Levodopa Research Articles

Analytical assessment of a novel RP-HPLC method for the concurrent quantification of selected pharmaceutical drugs levodopa and carbidopa using eight greenness metrics comparing to the lean six sigma approach

BackgroundIntegrating green chemistry principles into analytical processes is vital for sustainability and accuracy. AimThis study is dedicated to finding eco-friendly solutions that replace harmful substances and reduce waste production. The suggested work examined eight tools for assessing the greenness and sustainability of a newly validated RP-HPLC technique that quantitatively determines levodopa (LEV) and carbidopa (CAR) drugs in their bulk and pharmaceutical formulations. We also incorporated the lean six sigma methodology to ensure accuracy and efficiency. MethodThe optimal liquid chromatographic conditions (HPLC) for achieving the highest resolution and results in our method are as follows: employing a mobile phase composition consisting of a mixture of phosphate buffer pH 2.2 and ethanol (90:10 v/v) at a flow rate of 1 mL/min, using a C18 column (150 mm × 4.6 mm) and employing an isocratic mode of elution at a wavelength of 280 nm. ResultsThe calibration curves were established for LEV and CAR in the 3–50 μg/mL range to study the linearity with coefficients of determination (R2 ∼0.999). The study determined that the limits of detection (LOD) and quantification (LOQ) for LEV were 1.95 μg/mL and 5.93 μg/mL, respectively. Meanwhile, the results for CAR were 0.67 μg/mL and 2.04 μg/mL for LOD and LOQ, respectively. The developed method has demonstrated accuracy and validity in the simultaneous determination and quantification of LEV and CAR, with a relative standard deviation (RSD) of less than 2%. The method's accuracy was confirmed through recovery studies, demonstrating significant results within the acceptable range of 98–102%. Specifically, the recovery test values for LEV and CAR were 99.75% and 98.97%, respectively. ConclusionThe specificity and selectivity of the developed method have been revealed through forced degradation studies conducted through The International Council for Harmonization (ICH) criteria. The technique could determine and quantify the two drugs even in the presence of their degradants. Our proposed approach beats the previous HPLC methods in adherence to green chemistry principles, providing reliable and precise outcomes with better qualitative and quantitative metrics. It's the most effective and eco-friendly solution for chemical analysis.

Levodopa-induced orthostatic hypotension in parkinsonism: A red flag of autonomic failure.

Levodopa (LD) is the main treatment for parkinsonism, but its use may be limited by a potential hypotensive effect. We evaluated the cardiovascular effect of LD performing head-up tilt test (HUTT) before and 60 min after 100/25 mg LD/dopa-decarboxylase inhibitor (pre-LD vs. post-LD HUTT) in 164 patients with parkinsonism on chronic LD treatment. Features predictive of LD-induced orthostatic hypotension (OH) were assessed by logistic regression analysis. Basal supine blood pressure (BP) and heart rate (HR) decreased after LD. During post-LD HUTT, BP drop and HR increase were significantly greater than at pre-LD HUTT. Thirty-eight percent of patients had OH at post-LD HUTT compared to 22% of patients presenting OH at pre-LD HUTT (p < 0.001). Risk factors for LD-induced/worsened OH were pre-LD OH (odds ratio [OR] = 36, 95% confidence interval [CI] = 10-131), absence of overshoot at Valsalva maneuver (OR = 9, 95% CI = 4-20), and pathological Valsalva ratio (OR = 6, 95% CI = 2-15). LD administration caused/worsened hypotension in both supine and orthostatic conditions. Patients with cardiovascular autonomic failure had a higher risk of developing LD-induced OH. In clinical practice, LD-induced OH could represent a red flag for cardiovascular autonomic failure.

Investigation of PRKN Mutations in Levodopa-Induced Dyskinesia in Parkinson's Disease Treatment.

