens Pectobacterium sp. and Xanthomonas sp. were tested the dispersion was mainly limited to Pectobacterium carotovorum biofilms, decreasing up to 15 % after exposure to molsidomine. Finally, the association of selected nitric oxide donors with sanitizers (DiQuat, H2O2, peracetic acid and PhenoTek II) was effective in dispersing biofilms. The best dispersal was achieved by pre-treating P. carotovorum with molsidomine and then peracetic acid. The synergistic effect was estimated up to ~35 % in dispersal when compared with peracetic acid alone. The association of nitric oxide donors with sanitizers could provide a foundation for an improved sanitization procedure for cleaning refrigerate environments.

Evaluation of nitric oxide donors impact on cisplatin resistance in various ovarian cancer cell lines

Ovarian cancer chemoresistance, both intrinsic and acquired, is the main obstacle in improving the outcome of anticancer therapies. Therefore the development of new treatment strategies, including the use of new compounds that can support the standard therapeutics is required. Among many candidates, nitric oxide (NO) donors, agents with multivalent targeted activities in cancer cells, are worth considering. The aim of this study was evaluation of SPER/NO and DETA/NO ability to enhance cisplatin cytotoxicity against different ovarian cancer cell lines. Obtained data indicate that NO donors action varies between different cancer cell lines and is strongest in low aggressive and cisplatin sensitive cells. While statistically significant, the enhancement of cisplatin cytotoxicity by NO donors is of low magnitude. The rise in the percentage of late apoptotic/necrotic ovarian cancer cells may suggest that NO donors enhancement action might be based on the cellular ATP depletion. Nevertheless, no significant impact of the NO donors, cisplatin or their combination on the expressions of ABCB1, BIRC5 and PTEN genes has been found. Although our data puts the therapeutical potential of NO donors to aid cisplatin action in question it may also point out at the further approach to utilize these compounds in therapies.

Medications to ease intrauterine device insertion: a systematic review

BACKGROUND

Potential barriers to intrauterine device (IUD) use include provider concern about difficult insertion, particularly for nulliparous women.

OBJECTIVE

This study aims to evaluate the evidence on the effectiveness of medications to ease IUD insertion on provider outcomes (i.e., ease of insertion, need for adjunctive insertion measures, insertion success).

SEARCH STRATEGY

We searched the PubMed database for peer-reviewed articles published in any language from database inception through February 2016.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that examined medications to ease interval insertion of levonorgestrel-releasing IUDs and copper T IUDs.

RESULTS

From 1855 articles, we identified 15 RCTs that met our inclusion criteria. Most evidence suggested that misoprostol did not improve provider ease of insertion, reduce the need for adjunctive insertion measures or improve insertion success among general samples of women seeking an IUD (evidence Level I, good to fair). However, one RCT found significantly higher insertion success among women receiving misoprostol prior to a second IUD insertion attempt after failed attempt versus placebo (evidence Level I, good). Two RCTs on 2% intracervical lidocaine as a topical gel or injection suggested no positive effect on provider ease of insertion (evidence Level I, good to poor), and one RCT on diclofenac plus 2% intracervical lidocaine as a topical gel suggested no positive effect on provider ease of insertion (evidence Level I, good). Limited evidence from two RCTs on nitric oxide donors, specifically nitroprusside or nitroglycerin gel, suggested no positive effect on provider ease of insertion or need for adjunctive insertion measures (evidence Level I, fair).

CONCLUSIONS

Overall, most studies found no significant differences between women receiving interventions to ease IUD insertion versus controls. Among women with a recent failed insertion who underwent a second insertion attempt, one RCT found improved insertion success among women using misoprostol versus placebo.

