Ying Shih

Determination of codeine in urine and drug formulations using a clay-modified screen-printed carbon electrode.

Both flow-injection analysis and square-wave stripping voltammetry were evaluated for the determination of codeine in pharmaceutical formulations using a nontronite clay-modified screen-printed carbon electrode. Compared with a bare screen-printed carbon electrode, the nontronite clay-modified screen-printed carbon electrode exhibited a marked enhancement of the current response of codeine. A linear calibration plot was obtained over the 2.5-45 microM range (correlation coefficient=0.999) in pH 6.0 phosphate buffer solution with a detection limit of 20 nM (S/N=3) by square-wave voltammetry (SWV). While, in flow-injection analysis, the linearity was over 5-120 ng range with a detection limit of 1 ng in 20 microl loop. The nontronite clay-modified screen-printed carbon electrode can be either disposable or reused since the renewal gave a good reproducible surface. Quantitative analysis was performed by the standard addition method for codeine content in both urine and commercially available drugs.

Determination of theophylline in tea and drug formulation using a Nafion (R)/lead-ruthenium oxide pyrochlore chemically modified electrode

Square-wave voltammetry was used for the determination of trace amounts of theophylline in tea and drug formulation at a Nafion(R)/lead-ruthenium oxide pyrochlore chemically modified electrode. This chemically modified electrode exhibits a marked enhancement of the current response compared to a bare glassy carbon electrode. The calibration graph for the determination of theophylline was linear up to 100 muM in 0.1 M, pH 3 phosphate solution with a detection limit (S/N=3) of 0.1 muM. The results of 15 successive repetitive measurement-regeneration cycles showed a relative standard deviation of 1.3% for 10 muM theophylline indicating that the electrode renewal gives a good reproducible surface. Quantitative analysis was performed by the standard addition method for the theophylline content in commercially available tea and drug.

Cinnamomum cassia Essential Oil Inhibits α-MSH-Induced Melanin Production and Oxidative Stress in Murine B16 Melanoma Cells

Essential oils extracted from aromatic plants exhibit important biological activities and have become increasingly important for the development of aromatherapy for complementary and alternative medicine. The essential oil extracted from Cinnamomum cassia Presl (CC-EO) has various functional properties; however, little information is available regarding its anti-tyrosinase and anti-melanogenic activities. In this study, 16 compounds in the CC-EO have been identified; the major components of this oil are cis-2-methoxycinnamic acid (43.06%) and cinnamaldehyde (42.37%). CC-EO and cinnamaldehyde exhibited anti-tyrosinase activities; however, cis-2-methoxycinnamic acid did not demonstrate tyrosinase inhibitory activity. In murine B16 melanoma cells stimulated with α-melanocyte-stimulating hormone (α-MSH), CC-EO and cinnamaldehyde not only reduced the melanin content and tyrosinase activity of the cells but also down-regulated tyrosinase expression without exhibiting cytotoxicity. Moreover, CC-EO and cinnamaldehyde decreased thiobarbituric acid-reactive substance (TBARS) levels and restored glutathione (GSH) and catalase activity in the α-MSH-stimulated B16 cells. These results demonstrate that CC-EO and its major component, cinnamaldehyde, possess potent anti-tyrosinase and anti-melanogenic activities that are coupled with antioxidant properties. Therefore, CC-EO may be a good source of skin-whitening agents and may have potential as an antioxidant in the future development of complementary and alternative medicine-based aromatherapy.

The Melanogenesis Alteration Effects of Achillea millefolium L. Essential Oil and Linalyl Acetate: Involvement of Oxidative Stress and the JNK and ERK Signaling Pathways in Melanoma Cells

The mitogen-activated protein kinase (MAPK) family, including extracellular signal-regulated kinase (ERK)1/2, c-Jun N-terminal kinase (JNK)1/2 and p38 MAPK, is known to be activated by ultraviolet (UV) radiation in melanocytes to regulate melanin production. Reactive oxygen species (ROS) play important roles in the pathway of ERK and JNK activation. It has been established that the essential oil of Achillea millefolium L. (AM-EO) has activities that suppress the oxidative stress and inflammatory responses. Thus, we analyzed the effects of AM-EO on melanogenesis in melanocyte stimulating hormone (α-MSH) treated melanoma cells. The results demonstrated that AM-EO suppresses melanin production by decreasing tyrosinase activity through the regulation of the JNK and ERK signaling pathways. This effect might be associated with the AM-EO activity leading to the suppression of ROS, and linalyl acetate is its major functional component. Therefore, we propose that AM-EO has the potential to treat hyperpigmentation in the future.

Achillea millefolium L. essential oil inhibits LPS-induced oxidative stress and nitric oxide production in RAW 264.7 Macrophages.

