Anti-sickling effect of MX-1520, a prodrug of vanillin: anin vivostudy using rodents

Vanillin improves glucose homeostasis and modulates metabolic activities linked to type 2 diabetes in fructose-streptozotocin induced diabetic rats

OBJECTIVE

This study investigated the antidiabetic effect of vanillin using in vitro, in silico, and in vivo experimental models.

METHODOLOGY

Type 2 diabetes (T2D) was induced in male Sprague-Dawley (SD) rats using fructose-streptozotocin (STZ), then orally administered low (150 mg/kg bodyweight) or high (300 mg/kg bodyweight) dose of vanillin for 5 weeks intervention period.

RESULTS

Vanillin suppressed the levels of blood glucose, serum cholesterol, triglyceride, low-density lipoprotein cholesterol (LDL-c), alanine transaminase (ALT), aspartate transaminase (AST), creatinine, urea, uric acid, when elevated serum insulin, HDL-cholesterol, and concomitantly improved pancreatic β-cell function, glucose tolerance, and pancreatic morphology. It also elevated both serum and pancreatic tissue GSH level, SOD and catalase activities, and hepatic glycogen level, while depleting malondialdehyde level, α-amylase, lipase, acetylcholinesterase, ATPase, ENTPDase and 5'-nucleotidase, glucose-6-phosphatase, fructose-1,6-bisphosphatase, and glycogen phosphorylase activities.

CONCLUSIONS

The results indicate the potent antidiabetic effect of vanillin against T2D and its associated complications.

Design, Synthesis, and Antisickling Investigation of a Thiazolidine Prodrug of TD-7 That Prolongs the Duration of Action of Antisickling Aromatic Aldehyde

The synthetic allosteric effector of hemoglobin, TD-7 has been investigated as a potential therapeutic agent for the treatment of sickle cell disease. The pharmacologic activity of TD-7 is due to formation of a Schiff-base interaction between its aldehyde group and the two N-terminal αVal1 amines of hemoglobin, effectively inhibiting sickling of red blood cells. However, TD-7 faces a challenge in terms of poor oral bioavailability due to rapid in-vivo oxidative metabolism of its aldehyde functional group. To address this shortcoming, researches have explored the use of a L-cysteine ethyl ester group to cap the aldehyde group to form a thiazolidine aromatic aldehyde prodrug complex, resulting in the improvement of the metabolic stability of this class of compounds. This report details the synthesis of a thiazolidine prodrug of TD-7, referred to as Pro-7, along with a comprehensive investigation of Pro-7 functional and biological properties. In an in-vitro Hb modification and Hb oxygen affinity studies using normal whole blood, as well as erythrocyte sickling inhibition using sickle whole blood, Pro-7 exhibited a gradual onset but progressive increase in all activities. Additionally, in-vivo pharmacokinetic studies conducted with Sprague Dawley rats demonstrated that Pro-7 can undergo hydrolysis to release TD-7. However, the blood concentration of TD-7 did not reach the desired therapeutic level. These findings suggest that the incorporation of the L-cysteine ethyl ester group to TD-7 represents a promising strategy to enhance the metabolic stability of aromatic aldehydes that could lead to the development of a more effective drug for the treatment of sickle cell disease.

Emerging drug targets for sickle cell disease: shedding light on new knowledge and advances at the molecular level

INTRODUCTION

In sickle cell disease (SCD), a single amino acid substitution at β6 of the hemoglobin (Hb) chain replaces glutamate with valine, forming HbS instead of the normal adult HbA. Loss of a negative charge, and the conformational change in deoxygenated HbS molecules, enables formation of HbS polymers. These not only distort red cell morphology but also have other profound effects so that this simple etiology belies a complex pathogenesis with multiple complications. Although SCD represents a common severe inherited disorder with life-long consequences, approved treatments remain inadequate. Hydroxyurea is currently the most effective, with a handful of newer treatments, but there remains a real need for novel, efficacious therapies.

AREAS COVERED

This review summarizes important early events in pathogenesis to highlight key targets for novel treatments.

EXPERT OPINION

A thorough understanding of early events in pathogenesis closely associated with the presence of HbS is the logical starting point for identification of new targets rather than concentrating on more downstream effects. We discuss ways of reducing HbS levels, reducing the impact of HbS polymers, and of membrane events perturbing cell function, and suggest using the unique permeability of sickle cells to target drugs specifically into those more severely compromised.

