Synthesis and antitumor activity of dolutegravir derivatives bearing 1,2,3-triazole moieties.

Modification of marketed drugs is an important way to develop drugs because its safety and clinical applicability. Oxygen-nitrogen heterocycles are a class of important active substances discovered in the process of new drug development. Dolutegravir, an HIV drug with a nitrogen-oxygen heterocycle structure, has the potential ability to inhibit cell survival. In order to find and explore novel anti-tumor drugs, new dolutegravir derivatives bearing different 1,2,3-triazole moieties were prepared via click reactions. In vitro biological experiments performed in several lung cancer cell lines suggested that these novel compounds displayed potent anti-tumor ability. Especially, the compound 9e with a substituent of 2-methyl-3-nitrophenyl and the compound 9p with a substituent of 3-trifluoromethylphenyl were effective against PC-9 cell line with IC50 values of 3.83 and 3.17 µM, respectively. Moreover, compounds 9e and 9p were effective against H460 and A549 cells. Further studies suggested that compounds 9e and 9p could induce cancer cell apoptosis in PC-9 and H460, inhibit cancer cell proliferation, change the cell cycle, and increase the level of reactive oxygen species (ROS) which further induce tumor cell apoptosis. In addition, compounds 9e and 9p increased LC3 protein expression which was the key regulator in autophagy signaling pathway in PC-9 cells. Compound 9e also showed low toxicity against normal cells, and could be regarded as an interesting lead compound for further structure optimization.

Discovery of Dolutegravir Derivative against Liver Cancer via Inducing Autophagy and DNA Damage.

We introduced a terminal alkyne into the core structure of dolutegravir, resulting in the synthesis of 34 novel dolutegravir-1,2,3-triazole compounds through click chemistry. These compounds exhibited remarkable inhibitory activities against two hepatocellular carcinoma cell lines, Huh7 and HepG2. Notably, compounds 5e and 5p demonstrated exceptional efficacy, particularly against Huh7 cells, with IC50 values of 2.64 and 5.42 µM. Additionally, both compounds induced apoptosis in Huh7 cells, suppressed tumor cell clone formation, and elevated reactive oxygen species (ROS) levels, further promoting tumor cell apoptosis. Furthermore, compounds 5e and 5p activated the LC3 signaling pathway, inducing autophagy, and triggered the γ-H2AX signaling pathway, resulting in DNA damage in tumor cells. Compound 5e exhibited low toxicity, highlighting its potential as a promising anti-tumor drug.

Design, synthesis and antitumour activity evaluation of novel dolutegravir derivatives.

Based on the modification of the structure of dolutegravir, we introduced 1,2,3-triazole moieties with different substituted groups and obtained a lot of novel dolutegravir derivatives. The activity of A549 cells treated with the derivatives was examined, and most compounds showed good inhibitory effects. Among them, compounds 4b and 4g were the most effective, and inhibited the growth of A549 cells with IC50 values of 8.72 ± 0.11 µM and 12.97 ± 0.32 µM, respectively. In addition, compound 4g induced apoptosis and clonal suppression in A549 tumor cells. Compound 4g also activated the LC3 signaling pathway to induce autophagy in tumor cells, and activated the γ-H2AX signaling pathway to induce DNA damage in tumor cells.

Synthesis and activity study of novel N,N-diphenylurea derivatives as IDO1 inhibitors.

Indoleamine 2,3-dioxygenase 1 (IDO1) has attracted much attention in the field of cancer immunotherapy as an immunomodulatory enzyme. To identify potential IDO1 inhibitors, a novel series of compounds with N,N-diphenylurea and triazole structures were synthesized. The designed compounds underwent organic synthesis, and subsequent enzymatic activity experiments targeting IDO1 confirmed their activity at the molecular level. These experiments provided validation for the efficacy of the designed compounds in inhibiting IDO1, compound 3g exhibited an IC50 value of 1.73 ± 0.97 µM. Further molecular docking study further explained the binding mode and reaction potential of compound 3g with IDO1. Our research has resulted in a series of novel IDO1 inhibitors, which is beneficial to the development of drugs targeting IDO1 in numerous cancer diseases.

Discovery of Novel 1,2,3-triazole Derivatives as IDO1 Inhibitors.

