Allantoin Research Articles

Chitosan and neem gum-based polyelectrolyte complex for design of allantoin loaded biocomposite film: In-vitro, ex-vivo, and in-vivo characterization

Presently, the preference for chitosan (CS) and gum polysaccharides in biomedical applications including drug delivery and wound healing has been extensively documented. Despite this, the demerits of CS and gum polysaccharides such as poor mechanical properties, degradation rate, swelling, etc., limit their applications for designing biocomposite films for drug delivery. Therefore, the anticipated work aims to design a CS and neem gum polysaccharides (NGP) polyelectrolyte complex-based allantoin (AT)-loaded (CS/NGP-AT) biocomposite film for improved wound healing. In brief, CS, NGP, and CS/NGP-AT-based biocomposite films were prepared using the solvent-casting method, and in-vitro, ex-vivo, and in-vivo characterizations were performed to assess the performance of these biocomposite films compared to their counterparts. In this, diffractogram and thermogram analysis assured the conversion of crystalline AT into an amorphous form. The optimized CS/NGP/AT-3 formulation exhibited controlled water absorption, appropriate water uptake capacity, good water retention ability, excellent water vapor transmission rate, controlled degradation rate, enhanced mechanical properties, cell and blood biocompatibility, etc. Furthermore, it offered improved antimicrobial, anti-inflammatory, and antioxidant potential. The optimized film provided a modified release (88.3 ± 0.3 %) of AT from the film for up to 48 h. Wound healing experiments on rats and their histopathology studies confirmed a significantly higher rate of wound recovery within 14 days compared to the control and CS/NGP film, attributable to the combined effects of CS, NGP, and AT. In conclusion, the fabricated CS/NGP-based biocomposite film presents promising prospects as an excellent candidate for wound healing applications.

Chia (Salvia hispanica L.) seed mucilage (a heteropolysaccharide) based antimicrobial hydrogel scaffold for wound healing: In vitro-in-vivo characterization

Wound healing is an intricate process necessitating the utilization of innovative bioactive materials to enhance and expedite recovery. Polysaccharide-based hydrogels for wound dressing have garnered significant attention due to their commendable biocompatibility, biodegradability, and non-toxic properties. Consequently, this study will design zinc oxide nanoparticles (ZnONP) and allantoin (AT) incorporated chia seed mucilage (CSM) based antimicrobial hydrogel scaffold via solvent casting method to accelerate the wound healing process. The confirmation of an ideal CSM/20 %ZnONP/AT hydrogel scaffold is achieved through spectral analysis and assessment of mechanical properties. The scaffold exhibits notable characteristics, including 36.99 % of porosity, 20.34 degrees of swelling, 63.38 % of water retention capacity, and 11.16 % of moisture content. Importantly, the hydrogel demonstrates no cytotoxicity towards normal cell lines (log p > 0.05), high drug loading efficiency (98.75 %), and 34.16 % release of AT within 8 h, following a first-order release (R2 = 0.9892). Additionally, it manifests good antibacterial and antifungal activity attributed to the presence of ZnONP within the scaffold. In vivo studies conducted using a Wistar rat model displayed a substantial reduction in wound size (90.70 %) within 14 days compared to the control group. Histopathological analysis indicates the dynamic progression of the healing process facilitated by the application of AT in conjunction with CSM and ZnONP. The enhanced performance of the CSM/20 %ZnONP/AT hydrogel scaffold is attributed to the distinctive characteristics of CSM, ZnONP, and AT. This study anticipates that CSM-based hydrogel scaffolds will pave the way for novel and promising applications in the field of wound healing.

Fabrication and characterization of an antibacterial chitosan-coated allantoin-loaded NaCMC/SA skin scaffold for wound healing applications