Nitric oxide donors improve the ovulation and pregnancy rates in anovulatory women with polycystic ovary syndrome treated with clomiphene citrate: A RCT

BACKGROUND

Clomiphene citrate (CC) is the first line agent used for ovulation induction in patients with polycystic ovarian syndrome (PCOS). However, there is marked discrepancy between the ovulation and pregnancy rates achieved, which may be attributed to the undesirable effect of CC on cervical mucus and endometrium.

OBJECTIVE

The aim of this study was to evaluate the effect of Isosorbid monoitrate (ISMN) as nitric oxide (NO) donors on the ovulation and pregnancy rates in an ovulatory women with PCOS treated with CC.

MATERIALS AND METHODS

Ninety patients with PCOS were randomly allocated into three groups. Patients in group A) were treated with 100 mg CC for five days starting from the fifth day of the cycle. Patients in group B) and C) received 10 mg and 20 mg of ISMN respectively in addition to CC, applied vaginally till the diagnosis of ovulation.

RESULTS

There was a significant increase in the ovulation and pregnancy rates in the patients treated with CC+ISMN as compared with patients treated with CC alone (p< 0.001).

CONCLUSION

Concomitant use of NO with CC seems to improve the ovulation and pregnancy rates in the patients with PCOS with no significant increase in side effects as compared with CC alone.

Prophylactic treatment for preeclampsia in high-risk teenage primigravidae with nitric oxide donors: a pilot study

OBJECTIVES

Preeclampsia is associated with significant morbidity and mortality especially in high-risk groups. Impairment of endogenous nitric oxide has been shown to be associated with the disease and prophylactic therapy may ameliorate this condition and improve pregnancy outcome. This study valuated nitric oxide donors prophylactic treatment for preeclampsia in high-risk teenage primigravidae.

METHODS

The study included three hundred primigravidae aged ≤ 20 years with singleton pregnancy. Abdominal pulsed color Doppler ultrasound was done at 24 weeks gestation and pregnancies with uterine artery diastolic notch were randomly allocated to a control group received placebo vaginal tablets and a study group received isosorbid mononitrate 20 mg tablet once daily applied vaginally until delivery.

OUTCOMES

Incidence of preeclampsia and maternal, fetal, and neonatal outcome in both groups.

RESULTS

The study group had significant lower incidence of preeclampsia, preterm birth, intrauterine growth restriction and of neonatal admission to the intensive care (p < 0.05).

CONCLUSIONS

Nitric oxide donors prophylactic treatment for preeclampsia in high-risk teenage pregnancies decrease the incidence of preeclampsia and improve maternal, fetal, and neonatal outcomes. Further studies on larger sample size are required to confirm these results.

Time lasting S-nitrosoglutathione polymeric nanoparticles delay cellular protein S-nitrosation

Physiological S-nitrosothiols (RSNO), such as S-nitrosoglutathione (GSNO), can be used as nitric oxide (NO) donor for the treatment of vascular diseases. However, despite a half-life measured in hours, the stability of RSNO, limited by enzymatic and non-enzymatic degradations, is too low for clinical application. So, to provide a long-lasting effect and to deliver appropriate NO concentrations to target tissues, RSNO have to be protected. RSNO encapsulation is an interesting response to overcome degradation and provide protection. However, RSNO such as GSNO raise difficulties for encapsulation due to its hydrophilic nature and the instability of the S-NO bound during the formulation process. To our knowledge, the present study is the first description of the direct encapsulation of GSNO within polymeric nanoparticles (NP). The GSNO-loaded NP (GSNO-NP) formulated by a double emulsion process, presented a mean diameter of 289 ± 7 nm. They were positively charged (+40 mV) due to the methacrylic acid and ethylacrylate polymer (Eudragit® RL) used and encapsulated GSNO with a satisfactory efficiency (i.e. 54% or 40 mM GSNO loaded in the NP). In phosphate buffer (37 °C; pH 7.4), GSNO-NP released 100% of encapsulated GSNO within 3h and remained stable still 6h. However, in contact with smooth muscle cells, maximum protein nitrosation (a marker of NO bioavailability) was delayed from 1h for free GSNO to 18h for GSNO-NP. Therefore, protection and sustained release of NO were achieved by the association of a NO donor with a drug delivery system (such as polymeric NP), providing opportunities for vascular diseases treatment.