Mitophagy is an important process that participates in mitochondrial quality control. Dysfunctions in this process can be caused by mutations in genes like PRKN and are associated with the development and progression of Parkinson's Disease (PD). The most used drug in the treatment of PD is levodopa (LD), but it can cause adverse effects, such as dyskinesia. Currently, few studies are searching for biomarkers for an effective use of lLD for this disease, especially regarding mitophagy genetics. Thus, this work investigates the association of 14 variants of the PRKN gene with LD in the treatment of PD. We recruited 70 patients with PD undergoing treatment with LD (39 without dyskinesia and 31 with dyskinesia). Genotyping was based on Sanger sequencing. Our results reinforce that age at onset of symptoms, duration of PD, and treatment and dosage of LD can influence the occurrence of dyskinesia but not the investigated PRKN variants. The perspective presented here of variants of mitophagy-related genes in the context of treatment with LD is still underexplored, although an association has been indicated in previous studies. We suggest that other variants in PRKN or in other mitophagy genes may participate in the development of levodopa-induced dyskinesia in PD treatment.

Dihydroxyphenylacetaldehyde Lowering Treatment Improves Locomotor and Neurochemical Abnormalities in the Rat Rotenone Model: Relevance to the Catecholaldehyde Hypothesis for the Pathogenesis of Parkinson's Disease.

The catecholaldehyde hypothesis for the pathogenesis of Parkinson's disease centers on accumulation of 3,4-dihydroxyphenylacetaldehyde (DOPAL) in dopaminergic neurons. To test the hypothesis, it is necessary to reduce DOPAL and assess if this improves locomotor abnormalities. Systemic administration of rotenone to rats reproduces the motor and central neurochemical abnormalities characterizing Parkinson's disease. In this study, we used the monoamine oxidase inhibitor (MAOI) deprenyl to decrease DOPAL production, with or without the antioxidant N-acetylcysteine (NAC). Adult rats received subcutaneous vehicle, rotenone (2 mg/kg/day via a minipump), or rotenone with deprenyl (5 mg/kg/day i.p.) with or without oral NAC (1 mg/kg/day) for 28 days. Motor function tests included measures of open field activity and rearing. Striatal tissue was assayed for contents of dopamine, DOPAL, and other catechols. Compared to vehicle, rotenone reduced locomotor activity (distance, velocity and rearing); increased tissue DOPAL; and decreased dopamine concentrations and inhibited vesicular sequestration of cytoplasmic dopamine and enzymatic breakdown of cytoplasmic DOPAL by aldehyde dehydrogenase (ALDH), as indicated by DA/DOPAL and DOPAC/DOPAL ratios. The addition of deprenyl to rotenone improved all the locomotor indices, increased dopamine and decreased DOPAL contents, and corrected the rotenone-induced vesicular uptake and ALDH abnormalities. The beneficial effects were augmented when NAC was added to deprenyl. Rotenone evokes locomotor and striatal neurochemical abnormalities found in Parkinson's disease, including DOPAL buildup. Administration of an MAOI attenuates these abnormalities, and NAC augments the beneficial effects. The results indicate a pathogenic role of DOPAL in the rotenone model and suggest that treatment with MAOI+NAC might be beneficial for Parkinson's disease treatment.

Classification of l-DOPA pharmacokinetics shapes and creating a predictive model

BackgroundIt is known that the pharmacokinetics (PK) of levodopa (LD) varies considerably. Difference in PK shapes is expected to affect drug efficacy and development of dyskinesia. In this study, the authors aimed to explore correlations between PK series data of LD and clinical characteristics and dyskinesia in patients with Parkinson's disease (PD). MethodsWe studied 270 PD patients who underwent PK assessment after administration of LD/carbidopa (100/10 mg) in non-compartmental analysis. The patients were grouped according to similarities in time series data of blood LD concentration. Each group was analyzed with respect to clinical characteristics and PK parameters. We created a model to predict PK patterns based on these findings. ResultsPD patients were divided into three groups by clustering analysis: blood LD concentration of the patients in Groups 1 (n = 129), 3 (n = 44) and 2 (n = 97) rose rapidly, relatively slowly and at an intermediate rate, respectively. There were no statistically significant differences in patient characteristics except age among the three groups (one-way ANOVA). Multivariate analysis showed that frequency of dyskinesias in Group 1 was significantly higher than that in Group 2. We successfully created a PK pattern prediction model based on body weight and blood LD concentration at 15 and 30 min after administration. ConclusionsThe PK series data of LD was classified into three patterns. The rapid absorption was associated with dyskinesias. Patients’ PK patterns were successfully predicted based on their body weight and two-point LD concentration.