Molecular dynamics simulation, synthesis and topoisomerase inhibitory actions of vanillin derivatives: a systematic computational structural integument

A series of 4-hydroxy-3-methoxy benzaldehyde (vanillin) derivatives (3a-3r) was designed for the principle of Schiff base condensation with several individual sulfanilamide analogues. The inhibitory potencies of the designed compounds were evaluated through molecular docking simulation studies against the targets, breast cancer-topo isomerase-IIα and estrogen receptor-α; and the top scoring poses with higher binding energy were selected to assess the mode of binding and stability of each complex through molecular dynamics simulations. Compounds that remained stable in the active sites of the both target receptors through a number of strong H-bonds and hydrophobic contacts were selected. Based on the computational results, these selected compounds, 3b, 3e and 3f were synthesized and were followed up for structural elucidation attempts, by FT/ATR, ¹H NMR and ¹³C NMR. From the experimental in vitro studies on 3b, 3e and 3f, the following remarkable activities against breast cancer cell line were done; IC₅₀ values of 3b, 3e and 3f were noted, 6.7, 4.3 and 11 ng/mL, respectively. These newly synthesized compounds may be used as novel inhibitors of nuclear receptors with potential therapeutic applications in control of cancer.Communicated by Ramaswamy H. Sarma.

Epicatechin exerts dual action to shield sickling and hydroxyurea-induced myelosuppression: Implication in sickle cell anemia management

Hydroxyurea (HU) is the key drug to treat Sickle cell anemia (SCA). However, its treatment is associated with the liability of myelosuppression. The present study aimed to investigate the potential of epicatechin as a supplementation therapy for the symptomatic management of SCA under HU therapy. A panel of experiments were performed at first to observe epicatechin's effect on sickling and hemolytic behaviour using SCA patient's blood (ex vivo). Thereafter, the effect of HU in the presence or absence of epicatechin was investigated on cytokine inhibition in rat splenocytes (ex vivo) as well as alterations in hematological parameters and kidney function tests in rats (in vivo). Then, any effect of epicatechin on pharmacokinetic modulation of HU in rats was elucidated along with the underlying mechanism using a battery of in vitro and in vivo models. Epicatechin exhibited potent action on anti-sickling, polymerization inhibition, and erythrocyte membrane stability. It did not show any inherent hemolytic activity and reduced TNF-α level during concomitant administration with HU. Based on hematological changes in rats, epicatechin treatment aided to the beneficial effect of HU and prevented the treatment-linked disadvantageous effects of HU like neutropenia. The plasma exposure of HU was significantly augmented in rats upon simultaneous oral administration of epicatechin with HU. Down-regulation of Oatp1b2 and catalase possibly contributed to the pharmacokinetic interaction of HU. Epicatechin is found to be a promising candidate and should be explored at a reduced dose level of HU towards offsetting the dose-dependent myelosuppressive effect of HU under the frame of supplementation therapy in SCA.

Modulating hemoglobin allostery for treatment of sickle cell disease: current progress and intellectual property

INTRODUCTION

Sickle cell disease (SCD) is a debilitating inherited disorder that affects millions worldwide. Four novel SCD therapeutics have been approved, including the hemoglobin (Hb) modulator Voxelotor.

AREAS COVERED

This review provides an overview of discovery efforts toward modulating Hb allosteric behavior as a treatment for SCD, with a focus on aromatic aldehydes that increase Hb oxygen affinity to prevent the primary pathophysiology of hypoxia-induce erythrocyte sickling.

EXPERT OPINION

The quest to develop small molecules, especially aromatic aldehydes, to modulate Hb allosteric properties for SCD began in the 1970s; however, early promise was dogged by concerns that stalled support for research efforts. Persistent efforts eventually culminated in the discovery of the anti-sickling agent 5-HMF in the 2000s, and reinvigorated interest that led to the discovery of vanillin analogs, including Voxelotor, the first FDA approved Hb modulator for the treatment of SCD. With burgeoning interest in the field of Hb modulation, there is a growing landscape of intellectual property, including drug candidates at various stages of preclinical and clinical investigations. Hb modulators could provide not only the best chance for a highly effective oral therapy for SCD, especially in the under-developed world, but also a way to treat a variety of other human conditions.