Indoleamine 2,3-dioxygenase 1 (IDO1) has received much attention as an immunomodulatory enzyme in the field of cancer immunotherapy. While several IDO1 inhibitors have entered clinical trials, there are currently no IDO1 inhibitor drugs on the market. To explore potential IDO1 inhibitors, we designed a series of compounds with urea and 1,2,3-triazole structures. Organic synthesis and IDO1 enzymatic activity experiments verified the molecular-level activities of the designed compounds, and the IC50 value of compound 3a was 0.75 µM. Molecular docking and quantum mechanical studies further explained the binding mode and reaction potential of compound 3a with IDO1. Our research has resulted in a series of novel IDO1 inhibitors, which is beneficial to the development of drugs targeting IDO1 in numerous cancer diseases.

Design, synthesis and biological evaluation of erlotinib-based IDO1 inhibitors.

Erlotinib is a highly specific and reversible epidermal growth factor receptor tyrosine kinase inhibitor for the targeted therapy of non-small-cell lung cancer (NSCLC) However, the efficacy of erlotinib is limited because the development of drug resistance during chemotherapy. Indoleamine 2,3-dioxygenase-1 (IDO1) is a rate-limiting tryptophan catabolic enzyme that is activated in many human cancers. In this study, we designed a series of erlotinib-based 1,2,3-triazole compounds by combining erlotinib with phenyl or benzyl azide. Attentive FP prediction model was used to predict the bioactivity of those compounds. We discovered that most of the erlotinib-based 1,2,3-triazole compounds are capable of suppressing IDO1 activities in vitro experiments. Among them, compound 14b (IC50 = 0.59 ± 0.05 µM) had the strongest inhibitory effect on IDO1. In addition, compound 14b significantly inhibited tumor growth comparable to the antitumor activity of erlotinib and the IDO1 inhibitor epacadostat in murine tumor models.

Novel 1,2,3-Triazole Erlotinib Derivatives as Potent IDO1 Inhibitors: Design, Drug-Target Interactions Prediction, Synthesis, Biological Evaluation, Molecular Docking and ADME Properties Studies.

Indoleamine 2,3-dioxygenase 1 (IDO1) plays a predominant role in cancer immunotherapy which catalyzes the initial and rate limiting steps of the kynurenine pathway as a key enzyme. To explore novel IDO1 inhibitors, five derivatives of erlotinib-linked 1,2,3-triazole compounds were designed by using a structure-based drug design strategy. Drug-target interactions (DTI) were predicted by DeePurpose, an easy-to-use deep learning library that contains more than 50 algorithms. The DTI prediction results suggested that the designed molecules have potential inhibitory activities for IDO1. Chemical syntheses and bioassays showed that the compounds exhibited remarkable inhibitory activities against IDO1, among them, compound e was the most potent with an IC50 value of 0.32 ± 0.07 µM in the Hela cell assay. The docking model and ADME analysis exhibited that the effective interactions of these compounds with heme iron and better drug-likeness ensured the IDO1 inhibitory activities. The studies suggested that compound e was a novel and interesting IDO1 inhibitor for further development.

Design, Synthesis, and Antitumor Activity of Erlotinib Derivatives.

Nineteen erlotinib derivatives bearing different 1,2,3-triazole moieties were designed, synthesized, and evaluated for their potential against different cancer cell lines. The structures of the synthesized compounds were confirmed via 1H NMR, 13C NMR, and HR MS. Preliminary antitumor activity assay results suggested that some compounds showed remarkable inhibitory activity against different cancer cell lines including the corresponding drug-resistant ones. Among these compounds, 3d was the most promising one with an IC50 of 7.17 ± 0.73 µM (KYSE70TR), 7.91 ± 0.61 µM (KYSE410TR), 10.02 ± 0.75 µM (KYSE450TR), 5.76 ± 0.3 3 µM (H1650TR), and 2.38 ± 0.17 µM (HCC827GR). A preliminary mechanism study suggested that compound 3d suppressed cancer cell proliferation through the EGFR-TK pathway.

Discovery of a Series of Theophylline Derivatives Containing 1,2,3-Triazole for Treatment of Non-Small Cell Lung Cancer.

