Candida Antartica Lipase B Mediated Kinetic Resolution Of Racemic Acebutolol

Asebutolol masih lagi dipasarkan dalam bentuk rasemik sehingga kini. Kecenderungan terhadap penghasilan enantiomer tunggal bagi ubat-ubatan berbentuk kiral adalah didorong oleh beberapa faktor antaranya kesan yang berbeza daripada enantiomer tersebut, permintaan dalam pasaran yang semakin meningkat, juga peraturan yang semakin ketat terhadap pengeluaran ubat-ubatan tersebut. Oleh itu, resolusi kinetik terhadap rasemik asebutolol dikaji menggunakan perantaraan lipase dalam reaktor kelompok dan reaktor membran berenzim. Kaedah sambutan permukaan dengan rekabentuk central composite design (CCD) digunakan untuk analisis data bagi reaktor kelompok. Faktor yang dikaji adalah merangkumi jumlah enzim, kepekatan substrat dan penderma asil dan suhu tindakbalas. Kajian mendapati bahawa tindabalas di dalam reaktor kelompok ini mencapai optimum dengan 320 mg enzim, 50 mM kepekatan Asebutolol, 140 mM kepekatan vinil asetat and suhu 40 oC, memberikan kadar pertukaran sebanyak 46% dengan nilai E dan ees masing-masing 15 and 73%. Tenaga pengaktifan dan penyahtabii bagi enzim di dalam reaktor kelompok dalam kajian ini dianggarkan masing-masing sebanyak 39.63 kJ/mol dan 54.90 kJ/mol. Pemalar pendeaktifan kd meningkat sebanyak 0.012-0.031 per jam dengan peningkatan suhu daripada 45 oC ke 60 oC. Nilai entalpi adalah 52.12 kJ/mol.K dan entropi adalah -0.18 kJ/mol.K. Berdasarkan dapatan daripada tindak balas di dalam reaktor kelompok, resolusi kinetik Acebutolol telah berjaya dilakukan di dalam reaktor membran berenzim. Kesan jumlah enzim, kepekatan substrat dan penderma asil, pH larutan penimbal, suhu tindakbalas, kadar aliran fasa organik dan tekanan transmembran. Tindakbalas di dalam reaktor membran berenzim mencapai nilai optimum pada pH 7, 40 oC dan TMP 6 psi, dengan kadar aliran fasa organik sebanyak 40 ml/min. Ia memberikan nilai pertukaran 40%, E sebanyak 23 dan ees sebanyak 84%. Tindakbalas enzim di dalam reaktor kelompok dan reaktor membran berenzim kedua-duanya mematuhi mekanisme Ping Pong Bi Bi. Parameter kinetik untuk enzim bebas di dalam reaktor kelompok adalah seperti berikut: KMace =8.53 mM, KMva =5.19 mM, dan Vmax =1.18 mM/h. Manakala parameter kinetik untuk enzim tersekatgerak di dalam reaktor membran berenzim adalah seperti berikut; Kmace app = 2.13 mM, KMvaapp = 1.23 mM dan Vmax app =2.33 mM/h. Nilai pemalar perencat pula adalah KIace=10.72 mM, KIva,= 3.71 mM, KIace app = 11.56 mM dan KIva app=3.89 mM. Prestasi CALB di dalam kedua-dua jenis reaktor telah dibandingkan. Enzim tersekatgerak di dalam reaktor membran berenzim memberikan kapasiti tindak balas yang lebih tinggi, kestabilan terma yang lebih baik, afiniti yang lebih tinggi kepada substrat dan juga menunjukkan rintangan tinggi terhadap kesan perencat berbanding enzim bebas di dalam reaktor kelompok. Kelebihan enzim tersekatgerak dilihat amat berpotensi untuk diaplikasikan dalam industri penghasilan enantiomer tunggal, terutamanya penyekat beta dalam masa terdekat. ________________________________________________________________________________________________________________________ Acebutotol is still available in racemic form. The increasing preference for single or pure enantiomer of chiral drugs is driven mainly by the different effects of the enantiomers, the high market demand and the guidelines issued by regulatory authorities. Therefore, the kinetic resolution of racemic acebutolol is studied in batch and enzymatic membrane reactor. The response surface methodology based on central composite design (CCD) was employed for optimization and analysis of kinetic resolution of racemic acebutolol in a batch reactor. The process variables which were taken into account include; enzyme loading, substrate concentration, acyl donor concentration and temperature. The optimum conditions were found to be 320 mg of enzyme loading, with acebutolol concentration of 50 mM, vinyl acetate concentration of 140 mM and temperature at 40 oC, giving the overall conversion of 46.6%. The value of enantioselectivity E and enantiomeric excess of the substrate ees were found to be 15 and 73%, respectively. Lipase activation and deactivation energy was estimated to be 39.63 kJ/mol and 54.90 kJ/mol, respectively. Denaturation constant, kd was increasing from 0.012-0.031 h-1 with the increasing temperature from 45 0C to 60 0C. The value of enthalpy and entropy for free Candida antartica lipase B were 52.12 kJ/mol.K and -0.18 kJ/mol.K, respectively. Based on the finding from the batch reaction, kinetic resolution of acebutolol has been successfully conducted in enzymatic membrane reactor (EMR). The effects of enzyme loading, substrate and acyl donor concentration, pH of buffer solution, reaction temperature, and organic phase flow rates, and transmembrane pressure (TMP) were investigated. The optimum operating conditions for the lipase-catalyzed kinetic resolution in an EMR system were pH 7, 40 oC and TMP of 6 psi at organic flow rate of 40 ml/min. This condition gave 40% overall conversion, enentioselectivity of 23 and ees of 84%. The reaction kinetic was found to obey the Ping Pong Bi Bi mechanisms for both free and immobilized lipase from Candida antartica B . The kinetic parameters for the free lipase were: KMace =8.53 mM, KMva =5.19 mM, and Vmax =1.18 mM/h. The apparent kinetic parameters for the immobilized lipase were: Kmace app = 2.13 mM, KMvaapp = 1.23 mM and Vmax app =2.33 mM/h. The kinetics of kinetic resolution accounted for both substrates inhibitions. The inhibition constants were given by KIace=10.72 mM, KIva,= 3.71 mM, KIace app = 11.56 mM and KIva app=3.89 mM. The performance of free and immobilized CALB were compared. The immobilized lipase in EMR gave higher reaction capacity, better thermal stability, higher affinity to the substrates and exhibited higher resistance towards the inhibition effect. The advantages of immobilized enzyme makes it possible for economical industrial production of chiral drugs, particularly beta blockers in the near future