The field of tissue engineering has recently emerged as one of the most promising approaches to address the limitations of conventional tissue replacements for severe injuries. This study introduces a chitosan-coated porous skin scaffold based on sodium carboxymethyl cellulose (NaCMC) and sodium alginate (SA) hydrogels, incorporating allantoin (AL) as an antibacterial agent. The NaCMC/SA hydrogel was cross-linked with epichlorohydrin (ECH) and freeze-dried to obtain a three-dimensional porous structure. The coated and non-coated scaffolds underwent comprehensive evaluation and characterization through various in-vitro analyses, including SEM imaging, swelling, degradation, and mechanical assessments. Furthermore, the scaffolds were studied regarding their allantoin (AL) release profiles, antibacterial properties, cell viability, and cell adhesion. The in-vitro analyses revealed that adding a chitosan (CS) coating and allantoin (AL) to the NaCMC/SA hydrogel significantly improved the scaffolds' antibacterial properties and cell viability. It was observed that the NaCMC:SA ratio and ECH concentration influenced the swelling capacity, biodegradation, drug release profile, and mechanical properties of the scaffolds. Samples with higher NaCMC content exhibited enhanced swelling capacity, more controlled allantoin (AL) release, and improved mechanical strength. Furthermore, the in-vivo results demonstrated that the proposed skin scaffold exhibited satisfactory biocompatibility and supported cell viability during wound healing in Wistar rats, highlighting its potential for clinical applications.

The Mechanism of Frabot Test for Uric Acid

Uric acid is an Analyte. Excess uric acid ─ hyperuricemia ─ leads to gout and renal stones. Frabot noted that uric acid added to an alkaline tungstate solution developed an intense blue colour. A colorimetric method widely utilized to quantify uric acid depends on the reduction of the chromogen sodium tungstate by uric acid to produce a measurable colour change. The reaction route from the initial products to the coloured compounds and the oxido-degradation of the organic substance has not been advanced. In this communication the electron flow is given in each step of the series of reactions that take place. These are isomerization to imidol, Michael addition to enone, oxirane formation in a redox step, hydrolysis of imido group, oxirane ring opening, ring contraction to five- member ring, ring opening via alkoxide, and finally assisted decarboxylation to the end product, 5-ureido hydantoin (allantoin).

The role of the allantoin in promoting fracture healing in osteoclast-deficient zebrafish.

Fracture healing is a rigorous and orderly process with multiple steps that are mediated by multiple cells. During this process, osteoclast-mediated bone remodeling plays a critical role, and its abnormal activity leads not only to fracture susceptibility but also to impaired fracture healing. However, few studies have focused on impaired healing caused by osteoclast defects, and clinical drugs for this type of impaired fracture healing are still lacking. The cell types and regulatory pathways in the zebrafish skeletal system are highly similar to those of mammals, making the zebrafish skeletal system being widely used for skeletal-related studies. To study the process of fracture healing disorders caused by osteoclast defects and discover potential therapeutic drugs, we established an in vivo osteoclast-deficient fracture model using a previously generated fms gene mutant zebrafish (fmsj4e1). The results showed that reduced functional osteoclasts could affect fracture repair in the early stages of fracture. Then we applied an in vitro scale culture system to screen for osteoclast-activating drugs. We found the small molecule compound allantoin (ALL) being able to activate osteoclasts. Subsequently, we verified the activation role of ALL on osteoclasts and the promotion of fracture repair in an in vivo fmsj4e1 fracture defect model. Finally, by examining the osteoclastogenesis and maturation process, we found that ALL may promote osteoclast maturation by regulating RANKL/OPG, thus promoting fmsj4e1 fracture healing. Our study provides a potential new approach for the future improvement of fracture healing disorders caused by osteoclast defects.

Allantoin Inhibits Compound 48/80-Induced Pseudoallergic Reactions In Vitro and In Vivo.

Pseudoallergic reactions are hypersensitivity reactions mediated by an IgE-independent mechanism. Since allantoin (AT)-mediated pseudoallergy has not been studied, in this study, our objective is to investigate the anti-pseudoallergy effect of AT and its underlying mechanism. In vitro, β-hexosaminidase (β-Hex) and histamine (HIS) release assays, inflammatory cytokine assays, toluidine blue staining, and F-actin microfilament staining were used to evaluate the inhibitory effect of AT in RBL-2H3 cells stimulated with Compound 48/80 (C48/80). Western blot analysis is further performed to investigate intracellular calcium fluctuation-related signaling pathways. In vivo, Evans Blue extraction, paw swelling, and the diameter of Evans Blue extravasation were evaluated, and skin tissues are examined for histopathological examination in mice with passive cutaneous anaphylaxis (PCA) induced by C48/80. Body temperature is measured, and the levels of cytokines are further determined by ELISA kits in mice with active systemic anaphylaxis (ASA) induced by C48/80. The results show that AT dose-dependently inhibited degranulation in C48/80-stimulated RBL-2H3 cells by inhibiting β-Hex and HIS release, reducing the levels of TNF-α, IL-8, and MCP-1, inhibiting shape changes due to degranulation and disassembling the F-actin cytoskeleton. Furthermore, AT dose-dependently inhibits the phosphorylation of PLCγ and IP3R. In vivo, AT decreased Evans Blue extravasation, paw swelling, and the diameter of Evans Blue extravasation and significantly ameliorate pathological changes and mast cell degranulation in C48/80-induced PCA. Furthermore, AT help the mice recover from the C48/80-induced decrease in body temperature and decreased the levels of cytokines in C48/80-treated ASA mice. Our results indicate that allantoin inhibits compound 48/80-induced pseudoallergic reactions. AT has the potential to be used in IgE-independent anti-allergic and anti-inflammatory therapies.