Chemotherapy is the most common clinical treatment for non-small cell lung cancer (NSCLC), but low efficiency and high toxicity of current chemotherapy drugs limit their clinical application. Therefore, it is urgent to develop hypotoxic and efficient chemotherapy drugs. Theophylline, a natural compound, is safe and easy to get, and it can be used as a modified scaffold structure and hold huge potential for developing safe and efficient antitumor drugs. Herein, we linked theophylline with different azide compounds to synthesize a new type of 1,2,3-triazole ring-containing theophylline derivatives. We found that some theophylline1,2,3-triazole compounds showed a good tumor-suppressive efficacy. Especially, derivative d17 showed strong antiproliferative activity against a variety of cancer cells in vitro, including H460, A549, A2780, LOVO, MB-231, MCF-7, OVCAR3, SW480, and PC-9. It is worth noting that the two NSCLC cell lines H460 H and A549 are sensitive to compound d17 particularly, with IC50 of 5.929 ± 0.97 µM and 6.76 ± 0.25 µM, respectively. Compound d17 can significantly induce cell apoptosis by increasing the ratio of apoptotic protein Bax/Bcl-2 by downregulating the expression of phosphorylated Akt protein, and it has little toxicity to normal hepatocyte cells LO2 at therapeutic concentrations. These data indicate that these theophylline acetic acid-1,2,3-triazole derivatives may be potential drug candidates for anti-NSCLC and are worthy of further study.

Efficacy and Safety of Rotigotine Transdermal Patch on Neuropsychiatric Symptoms of Parkinson's Disease: An Updated Meta-Analysis and Systematic Review.

Objective: The effects of rotigotine transdermal patch (RTG) on the neuropsychiatric symptoms of Parkinson's disease (PD) outcomes remain controversial. The aim of this review was to determine the efficacy and safety of RTG on the neuropsychiatric symptoms of PD. Methods: In this systematic review and meta-analysis, PubMed, Cochrane Library, EMBASE, and Web of Science were searched for randomized controlled trials comparing RTG and placebo in PD up to May 10, 2021. We analyzed the data using Review Manager 5.2 software. The quality of evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation Approach. In order to avoid false-positive results caused by random error, we use TSA software for trial sequential analysis (TSA). Results: We included 10 studies (1,844 patients). The meta-analysis showed that, compared with placebo, RTG can significantly improve the scores for Apathy Scale (MD = -1.68, 95% confidence interval, CI: -2.74 to -0.62, P = 0.002; moderate certainty), Beck Depression Inventory-II (MD = -1.19, 95% CI: -2.26 to -0.11, P = 0.03; moderate certainty), the Non-Motor Symptoms Scale (MD = -3. 66, 95% CI: -4. 30 to -3.01, P < 0.00001; moderate certainty), the sleep/fatigue domains of the Parkinson's Disease Non-motor Symptom Assessment Scale (MD = -2.03, 95% CI: -3.08 to -0.98, P = 0.0001; moderate certainty), the mood/apathy domains of the Non-motor Symptom Scale (MD = -2.48, 95% CI: -4.07 to -0.89, P = 0.002; high certainty), the eight-item Parkinson's Disease Questionnaire (MD = -4. 93, 95% CI: -6.79 to -3.07, P < 0.00001; moderate certainty), and the 39-item Parkinson's Disease Questionnaire (MD = -3.52, 95% CI: -5.25 to -1.79, P < 0.0001; high certainty). However, there was no statistically significant difference on the Snaith-Hamilton Pleasure Scale (MD = -0.12, 95% CI: -0.58 to 0.34, P = 0.61). Our results showed that RTG exerts a positive effect on sleep. According to the TSA, the results implied that, except for the Beck Depression Inventory-II, conclusive evidence have been obtained in the RTG group. It has been proven in our meta-analysis that rotigotine has good safety and tolerability. Conclusions: RTG can effectively improve the neuropsychiatric symptoms, sleep quality, and quality of life in patients with PD.

Pharmacological Interventions for REM Sleep Behavior Disorder in Parkinson's Disease: A Systematic Review.

To review the therapeutic effects of drugs on REM sleep behavior disorder (RBD) in Parkinson's disease (PD) by searching the MEDLINE/PubMed, Embase, Cochrane, and CBM databases. According to the inclusion and exclusion criteria, studies were included after excluding duplicate data. We evaluated the safety and efficacy of pharmacological intervention to improve RBD in patients with Parkinson's disease (PD-RBD). This systematic review mainly describes the drugs that can be used to treat PD-RBD patients. The results have shown that melatonin can be used as the first-line drug for PD-RBD, and clonazepam provides significant improvement on PD-RBD, androtigotine can be used as an alternative drug. However, further large-scale clinical trial studies are still needed to provide the best guidelines for the pharmacological treatment of PD-RBD.

