Phytochemical Profiling of Methanolic Fruit Extract of Gardenia latifolia Ait. by LC-MS/MS Analysis and Evaluation of Its Antioxidant and Antimicrobial Activity.

Gardenia latifolia Ait. (Rubiaceae) is also known as Indian Boxwood is a small deciduous tree often growing in southern states of India. In the present study, phytochemical profiling of methanolic extract of G. latifolia fruits were carried out using FTIR and LC-MS/MS analysis. Besides, its antioxidant and antimicrobial potential have been analysed using DPPH activity, differential pulse voltammetry and resazurin microtiter assay, respectively. Phytochemical profiling revealed the presence of 22 major diversified compounds and main were 3-caffeoyl quinic acid (chlorogenic acid), 3,4-Di-O-caffeoyl quinic acid, 6-O-trans-feruloylgenipin gentiobioside, 10-(6-O-trans sinapoyl glucopyranosyl) gardendiol, isoquercitrin, scortechinones, secaubryenol, iridoids and quercetin 3-rutinoside (rutin). The extract showed antioxidant activity (IC50 = 65.82) and powerful antibacterial activity with lowest minimum inhibitory concentration against Gram-positive Staphylococcus aureus (15.62 µg/µL), Bacillus subtilis (31.25 µg/µL) than gram negative Escherichia coli (62.5 µg/µL), Klebsiella pneumoniae (62.5 µg/µL), Pseudomonas aeruginosa (31.25 µg/µL). This study shows that the fruits of G. latifolia have tremendous potential to be used in food industries, phyto-therapeutics and cosmetic industries.

A novel horseradish peroxidase biosensor towards the detection of dopamine: a voltammetric study.

A polymerized film of glycine (Gly) was prepared on the surface of carbon paste electrode (CPE) through the cyclic voltammetry (CV) technique. A novel biosensor for the determination of dopamine (DA) has been constructed based on horseradish peroxidase (HRP) and multiwalled carbon nanotubes (MWCNTs) immobilizing on Poly (Gly)/CPE through silica sol-gel (SiSG) entrapment. CV measurements were employed in order to understand the feasibility of poly (Gly) as an electron carrier between the immobilized peroxidase and the surface of CPE. By using differential pulse voltammetry (DPV) the calibration curves of DA was obtained in the range of 15-865 µM. The limit of detection (LOD) and limit of quantification (LOQ) of DA was found to be 6×10⁻7 M and 2×10⁻6 M respectively. The apparent Michaelis-Menten constant (Km(app)) was found to be 0.5 mM and illustrated that the good biological activity of the fixed enzyme. Electrochemical impedance spectroscopy (EIS) results confirmed the rapid electron transfer and also the immobilization of enzyme on the electrode surface. The biosensor showed high sensitivity, selectivity and reproducibility. This method has been used to determine DA in the presence of various interferences and in clinical preparations.

Sol-gel immobilized biosensor for the detection of organophosphorous pesticides: a voltammetric method.

Organophosphorous compounds are important neuroactive molecules whose presence exhibits significant analytical challenges. An acetylcholinesterase (AChE) based amperometric biosensor was developed by silica sol-gel film immobilization of the enzyme onto the carbon paste electrode. The mono enzyme biosensor was used for the determination of two organophosphorous compounds such as methyl parathion (MP) and acephate in 0.1M phosphate buffer (pH 7.0). The substrate used was acetylthiocholine chloride (ASChCl) confirmed the formation of thiocholine and it was electrochemically oxidized giving significant increase in anodic peak current around at 0.60 V versus calomel electrode. The influence of pH, enzyme loading and substrate concentration on the response of the biosensor was investigated. The monoenzyme biosensor provided linearity to methyl parathion and acephate in the concentration range of 0.1-0.5 ppb and 50-750 ppb with an incubation time of 20 min and 4 min. The detection limits under the optimum working conditions were found to be 0.08 ppb for methyl parathion and 87 ppb for acephate. The sensor shows good operational stability 89% of its original activity for 60 successive measurements.

Voltammetric behavior of cefixime and cefpodoxime proxetil and determination in pharmaceutical formulations and urine.

Electrochemical reduction behavior of cephalosporins, Cefixime (CF) and Cefpodoxime Proxetil (CP) have been studied by using different voltammetric techniques in Britton-Robinson buffer system. Two well defined cathodic waves are observed for both the compounds in the entire pH range. Number of electrons transferred in the reduction process was calculated and the reduction mechanism is proposed. The results indicate that the process of both the compounds is irreversible and diffusion-controlled. The peak currents for CF and CP are found to be linear over the range of concentration 6.0 x 10(-8) to 1.2 x 10(-5) mol l(-1) and 8.8 x 10(-8) to 1.1 x 10(-5) mol l(-1), respectively. The lower detection limits are found to be 4.6 x 10(-8) and 8.52 x 10(-8) mol l(-1) for the two compounds. A differential pulse voltammetric method has been developed for the determination of these drugs in pharmaceutical formulations and urine samples.