Vanillin exerts therapeutic effects against hyperglycemia-altered glucose metabolism and purinergic activities in testicular tissues of diabetic rats

Testicular dysfunctions leading to male infertility has been reported in type 2 diabetes (T2D), with glucose dysmetabolism, cholinergic and purinergic dysfunction being major contributors. In the present study, the effect of vanillin on glucose metabolism, purinergic and cholinergic dysfunctions were investigated in testicular tissues of T2D rats. Male Sprague-Dawley rats were divided into 6 groups containing 5 rats each. T2D was induced in rats by administering 10 % fructose ad libitum for 14 days followed by a single intraperitoneal injection (40 mg/kg body weight) of streptozotocin. T2D rats were orally administered with vanillin at 150 and 300 mg/kg body weight (bw). Diabetic control (DC) consisted of untreated diabetic rats, while normal control (NC) consisted of normal rats and they were administered with distilled water only. Metformin was used as the standard antidiabetic drug. After 5 weeks treatment, the rats were sacrificed, and the testes were harvested. Induction of T2D led to significantly depleted testicular levels of glutathione, glycogen content, superoxide dismutase and catalase enzyme activities, with concomitantly elevated levels of nitric oxide, malondialdehyde, acetylcholinesterase, glucose-6-phosphatase, fructose-1,6-biphophastase, glycogen phosphorylase, amylase and lipase activities. These activities and levels were significantly reversed to near normal in rats treated with both doses of vanillin as compared with metformin. These results, when taken together, suggest the therapeutic effect of vanillin against hyperglycemia-mediated metabolic dysfunctions in testes of T2D rats. This is depicted by the ability of the phenolic to attenuate oxidative imbalance, purinergic and cholinergic dysfunctions, while suppressing glucose dysmetabolism.

Sulfated non-anticoagulant heparin derivative modifies intracellular hemoglobin, inhibits cell sickling in vitro, and prolongs survival of sickle cell mice under hypoxia

Sickle cell disease (SCD) is an autosomal recessive genetic disease caused by a single point mutation, resulting in abnormal sickle hemoglobin (HbS). During hypoxia or dehydration, HbS polymerizes to form insoluble aggregates and induces sickling of red blood cells, which increases the adhesiveness of the cells, thereby altering the rheological properties of the blood, and triggers inflammatory responses, leading to hemolysis and vaso-occlusive crises. Unfractionated heparin and low-molecular weight heparins have been suggested as treatments to relieve coagulation complications in SCD. However, they are associated with bleeding complications after repeated dosing. An alternative sulfated non-anticoagulant heparin derivative (S-NACH) was previously reported to have no to low systemic anticoagulant activity and no bleeding side effects, and it interfered with P-selectin-dependent binding of sickle cells to endothelial cells, with concomitant decrease in the levels of adhesion biomarkers in SCD mice. S-NACH has been further engineered and structurally enhanced to bind with and modify HbS to inhibit sickling directly, thus employing a multimodal approach. Here, we show that S-NACH can: (i) directly engage in Schiff-base reactions with HbS to decrease red blood cell sickling under both normoxia and hypoxia in vitro, (ii) prolong the survival of SCD mice under hypoxia, and (iii) regulate the altered steady state levels of pro- and anti-inflammatory cytokines. Thus, our proof-of-concept, in vitro and in vivo preclinical studies demonstrate that the multimodal S-NACH is a highly promising candidate for development into an improved and optimized alternative to low-molecular weight heparins for the treatment of patients with SCD.