Metabolic Pathway Reconstruction Indicates the Presence of Important Medicinal Compounds in Coffea Such as L-DOPA.

The use of transcriptomic data to make inferences about plant metabolomes is a useful tool to help the discovery of important compounds in the available biodiversity. To unveil previously undiscovered metabolites of Coffea, of phytotherapeutic and economic value, we employed 24 RNAseq libraries. These libraries were sequenced from leaves exposed to a diverse range of environmental conditions. Subsequently, the data were meticulously processed to create models of putative metabolic networks, which shed light on the production of potential natural compounds of significant interest. Then, we selected one of the predicted compounds, the L-3,4-dihydroxyphenylalanine (L-DOPA), to be analyzed by LC-MS/MS using three biological replicates of flowers, leaves, and fruits from Coffea arabica and Coffea canephora. We were able to identify metabolic pathways responsible for producing several compounds of economic importance. One of the identified pathways involved in isoquinoline alkaloid biosynthesis was found to be active and producing L-DOPA, which is a common product of POLYPHENOL OXIDASES (PPOs, EC 1.14.18.1 and EC 1.10.3.1). We show that coffee plants are a natural source of L-DOPA, a widely used medicine for treatment of the human neurodegenerative condition called Parkinson's disease. In addition, dozens of other compounds with medicinal significance were predicted as potential natural coffee products. By further refining analytical chemistry techniques, it will be possible to enhance the characterization of coffee metabolites, enabling a deeper understanding of their properties and potential applications in medicine.

Calcineurin inhibition protects against dopamine toxicity and attenuates behavioral decline in a Parkinson’s disease model

BackgroundParkinson’s disease (PD), a highly prevalent neuro-motor disorder is caused due to progressive loss of dopaminergic (DAergic) neurons at substantia nigra region of brain. This leads to depleted dopamine (DA) content at striatum, thus affecting the fine tuning of basal ganglia. In patients, this imbalance is manifested by akinesia, catalepsy and tremor. PD associated behavioral dysfunctions are frequently mitigated by l-DOPA (LD) therapy, a precursor for DA synthesis. Due to progressive neurodegeneration, LD eventually loses applicability in PD. Although DA is cytotoxic, it is unclear whether LD therapy can accelerate PD progression or not. LD itself does not lead to neurodegeneration in vivo, but previous reports demonstrate that LD treatment mediated excess DA can potentiate neurotoxicity when PD associated genetic or epigenetic aberrations are involved. So, minimizing DA toxicity during the therapy is an absolute necessity to halt or slowdown PD progression. The two major contributing factors associated with DA toxicity are: degradation by Monoamine oxidase and DAquinone (DAQ) formation.ResultsHere, we report that apoptotic mitochondrial fragmentation via Calcineurin (CaN)-DRP1 axis is a common downstream event for both these initial cues, inhibiting which can protect cells from DA toxicity comprehensively. No protective effect is observed, in terms of cell survival when only PxIxIT domain of CaN is obstructed, demonstrating the importance to block DRP1-CaN axis specifically. Further, evaluation of the impact of DA exposure on PD progression in a mice model reveal that LD mediated behavioral recovery diminishes with time, mostly because of continued DAergic cell death and dendritic spine loss at striatum. CaN inhibition, alone or in combination with LD, offer long term behavioral protection. This protective effect is mediated specifically by hindering CaN-DRP1 axis, whereas inhibiting interaction between CaN and other substrates, including proteins involved in neuro-inflammation, remained ineffective when LD is co-administered.ConclusionsIn this study, we conclude that DA toxicity can be circumvented by CaN inhibition and it can mitigate PD related behavioral aberrations by protecting neuronal architecture at striatum. We propose that CaN inhibitors might extend the therapeutic efficacy of LD treatment.

Brainstem Modulates Parkinsonism-Induced Orofacial Sensorimotor Dysfunctions.