Formulation, optimization and characterization of allantoin-loaded chitosan nanoparticles to alleviate ethanol-induced gastric ulcer: in-vitro and in-vivo studies

Allantoin (ALL) is a phytochemical possessing an impressive array of biological activities. Nonetheless, developing a nanostructured delivery system targeted to augment the gastric antiulcerogenic activity of ALL has not been so far investigated. Consequently, in this survey, ALL-loaded chitosan/sodium tripolyphosphate nanoparticles (ALL-loaded CS/STPP NPs) were prepared by ionotropic gelation technique and thoroughly characterized. A full 24 factorial design was adopted using four independently controlled parameters (ICPs). Comprehensive characterization, in vitro evaluations as well as antiulcerogenic activity study against ethanol-induced gastric ulcer in rats of the optimized NPs formula were conducted. The optimized NPs formula, (CS (1.5% w/v), STPP (0.3% w/v), CS:STPP volume ratio (5:1), ALL amount (13 mg)), was the most convenient one with drug content of 6.26 mg, drug entrapment efficiency % of 48.12%, particle size of 508.3 nm, polydispersity index 0.29 and ζ-potential of + 35.70 mV. It displayed a sustained in vitro release profile and mucoadhesive strength of 45.55%. ALL-loaded CS/STPP NPs (F-9) provoked remarkable antiulcerogenic activity against ethanol-induced gastric ulceration in rats, which was accentuated by histopathological, immunohistochemical (IHC) and biochemical studies. In conclusion, the prepared ALL-loaded CS/STPP NPs could be presented to the phytomedicine field as an auspicious oral delivery system for gastric ulceration management.

Mechanistic Insight of Allantoin in Protecting Tomato Plants Against Ultraviolet C Stress.

Allantoin ((AT) a purine metabolite)-mediated ultraviolet C (UVC) stress mitigation has not been studied to date. Here, we reported the physicochemical mechanisms of UVC-induced stress in tomato (Solanum lycopersicum L.) plants, including an AT-directed mitigation strategy. UVC stress reduced plant growth and photosynthetic pigments. Heatmap and principal component analysis (PCA) revealed that these toxic impacts were triggered by the greater oxidative damage and disruption of osmolyte homeostasis. However, pre-treatment of AT noticeably ameliorated the stress-induced toxicity as evident by enhanced chlorophyll, soluble protein, and soluble carbohydrate contents in AT-pretreated UVC-stressed plants relative to only stressed plants leading to the improvement of the plant growth and biomass. Moreover, AT pre-treatment enhanced endogenous AT and allantoate content, phenylalanine ammonia-lyase, non-enzymatic antioxidants, and the enzymatic antioxidants leading to reduced oxidative stress markers compared with only stressed plants, indicating the protective effect of AT against oxidative damage. Moreover, PCA displayed that the protective roles of AT strongly associate with the improved antioxidants. On the other hand, post-treatment of AT showed less efficacy in UVC stress mitigation relative to pre-treatment of AT. Overall, this finding illustrated that AT pre-treatment could be an effective way to counteract the UVC stress in tomato, and perhaps in other crop plants.