Achillea millefolium L. is a member of the Asteraceae family and has been used in folk medicine in many countries. In this study, 19 compounds in A. millefolium essential oil (AM-EO) have been identified; the major components are artemisia ketone (14.92%), camphor (11.64%), linalyl acetate (11.51%) and 1,8-cineole (10.15%). AM-EO can suppress the inflammatory responses of lipopolysaccharides (LPS)-stimulated RAW 264.7 macrophages, including decreased levels of cellular nitric oxide (NO) and superoxide anion production, lipid peroxidation and glutathione (GSH) concentration. This antioxidant activity is not a result of increased superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) activities, but rather occurs as a result of the down-regulation of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and heme oxygenase-1 (HO-1) expression, thus reducing the inflammatory response. Therefore, AM-EO can be utilized in many applications, including the treatment of inflammatory diseases in the future.

Flow injection analysis of zinc pyrithione in hair care products on a cobalt phthalocyanine modified screen-printed carbon electrode

Zinc pyrithione (ZPT) is an antibacterial and antifungal reagent that is often utilized for the antidandruff activity in hair-care shampoos with a composition level up to 1% in the formulation. It has some adverse effects to human and animal if consumed orally. A disposable type of cobalt phthalocyanide modified screen-printed carbon electrode (CoPc/SPE) in couple with flow injection analysis (FIA) was developed for easy and selective analysis of ZPT in commercial hair-care products. Under the optimized FIA conditions, the CoPc/SPE yielded a linear calibration plot in the window of 6-576muM with sensitivity and detection limit of 1.65nAmuM(-1) and 0.9muM (i.e. 1.42pg in 5mul sample loop), respectively, in 0.1M KOH solution at an applied potential of 0.3V versus Ag/AgCl. Since the approach is simple, easy, selective, and inexpensive, it offers a potential application of daily ZPT analysis in hair-care products.

Voltammetric Determination of Kojic Acid in Cosmetic Bleaching Products Using a Disposable Screen-Printed Carbon Electrode

A preanodized screen-printed carbon electrode is used for the determination of kojic acid in cosmetic bleaching products by square-wave voltammetry. The preanodization process leads to a marked enhancement of the current response of kojic acid at the screen-printed carbon electrode. The linear range is up to 260 μM in pH 10 Britton-Robinson buffer with a detection limit (S/N=3) of 0.17 μM. The electrode has the advantages of low cost, of being easy to handle, and it can be either disposable or reused since the renewal gives a reproducible surface. Quantitative analysis for the kojic acid content in cosmetic products was performed by the standard addition method.

Determination of sunscreen agents in cosmetic products using microwave-assisted extraction and liquid chromatography

Microwave-assisted extraction (MAE), was used to extract sunscreen agents from cosmetic products. The extracts were analyzed by liquid chromatography (LC). The present method allows the determination of three sunscreen agents, Eusolex 2292, 4360 and 6300. The precision of the assay at 40 microg/ml of sunscreen agents ranged from 1.5 to 2.2%, and the detection limits were 2.0-4.0 ng/ml.

Determination of Codeine in Human Plasma and Drug Formulation Using a Chemically Modified Electrode

Both flow injection methodology and square-wave voltammetry were developed and evaluated for determining codeine in human plasma and pharmaceutical formulations using a Nafion/ruthenium oxide pyrochlore chemically modified electrode. Combining the electrocatalytic function of the ruthenium-oxide pyrochlore with charge-exclusion and the preconcentration features of Nafion perform well in codeine detection. Compared to a bare glassy carbon electrode, the chemically modified electrode exhibits a shift of the oxidation potential in cathodic direction and a marked enhancement of the current response. A linear calibration plot is obtained over the 0–32 μM range in 0.05 M HClO4 solution with a detection limit (3σ) of 10 nM in the square-wave voltammetric method. While, in flow-injection analysis, a linear calibration plot is obtained over the 0.5–40 μM range with a detection limit of 0.86 ng. Quantitative analysis was performed by the standard addition method for codeine content in human plasma and a commercially available drug.

An electrochemical sensor based on a clay-coated screen-printed electrode for the determination of arbutin

A preanodized clay-coated screen-printed electrode (CCSPE) is used for the determination of arbutin (hydroquinone-β-D-glucopyranoside) in cosmetic bleaching products by square-wave voltammetry. The preanodization process exhibits a marked enhancement in the current response of arbutin at the CCSPE. Compared to the performance at a preanodized SPE, the coating of clay was found to further improve the sensitivity and reproducibility. Under optimized conditions, the linear range for arbutin detection is up to 90 μM (correlation coefficient=0.999) in pH 10.0 ammonium buffer with a detection limit of 0.18 μM (S/N=3). The electrode can be either disposable or reused since renewal provides good reproducible surfaces. Quantitative analysis was performed by standard addition for the arbutin content in commercial available cosmetic bleaching products.