In vitro assessment of the anti-sickling properties of Buchholzia coriacea and Mucuna pruriens seed extracts

Sickle cell disease is a group of diseases inherited through the gene and it affects the haemoglobin in the red blood cell. This study investigated the methanol seed extract of Buchholzia coriacea for possible in vitro anti-sickling effects and also determined the effect of Mucuna pruriens seed extract on the solubility and oxygen-binding rate of sickle cell haemoglobin. Sickle cell blood was collected from sickle cell disease patients with subsequent addition of 2% sodium metabisulphite to cause more sickling. Varying concentrations of the seed extracts (50%, 25%, 12.5% and 6.25%) were added to the pre-treated blood for these in vitro assays. The results showed that the extract of Buchholzia coriacea significantly (P < 0.05) inhibited sickling at all concentrations with the highest percentage inhibition of 73.3 ± 5.8, reversed sickled erythrocytes at all concentrations with the highest percentage reversal of 83.3 ± 5.8 and significantly (P < 0.05) inhibited polymerisation at all concentrations used in comparison to the parallel control. The extract of Mucuna pruriens seed significantly (P < 0.05) increased the solubility of sickle haemoglobin at 50%, 25%, 12.5% and 6.25% concentrations, increased Fe^2+/Fe³⁺ ratio from 1.7 (control) to 12.2 (50% concentration) and reduced osmotic fragility (at 12.5% and 6.25% concentrations) when compared with parallel control. The results indicate the feasibility of the seed extracts as promising agents in the management of sickle cell disease.

100 years of sickle cell disease research: etiology, pathophysiology and rational drug design (part 1)

Background

Sickle cell disease (SCD) is a chronic hemolytic disease caused by an altered hemoglobin molecule (HbS) and was first termed as a molecular disease. Glutamic acid in the normal hemoglobin molecule (HbA), was replaced by valine in HbS at the sixth position of both β-chains. This alteration was proved to be due to a single point mutation GTG instead of GAG in the genetic code. Since the discovery of sickle cell disease in 1910, great efforts have been done to study this disease on a molecular level. These efforts aimed to identify the disease etiology, pathophysiology, and finally to discover efficient treatment. Despite the tremendous work of many research groups all over the world, the only approved drug up to this moment, for the treatment of SCD is the hydroxyurea.

Main text

In this review, the antisickling pharmaco-therapeutics will be classified into two major groups: hemoglobin site directed modifiers and ex-hemoglobin effectors. The first class will be discussed in details, here in, focusing on the most important figures in the way of the rational drug design for SCD treatment aiming to help scientists solve the mystery of this problem and to get clear vision toward possible required therapy for SCD.

Conclusion

Despite the large number of the antisickling candidates that have been reached clinical studies yet, none of them has been introduced to the market. This may be due to the fact that hemoglobin is a large molecule with different target sites, which requires highly potent therapeutic agent. With this potency, these drugs should be safe, with acceptable oral pharmacokinetic and pharmacodynamic properties. Such ideal drug candidate needs more efforts to be developed.

Effects of vanillin on potassium bromate-induced neurotoxicity in adult mice: impact on behavior, oxidative stress, genes expression, inflammation and fatty acid composition

CONTEXT

Vanillin is known to possess important antioxidant activity.

OBJECTIVE

The current study was conducted to establish the therapeutic efficiency of vanillin against potassium bromate (KBrO₃)-induced depression-like behavior and oxidative stress in mice.

MATERIAL AND METHODS

Mice were exposed during 15 days either to potassium bromate (KBrO₃), KBrO₃+ vanillin or to only vanillin.

RESULTS

Our results revealed a significant modification in the fatty acid composition of the KBrO₃-treated mice. In addition, KBrO₃ induced a significant reduction in enzymatic activities and gene expressions, Na⁺ -K⁺ and Mg²⁺-ATPases, acetylcholinesterase and butylcholinesterase activities. The gene expression of tumor necrosis factor-α, interleukin-1β, interleukin-6 and COX₂, significantly increased in the cerebrum of KBrO₃-treated group. Histopathological observations were consistent with these effects. Co-treatment with vanillin significantly attenuated KBrO₃-induced oxidative stress and inflammation.

CONCLUSION

This work suggests that vanillin mitigates KBrO₃-induced depression, and that this neuroprotective effect proceeds through anti-oxidant and anti-inflammatory activities.