A case report and discussion of Lichen myxedematosus

A case of myxedematous lichen is reported. A 60 years old male presented with pigmentation and pruritus for 2 years, and aggravated for 1 month. He was admitted to Hainan Fifth People's Hospital on March 6, 2019. Two years ago, there was no obvious inducement for the patient to have plaque on his face, which gradually increased, hardened and appeared dark brown pigmentation. With the gradual development of the disease, trunk skin appeared rough, hypertrophy, hardening and pigmentation, hand joints appeared stiff and affected activity. Special examination showed diffuse yellowish brown patches and plaques on the forehead, which were distributed in a grid shape, and scattered with atrophic hypopigmentation spots. Black and brown patches were scattered on the back, partially fused into pieces. Sclerotic and atrophic white plaques can be seen in the neck. The skin of the front chest and back is slightly thickened, and obviously hardened. It can still be pinched up. The skin lesions have no tenderness. The joints of the fingers are stiff and the movement is limited. Skin biopsy: The trochanterellus of epidermis disappeared, fibroblasts were arranged in the whole dermis, and some of them were disordered. Ashen blue staining showed that there were clumps of positive material deposition between collagen fibers and around hair follicles in the whole dermis, which was consistent with lichen myxedematosus (LM). The patient was treated with thalidomide 50 mg 3 times a day, prednisone 30 mg orally and acitretin 10 mg twice a day orally, combined with twice a week photochemical therapy (PUVA), external application of allantoin ointment, desonide cream, Halometasone Cream. On June 10, 2019, the patient's condition gradually became stable when he came to the follow-up visit, so the drug dosage was reduced to prednisone 15 mg once a day and acitretin 10 mg twice a day, once a week for photochemical therapy, and topical plaster continued. On September 8, 2019, the patient's condition was further improved when he came to the follow-up visit, so the patient's oral medication was reduced to acitretin 10 mg/d, and allantoin ointment was applied externally. On December 1, 2019, the patient's condition had improved significantly (the patient refused to take photos). Continued treatment was given to the case. 摘要： 报道1例黏液水肿性苔藓案例。患者男,60岁,因全身皮肤变硬伴色素沉着、瘙痒2年,加重1月,于2019年3 月6日就诊于海南省第五人民医院。患者2年前无明显诱因面部皮肤出现斑块,并逐渐增大、变硬及出现黑褐色色素 沉着。随病情逐渐发展,躯干皮肤出现粗糙,肥厚,变硬及色素沉着,手关节出现僵硬且影响活动。专科检査额部见弥 漫性黄褐色斑片、斑块,呈网格状分布,其上散在萎缩性色素减退斑。背部散在黑褐色斑片,部分融合成片。颈部可见 硬化萎缩性白色斑块。前胸后背皮肤轻度增厚,明显变硬,仍可捏起,皮损无触痛。指关节较僵硬,活动受限。皮肤病 理活检:表皮突变平消失,真皮全层见较多的成纤维细胞排列,部分混乱,阿申蓝染色:真皮全层的胶原纤维间、毛囊周 围见团块状阳性物质沉积,结合临床符合黏液水肿性苔藓（Lichen myxedematosus,LM)。予以沙利度胺50 mg 3次/d,强 的松30 mg顿服及阿维A 10mg2次/d 口服治疗,并结合每周两次的光化学疗法(PUVA),外擦尿囊素软膏、地奈德乳 膏,卤米松乳膏。2019年6月10日患者前来复诊时病情逐渐稳定,遂将药物用量减至强的松15 mg顿服及阿维A 10 mg 2次/d,每周一次光化学疗法,外用膏药继续。2019年9月8日患者前来复诊,病情进一步好转,遂将患者口服药 物减为阿维A 10 mg/d,外擦尿囊素软膏。2019年12月1日患者再次前来复诊,病情已明显好转(患者拒绝拍照）。遂对 该病例临床症状及治疗进行讨论。

A Systematic Review on Urinary Biomarkers for Early Diagnosis of Alzheimer’s Disease (AD)

Alzheimer’s disease (AD) is a neurodegenerative disease that commonly affects the older population whose symptoms are only visible during the later stage which renders the available treatment ineffective. Our study attempts to provide a solution to this problem by identifying urinary biomarkers that could be used in the first-line screening of a larger population for AD before analysing with more sophisticated blood and CSF based biomarkers, which provide high sensitivity on comparison. A systematic review was performed using the keywords “Alzheimer”, “urine”, “biomarkers” and “metabolomics” following the PRISMA criteria, to identify urinary biomarkers for the early diagnosis of Alzheimer’s disease. From the performed study, three metabolites were identified namely 5-hydroxy indole acetic acid, L-arginine and allantoin as biomarkers whose level was altered in AD samples compared to controls. In AD, 5-hydroxy indole acetic acid level was downregulated in urine probably because of the extensive serotonergic denervation that has been observed in the AD brain. Increased levels of L-arginine in the brain which act as a precursor to nitric oxide due to the action of NO synthase might potentially lead to neurotoxicity when present in excess, and is also known to be in synergy with ROS. Increased levels of allantoin in urine is due to the action of increased ROS in the system reacting with uric acid. Here, we provide an overview of all the reported metabolites obtained from the search, by discussing their influence in AD pathology. This study identified three metabolites in urine that could function as potential biomarkers for AD based on significant changes observed between disease and control samples, along with its recurrence and commonality in different models namely mice and human. However, longitudinal and cross-sectional follow-up studies are required for the validation of these biomarkers.

