Photostability study of amlodipine besylate tablets packed in primary packaging

In this study, the modified stability-indicating RP-HPLC method was validated for quantitative analysis of amlodipine besylate in the presence of its impurity D (3-ethyl 5-methyl 2-[(2-aminoethoxy)methyl]-4-(2-chlorophenyl)-6-methylpyridine-3,5-dicarboxylate). The method was applied for the determination of an analyte in the tablets and irradiated samples packed in the primary packaging (Alu/PVC/PVDC blister packaging). The efficient chromatographic separation was achieved using a ZORBAX Eclipse XDB-C18 column (4.6×250 mm, 5 mm) with isocratic elution of mobile phase which consisted of acetonitrile:methanol:triethylamine solution (15:35:50, v/v/v) (pH 3.0). The flow rate of the mobile phase was 1 mL min-1, while the detection of amlodipine besylate was carried out at 273 nm. Amlodipine besylate and its impurity D were identified at the retention times of 16.529 min and 2.575 min, respectively. The linearity of the method with the coefficient of determination of 0.999 was confirmed in the concentration range of 10 - 75 µg mL-1 for amlodipine besylate. The limit of detection was 0.2 µg mL-1, while the limit of quantification was 0.66 µg mL-1. After UV and Vis radiation of the tablets packed in the primary packaging, the content of amlodipine besylate was reduced by 22.38% and 19.89%, respectively. The presence of new degradation products was not detected under the given chromatographic conditions. The photodegradation of amlodipine besylate followed pseudo-first-order kinetics. Based on the half-life of amlodipine besylate (38.4 days for UV radiation and 43.3 days for Vis radiation), it was concluded that amlodipine besylate in the tablets has satisfactory photostability after its packing in the Alu/PVC/PVDC blister packaging.

Influence of additives on suspension structure

The aim of this study was to compare the stability and texture of three zinc oxide suspensions with different additives. Suspension 1 was made as official magistral formulation Suspensio album 7.5% from Formulae magistrales 2008. Suspension 2 was prepared when 1% carbomer gel was added to suspension 1 and suspension 3 was prepared when polysorbate 20 was added to suspension 2. After stability tests, texture analysis was performed on all suspensions. Following parameters were measured: hardness cycle 1, hardness cycle 2, cohesiveness, adhesiveness, resilience and springiness. The study showed that suspension 3 had the lowest value of hardness, and therefore the best spreadability. Also, suspension 3 was the least sticky of all three, since it was characterized with the lowest adhesiveness. Further, suspension 3 was the most cohesive and is predicted to withstand the stress during packing and use longer than others. On the other hand, the highest values of resilience and springiness were detected for suspension 1, while the lowest was related to suspension 2. Therefore, the best textural characteristics were assigned to suspension 3. This result is in accordance with the results of performed stability tests. The results of our study offer insight into potential improvements of the current magistral formulation Suspensio album 7.5%.

The effect of the nitrogen source type on the growth and consumption of crude glycerol by Streptomyces hygroscopicus CH-7

In this paper we studied the effect of different amino acids (arginine, tryptophan, tyrosine, and phenylalanine) as nitrogen sources on the growth of actinomycete Streptomyces hygroscopicus CH-7 and the consumption of crude glycerol, obtained as a by-product in the biodiesel production from sunflower oil. The highest biomass concentration (9.5 g/L) was achieved using the basic medium and the medium with tryptophan (9.2 g/L), while the crude glycerol consumption was the highest in the basic medium (5.9 mg/mL) and the medium with phenylalanine (3.3 mg/mL).

A short review of titania-graphene oxide based composites as a photocatalysts

New and effective methods of water purification are necessary to minimize pollution. Many methods have been used in wastewater treatment, but sorption is considered as an easy and economic process. The efficiency of any sorption process mainly depends on the physicochemical properties of the used adsorbent. Since photocatalysts can initiate reactions of decomposition organic contaminants under ultraviolet or sunlight irradiation without using chemicals or producing chemical wastes, photocatalytic reactions are considered a sustainable way to remove a variety of environmental pollutants. Ultraviolet water purification became the most effective method of water disinfection and purification. Heterogeneous semiconductor photocatalysts have recently emerged as an efficient material for purifying water. The crystal structure is crucial for photocatalytic activity and efficiency of semiconductors, thus optimal parameters must be provided during the preparation of photocatalysts. To overcome problems with semiconductors usage, the use of co-catalysts and photocatalyst carriers is one of the solutions. Recently, much emphasis has been placed on using graphene oxide (GO) supported semiconductor photocatalysts. In this paper, a short review of composites of titanium dioxide and graphene oxide-based materials is given.

Synthesis, characterization, and evaluation of antioxidant and antimicrobial activity of three novel n-heteroaromatic hydrazonyl-thiazoles

(Thiazolyl-2-yl)hydrazones (THs) are a group of organic compounds containing both hydrazone and 1,3-thiazole pharmacophores present in many approved drugs. They have been investigated greatly in recent years due to potent anticancer, antibacterial, antifungal, antituberculosis, anti-inflammatory, and antiparasitic activities. In this study, one pyridine-based and two quinoline-based, novel THs were synthesized and characterized by elemental analysis, Fourier-transform infrared spectroscopy (FTIR), and nuclear magnetic resonance spectroscopy (NMR). The antimicrobial activity of the compounds was tested against five Gram-positive and five Gram-negative bacteria, as well as against three fungi. The antioxidant capacity of the compounds was tested in six antioxidative assays. The results showed that quinoline-based THs were more active against tested Gram-negative bacteria and fungi strains than pyridine-based compounds. All the compounds showed excellent antioxidative activity comparable to or greater than the used standards (vitamin C and Trolox). Absorption, distribution, metabolism, excretion, and toxicity (ADMET) parameters were calculated in-silico. Results pointed to promising good pharmacokinetics profiles of investigated compounds, especially 2-quinoline carboxaldehyde-based compound, which can be a lead drug candidate.