Discovery of a Series of 1,2,3-Triazole-Containing Erlotinib Derivatives With Potent Anti-Tumor Activities Against Non-Small Cell Lung Cancer.

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are emerging at the vanguard of therapy for non-small-cell lung cancer (NSCLC) patients with EGFR-activating mutations. However, the increasing therapeutic resistance caused by novel mutations or activated bypass pathways has impaired their performance. In this study, we link one of the commercial EGFR-TKIs, Erlotinib, to different azide compounds to synthesize a novel class of 1,2,3-triazole ring-containing Erlotinib derivatives. We discovered that several new compounds show robust antiproliferation activity against diverse NSCLC cells in vitro including PC-9, H460, H1975 and A549. Two of the most potent compounds, e4 and e12 have been found to be more efficient than Erlotinib in all NSCLC cell lines except PC-9. They significantly induce apoptosis and cell cycle arrest in PC-9 and H460 cells. The antitumor efficacy of compound e4 in vivo is close to that of Erlotinib in a PC-9 xenograft mouse model. Most Erlotinib-1,2,3-triazole compounds exhibit moderate to good inhibitory activities toward wild-type EGFR as indicated by enzyme-linked immunosorbent assay (ELISA), and the EGFR phosphorylation was inhibited in H460 and PC-9 cells exposed to e4 or e12. These data suggest that these Erlotinib-1,2,3-triazole compounds are suitable candidates for use against NSCLC and more unknown mechanisms merit further investigation.

Atorvastatin improves motor function, anxiety and depression by NOX2-mediated autophagy and oxidative stress in MPTP-lesioned mice.

Parkinson's disease (PD) is a neurodegenerative disease caused by the loss of dopaminergic neurons. It is characterized by static tremors, stiffness, slow movements, and gait disturbances, but it is also accompanied by anxiety and depression. Our previous study showed that atorvastatin could reduce the risk of PD, but the mechanism is still unclear. In this paper, Our findings showed that atorvastatin increased muscle capacity and the coordination of movement and improved anxiety and depression. Atorvastatin could decrease the expression of α-synuclein Ser129 and NADPH oxidase 2 (NOX2), increase the protein expression of LC3II/I, and promote autophagy flow. To further confirm that atorvastatin protection was achieved by inhibiting NOX2, we injected at midbrain with NOX2 shRNA (M) lentivirus and found that silent NOX2 produced the same effect as atorvastatin. Further research found that atorvastatin could reduce MPTP-induced oxidative stress damage, while inhibiting NOX2 decreased the antioxidative stress effect of atorvastatin. Our results suggest that atorvastatin can improve muscle capacity, anxiety and depression by inhibiting NOX2, which may be related to NOX2-mediated oxidative stress and autophagy. Atorvastatin may be identified as a drug that can effectively improve behavioral disorders. NOX2 may be a potential gene target for new drug development in PD.

Association between thyroglobulin polymorphisms and autoimmune thyroid disease: a systematic review and meta-analysis of case-control studies.

Emerging evidence revealed that thyroglobulin (TG) contributes to the development of autoimmune disease, and the relationship between TG and autoimmune thyroid disease (AITD) is still controversial. The aim of this study was to quantify the association between rs2076740, rs853326, rs180223, and rs2069550 TG polymorphisms and risk of AITD using a meta-analysis approach. We identified all studies that assessed the association between TG polymorphisms and AITD from PubMed, Embase, and Web of Science databases. A total of 3013 cases and 1812 controls from ten case-control studies were included. There was no significant associations found between rs2069550, rs180223, and rs853326 polymorphisms and AITD risk. The association between the rs2076740 polymorphism and AITD risk was significant in the codominant model (P = 0.005), suggesting the CC rs2076740 genotype might be a protective factor for AITD. Sensitivity analysis by removing one or two study changed the results in dominant rs2076740 and rs853326 and rs2069550 allele models (P = 0.016, 0.024, 0.027). Latitude and ethnicity significantly affected the association between rs2076740 and rs2069550 polymorphisms and AITD, indicating their protective effects in allele or dominant model (P = 0.012, 0.012, 0.012, 0.009, 0.009). The association between rs2076740, rs2069550, and rs853326 polymorphisms and AITD risk is significantly affected by study characteristics.

Ketamine attenuates sepsis-induced acute lung injury via regulation of HMGB1-RAGE pathways.