Fabrication of bioinspired chitosan/gelatin/allantoin biocomposite film for wound dressing application

A biocomposite film composed of biopolymers chitosan (CS), gelatin (GE) and allantoin (AT) was fabricated by solution casting technique. The functional group interaction of the biocomposite films was inspected through the Attenuated total reflectance Fourier transform spectrometer (ATR-FTIR). The morphological changes and crystallinity of biocomposite films with varied ratios of chitosan/gelatin (CS/GE) and allantoin were examined under Scanning electron microscope (SEM) and X-ray diffractometer (XRD). The water-absorbing capacity was found enhanced by an increase in the chitosan ratio. The biocomposite films exhibit good antioxidant, anti-inflammatory properties. The biocomposite films also display enhanced stability with steady degradation under the PBS medium. The biocomposite films reveal improved antibacterial activity against Escherichia coli (E.coli) and Staphylococcus aureus (S.aureus). Blood compatibility studies explore the non-hemolytic nature. The in vitro cytotoxicity by MTT assay shows excellent biocompatibility. The fibroblast adhesion on the biocomposite film displays enhanced proliferation and viability. These significant biological properties of biocomposite film make it an appropriate candidate for wound dressing application.

Bacterial Isolate Inhabiting Spitsbergen Soil Modifies the Physiological Response of Phaseolus coccineus in Control Conditions and under Exogenous Application of Methyl Jasmonate and Copper Excess.

The aim of the study was to demonstrate the potential of the promotion and regulation of plant physiology and growth under control and copper stress conditions, and the impact of the exogenous application of methyl jasmonate on this potential. Runner bean plants were treated with methyl jasmonate (1 or 10 µM) (J; J1 or J10) and Cu (50 µM), and inoculated with a bacterial isolate (S17) originating from Spitsbergen soil, and identified as Pseudomonas luteola using the analytical profile index (API) test. Above- and under-ground plant parts were analyzed. The growth parameters; the concentration of the photosynthetic pigments, elements, flavonoids (FLAVO), phenolics (TPC), allantoin (ALLA), and low molecular weight organic acids (LMWOAs); the activity of antioxidant enzymes and enzymes of resistance induction pathways (e.g., superoxide dismutase (SOD), catalase (CAT), ascorbate (APX) and guaiacol (GPX) peroxidase, glucanase (GLU), and phenylalanine (PAL) and tyrosine ammonia-lyase (TAL)), and the antioxidant capacity (AC) were studied. The leaves exhibited substantially higher ALLA and LMWOA concentrations as well as PAL and TAL activities, whereas the roots mostly had higher activities for a majority of the enzymes tested (i.e., SOD, CAT, APX, GPX, and GLU). The inoculation with S17 mitigated the effect of the Cu stress. Under the Cu stress and in the presence of J10, isolate S17 caused an elevation of the shoot fresh weight, K concentration, and TAL activity in the leaves, and APX and GPX (also at J1) activities in the roots. In the absence of Cu, isolate S17 increased the root length and the shoot-to-root ratio, but without statistical significance. In these conditions, S17 contributed to a 236% and 34% enhancement of P and Mn, respectively, in the roots, and a 19% rise of N in the leaves. Under the Cu stress, S17 caused a significant increase in FLAVO and TPC in the leaves. Similarly, the levels of FLAVO, TPC, and AC were enhanced after inoculation with Cu and J1. Regardless of the presence of J, inoculation at Cu excess caused a reduction of SOD and CAT activities, and an elevation of GPX. The effects of inoculation were associated with the application of Cu and J, which modified plant response mainly in a concentration-dependent manner (e.g., PAL, TAL, and LMWOA levels). The conducted studies demonstrated the potential for isolate S17 in the promotion of plant growth.

5-N-Carboxyimino-6-N-chloroaminopyrimidine-2,4(3H)-dione as a hypochlorite-specific oxidation product of uric acid.

