In this work, an electrochemical sensor was fabricated for determination of an anthracycline, doxorubicin (DOX) as a chemotherapy drug in plasma based on multi-walled carbon nanotubes modified platinum electrode (Pt/MWCNTs). DOX was effectively accumulated on the surface of modified electrode and generated a pair of redox peaks at around 0.522 and 0.647 V (vs. Ag/AgCl) in Britton Robinson (B-R) buffer (pH 4.0, 0.1 M). The electrochemical parameters including pH, type of buffer, accumulation time, amount of modifier and scan rate were optimized. Under the optimized conditions, there was a linear correlation between cathodic peak current and concentration of DOX in the range of 0.05-4.0 µg/mL with the detection limit of 0.002 µg/mL. The number of electron transfers (n) and electron transfer-coefficient (α) were estimated as 2.0 and 0.25, respectively. The constructed sensor displayed excellent precision, sensitivity, repeatability and selectivity in the determination of doxorubicin in plasma. Moreover, cyclic voltammetry studies of DOX in the presence of DNA showed an intercalation mechanism with binding constant (Kb) of 1.12×105 L/mol.
Management of cardiovascular risk factors in diabetes demands special attention due to their co-existence. Pioglitazone (PIO) and telmisartan (TLM) combination can be beneficial in effective control of cardiovascular complication in diabetes. In this research, we developed and validated a high throughput LC-MS/MS method for simultaneous quantitation of PIO and TLM in rat plasma. This developed method is more sensitive and can quantitate the analytes in relatively shorter period of time compared to the previously reported methods for their individual quantification. Moreover, till date, there is no bioanalytical method available to simultaneously quantitate PIO and TLM in a single run. The method was validated according to the USFDA guidelines for bioanalytical method validation. A linear response of the analytes was observed over the range of 0.005-10 µg/mL with satisfactory precision and accuracy. Accuracy at four quality control levels was within 94.27%-106.10%. The intra- and inter-day precision ranged from 2.32%-10.14 and 5.02%-8.12%, respectively. The method was reproducible and sensitive enough to quantitate PIO and TLM in rat plasma samples of a preclinical pharmacokinetic study. Due to the potential of PIO-TLM combination to be therapeutically explored, this method is expected to have significant usefulness in future.
In this study, the molecular interactions between valrubicin, an anticancer drug, and fish sperm DNA have been studied in phosphate buffer solution (pH 7.4) using UV-Vis spectrophotometry and cyclic voltammetry techniques. Valrubicin intercalated into double stranded DNA under a weak displacement reaction with methylene blue (MB) molecule in a competitive reaction. The binding constant (kb) of valrubicin-DNA was determined as 1.75×103 L/mol by spectrophotometric titration. The value of non-electrostatic binding constant ([Formula: see text]) was almost constant at different ionic strengths while the ratio of [Formula: see text]/kb increased from 4.51% to 23.77%. These results indicate that valrubicin binds to ds-DNA via electrostatic and intercalation modes. Thermodynamic parameters including ΔH0, ΔS0 and ΔG0 for valrubicin-DNA interaction were determined as -25.21×103 kJ/mol, 1.55×102 kJ/mol K and -22.03 kJ/mol, respectively. Cyclic voltammetry study shows a pair of redox peaks for valrubicin at 0.45 V and 0.36 V (vs. Ag/AgCl). The peak currents decreased and peak positions shifted to positive direction in the presence of DNA, showing intercalation mechanism due to the variation in formal potential.
The present study used in vitro and in silico techniques, as well as the metabolomics approach to characterise α-glucosidase inhibitors from different fractions of Clinacanthus nutans. C. nutans is a medicinal plant belonging to the Acanthaceae family, and is traditionally used to treat diabetes in Malaysia. n-Hexane, n-hexane: ethyl acetate (1:1, v/v), ethyl acetate, ethyl acetate: methanol (1:1, v/v), and methanol fractions were obtained via partitioning of the 80% methanolic crude extract. The in vitro α-glucosidase inhibitory activity was analyzed using all the fractions collected, followed by profiling of the metabolites using liquid chromatography combined with mass spectrometry. The partial least square (PLS) statistical model was developed using the SIMCA P+14.0 software and the following four inhibitors were obtained: (1) 4,6,8-Megastigmatrien-3-one; (2) N-Isobutyl-2-nonen-6,8-diynamide; (3) 1',2'-bis(acetyloxy)-3',4'-didehydro-2'-hydro-β, ψ-carotene; and (4) 22-acetate-3-hydroxy-21-(6-methyl-2,4-octadienoate)-olean-12-en-28-oic acid. The in silico study performed via molecular docking with the crystal structure of yeast isomaltase (PDB code: 3A4A) involved a hydrogen bond and some hydrophobic interactions between the inhibitors and protein. The residues that interacted include ASN259, HID295, LYS156, ARG335, and GLY209 with a hydrogen bond, while TRP15, TYR158, VAL232, HIE280, ALA292, PRO312, LEU313, VAL313, PHE314, ARG315, TYR316, VAL319, and TRP343 with other forms of bonding.
1, 3, 4-Oxadiazole derivatives (4a-5f) were previously synthesized to investigate their anticancer properties. However, studies relating to their antioxidant potential and signal transducer and activator of transcription (STAT) inhibition have not been performed. We investigated previously synthesized 1, 3, 4-oxadiazole derivatives (4a-5f) for various radical scavenging properties using several in vitro antioxidant assays and also for direct inhibition of STAT3 through molecular docking. The data obtained from various antioxidant assays such as 2, 2,-diphenyl-1-picrylhydrazyl radical (DPPH), nitric oxide, hydrogen peroxide, and superoxide anion radical revealed that among all the derivatives, compound 5e displayed high antioxidant activities than the standard antioxidant L-ascorbic acid. Additionally, the total reduction assay and antioxidant capacity assay further confirmed the antioxidant potential of compound 5e. Furthermore, the molecular docking studies performed for all derivatives along with the standard inhibitor STX-0119 showed that binding energy released in direct binding with the SH2 domain of STAT3 was the highest for compound 5e (-9.91kcal/mol). Through virtual screening, compound 5e was found to exhibit optimum competency in inhibiting STAT3 activity. Compound 5e decreased the activation of STAT3 as observed with Western blot. In brief, compound 5e was identified as a potent antioxidant agent and STAT3 inhibitor and effective agent for cancer treatment.