Parkinson's Disease (PD), treated with the dopamine precursor l-3,4-dihydroxyphenylalanine (L-DOPA), displays motor and non-motor orofacial manifestations. We investigated the pathophysiologic mechanisms of the lateral pterygoid muscles (LPMs) and the trigeminal system related to PD-induced orofacial manifestations. A PD rat model was produced by unilateral injection of 6-hydroxydopamine into the medial forebrain bundle. Abnormal involuntary movements (dyskinesia) and nociceptive responses were determined. We analyzed the immunodetection of Fos-B and microglia/astrocytes in trigeminal and facial nuclei and morphological markers in the LPMs. Hyperalgesia response was increased in hemiparkinsonian and dyskinetic rats. Hemiparkinsonism increased slow skeletal myosin fibers in the LPMs, while in the dyskinetic ones, these fibers decreased in the contralateral side of the lesion. Bilateral increased glycolytic metabolism and an inflammatory muscle profile were detected in dyskinetic rats. There was increased Fos-B expression in the spinal nucleus of lesioned rats and in the motor and facial nucleus in L-DOPA-induced dyskinetic rats in the contralateral side of the lesion. Glial cells were increased in the facial nucleus on the contralateral side of the lesion. Overall, spinal trigeminal nucleus activation may be associated with orofacial sensorial impairment in Parkinsonian rats, while a fatigue profile on LPMs is suggested in L-DOPA-induced dyskinesia when the motor and facial nucleus are activated.

Effect of the mGlu4 positive allosteric modulator ADX-88178 on parkinsonism, psychosis-like behaviours and dyskinesia in the MPTP-lesioned marmoset.

Positive allosteric modulation of metabotropic glutamate type 4 (mGlu4) receptors is a promising strategy to alleviate parkinsonian disability and L-3,4-dihydroxyphenylalanine (L-DOPA) induced dyskinesia. ADX-88178 is a highly selective mGlu4 positive allosteric modulator (PAM) that previously enhanced the anti-parkinsonian action of L-DOPA in the 6-hydroxydopamine-lesioned rat model of Parkinson's disease (PD). We sought to explore the effects of ADX-88178 on psychosis-like behaviours (PLBs) in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned marmoset. We also aimed to determine the effect of ADX-88178 on parkinsonism and dyskinesia. Six MPTP-lesioned marmosets were administered L-DOPA chronically to induce stable PLBs and dyskinesias. They were then administered ADX-88178 (0.01, 0.1 and 1mg/kg) or vehicle, in combination with L-DOPA/benserazide (15/3.75mg/kg), both sub-cutaneously, in a randomised fashion. PLBs, parkinsonism and dyskinesia were then measured. ADX-88178 mildly worsened global PLBs at the dose of 1mg/kg (by 13%, P = 0.020). L-DOPA alone conferred 158min of on-time, while the duration of on-time was 212min (34% increase, P = 0.011), after adding ADX-88178 1mg/kg to L-DOPA. Accordingly, ADX-88178 1mg/kg reduced global parkinsonian disability, by 38% (P = 0.0096). ADX-88178 1mg/kg diminished peak dose dyskinesia by 34% (P = 0.015). Minimal effects were provided by lower doses. Whereas these results provide additional evidence of the anti-parkinsonian and anti-dyskinetic effects of mGlu4 positive allosteric modulation as an adjunct to L-DOPA, they also suggest that ADX-88178 may exacerbate dopaminergic psychosis. Further studies are needed to evaluate this possible adverse effect of mGlu4 PAMs on PD psychosis.

The 5-HT2A/2C inverse agonist nelotanserin alleviates L-DOPA-induced dyskinesia in the MPTP-lesioned marmoset.