A current review on the application of enzymes in anaerobic digestion

Although the anaerobic digestion process is widely applied in waste management, it is recognised that the hydrolysis step in the treatment is a bottleneck that can restrict the rate that methane is produced. Enzyme addition during hydrolysis of a substrate has been reported as a promising alternative to overcome this limitation. This chapter presents a review of the supplementation of enzymes to facilitate the hydrolysis process of various types of substrates in the anaerobic digestion system

Utilisation of Guava discarded product: extraction of antioxidant from guava leaves using an Ultrasound Assisted Method

Background: In this research, guava leaves are utilised as a potential source of natural antioxidants. Various extraction techniques have been applied for the extraction of phenolic compounds from plants. However, the high temperature and long extraction time used in these methods can cause degradation of the bioactive compounds. In order to overcome this limitation, ultrasound assisted extraction is one of the techniques that can be applied. The advantages of this method include increased extraction yield, less solvent amount required, lower temperature and shorter extraction time. Objective: The main objective of this work is to apply ultrasound assisted method in the extraction of antioxidant from guava leaves. The effect of extraction time, temperature and the solid-to-liquid ratio on the extraction performance are investigated. Method: The extraction was conducted by following the standard method described in the literature. Total phenolic content and antioxidant activity were analysed according to Folin-Ciocalteu and 1,1- Diphenyl-2-picryl-hydrazyl (DPPH) method, respectively. Results: The results show that both total phenolic content and antioxidant activity increase with an increase in extraction time. The most appropriate temperature was found to be 55 °C, while increasing the solid-to-liquid ratio led to a drastic drop in the phenolic content and the antioxidant activity of the guava leaves. Conclusion: The ultrasound assisted extraction method was successfully applied in the extraction of antioxidant compounds from guava leaves. The utilisation of guava leaves in this manner is expected to reduce the amount of waste disposal from food industries

Effect of temperature on Candida antartica lipase B activity in the kinetic resolution of acebutolol

Thermodynamic studies of free Candida antartica lipase B in kinetic resolution of acebutolol have been carried out to characterize the temperature effects towards enzyme stability and activity. A decreased in reaction rate was observed in temperature above 40oC. Thermodynamic studies on lipase deactivation exhibited a first-order kinetic pattern. The activation and deactivation energies were 39.63 kJ/mol and 54.90 kJ/mol, respectively. The enthalpy and entropy of the lipase deactivation were found to be 52.12 kJ/mol and -0.18 kJ/mol, respectively

Energy Efficiency through Building Envelope in Malaysia and Singapore

The optimisation of fossil fuel consumption for generating electricity for building cooling is among the objectives set by most of the countries in the world. Currently, the American and European standards are among the most referred standards in the world for optimising heat transfer through the building envelope. However both standards do not reflect climate specifications of some countries such as those located in the humid tropics. The divergence in the approaches adopted by several Asian countries in minimising the heat transfer through the building envelope added another complexity to the topic. Other complexities are the divergence of European and American standards and the additional issue about the lack of validated weather data (TRY) in the humid tropics such as the case of Malaysia and Singapore. Those and other relevant issues on energy efficiency through the building envelope were addressed in the present article. Additionally a worked example and Excel sheet formulas were developed while considering Malaysian and Singaporean codes. Some recommendations were also suggested in the present article when deemed necessary

Effect of Reaction Parameters on the Lipase-Catalyzed Kinetic Resolution of (RS)-Metoprolol