Filterability of freshly-collected sickle erythrocytes under venous oxygen pressure without exposure to air

We previously found that blood samples collected from steady-state patients with sickle cell disease (SCD) without exposure to air contain a new type of reversibly sickled cells (RSCs) with blunt edges at a level of as high as 78%. Since partial oxygenation of once-deoxygenated sickled cells with pointy edges to near venous oxygen pressure generates similar sickled cells with blunt edges in vitro, we named them as partially oxygenated sickled cells (POSCs). On the other hand, partial deoxygenation of once-oxygenated SS cells to venous oxygen pressure generates partially deoxygenated sickled cells (PDSCs) with pointy edges. In this study, we obtained blood samples from 6 steady-state patients with SCD under venous oxygen pressure without exposure to air, subjected them to various oxygenation/deoxygenation/reoxygenation cycles, and studied their filterability through a membrane filter with pore diameter of 3μm, the theoretical minimum diameter of a capillary. Our results indicated that discocytes, POSCs with blunt edges, and irreversibly sickled cells could deform and pass through the filter, while PDSCs with pointy edges were rigid and could not. The filterability of SS cells seems to be related to the length and amount of deoxy-hemoglobin S fibers in the cells.

Effects of o-vanillin on K⁺ transport of red blood cells from patients with sickle cell disease

Aromatic aldehydes like o-vanillin were designed to reduce the complications of sickle cell disease (SCD) by interaction with HbS, to reduce polymerisation and RBC sickling. Present results show that o-vanillin also directly affects RBC membrane permeability. Both the K(+)-Cl(-) cotransporter (KCC) and the Ca(2+)-activated K(+) channel (or Gardos channel) were inhibited with IC50 of about 0.3 and 1 mM, respectively, with activities almost completely abolished by 5 mM. Similar effects were observed in RBCs treated with the thiol reacting reagent N-ethylmaleimide or with the Ca(2+) ionophore A23187, to circumvent any action via HbS polymerisation. The deoxygenation-induced cation conductance (sometimes termed P(sickle)) was partially inhibited, whilst deoxygenation-induced exposure of phosphatidylserine was completely abrogated. Na(+)/K(+) pump activity was also reduced. Notwithstanding, o-vanillin stimulated K(+) efflux through an unidentified pathway and resulted in reduction in cell volume (as measured by wet weight-dry weight). These actions are relevant to understanding how aromatic aldehydes may affect RBC membrane permeability per se as well as HbS polymerisation and thereby inform design of compounds most efficacious in ameliorating the complications of SCD.

Vanilla--its science of cultivation, curing, chemistry, and nutraceutical properties

Vanilla is a tropical orchid belonging to the family Orchidaceae and it is mainly used in food, perfumery, and pharmaceutical preparations. The quality of the bean depends on the volatile constituent's, viz., the vanillin content, the species of the vine used, and the processing conditions adopted. Hence, proper pollination during flowering and curing by exercising utmost care are the important aspects of vanilla cultivation. There are different methods of curing, and each one is unique and named after the places of its origin like Mexican process and Bourbon process. Recently, Central Food Technological Research Institute, Mysore has developed know-how of improved curing process, where the green vanilla beans are cured immediately after harvest and this process takes only 32 days, which otherwise requires minimum of 150-180 days as reported in traditional curing methods. Vanillin is the most essential component of the 200 and odd such compounds present in vanilla beans. Vanillin as such has not shown any antioxidant properties, it is along with other compounds has got nutraceutical properties and therefore its wide usage. The medicinal future of vanilla may definitely lie in further research on basic science and clinical studies on the constituents and their mechanism of action.

Therapeutic strategies to alter the oxygen affinity of sickle hemoglobin

The pathophysiology of sickle cell disease involves the polymerization of sickle hemoglobin in its T state, which develops under low oxygen saturation. One therapeutic strategy is to develop pharmacologic agents to stabilize the R state of hemoglobin, which has higher oxygen affinity and is expected to have slower kinetics of polymerization, potentially delaying the sickling of red cells during circulation. This strategy has stimulated the investigation of aromatic aldehydes, aspirin derivatives, thiols, and isothiocyanates that can stabilize the R state of hemoglobin in vitro. One representative aromatic aldehyde agent, 5-hydoxymethyl-2-furfural, protects sickle cell mice from the effects of hypoxia.