Nelotanserin is a serotonin 2A and 2C (5-HT2A/2C) inverse agonist that was previously tested in the clinic for rapid-eye movement sleep behaviour disorder and psychosis in patients with Parkinson's disease (PD) dementia. Its effect on L-3,4-dihydroxyphenylalanine (L-DOPA)-induced dyskinesia has however not been investigated. As 5-HT2A antagonism/inverse agonism is a validated approach to alleviate dyskinesia, we undertook the current study to evaluate the anti-dyskinetic potential of nelotanserin in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned marmoset. Parkinsonism was induced in six common marmosets (Callithrix jacchus, three females and three males) that were then chronically treated with L-DOPA to induce dyskinesia. On experimental days, they were administered L-DOPA in combination with vehicle or nelotanserin (0.1, 0.3 and 1mg/kg) subcutaneously, in a randomised fashion. Dyskinesia and parkinsonism were rated post hoc by a blinded observer. In comparison to vehicle, the addition of nelotanserin 0.3 and 1mg/kg to L-DOPA diminished peak dose dyskinesia by 47% (P < 0.05) and 69% (P < 0.001). Nelotanserin 0.3 and 1mg/kg also reduced the severity of global dyskinesia, by 40% (P < 0.01) and 55% (P < 0.001), when compared to vehicle. Nelotanserin 0.1mg/kg did not alleviate peak dose or global dyskinesia severity. Nelotanserin had no impact on the anti-parkinsonian action of L-DOPA. Our results highlight that nelotanserin may represent an efficacious anti-dyskinetic drug and provide incremental evidence of the potential benefit of 5-HT2A/2C antagonism/inverse agonism for drug-induced dyskinesia in PD.

Importance of time to ON versus wearing OFF in total daily OFF time experienced by patients with Parkinson's disease

Most patients with Parkinson's disease (PD) receiving levodopa (LD)/DOPA decarboxylase inhibitors develop motor fluctuations with an increasing amount of OFF time, negatively impacting patient quality of life. Herein, we review the evidence supporting the substantial, yet underappreciated contribution of delays in time to ON (including delayed ON and no ON) to total daily OFF time. Most clinical studies use patient diaries that do not capture time to ON and wearing OFF separately as related to LD dosing, and consequently, most OFF time has generally been attributed to wearing OFF. Hence, most treatment regimens focus on reducing wearing OFF by changing LD dosing/formulations and/or using “ON-extenders” (eg, catechol-o-methyltransferase inhibitors, monoamine oxidase-B inhibitors, extended-release amantadine, and adenosine A2A receptor antagonists). However, the literature describing approved treatments for PD that has focused on delays in time to ON is sparse and suggests this type of OFF may comprise more than twice the amount of total daily OFF time as wearing OFF. Here, we advocate for the importance of measuring and adequately addressing delays in time to ON and build support for the consistent inclusion of the time to ON measurement in future clinical trials.

Novel liposomal formulations for protection and delivery of levodopa: Structure-properties correlation

Liposomes are promising drug carriers for a wide range of central nervous system disorders, such as Parkinson’s disease (PD), since they can protect active substances from degradation and could be administered intranasally, ensuring a direct access to the brain. Levodopa (LD), the drug commonly used to treat PD, spontaneously oxidizes in aqueous solutions and thus needs to be stabilized. Our investigation focuses on the preparation and the physico-chemical characterization of mixed liposomes to vehiculate LD and two natural substances (L-ascorbic acid and quercetin) that can prevent its oxidation and contribute to the treatment of Parkinson's disease. These co-loaded vesicles were prepared using a saturated phospholipid and structurally related cationic or analogue N-oxide surfactants and showed different properties, based on their composition. In particular, ex-vivo permeability tests using porcine nasal mucosa were performed, denoting that subtle variations of the lipids structure can significantly affect the delivery of LD to the target site.

Construction of Pt/Pt-Au doped chiral nanostructures using arginine and porphyrin assemblies as templates for enantioselective photocatalysis

Chiral nanomaterials with different functions have been widely developed, but the deep understanding of the structural effects of nanocatalysts on enantioselective photocatalytic efficiency is still highly demanded. Herein, Pt and Pt-Au-bimetal-doped chiral nanostructures with various morphologies and compositions are facilely constructed using L-/D-arginine (L-/D-Arg) and mono-sulfonate tetraphenyl porphyrin (H2TPPS) assemblies as chiral templates. Interestingly, these Pt and Pt-Au-doped chiral nanostructures, including nanorods (NR) and nanospheres (NS), can be well regulated by controlling pH, ionic strength, and reaction time of the assembling system of Arg and H2TPPS. More impressively, specific Au growth direction along the Pt-doped chiral NR (L-/D-Pt-NR) is observed (from tip to middle) during the preparation of Pt-Au-bimetal-doped chiral NR (L-/D-Pt-Au-NR) and their compositions can be finely controlled by simply adjusting the concentrations of HAuCl4. As expected, the chiral nanostructures exhibit superior enantioselective photocatalytic ability toward chiral organics under visible light: the oxidation rate of L-dihydroxy-phenylalanine (L-DOPA) catalyzed by L-Pt-NR (or D-DOPA catalyzed by D-Pt-NR) is about 60% higher than that of L-DOPA catalyzed by D-Pt-NR (or L-DOPA catalyzed by D-Pt-NR). This study provides a facile strategy to construct chiral nanostructures for the photocatalytic conversion of chiral organics.

