Monooxygenase- and Dioxygenase-Catalyzed Oxidative Dearomatization of Thiophenes by Sulfoxidation, cis-Dihydroxylation and Epoxidation

Enzymatic oxidations of thiophenes, including thiophene-containing drugs, are important for biodesulfurization of crude oil and drug metabolism of mono- and poly-cyclic thiophenes. Thiophene oxidative dearomatization pathways involve reactive metabolites, whose detection is important in the pharmaceutical industry, and are catalyzed by monooxygenase (sulfoxidation, epoxidation) and dioxygenase (sulfoxidation, dihydroxylation) enzymes. Sulfoxide and epoxide metabolites of thiophene substrates are often unstable, and, while cis-dihydrodiol metabolites are more stable, significant challenges are presented by both types of metabolite. Prediction of the structure, relative and absolute configuration, and enantiopurity of chiral metabolites obtained from thiophene enzymatic oxidation depends on the substrate, type of oxygenase selected, and molecular docking results. The racemization and dimerization of sulfoxides, cis/trans epimerization of dihydrodiol metabolites, and aromatization of epoxides are all factors associated with the mono- and di-oxygenase-catalyzed metabolism of thiophenes and thiophene-containing drugs and their applications in chemoenzymatic synthesis and medicine.

Oxidase enzymes as sustainable oxidation catalysts

Oxidation is one of the most important processes used by the chemical industry. However, many of the methods that are used pose significant sustainability and environmental issues. Biocatalytic oxidation offers an alternative to these methods, with a now significant enzymatic oxidation toolbox on offer to chemists. Oxidases are one of these options, and as they only depend on molecular oxygen as a terminal oxidant offer perfect atom economy alongside the selectivity benefits afforded by enzymes. This review will focus on examples of oxidase biocatalysts that have been used for the sustainable production of important molecules and highlight some important processes that have been significantly improved through the use of oxidases. It will also consider emerging classes of oxidases, and how they might fit in a future biorefinery approach for the sustainable production of important chemicals.

Effect of thermosonication on enzymatic oxidation and physicochemical properties of soursop (Annona muricata) pulp

Soursop is an exotic tropical fruit, highly perishable, presents losses around 30% in postharvest, has marked commercial importance especially for internal consumption and a maximum shelf life. The objective of the present work was to study the effect of thermosonication (TS) on some physicochemical properties and the enzymatic oxidation of soursop pulp. The thermosonication treatments used on the samples were at 40 kHz, in a temperature range between 20-60 ºC, for 25 minutes. The soluble solids, pH, vitamin C concentration, inactivation of peroxidase (POD) and polyphenoloxidase (PPO) in the soursop pulp were evaluated before and after the treatments. The results indicate a loss of vitamin C was observed in a 2.63; 13.16 and 28.95% for temperatures at 20, 40 and 60 ºC, respectively. On the other hand, a partial inactivation of the enzymes, POD, in 48.41; 69.83 and 74.24% and for PPO in 56.38; 74.47 and 81.91% was achieved at temperatures at 20, 40 and 60 ºC respectively. Finally, it was demonstrated that the US combined with heat (TS) inactivates in a large percentage the POD and PPO enzymes in the soursop pulp needing less heat, which could make it more efficient in comparison with the thermal treatments. Highlights Ultrasound combined with heat (TS) can inactivate POD and PPO enzymes in the soursop pulp, achieving considerable retention of vitamin C. Peroxidase (POD) and Polyphenoloxidase (PPO) trigger enzymatic processes affecting product natural color. Soursop is an exotic fruit with high levels of bioactive compounds, and great agro-industrial potential given its high recovery yields and excellent sensory characteristics. A vitamin C retention level of 71.05- to 86.84% was achieved in soursop pulps that have undergone thermosonification.