Investigation of sickle-cell haemoglobin polymerisation under electrochemical control

We describe an electrochemistry-based technique to control and monitor the polymerisation of sickle-cell haemoglobin (HbS). The polymerisation was monitored as a change in turbidity during the depletion of oxygen in a small volume custom-built thin-layer electrochemical cell. The cell allowed the investigation of HbS polymerisation as a function of HbS concentration, temperature and solution pH. We confirm that the oxygen was efficiently depleted using finite-element modelling to accurately recreate the electrochemical thin-layer cell. Understanding the nucleation and growth of HbS polymerisation will provide a better understanding of the pathophysiology of sickle-cell disease in vivo, and thus help improve therapeutic strategies for this common and frequently disabling disorder.

Phytomedicines and nutraceuticals: alternative therapeutics for sickle cell anemia

Sickle cell anemia is a genetically inherited disease in which the "SS" individual possesses an abnormal beta globin gene. A single base substitution in the gene encoding the human β -globin subunit results in replacement of β 6 glutamic acid by valine, leading to the devastating clinical manifestations of sickle cell disease. This substitution causes drastic reduction in the solubility of sickle cell hemoglobin (HbS) when deoxygenated. Under these conditions, the HbS molecules polymerize to form long crystalline intracellular mass of fibers which are responsible for the deformation of the biconcave disc shaped erythrocyte into a sickle shape. First-line clinical management of sickle cell anemia include, use of hydroxyurea, folic acid, amino acids supplementation, penicillinprophylaxis, and antimalarial prophylaxis to manage the condition and blood transfusions to stabilize the patient's hemoglobin level. These are quite expensive and have attendant risk factors. However, a bright ray of hope involving research into antisickling properties of medicinal plants has been rewarding. This alternative therapy using phytomedicines has proven to not only reduce crisis but also reverse sickling (in vitro). The immense benefits of phytomedicines and nutraceuticals used in the management of sickle cell anemia are discussed in this paper.

Carbon tetrachloride-induced nephrotoxicity and DNA damage in rats

In this study, the protective effects of vanillin were evaluated against carbon tetrachloride (CCl4)-induced kidney damages in Wistar albino rats. CCl4 (1 ml/kg, intraperitoneally [i.p.]) caused a significant induction of renal disorder, oxidative damage and DNA fragmentation as evidenced by increased plasma creatinine, urea and uric acid levels, increased lipid peroxidation (malondialdehyde [MDA]) and protein carbonyl. Furthermore, glutathione levels, catalase, superoxide dismutase, glutathione transferase and glutathione peroxidase activities were significantly decreased. A smear without ladder formation on agarose gel was also shown, indicating random DNA degradation. Pretreatment of rats with vanillin (150 mg/kg/day, i.p.), for 3 consecutive days before CCl4 injection, protected kidney against the increase of MDA and degradation of membrane proteins compared to CCl4-treated rats and exhibited marked prevention against CCl4-induced nephropathology, oxidative stress and DNA damage. Kidney histological sections showed glomerular hypertrophy and tubular dilatation in CCl4-treated rats, however, in vanillin pretreated rats, these histopathological changes were less important and present a similar structure to that of control rats. These data indicated the protective role of vanillin against CCl4-induced nephrotoxicity and suggested its significant contribution of these beneficial effects.

Effect of vanillin and ethyl vanillin on cytochrome P450 activity in vitro and in vivo

Food safety is of extreme importance to human health. Vanillin and ethyl vanillin are the widely used food additives and spices in foods, beverages, cosmetics and drugs. The objective of the present work was to evaluate the impact of vanillin and ethyl vanillin on the activities of CYP2C9, CYP2E1, CYP3A4, CYP2B6 and CYP1A2 in human liver microsomes (HLM) in vitro, and impact on the activities of CYP1A2, CYP2C, CYP3A and CYP2E1 in rat liver microsomes (RLM) in vivo. The in vitro results demonstrated that vanillin and ethyl vanillin had no significant effect on the activity of five human CYP450 enzymes with concentration ranged from 8 to 128 μM. However, after rats were orally administered vanillin or ethyl vanillin once a day for seven consecutive days, CYP2E1 activity was increased and CYP1A2 activity was decreased in RLM. The in vivo results revealed that drug interaction between vanillin/ethyl vanillin and the CYP2E1/CYP1A2-metabolizing drugs might be possible, and also suggested that the application of the above additives in foods and drugs should not be unlimited so as to avoid the adverse interaction.