The mGluR2/3 orthosteric agonist LY-404,039 reduces dyskinesia, psychosis-like behaviours and parkinsonism in the MPTP-lesioned marmoset.

LY-404,039 is an orthosteric agonist of metabotropic glutamate 2 and 3 receptors (mGluR2/3) that may harbour additional agonist effect at dopamine D2 receptors. LY-404,039 and its pro-drug, LY-2140023, have previously entered clinical trials as treatment options for schizophrenia. They could therefore be repurposed, if proven efficacious, for other conditions, notably Parkinson's disease (PD). We have previously shown that the mGluR2/3 orthosteric agonist LY-354,740 alleviated L-3,4-dihydroxyphenylalanine (L-DOPA)-induced dyskinesia and psychosis-like behaviours (PLBs) in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned marmoset. Unlike LY-404,039, LY-354,740 does not stimulate dopamine D2 receptors, suggesting that LY-404,039 may elicit broader therapeutic effects in PD. Here, we sought to investigate the effect of this possible additional dopamine D2-agonist action of LY-404,039 by assessing its efficacy on dyskinesia, PLBs and parkinsonism in the MPTP-lesioned marmoset. We first determined the pharmacokinetic profile of LY-404,039 in the marmoset, in order to select doses resulting in plasma concentrations known to be well tolerated in the clinic. Marmosets were then injected L-DOPA with either vehicle or LY-404,039 (0.1, 0.3, 1 and 10mg/kg). The addition of LY-404,039 10mg/kg to L-DOPA resulted in a significant reduction of global dyskinesia (by 55%, P < 0.01) and PLBs (by 50%, P < 0.05), as well as reduction of global parkinsonism (by 47%, P < 0.05). Our results provide additional support of the efficacy of mGluR2/3 orthosteric stimulation at alleviating dyskinesia, PLBs and parkinsonism. Because LY-404,039 has already been tested in clinical trials, it could be repurposed for indications related to PD.

L-DOPA Receptor GPR143 Functionally Couples with Adrenergic α1B Receptor at the Second Transmembrane Interface.

Adrenergic receptors (ADRs) are widely distributed in the peripheral and central nervous systems. We previously reported that L-3,4-dihydroxyphenylalanine (L-DOPA), the precursor of dopamine, sensitizes adrenergic α1 receptor (ADRA1) through a G protein-coupled receptor GPR143. Chimeric analysis, in which the transmembrane (TM) domains of GPR143 were replaced with those of GPR37, revealed that the second TM region was essential for the potentiation of phenylephrine-induced extracellular signal-regulated kinase (ERK) phosphorylation by GPR143. In HEK293T cells expressing ADRA1B, phenylephrine-induced ERK phosphorylation was augmented by the co-expression of GPR143, compared to the mock vector. Immunoprecipitation analysis revealed that a synthetic transactivator of the transcription peptide fused with TM2 of GPR143 (TAT-TM2) disrupts the interaction between GPR143 and ADRA1B. This TAT-TM2 peptide suppressed the augmentation of phenylephrine-induced ERK phosphorylation by GPR143 in HEK293T cells co-expressing ADRA1B and GPR143. These results indicate that the interaction between GPR143 and ADRA1B is required for the potentiation of ADRA1B-mediated signaling by GPR143. The TM2 region of GPR143 is a crucial dimeric interface for the functional coupling between ADRA1B and GPR143.

