Effect of alkynyloxy derivatives of lawsone as an antifungal spray for acrylic denture base: An in vitro study.

Objective: The purpose of this study was to (i) synthesize and develop an alkynyloxy derivative of lawsone as an antifungal spray and (ii) assess the antifungal spray's effectiveness in reducing the viability of Candida albicans (C. albicans) on polymethylmethacrylate (PMMA) specimens. Methods: Lawsone methyl ether (LME) and its derivative, 2-(prop-2-ynyloxy)naphthalene-1,4-dione (compound 1) were synthesized and characterized. The synthetic compounds were screened for antimicrobial activities against C. albicans using the microtiter broth dilution method to determine the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC). Compound 1 was further formulated as an antifungal spray in three concentrations (100, 200, and 400 µg/mL). C. albicans biofilms were developed for 48 h on PMMA specimens. The efficacy of using an antifungal spray for 1 and 3 min to remove biofilm was assessed using colony counting and scanning electron microscopy (SEM). Chlorhexidine gluconate (CHX), polident®, and distilled water were used as positive and negative control cleansing solutions, respectively. Results: LME and compound 1 showed comparable inhibition against C. albicans with a MIC of 25 µg/mL and MFC of 50 µg/mL. For immediate treatment, C. albicans was not detected on PMMA specimens when expose to 2% CHX and compound 1 (100, 200, and 400 µg/mL) antifungal spray for 3 min. However, after recolonization, a small number of viable cells were observed in denture soaked in compound 1 antifungal spray for 3 min group. Following recolonization, polident® and distilled water had comparable viable cell counts of C. albicans to the no treatment group. Scanning electron microscope (SEM) images revealed that CHX, polident®, and compound 1 caused cell damage in various forms. Conclusion: Denture spray containing synthetic alkynyloxy derivative of lawsone is a promising antifungal agent for C. albicans biofilm removal from the PMMA surface.

Comparison of antimicrobial activities of naphthoquinones from Impatiens balsamina.

Lawsone (1), lawsone methyl ether (2), and methylene-3,3'-bilawsone (3) are the main naphthoquinones in the leaf extracts of Impatiens balsamina L. (Balsaminaceae). Antimicrobial activities of these three naphthoquinones against dermatophyte fungi, yeast, aerobic bacteria and facultative anaerobic and anaerobic bacteria were evaluated by determination of minimal inhibitory concentrations (MICs) and minimal bactericidal or fungicidal concentrations (MBCs or MFCs) using a modified agar dilution method. Compound 2 showed the highest antimicrobial activity. It showed antifungal activity against dermatophyte fungi and Candida albicans with the MICs and MFCs in the ranges of 3.9-23.4 and 7.8-23.4 µg mL(-1), respectively, and also had some antibacterial activity against aerobic, facultative anaerobic and anaerobic bacteria with MICs in the range of 23.4-93.8, 31.2-62.5 and 125 µg mL(-1), respectively. Compound 1 showed only moderate antimicrobial activity against dermatophytes (MICs and MFCs in the ranges of 62.5-250 and 125-250 µg mL(-1), respectively), but had low potency against aerobic bacteria, and was not active against C. albicans and facultative anaerobic bacteria. In contrast, 3 showed significant antimicrobial activity only against Staphylococus epidermidis and Bacillus subtilis (MIC and MBC of 46.9 and 93.8 µg mL(-1), respectively).

Simultaneous determination of three naphthoquinones in the leaves of Impatiens balsamina L. by reversed-phase high-performance liquid chromatography.

INTRODUCTION: Naphthoquinones; lawsone (1), lawsone methyl ether (2) and methylene-3,3'-bilawsone (3) are the main active compounds of Impatiens balsamina leaves. OBJECTIVE: To develop and validate an HPLC method for simultaneous quantitative determination of 1-3 in I. balsamina leaf extracts. METHODOLOGY: The method utilised a Supelco® C(18) column (5 µm, 4.6 × 150 mm) at 25°C with the mixture of 2% aqueous acetic acid : methanol (gradient elution as follows: 0-10 min, 25 : 75; 10-20 min, 32 : 68; 20-35 min, 55 : 45) as the mobile phase at a flow-rate of 1 mL/min, and UV detection at 280 nm. The parameters of linearity, repeatability, reproducibility, accuracy specificity and sensitivity of the method were evaluated. RESULTS: The recovery of the method was 96-101% and linearity (r(2) ≥ 0.9995) was obtained for all naphthoquinones. A high degree of specificity, as well as repeatability and reproducibility (RSD less than 5%), were also achieved.

Increased production of naphthoquinones in Impatiens balsamina root cultures by elicitation with methyl jasmonate.

Impatiens balsamina root cultures were treated with yeast extract (YE), Candida albicans homogenate (CAH), Trichophyton rubrum homogenate (TRH), chitosan (CHI) and methyl jasmonate (MJ). Different elicitors, depending on concentrations used exerted differential effects on the production of the three main naphthoquinones, lawsone (2-hydroxy-1,4-naphthoquinone), lawsone methyl ether and methylene-3,3'-bilawsone. Treatment with MJ (400microM) was capable of increasing production of lawsone, and lawsone methyl ether up to 8.6- and 11.3-fold higher, respectively, compared to the level in untreated cultures. Treatment of 21-day-old root cultures with 300microM MJ for 36h resulted in the production of 10.0, 0.78 and 0.23mg/g DW of lawsone, its methyl ether and methylene-3,3'-bilawsone, respectively. Such levels are sufficient for commercial production.

Quantitative HPLC determination and extraction of anthraquinones in Senna alata leaves.

A reversed-phase high-performance liquid chromatographic method is described for the simultaneous determination of four anthraquinones: rhein, aloe-emodin, emodin, and chrysophanol in Senna alata leaves. The method involves the use of a TSK-gel ODS-80Tm column (5 microm, 4.6 x 150 mm) at 25 degrees C with the mixture of methanol and 2% aqueous acetic acid (70:30, v/v) as the mobile phase and detection at 254 nm. The parameters of linearity, precision, accuracy, and specificity of the method were evaluated. The recovery of the method is 100.3-100.5%, and linearity (r(2) > 0.9998) was obtained for all anthraquinones. A high degree of specificity as well as repeatability and reproducibility (relative standard deviation values less than 5%) were also achieved. The solvent for extraction of anthraquinones from S. alata leaves was examined in order to increase the anthraquinone content of the leaf extract. It was found that a solution of 5% hydrochloric acid (v/v), 5% ferric chloride (w/v), and 15% water in methanol (v/v) was capable of increasing the anthraquinone content in the leaf extract up to 1.67% (w/w).