High mobility group box protein 1 (HMGB1) and receptor for the advanced glycation end product (RAGE) play important roles in the development of sepsis-induced acute lung injury (ALI). Ketamine is considered to confer protective effects on ALI during sepsis. In this study, we investigated the effects of ketamine on HMGB1-RAGE activation in a rat model of sepsis-induced ALI. ALI was induced in wild type (WT) and RAGE deficient (RAGE(-/-)) rats by cecal ligation and puncture (CLP) or HMGB1 to mimic sepsis-induced ALI. Rats were randomly divided to six groups: sham-operation+normal saline (NS, 10 mL/kg), sham-operation+ketamine (10 mg/kg), CLP/HMGB1+NS (10 mL/kg), CLP/HMGB1+ketamine (5 mg/kg), CLP/HMGB1+ketamine (7.5 mg/kg), and CLP/HMGB1+ketamine (10 mg/kg) groups. NS and ketamine were administered at 3 and 12 h after CLP/HMGB1 via intraperitoneal injection. Pathological changes of lung, inflammatory cell counts, expression of HMGB1 and RAGE, and concentrations of various inflammatory mediators in bronchoalveolar lavage fluids (BALF) and lung tissue were then assessed. Nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinases (MAPK) signaling pathways in the lung were also evaluated. CLP/HMGB1 increased the wet to dry weight ratio and myeloperoxidase activity in lung, the number of total cells, neutrophils, and macrophages in the BALF, and inflammatory mediators in the BALF and lung tissues. Moreover, expression of HMGB1 and RAGE in lung tissues was increased after CLP. Ketamine inhibited all the above effects. It also inhibited the activation of IκB-α, NF-κB p65, and MAPK. Ketamine protects rats against HMGB1-RAGE activation in a rat model of sepsis-induced ALI. These effects may partially result from reductions in NF-κB and MAPK.

Lidocaine sensitizes the cytotoxicity of cisplatin in breast cancer cells via up-regulation of RARß2 and RASSF1A demethylation.

It has been reported that lidocaine is toxic to various types of cells. And a recent study has confirmed that lidocaine exerts a demethylation effect and regulates the proliferation of human breast cancer cell lines. To recognize a potential anti-tumor effect of lidocaine, we evaluated the DNA demethylation by lidocaine in human breast cancer lines, MCF-7 and MDA-MB-231 cells, and determined the influence of demethylation on the toxicity to these cells of cisplatin, which is a commonly utilized anti-tumor agent for breast cancer. Results demonstrated that lidocaine promoted a significant global genomic demethylation, and particularly in the promoters of tumor suppressive genes (TSGs), RARß2 and RASSF1A. Further, the lidocaine treatment increased cisplatin-induced apoptosis and enhanced cisplatin-induced cytotoxicity. The combined treatment with both lidocaine and cisplatin promoted a significantly higher level of MCF-7 cell apoptosis than singular lidocaine or cisplatin treatment. Moreover, the abrogation of RARß2 or RASSF1A expression inhibited such apoptosis. In conclusion, the present study confirms the demethylation effect of lidocaine in breast cancer cells, and found that the demethylation of RARß2 and RASSF1A sensitized the cytotoxicity of cisplatin in breast cancer cells.

Enhancement of transdermal delivery of ibuprofen using microemulsion vehicle.

OBJECTIVES: The objective of this study was to find a stable microemulsion vehicle for transdermal delivery of ibuprofen to improve the skin permeability. MATERIALS AND METHODS: Microemulsion was prepared using different sorts of oils, surfactants and co-surfactants. Pseudo-ternary phase diagrams were used to evaluate the microemulsion domain. The effects of oleic acid and surfactant mixture on skin permeation of ibuprofen were evaluated with excised skins. RESULTS: The optimum formulation F3 consisting of 6% oleic acid, 30% Cremophor RH40/Transcutol P (2:1, w/w) and 59% water phase, showed a high permeation rate of 42.98 µg/cm(2)/hr. The mean droplet size of microemulsion was about 43 nm and no skin irritation signs were observed on the skin of rabbits. CONCLUSION: These results indicated that this novel microemulsion is a useful formulation for the transdermal delivery of ibuprofen.

[Value of QT hysteresis during treadmill exercise test for diagnosing coronary heart disease].