Crystallographic analysis of human hemoglobin elucidates the structural basis of the potent and dual antisickling activity of pyridyl derivatives of vanillin

Vanillin has previously been studied clinically as an antisickling agent to treat sickle-cell disease. In vitro investigations with pyridyl derivatives of vanillin, including INN-312 and INN-298, showed as much as a 90-fold increase in antisickling activity compared with vanillin. The compounds preferentially bind to and modify sickle hemoglobin (Hb S) to increase the affinity of Hb for oxygen. INN-312 also led to a considerable increase in the solubility of deoxygenated Hb S under completely deoxygenated conditions. Crystallographic studies of normal human Hb with INN-312 and INN-298 showed that the compounds form Schiff-base adducts with the N-terminus of the α-subunits to constrain the liganded (or relaxed-state) Hb conformation relative to the unliganded (or tense-state) Hb conformation. Interestingly, while INN-298 binds and directs its meta-positioned pyridine-methoxy moiety (relative to the aldehyde moiety) further down the central water cavity of the protein, that of INN-312, which is ortho to the aldehyde, extends towards the surface of the protein. These studies suggest that these compounds may act to prevent sickling of SS cells by increasing the fraction of the soluble high-affinity Hb S and/or by stereospecific inhibition of deoxygenated Hb S polymerization.

Protective effect of vanillin against carbon tetrachloride (CCl4)-induced oxidative brain injury in rats

This study investigated the protective effects of vanillin against acute brain damage induced by carbon tetrachloride (CCl4) in rats. The study was performed on 32 male rats divided into four groups: a control group, vanillin group ([Va] 150 mg/kg/day, intraperitoneally [i.p.]) and CCl4 toxication groups received a single injection of CCl4 (1 ml/kg, i.p.; CCl4 and Va + CCl4 groups). The degree of protection in brain tissue was evaluated by the levels of malondialdehyde (MDA), glutathione (GSH), superoxide dismutase, glutathione transferase, glutathione peroxidase and nitric oxide (NO). Vanillin showed a significant brain-protective effect by decreasing the level of lipid peroxidation and NO2 and elevated the activities of antioxidative enzymes and level of GSH. Consequently vanillin blocked oxidative brain damage induced by CCl4 in rats.

Evaluation of the antioxidant, anti-inflammatory and hepatoprotective properties of vanillin in carbon tetrachloride-treated rats

The antioxidant and anti-inflammatory effects of vanillin are considered as important forces in the protection against liver injury and fibrosis. This study investigated the protective effects of vanillin against carbon tetrachoride (CCl(4))-induced hepatotoxicity in rat. Pretreatment with vanillin prior the administration of CCl(4) significantly prevented the decrease of protein synthesis and the increase in plasma alanine (ALT) and aspartate (AST) aminotransferases. Furthermore, it inhibited hepatic lipid peroxidation (MDA) and protein carbonyl (PCO) formation and attenuated the (CCl(4))-mediated depletion of antioxidant enzyme catalase and superoxide dismutase (SOD) activities and glutathione level (GSH) in the liver. In addition, vanillin markedly attenuated the expression levels of pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) and prevented CCl(4)-induced hepatic cell alteration and necrosis, as indicated by liver histopathology. These findings suggest that the antioxidant and anti-inflammatory effects of vanillin against CCl(4)-induced acute liver injury may involve its ability to block CCl(4)-generated free radicals.

A comprehensive review on vanilla flavor: Extraction, isolation and quantification of vanillin and others constituents

Vanilla, being the world's most popular flavoring materials, finds extensive applications in food, beverages, perfumery and pharmaceutical industry. With the high demand and limited supply of vanilla pods and the continuing increase in their cost, numerous efforts of blending and adulteration in natural vanilla extracts have been reported. Thus, to ensure the quality of vanilla extracts and vanilla-containing products, it is important to develop techniques to verify their authenticity. Quantitatively, vanillin is the major compound present in the vanilla pods and the determination of vanillin is a vital consideration in natural vanilla extracts. This paper provides a comprehensive account of different extraction processes and chromatographic techniques applied for the separation, identification and determination of chemical constituents of vanilla. The review also provides an account of different methods applied for the quantification and the authentification of chemical constituents of vanilla extract. As the various properties of vanilla are attributed to its main constituent vanillin, its physico-chemical and bioactive properties have also been outlined.