Development of a novel vinylene‐linked covalent organic framework decorated with multi‐walled carbon nanotubes for electrochemical detection of tryptophan, uric acid, and 8‐hydroxy‐2′‐deoxyguanosine

AbstractBackgroundIn this study, a vinylene‐linked covalent organic framework (V‐COF‐1) was integrated with multi‐walled carbon nanotubes (MWCNTs) to create a modified electrode (V‐COF‐1/MWCNTs/SPCE) for electrochemical sensing applications.ObjectiveThis research focus to investigate the application of the modified electrode for the simultaneous determination of tryptophan (Trp), uric acid (UA), and 8‐hydroxy‐2'‐deoxyguanosine (8‐OHdG) in human urine samples and the mechanism between V‐COF‐1 and the analytes (Trp, UA, and 8‐OHdG) by studying tryptophan metabolites, dopamine, and L‐3,4‐dihydroxyphenylalanine (L‐DOPA).MethodsThe electrochemical performance of V‐COF‐1/MWCNTs/SPCE was evaluated using differential pulse voltammetry (DPV) and use cyclic voltammetry (CV) to detect the modified electrode to explore its electrochemical properties.ResultsUnder optimized conditions, V‐COF‐1/MWCNTs/SPCE exhibited efficient electron transfer for Trp, UA, and 8‐OHdG, with low detection limits (S/N = 3) of 0.03 μM, 0.06 μM, and 0.006 μM, respectively. The modified electrode demonstrated high selectivity for the target analytes in the presence of interfering species, as well as excellent repeatability and stability. The recoveries of Trp, UA, and 8‐OHdG in human urine samples ranged from 90.6% to 104.8%, which shows that this method has been successfully applied for the simultaneous detection of Trp, UA and 8‐OHdG in biological sample analysis.ConclusionsThe integration of V‐COF‐1 and MWCNTs onto the modified electrode showed promising results for the simultaneous detection of Trp, UA, and 8‐OHdG. The developed sensor exhibited excellent sensitivity, selectivity, repeatability, and stability. These findings contribute to the advancement of electrochemical sensor technology for biomedical applications and highlight the potential of V‐COF‐1/MWCNTs/SPCE in analytical chemistry.

Tyrosinase Inhibitory of Silver Nanoparticles Synthesized using Morus Nigra Leaves Extract

A novel preparation of silver nanoparticles using Morus nigra leaves extract, as opposed to the physical and chemical methods had been used in this work. Their active phytochemical compounds will reduce Ag+ and form AgNPs (Ag0). A peak spectrum at 460 nm was formed and confirmed as the Surface Plasmon Resonance (SPR). Vibration at 1643 cm-1 and 3286 cm-1 which characteristic of C=C bonds and (-OH) hydroxyl groups, respectively. An X-ray diffraction (XRD) examination of silver with good crystallinity revealed its distinctive pattern. According to the results of transmission electron microscopy (TEM), the produced AgNPs-Morus nigra leaves extract were between 10 and 20 nm in size. Using L-dihydroxyphenylalanine (L-DOPA) as the substrate, the synthesized AgNPs-Morus nigra were tested for their tyrosinase inhibitory activity, and the results are substantial when compared to kojic acid as a control. The percentages of inhibition from crude extract, AgNPs, and kojic acid at 100 µg/mL are to be found at 12.10 %, 64.80 %, and 59.84 %, respectively. Based on the results of this work, AgNPs can be produced by utilizing a green synthesis method with leaves extract, making them a promising candidate for use in medicine and cosmetics.

Analisis Potensi Farmakokinetik dan Toksisitas Pada Curcumin (Curcuma xanthorrhiza) Sebagai Brightening Terhadap Reseptor Protein Tirosinase Secara in Silico

Tyrosinase enzyme is an enzyme that plays an important role in melanin synthesis. This enzyme will oxidize the amino acid L-tyrosine into L- 3,4 dihydroxyphenylalanine (L-DOPA) and convert L-DOPA into DOPAquinone. Tyrosinase protein from Bacillus megaterium in complex with inhibitor kojic acid is the target protein that will interact with the ligand (Drug Candidate), Temulawak (Curcuma xanthorrhiza) is one of the medicinal plants of the Zingiberaceae family which is widely grown and used as a raw material for traditional medicine in Indonesia, the main content in Temulawak is curcumin which has antioxidant properties. Antioxidants in curcumin content can be used as ingredients for whitening preparations. In silico tests are used to predict pharmacokinetic activity and toxicity by docking using the Molegro Virtual Docker computer program. The receptor used was Protein Tyrosinase PDB code 3NQ1 with ligand KOJ_B_1351. Prediction of pharmacokinetic properties (ADME) and toxicity of Curcumin and Kojic Acid was performed using the pkCSM online tool program. Data analysis was performed by comparing the binding energy of docking results between Curcumin, Kojic Acid, and ligand on the target receptor. The in silico test results showed that the binding energy of Kurkumin =-142.766 kcal/mol, Kojic Acid = -60.6899 kcal/mol, and KOJ_B_1351 ligand =-62.266 kcal/mol. The results of in silico tests using the pkCSM online tool program show that Kurkumin compounds have good pharmacokinetic properties, and cause relatively low toxicity, and can be used as candidates for whitening materials.