Compression properties of knitted fabrics printed by sublimation transfer printing technique

Compression properties of textile materials are useful for determining fullness, softness, smoothness, and stiffness. In addition, compression parameters have significant influence on fabric hand value and quality of textile materials. The present paper reports a study of the sublimation printing process influence on the change in compression properties of knitted fabrics (polyester, cotton, and cotton/ polyester) intended for sportswear manufacturing. For that purpose, the KES-FB3-A Compression Tester was used for measuring compression parameters of knitted fabrics. The parameters, which contributed to the smallest reduction percentage in compression properties of polyester knitted fabrics were yarn linear density and weight. For cotton-rich knitted fabrics sublimation coating powder was used for paper modification to bond disperse dyes to cotton fibres. The analysis of the results showed that the printing process had a smaller influence on the change of compression parameters of polyesters in relation to cotton and cotton/polyester knitted fabrics. It was noted that the printing process had the effect of thickness reduction for all knitted fabrics to varying degrees. Printing process contributed to small decrease in compressibility and specific volume values for polyester knitted fabrics. The modification process contributed to the significant reduction of the compressibility for cotton (from 34.46% to 47.89%) and cotton/polyester (from 38.81% to 50.75%) knitted fabrics. In addition, reduction in specific volume values range from 41.86% to 44.19% for cotton and from 42.37% to 45.75% for cotton/ polyester knitted fabrics was notted.

Theoretical investigation of mollusk shells: Energy landscape exploration of CaCo3 polymorphs and element substitution: A short review

Due to the remarkable properties achieved under ambient conditions and with quite limited components, mollusk shells are very appealing natural bio-composites used as inspiration for new advanced materials. Calcium carbonate which is among the most widespread biominerals is used by mollusks as a building material that constitutes 95-99% of their shells. Within the investigation of calcium carbonate polymorphs present in the shells, diverse theoretical and experimental studies were performed, however, further research of these crystalline forms is required. There are very little researches on the energy landscapes of biogenic calcium carbonate which can provide us information about the free energies of already known as well as newly discovered plausible structures. To investigate the structural, mechanical, elastic, or vibrational properties and to predict new possible structures of biogenic calcium carbonate, different calculation methods could be employed. Some of these studies are presented and discussed in this paper.

Physical, chemical, and antioxidant stability studies of a topical formulation containing pot marigold (Calendula officinalis L.) flowers extract

Pot marigold flower extract (Calendula officinalis L.) has pharmacological properties due to the presence of various bioactive compounds. It is known that the extract has antioxidant, anti-inflammatory, antitumor, antibacterial, antifungal, antiviral, antimutagenic, antidermatitis properties, etc. The aim of this study was to improve the quality of the selected topical formulation by adding the ethanolic extract of pot marigold flower, as well as to monitor its stability. The topical formulation was water-in-oil emulsion prepared using the hot/hot emulsification process with an oil phase consisting of Vaseline, lanolin, and almond oil. The extract, prepared by ultrasound-assisted extraction, had an antioxidants content of 3.512 g gallic acid equivalent per 100 g-1 of dry weight and the half-maximal inhibitory concentration of 0.14 mg mL-1 determined by the DPPH assay. Chemical stability studies have shown that daylight has no significant effect on the stability of antioxidants in the extract, while an increase in temperature leads to their degradation. The shelf-life of the extract is about 8 months at 4 °C and 3 months at 22 °C (room temperature). The prepared uncategorized topical formulations containing 1% and 2% (w/w) pot marigold extract were stable at different temperatures during the storage. The uncategorized formulations showed antioxidant activity, but the activity of the extract in the formulations decreased with increasing storage temperature. Pot marigold flower extract and the developed uncategorized formulations showed an inhibitory effect on Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli, Proteus mirabilis, Klebsiella pneumoniae), as well as on Candida albicans. The uncategorized formulations with this activity can be used in the treatment of skin infection.

Mechanism of the electrocoagulation process and its application for treatment of wastewater: A review

Treatment of wastewater, especially of industrial origin, is a major challenge. Although wastewater treatment methods have already been established, active efforts are being made to develop more efficient and economical methods. In recent years, the attention has been focused on electrochemical methods, most of which are focused on electrocoagulation. This paper gives a detailed description of the mechanism of the electrocoagulation process, as well as the application of this method in wastewater treatment of different origins.

Investigation of different extraction conditions on the efficiency of gliadin extraction and determination by ELISA method

Gluten refers to a complex mixture of gliadins and glutenins. It can cause numerous foodborne disorders. In sensitive individuals gluten can lead to celiac disease (CD), wheat sensitivity and allergy. Gliadin proteins are one of the gluten fractions. The aim of this paper was to examine how different conditions, mixing time (2.5, 5, 7.5, and 10 min) of the sample with the most commonly solvent 70% (v/v) ethanol and 70% (v/v) isopropanol and incubation time (15, 20, 25, and 30 min) affect the efficiency of gliadin determination with the ELISA method. A commercial kit was used to determine gliadin concentrations, and absorbance was measured at 450 nm, using the ELISA reader. Based on the obtained results, the optimal mixing time of the sample with the solvents was 5 minutes and the incubation time was 25 minutes. Under these conditions, the extraction efficiency is the best, i.e., the highest gliadin concentration is obtained. The results of research can be of fundamental importance in the study of gluten proteins and the impact of technological procedures on their change and the possibility of reducing the allergic effect.