Prodrugs for the treatment of neglected diseases

Recently, World Health Organization (WHO) and Medicins San Frontieres (MSF) proposed a classification of diseases as global, neglected and extremely neglected. Global diseases, such as cancer, cardiovascular and mental (CNS) diseases represent the targets of the majority of the R&D efforts of pharmaceutical companies. Neglected diseases affect millions of people in the world yet existing drug therapy is limited and often inappropriate. Furthermore, extremely neglected diseases affect people living under miserable conditions who barely have access to the bare necessities for survival. Most of these diseases are excluded from the goals of the R&D programs in the pharmaceutical industry and therefore fall outside the pharmaceutical market. About 14 million people,mainly in developing countries, die each year from infectious diseases. From 1975 to 1999,1393 new drugs were approved yet only 1% were for the treatment of neglected diseases[3]. These numbers have not changed until now, so in those countries there is an urgent need for the design and synthesis of new drugs and in this area the prodrug approach is a very interesting field. It provides, among other effects, activity improvements and toxicity decreases for current and new drugs, improving market availability. It is worth noting that it is essential in drug design to save time and money, and prodrug approaches can be considered of high interest in this respect. The present review covers 20 years of research on the design of prodrugs for the treatment of neglected and extremely neglected diseases such as Chagas' disease (American trypanosomiasis), sleeping sickness (African trypanosomiasis), malaria, sickle cell disease, tuberculosis, leishmaniasis and schistosomiasis.

Blood samples collected under venous oxygen pressure from patients with sickle cell disease contain a significant number of a new type of reversibly sickled cells: constancy of the percentage of sickled cells in individual patients during steady state

We found various levels of a new type of reversibly sickled cell (RSC) with blunt edges in 44 blood samples obtained from 32 steady-state patients with sickle cell disease (SCD) without exposure to air (UnExp-blood). Because these RSCs could be generated in vitro by partial oxygenation of once-deoxygenated SS cells to venous oxygen pressure, we named them "partially oxygenated sickled cells" (POSCs). These RSCs were classified into elongated and non-elongated RSCs, depending on the ratio of the short axis to long axis. The presence of these cells was previously unknown because the standard blood collection method oxygenates most of the POSCs to discocytes due to oxygen in the air space in the needle, syringe, and blood collection tube (Exp-blood). Although the shape of elongated POSCs is similar to that of irreversibly sickled cells (ISCs), POSCs revert to discocytes upon exposure to air. We found the following: (1) the percentage of total sickled cells (total POSCs + ISCs) in UnExp-blood (29.0 +/- 14.5%) was significantly higher than the percentage of sickled cells (mainly ISCs) in Exp-blood (7.3 +/- 5.7%); (2) the percentage of sickled cells in UnExp-blood was specific to individual patients during steady state, while it decreased at the onset of a vaso-occlusive event; and (3) the percentage of sickled cells in UnExp-blood varied widely among steady-state patients (4-56%). This new type of RSC may be used as an internal biomarker to evaluate the disease state of individual patients.

5-hydroxymethyl-2-furfural modifies intracellular sickle haemoglobin and inhibits sickling of red blood cells

In an attempt to find new types of anti-sickling agents that specifically bind to intracellular sickle haemoglobin (HbS) without inhibition by plasma and tissue proteins or other undesirable consequences, we identified 5-hydroxymethyl-2-furfural (5HMF), a naturally occurring aromatic aldehyde, as an agent that fulfils this criterion. Preliminary studies in vitro showed that 5HMF forms a high-affinity Schiff-base adduct with HbS and inhibits red cell sickling by allosterically shifting oxygen equilibrium curves towards the left. Further studies with transgenic (Tg) sickle mice showed that orally administered 5HMF was rapidly absorbed into the bloodstream from the gastrointestinal tract without being destroyed, traversed the red blood cell membrane and specifically bound with, and modified, HbS molecules at levels as high as 90%. Pretreatment of Tg sickle mice with 5HMF inhibited the formation of sickle cells and significantly prolonged survival time under severe hypoxia, compared with untreated mice, which died within 15 min because of sickling-dependent pulmonary sequestration. These results indicate the feasibility of 5HMF as an attractive potential candidate for therapy of sickle cell disease.