The adenosine A2A receptor antagonist/inverse agonist, KW-6356 enhances the anti-parkinsonian activity of L-DOPA with a low risk of dyskinesia in MPTP-treated common marmosets

The adenosine A2A receptor antagonist/inverse agonist, KW-6356 has been shown to be effective in Parkinson's disease (PD) patients as monotherapy and as an adjunct therapy to L-3,4-dihydroxyphenylalanine (L-DOPA)/decarboxylase inhibitor. However, the effects of KW-6356 combined with L-DOPA on anti-parkinsonian activity and established dyskinesia has not been investigated in preclinical experiments. We examined the effects of combination of KW-6356 with L-DOPA in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated common marmosets. Oral administration of KW-6356 (1 mg/kg) enhanced the anti-parkinsonian activities of various doses of L-DOPA (2.5–10 mg/kg). In MPTP-treated common marmosets primed with L-DOPA to show dyskinesia, KW-6356 (1 mg/kg) also enhanced the anti-parkinsonian activities of various doses of L-DOPA (1.25–10 mg/kg) but not dyskinesia. Chronic co-administration of KW-6356 (1 mg/kg) with a low dose of L-DOPA (2.5 mg/kg) for 21 days increased the degree of dyskinesia induced by the low dose of L-DOPA, but the amplitude of dyskinesia induced by combined administration of KW-6356 (1 mg/kg) with L-DOPA (2.5 mg/kg) was lower than that induced by an optimal dose of L-DOPA (10 mg/kg). These results suggest that KW-6356 can be used to potentiate the effects of a wide range of L-DOPA doses with a low risk of dyskinesia for the treatment of PD.

Anti-parkinsonian activity of the adenosine A2A receptor antagonist/inverse agonist KW-6356 as monotherapy in MPTP-treated common marmosets

KW-6356 is a novel adenosine A2A receptor antagonist/inverse agonist that not only blocks binding of adenosine to adenosine A2A receptor but also inhibits the constitutive activity of adenosine A2A receptor. The efficacy of KW-6356 as both monotherapy and an adjunct therapy to L-3,4-dihydroxyphenylalanine (L-DOPA)/decarboxylase inhibitor in Parkinson's disease (PD) patients has been reported. However, the first-generation A2A antagonist istradefylline, which is approved for use as an adjunct treatment to L-DOPA/decarboxylase inhibitor in adult PD patients experiencing OFF episodes, has not shown statistically significant efficacy as monotherapy. In vitro pharmacological studies have shown that the pharmacological properties of KW-6356 and istradefylline at adenosine A2A receptor are markedly different. However, the anti-parkinsonian activity and effects on dyskinesia of KW-6356 in PD animal models and the differences in the efficacy between KW-6356 and istradefylline are unknown. The present study investigated the anti-parkinsonian activity of KW-6356 as monotherapy in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated common marmosets, and its efficacy was directly compared with that of istradefylline. In addition, we investigated whether or not repeated administration of KW-6356 induced dyskinesia. Oral administration of KW-6356 reversed motor disability in a dose-dependent manner up to 1 mg/kg in MPTP-treated common marmosets. The magnitude of anti-parkinsonian activity induced by KW-6356 was significantly greater than that of istradefylline. Repeated administration of KW-6356 induced little dyskinesia in MPTP-treated common marmosets primed to exhibit dyskinesia by prior exposure to L-DOPA. These results indicate that KW-6356 can be a novel non-dopaminergic therapy as monotherapy without inducing dyskinesia in PD patients.