Although uric acid is known to react with many reactive oxygen species, its specific oxidation products have not been fully characterized. We now report that 5-N-carboxyimino-6-N-chloroaminopyrimidine-2,4(3H)-dione (CCPD) is a hypochlorite (ClO−)-specific oxidation product of uric acid. The yield of CCPD was 40–70% regardless of the rate of mixing of ClO− with uric acid. A previously reported product, allantoin (AL), was a minor product. Its yield (0–20%) decreased with decreasing rate of mixing of ClO− with uric acid, indicating that allantoin is less important in vivo. Kinetic studies revealed that the formation of CCPD required two molecules of ClO− per uric acid reacted. The identity of CCPD was determined from its molecular formula (C5H3ClN4O4) measured by LC/time-of-flight mass spectrometry and a plausible reaction mechanism. This assumption was verified by the fact that all mass fragments (m/z −173, −138, −113, and −110) fit with the chemical structure of CCPD and its tautomers. Isolated CCPD was stable at pH 6.0–8.0 at 37°C for at least 6 h. The above results and the fact that uric acid is widely distributed in the human body at relatively high concentrations indicate that CCPD is a good marker of ClO− generation in vivo.

Исследование закономерностей синтеза аллантоина

Исследование закономерностей синтеза аллантоина

Effect of allantoin on the stabilization efficiency of Ca–Zn thermal stabilizers for poly(vinyl chloride)

The influence of allantoin (ALL) combined with zinc stearate (ZnSt2), calcium stearate (CaSt2), and ZnSt2–CaSt2 (1:1), respectively, in different mass ratios on thermal stability of poly(vinyl chloride) (PVC) was investigated by Congo red test, discoloration test, and thermogravimetric analysis. The results indicated that ALL behaved as a good long-term thermal stabilizer for PVC, which was attributed to its ability to absorb hydrogen chloride released from the degradation of PVC. Moreover, ALL was able to extend the stabilization time of PVC containing ZnSt2–CaSt2 and postpone “zinc burning.” Fourier transform infrared spectra confirmed that ALL can react with ZnCl2 to produce an inert complex, which is responsible for postponing “zinc burning.”

METABOLISM OF PURINE NUCLEOSIDES AND BASES IN SUSPENSION-CULTURED ARABIDOPSIS THALIANA CELLS

We study the metabolism of purine nucleosides and purine bases in suspension-cultured cells of the model plant Arabidopsis thaliana . [8- 14 C]Adenosine, [8- 14 C]guanosine, [8- 14 C]inosine, [8- 14 C]xanthosine, [8- 14 C]adenine, [8- 14 C]guanine, [8- 14 C]hypoxanthine and [8- 14 C]xanthine were administered to cells in the cell division phase, and the uptake and metabolic fate of these compounds were monitored for 4h. The rates of uptake of most purines were within the range 60-70 nmol/gFW. Xanthine and xanthosine were taken up more slowly. The rate of uptake was ordered as hypoxanthine > adenine > inosine > guanosine > guanine > adenosine > xanthosine> xanthine. A large amount of radioactivity from [8- 14 C]adenosine, [8- 14 C]guanosine, [8- 14 C]adenine and [8- 14 C]guanine, and a limited amount from [8- 14 C]inosine and [8- 14 C]hypoxanthine, was incorporated into nucleotides and RNA. The so-called purine salvage pathways of adenosine, guanosine, adenine, guanine, inosine and hypoxanthine are therefore functional in A. thaliana . These tracer experiments also reveal that significant amounts of these compounds were converted to xanthine, and enter the catabolic pathway via allantoin. Neither xanthosine nor xanthine is used in the synthesis of nucleotides and RNA. These compounds are entirely catabolized via allantoin and allantoic acid. Deamination of adenine and guanine rings takes place at the stage of AMP deaminase and guanosine deaminase, respectively. The pattern of purine metabolism in A. thaliana is similar to that in other plants. Adenine salvage activity estimated from the metabolism of [8- 14 C]adenine, the cellular concentration of ATP, and expression of the APT1 gene encoding adenine phosphoribosyltransferase all increased markedly at the lag phase of cell proliferation . These observations imply that the salvage pathway is important during the early stages of cell culture in A. thaliana .

Characterization of the gene cluster involved in allantoate catabolism and its transcriptional regulation by the RpiR-type repressor HpxU in Klebsiella pneumoniae.

