SIMULTANEOUS DETERMINATION OF TIGECYCLINE AND ITS POTENTIAL IMPURITIES BY A STABILITY-INDICATING RP-HPLC-UV DETECTION TECHNIQUE

Objective: Stability representing the RP-HPLC method was established for synchronized quantification of Tigecycline and its impurities. This method was confirmed for its applicability to both tablet dosage and bulk drug forms. Methods: Intended for an isocratic elution, a mobile phase containing methanol: 10 mmol Triethylamine Buffer mixture (75:25 v/v, pH 6.1) was used at 1 ml/min flow rate and Agilent ZORBAX Eclipse XDB C18 (250 mm × 4.6 mm, 5 μm) column. Results: At 231 nm as wavelength, high-pitched peaks of Tigecycline (Tig) and its impurities (1and2) were detected at 6.55, 8.73 and 4.87 min correspondingly. The linearity of tigecycline and its impurities (impurity-1 and 2 and) were estimated with ranging from 75–450 µg/ml for Tigecycline and 1–6 µg/ml for both impurity 1 and 2. The corresponding recognition limits (LOD and LOQ) of the tigecycline and its impurities were originated to be (1.37,0.047 and 0.071 µg/ml) and (4.15, 0.143 and 0.126 µg/ml). Conclusion: The technique was effectively stretched for stability signifying studies under different stress conditions. Justification of the method was done as per the current ICH guidelines.

Evaluation of nutritive values and digestibility’s cacao( Theobroma cacao L.) pod husk fermented with lingzhi mushroom (Ganoderma lucidum) at different concentration and incubation time

Cacao pod husk has been widely utilized as animal feed. The purpose of this study is to evaluate nutritive values and digestibility of fermented cacao pod husk with different concentration and incubation time. A completely randomized factorial design consisting two factors; lingzhi mushroom concentration (K1 = 7,5%; K2 = 15%) and incubation time (L1 = 15 d; L2 =30 d; L3 = 45 d) was employed in this study (n=3 replicates). Proximate analysis was performed to determine nutritive values of fermented cacao pod husk. Fermented samples were then subjected to an in vitro digestibility with rumen fluid and McDougall’s buffer mixture. The results of study reveal that cacao pod husk fermented with the concentration of 15% at 15d and 30 d significantly increased (P<0.05) crude protein content but not for other parameters. Dry and organic matter digestibility of cacao pod husk fermented with 7.5% of lingzhi mushroom at 45 d significantly improved (P<0.05) in vitro dry and organic matter of treatment. In conclusion, cacao pod husk fermented with different concentration and incubation time was able to improve the nutritive values and in vitro digestibility of cacao pod husk.

Enzymatic Polymerization of Dihydroquercetin (Taxifolin) in Betaine-Based Deep Eutectic Solvent and Product Characterization

Deep eutectic solvents (DESs) are an alternative to conventional organic solvents in various biocatalytic reactions. Meanwhile, there have been few studies reporting on synthetic reactions in DESs or DES-containing mixtures involving oxidoreductases. In this work, we have studied the effects of several DESs based on betaine as the acceptor of hydrogen bonds on the catalytic activity and stability of laccase from the basidial fungus Trametes hirsuta and performed enzymatic polymerization of the flavonoid dihydroquercetin (DHQ, taxifolin) in a DES–buffer mixture containing 60 vol.% of betaine-glycerol DES (molar ratio 1:2). The use of the laccase redox mediator TEMPO enabled an increased yield of DHQ oligomers (oligoDHQ), with a number average molecular weight of 1800 g mol−1 and a polydispersity index of 1.09. The structure of the synthesized product was studied using different physicochemical methods. NMR spectroscopy showed that oligoDHQ had a linear structure with an average chain length of 6 monomers. A scheme for enzymatic polymerization of DHQ in a DES–buffer mixture was also proposed.