The Effects of Nitric Oxide Donors on Uterine Artery and Sub-endometrial Blood Flow in Patients with Unexplained Recurrent Abortion

BACKGROUND

Nitric oxide plays a major role in increasing uterine blood flow during the luteal phase and early pregnancy. This study was done to compare uterine artery and sub-endometrial blood flow indices during the luteal phase between patients with unexplained recurrent abortion and fertile women and also to evaluate the effects of nitric oxide donors on blood flow indices in the abortion group.

METHODS

The study included a control group of 30 primiparae who had normal vaginal delivery and no history of abortion and an abortion group of 30 nulliparous women with history of two or more unexplained recurrent abortions. Transvaginal three-dimensional pulsed color Doppler ultrasound was done on days 21-23 of the cycle to measure uterine artery resistance and pulsation indices and the subendometrial vascular, flow and vascular-flow indices. Isosorbide mononitrate 20 mg tablet was administered vaginally in the abortion group and blood flow indices were measured again after two hours. The Student t-test and the paired t-test were used for analysis of results and a p-value of ≤0.05 was considered significant.

RESULTS

Patients with unexplained recurrent abortion had significantly higher uterine artery resistance and pulsation indices and lower sub-endometrial vascular, flow and vascular-flow index (p < 0.01-0.0001). Isosorbide mononitrite significantly decreased uterine artery and increased sub-endometrial blood flow indices (p < 0.001).

CONCLUSION

Uterine artery and sub-endometrial blood flow decreased during the luteal phase in patients with unexplained recurrent abortion. Nitric oxide donors increased blood flow and may be of a therapeutic value.

A comparative study of NONOate based NO donors: spermine NONOate is the best suited NO donor for angiogenesis

Nitric oxide (NO) is a known modulator of angiogenesis. The NONOate subfamily of NO donors has long been used in experimental and clinical studies to promote angiogenesis. However, no studies have been conducted yet to compare the angiogenesis potential of these NO donors in respect to their pattern of NO release. We hypothesize that having different pattern of NO release, each of the NO donors in NONOate subfamily can promote key stages of angiogenesis in differential manner. To verify our hypothesis, NO donors with half life ranging from seconds to several hours and having very different pattern of NO release were selected to evaluate their efficacy in modulating angiogenesis. Endothelial tube formation using EAhy926 cells was maximally increased by Spermine NONOate (SP) treatment. SP treatment maximally induced both ex vivo and in vivo angiogenesis using egg yolk and cotton plug angiogenesis models respectively. Experiment using chick embryo partial ischemia model revealed SP as the best suited NO donor to recover ischemia driven hampered angiogenesis. The present study elaborated that differential release pattern of NO by different NO donors can modulate angiogenesis differentially and also suggested that SP have a unique pattern of NO release that best fits for angiogenesis.

1,2,4-Triazole/oxime hybrids as new strategy for nitric oxide donors: Synthesis, anti-inflammatory, ulceroginicity and antiproliferative activities

A series of novel nitric oxide (NO) donating triazole/oxime hybrids was prepared and evaluated for their anti-inflammatory activity and antiproliferative activity. Most of the tested compounds showed significant anti-inflammatory activity using carrageenan-induced rat paw edema method compared to indomethacin. Calculation of the ulcer indices and histopathological investigation indicated that the prepared NO-donating oximes exhibited less ulcerogenicity compared to their ketone intermediates and indomethacin. The NO-donating oximes 7i and 7k achieved remarkable cell growth inhibition activity against most of the tested cell lines. Compound 7k was found to be with high selectivity against CNS subpanel with selectivity ratio of 11.99 at GI₅₀ level.