Bacteria, fungi, and plants have metabolic pathways for the utilization of nitrogen present in purine bases. In Klebsiella pneumoniae, the genes responsible for the assimilation of purine ring nitrogen are distributed in three separated clusters. We characterized the gene cluster involved in the metabolism of allantoate (genes KPN_01761 to KPN_01771). The functional assignments of HpxK, as an allantoate amidohydrolase, and of HpxU, as a regulator involved in the control of allantoate metabolism, were assessed experimentally. Gene hpxU encodes a repressor of the RpiR family that mediates the regulation of this system by allantoate. In this study, the binding of HpxU to the hpxF promoter and to the hpxU-hpxW intergenic region containing the divergent promoter for these genes was evidenced by electrophoretic mobility shift assays. Allantoate released the HpxU repressor from its target operators whereas other purine intermediate metabolites, such as allantoin and oxamate, failed to induce complex dissociation. Sequence alignment of the four HpxU identified operators identified TGAA-N8-TTCA as the consensus motif recognized by the HpxU repressor.

Development and validation of a method for allantoin determination in liposomes and pharmaceutical formulations

The aim of this work was to develop and validate an ultraviolet derivative spectrophotometric (UVDS) method for the quantitative determination of allantoin (ALL) in liposomes, gels and creams. Liposomes were prepared by methods of thin film hydration and mechanical agitation. Solutions of ALL in 0.1mol/L NaOH with ethanol:water (70:30, v/v) were prepared in order to destroy liposome vesicles. Spectral interference from components of liposomes, cream, gel and ALL degradation products was eliminated using the second-order derivative of the zero-order spectrum. Characterization of ALL in 0.1mol/L NaOH was carried out by direct infusion mass spectrometry. Absorbances of ALL solutions were measured at 266.6nm of the second-derivative spectrum and linearity was observed in the ALL concentration range of 50–300μgmL−1 (correlation coefficient (r)=0.9961). The mean recovery percentage was 100.68±1.61, repeatability expressed as relative standard deviation (RSD) was 1.07 and 2.12%, and intermediate precision (RSD) was 2.16%. The proposed UVDS method was found to be linear, precise, accurate, robust and selective, providing rapid and specific determination of ALL in raw materials and in topical formulations.

Magnetized water induces changes in the antioxidant properties of some medicinal plants extracts

Magnetized water or clustered water is an effective solvent and has the ability to dissolve the nutrients easier and faster than purified water. The objective was to explore the effect of magnet on the constituents of aqueous medicinal plants extracts. Aqueous extracts (infusion or overnight; 1% w/v) of Cinnamomum verum (cinnamon) bark, Salvia officinalis (sage) leaves, Zingiber officinale Rosc (ginger) tuberous and Symphytum officinale (comfrey) seeds were prepared and then divided into two parts, one part was exposed to magnetic disc (0.15 Tesla) for 1 hour. The UV-visible spectra of each extract were obtained and the total flavonoids, allantoin and the reducing power were determined. The UV-visible spectra showed changes in the magnitude of the absorbance peak, appearance of new peaks and shifted peaks in the magnetized aqueous extract compared with non-magnetized extracts. The changes in the total flavonoids, allantoin and the reducing power in the magnetized extract did not follow specific pattern. The magnet induces changes in the constituents of medicinal plants via its effect on the electrical properties of water. Key words: Medicinal plants, magnet, antioxidants

Control of Allantoin Accumulation in Comfrey

Comfrey, a medicinal herb with healing properties that are attributed to allantoin, was studied in this work. The accumulation and metabolism of allantoin (ALN) and its degradation product, allantoic acid (ALA), were examined. ALN was the main ureide in leaves and roots, with young leaves showing the highest content. ALA was the predominant ureide in the xylem sap, and together with ALN represented 27% of the nitrogen (N) transported in the xylem. Amino acids were the most abundant N-compound in the xylem sap with a high proportion of glutamine. [14C]Xanthine feeding experiments showed that ALN and ALA were actively formed in leaves and roots by degradation of xanthine. Both xanthine and uric acid were rapidly degraded to form ALN and ALA. Enzyme studies showed that calculated V max /K m are low for allantoinase and alantoicase, supporting the results from the feeding experiments, and indicating that accumulation of ALN in comfrey is due to a low capacity for the enzymatic degradation of ureides.