THE STUDY OF PHYSICAL AND MECHANICAL PROPERTIES OF PACKERS' CUFFS

In the drilling of wells, cementing of protective pipelines, development of productive horizons, as well as in operation, wells need to be divided into permanent or temporary areas. More advanced than these processes is the use of packing devices in the technological separation of layers and the insulation of protective belts. For example, delivery of the buffer mixture to the absorption zone by packer-mounted drill pipes saves 40-60% of time and reduces material consumption by 1.5-2 times compared to previous non-packer technologies. Keywords: packer, cuff, protective pipeline, sliding, sealing

A modified RP-HPLC method for the determination of the pKa values of synthesized β-hydroxy-β-arylalkanoic acids

The pKa values of twelve ?-hydroxy-?-arylalkanoic acids and ibuprofen were determined using a modified RP-HPLC method. The stationary phase was octadecyl modified (C-18) silica gel, and the mobile phases were mixtures of methanol and one of ten different buffers (60:40 volume ratio). The mean retention time of each compound was plotted against the pH of each of the ten used mobile phases. The inflection point of the obtained sigmoidal curve represents the s w pKa of a compound. Using s w pKa in previously established equations for the specific methanol/buffer mixture, the w w pKa values (in pure water) were calculated. The obtained w w pKa values for the synthesized compounds were in a range from 3.40 to 3.74, and the w w pKa for ibuprofen was 4.27. The Predicted pKa values for this type of compounds in the MarvinSketch 5.11.5. Program were in poor correlation with the experimental results, while in ACD/ /I-Labs pKa values were calculated as a wide range.

AMMONIATION OF RICE STRAW AND SUPPLEMENTATION OF Paraserianthes falcataria AND Sapindus rarak ON IN VITRO RUMEN FERMENTATION AND METHANE PRODUCTION

This study aimed to observe the effects of rice straw ammoniation and supplementation of Paraserianthes falcataria and Sapindus rarak on rumen fermentation and methane production in vitro. Rice straw was ammoniated by adding 2% urea. Rice straw, ammoniated rice straw, P. falcataria leaves and S. rarak fruits were oven-dried and finely ground. Experimental treatments were arranged as follow: rice straw (T1), ammoniated rice straw (T2), T2 80% + P. falcataria 20% (T3), T2 60% + P. falcataria 40% (T4), T2 80% + P. falcataria 10% + S. rarak 10% (T5), and T2 60% + P. falcataria 20% + S. rarak 20% (T6). An amount of 1 g sample from each treatment was added with 100 ml rumen fluid and buffer mixture (1:2 v/v), and incubated in a water bath at 39 ºC for 48 h. The incubation was performed in four replicates and each replicate was represented by four incubation bottles. Results showed that urea treatment increased gas production of rice straw at 24 and 48 h, higher ammonia production, higher IVDMD, and lower methane production as compared to the untreated rice straw (P<0.05). Addition of P. falcataria or S. rarak at lower level produced similar ammonia concentration as ammoniated rice straw whereas their addition at higher level decreased ammonia concentration (P<0.05). Paraserianthes falcataria addition to ammoniated rice straw decreased protozoa population (P<0.05) and S. rarak further decreased the fauna population (P<0.05) as well. Inclusion of S. rarak at 20% DM (T6) produced the lowest methane production both at 24 and 48 h after incubation and lowest methane production per unit of DM degraded. It was concluded that ammoniation of rice straw improved its nutritional quality with lower methane production, and its mixture with P. falcataria and S. rarak further increased the quality and lower the production of methane, respectively.

Enzymatic synthesis of 5-amino quinoline oligomers and evaluation of their free radical scavenging activity

The compound 5-aminoquinoline (AQ) was treated with horseradish peroxidase (HRP) and H2O2 in a reaction medium containing a dioxane:phosphate buffer mixture (70:30). Products (OAQ) with a degree of polymerization ranging from 4 to 12 were obtained. 1H NMR, FTIR, UV–vis, SEM, TG–DTA, DSC, XRD analysis, and conductivity measurements were conducted for characterization of OAQ. Compared with a monomer, OAQ showed higher thermal stability. After heating to 1000 °C, 46% of the initial weight of the OAQ remained. The antioxidant efficiencies of the monomer and oligomer were evaluated by the typical spectrophotometric method such as the bleaching of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals. OAQ showed improved DPPH activity compared with the AQ monomer.

Preparation of polydopamine nanocapsules in a miscible tetrahydrofuran–buffer mixture

A non-emulsion soft template method based on a miscible tetrahydrofuran–tris buffer mixture has been used to fabricate polydopamine nanocapsules.