Racemic metoprolol is a selective ß1-blocker, which is used in cardiovascular disease treatment. It has been found that (S)-metoprolol has a higher affinity to bind the ß-adrenergic receptor compared to (R)-metoprolol. Moreover, the regulatory authorities’ high market demand and guidelines have increased the preference for single enantiomer drugs. In this work, the lipase-catalyzed kinetic resolution of racemic metoprolol was performed to obtain the desired enantiomer. The type of lipase, acyl donor, and solvent were screened out. This was achieved by Candida antarctica B lipasecatalyzed transesterification of racemic metoprolol in hexane and vinyl acetate as the solvent and an acyl donor, which gave maximum conversion of (S)-metoprolol (XS) of 52%, enantiomeric excess of substrate, (ees) of 92% and product (eeP) of 90% with enantiomeric ratio (E) of 62. This method can be considered as green chemistry, which can be applied to produce other enantiopure beta-blockers

Formulation of polymeric inhibitor for viscosity reduction of crude oil

Generally, waxes and asphaltenes are classified as solid category which involved with deposition of high-molecular-weighted compounds along pipelines which leads to production issues. This study presents the effect of different mixture concentration consisting of copolymer and solvent on crude oil viscosity in order to find a solution for reduction of wax and asphalthene deposition along the surface of pipelines. There were two proportions used which are ethylene-vinyl acetate 25 (EVA 25), methylcyclohexane (MCH) and paraxylene as first proportion and EVA 40, MCH and paraxylene as second proportion. EVA is a polymer that comprises of linear chain of polyethylene fragment and vinyl acetate molecule which has the ability in controlling the size of formed wax crystals. Laboratory experiments were designed by response surface methodology (RSM) specifically using central composite design (CCD) to formulate ratio and analyzed optimum percentage composition of mixture to obtain a good model. The optimum parameters were 10.02% of EVA 25, 10.00% of MCH and 79.98% of paraxylene for first proportion and 10.00% of EVA 40, 45.78% of MCH and 44.22% of paraxylene for second proportion to minimize the viscosity of crude oil

Variation over time of the Du Mortier Calibration algorithm for ground-based spectrometer.

Having a stable and steady calibration constants increases the likelihood of a spectrometer to perform as expected over a reasonable period of time. The purpose of this paper is to study the variation over time of the Du Mortier calibration algorithm used in a spectrometer for atmospheric condition measurement. This is carried out over a course of six months and the measurements were taken for every minute intervals from 8.30am to 4.30pm in three locations in Kota Kinabalu. By using the improved Langley method, monthly calibration constants for eight wavelengths were determined for Du Mortier model. Results shows that there were statistically significant differences between mean calibration constants when comparing the selected months. However, if only wavelengths of 460nm, 500nm, 540nm, 580nm and 620nm are taken into account, the results say otherwise

A review of vegetable waste bio-processing techniques in rural areas

Purpose: Vegetable waste (VW) could cause environmental problems if not properly managed. Due to rural living conditions and a relatively low residence density, VW is usually disposed of in landfills. Waste management should be engineered in a way to process the waste into value-added products in a sustainable manner. This review evaluates four bioprocessing techniques for this purpose: anaerobic digestion (AD), vermicomposting (VC), black soldier fly composting (BSFC), and composting. Method: A systematic search involved databases from Scopus using keywords like “vegetable waste; anaerobic digestion; composting; vermicomposting; black soldier fly”. By reviewing and synthesizing 173 articles (with 162 from 2019−2023), this paper summarizes and illustrates the information collected. Results: In a systematic search, AD and composting easily surpassed 2000 publications (from 2013 to January 2023). Besides composting emerged as a cost-effective (for MYR 1.40/kg) bio-processing technique in terms of production cost. This review on VW composting is based on an acceptable C/N ratio (30−50), moisture content (50% −80%), ratio of VW to additives (typically 30:70), efficient additives, and inoculation strategy. This review also summarizes the maturity index and illustrates the usage of compost and leachate as fertilizer. Conclusion: VW composting in rural areas is reliable and beneficial because it uses a small-scale reactor and has the potential for a circular economy in the community

A review on bamboo as an adsorbent for removal of pollutants for wastewater treatment

Water and wastewater treatment are very important for obtaining clean and sanitary water as well as protecting the environment from toxic pollutants. Not only enriched with cellulose and carbon but the abundant resources of bamboo also make it suitable to be utilized as an adsorbent. With the right processing technologies and improvements, the potential of bamboo is unlimited. This study review provides knowledge on the use of bamboo-based adsorbents for the removal of contaminants and pollutants in wastewater in the form of activated carbon, biochar, and aerogel. This review highlighted bamboo utilization and its relevance as an adsorbent for wastewater treatment. The technologies for the processing and improvement of bamboo as well as the performance of the bamboo-based adsorbents are also discussed in this study. The adsorption capacity of bamboo has shown improvement with modification and good adsorption capacity achieved with some of the adsorbent being able to be recycled and reused