OBJECTIVE: To investigate the value of QT hysteresis index during treadmill exercise test (TET) in diagnosing coronary heart disease (CHD). METHODS: One hundred consecutive patients suspected for CHD were referred for TET and selective coronary angiography (CAG). Patients were divided into positive [n = 55, age (56.0 ± 7.9) years] and negative [n = 45, age (53.2 ± 6.7) years] group based on their CAG results. For each TET recording, 50 points were selected for the RR, QTp, and QTe interval measurements. QTp and QTe interval was plotted against corresponding RR interval. QT/RR curve was constructed by connect all point, QT hysteresis index was calculated for each patient. RESULTS: The QTp [(22.4 ± 10.3) ms vs. (6.7 ± 4.6) ms, P < 0.001] and QTe [(27.1 ± 11.1) ms vs. (7.6 ± 4.6) ms, P < 0.001] hysteresis index of patients in positive group were significantly higher than those in negative group. The sensitivity of QTp and QTe hysteresis index for diagnosing CHD was 89.1% (49/55) and 94.5% (52/55), respectively, and the specificity was 82.2% (37/45) and 80.0% (36/45), respectively. If the patient fulfilled both the classical TET and QT hysteresis criteria, the sensitivity for diagnosing CHD increased to 94.3% (33/35, QTp) and 94.6% (35/37, QTe), and the specificity were both 100% (26/26, 26/26). Moreover, QTp (r = -0.399, P < 0.001) and QTe (r = -0.547, P < 0.001) hysteresis index highly correlated to Duke treadmill score. CONCLUSION: QT hysteresis index is useful parameter for CHD diagnosis and which could improve the diagnostic value of TET for CHD in combination with the classical TET criteria for diagnosis of CHD.

Effect of erythrocytes on brain water content and haem oxygenase-1 expression in rats with traumatic intracerebral haemorrhage.

BACKGROUND: Studies have demonstrated that brain oedema formation following spontaneous intracerebral haemorrhage is associated with substances derived from blood clots or blood components. However, these studies did not completely reveal the role of blood components in brain oedema formation following traumatic intracerebral haemorrhage (TICH). Here, we explore the role of erythrocytes in brain oedema development by studying the effect of erythrocytes on brain water content (BWC) and expression of haem oxygenase-1 (HO-1) in rats with TICH. METHODS: A total of 120 Sprague-Dawley rats were randomly divided into four experimental treatment groups: traumatic brain injury (TBI), TBI plus whole blood (WB), TBI plus lysed red blood cells (RBCs; LRBC) and TBI plus packed RBCs (PRBC). Following TBI, which was established by applying a free-falling device, WB, LRBC or PRBC were infused with stereotactic guidance into the injured cortex to produce a model of TICH. All rats were killed at 1, 3 or 5 days after TBI or TICH. BWC was measured, and immunohistochemistry for HO-1 was performed. RESULTS: In the WB, PRBC and TBI groups, BWC at 3 days post-TBI or post-TICH was the greatest. However, BWC in the LRBC group at 1 day was markedly higher than that at 3 and 5 days. Comparisons among the four groups showed that BWC in the LRBC group was the highest at 1 day, and the highest at 3 days in the WB and PRBC groups; there was no significant difference at 5 days. Positive expression of HO-1 in the WB, PRBC and LRBC groups coincided with changes in BWC. CONCLUSIONS: Our results indicate that erythrocytes play an important role in delayed brain oedema formation (3 days post-injury) following TICH, but have no significant influence on brain oedema at early stages (1 day post-injury), and that the mechanisms of delayed brain oedema involve RBC breakdown products.

Determination of trace vitamin C by ion-pair HPLC with UV detection in calcium gluconate and vitamin C compound oral solution.

A sensitive and specific reversed-phase high-performance liquid chromatographic method with ultraviolet detection was developed for the determination of vitamin C, using tetrabutylammonium hydroxide as an ion-pair reagent in a compound oral solution containing 100 mg/mL calcium gluconate and 1.25 mg/mL vitamin C. The aqueous phase contained 0.005 mol/L tetrabutylammonium hydroxide and the mobile phase consisted of a mixture of the aqueous phase-methanol (80:20, v/v, pH 6.0 adjusted by phosphoric acid). The linearity, sensitivity and specificity, accuracy, and stability of the procedure were evaluated. The calibration curves for vitamin C were linear in the range of 10.0-100.0 µg/mL. The percentage coefficient of variation of the quantitative analysis of the vitamin C in the products analysis was within 5%. The method was successfully applied to determine the stability of vitamin C in the compound oral solution. It was found that the vitamin C peak was symmetrical and the column efficiency was high. The method is simple and suitable for stability testing of a low concentration of vitamin C preparation.