Medical Waste Treatment Technologies for Energy, Fuels, and Materials Production: A Review

The importance of medical waste management has grown during the COVID-19 pandemic because of the increase in medical waste quantity and the significant dangers of these highly infected wastes for human health and the environment. This innovative review focuses on the possibility of materials, gas/liquid/solid fuels, thermal energy, and electric power production from medical waste fractions. Appropriate and promising treatment/disposal technologies, such as (i) acid hydrolysis, (ii) acid/enzymatic hydrolysis, (iii) anaerobic digestion, (vi) autoclaving, (v) enzymatic oxidation, (vi) hydrothermal carbonization/treatment, (vii) incineration/steam heat recovery system, (viii) pyrolysis/Rankine cycle, (ix) rotary kiln treatment, (x) microwave/steam sterilization, (xi) plasma gasification/melting, (xii) sulfonation, (xiii) batch reactor thermal cracking, and (xiv) torrefaction, were investigated. The medical waste generation data were collected according to numerous researchers from various countries, and divided into gross medical waste and hazardous medical waste. Moreover, the medical wastes were separated into categories and types according to the international literature and the medical waste fractions’ percentages were estimated. The capability of the examined medical waste treatment technologies to produce energy, fuels, and materials, and eliminate the medical waste management problem, was very promising with regard to the near future.

Konsentrasi Polyfenol pada Teh Hitam Celup Komersial Produksi Perkebunan Teh di Jawa Tengah

Teh merupakan minuman yang dihasilkan dari pucuk daun tanaman Camellia sinensis yang tumbuh di pegunungan pada ketinggian 600–2500 m dpl. Teh hitam merupakan jenis teh yang banyak dikonsumsi masyarakat Indonesia. Teh ini diproduksi dengan cara fermentasi melalui proses oksidasi enzimatis katekin oleh polifenol oksidase. Teh hitam yang dikemas dalam bentuk the celup banyak digemari konsumen. Tujuan dari penelitian ini mengetahui konsentrasi polyfenol dalam teh hitam celup komersial. Sampel teh hitam celup komersial dengan merk dagang TP, TDT, TB, TL, TD, dan TM diproduksi oleh enam perkebunan teh di Jawa Tengah yang diperoleh secara acak dari swalayan di Kota Semarang. Kandungan polyfenol pada sampel teh hitam celup dianalisa dengan menggunakan spetrofotometer UV-Vis pada panjang gelombang 725nm. Hasil penelitian menunjukkan bahwa teh hitam celup komersial yang beredar di Kota Semarang telah memenuhi standard SNI 3753–2014, dengan rata-rata konsentrasi polyfenol 8,83-43,63 %b/b. Analisa Zscore menunjukkan tidak ada perbedaan yang sangat nyata antar konsentrasi polyfenol di enam sampel teh hitam celup komersial, hal ini dimungkinkan dengan adanya standarisasi proses produksi teh hitam di berbagai industri teh di Indonesia. Dan teh hitam celup komersial TDT mempunyai konsentrasi polyfenol diatas rata-rata yaitu 43,63 % b/b. Tea is a drink produced from the leaves of the Camellia sinensis plant that thrives in the mountains at an altitude of 600–2500 m above sea level. Black tea is a type of tea that is widely consumed by Indonesian people. Black tea is produced by fermentation, namely the process of enzymatic oxidation of catechins by polyphenol oxidase. Black tea is produced in several packages, including as black tea bags. The purpose of this study was to determine the concentration of polyphenols in commercial black tea bags. Samples of commercial black tea bags with the trademarks TP, TDT, TB, TL, TD, and TM were produced by six tea plantations in Central Java which were obtained randomly from supermarkets/stores in Semarang City. The polyphenol content in black teabag samples was analyzed using a UV-Vis spectrophotometer at a wavelength of 725nm. The results showed that the commercial black tea bags marketed in the Semarang City had met the standards of SNI 3753–2014, with an average polyphenol concentration of 8.83-43.63% w/w. The Zscore analysis showed that there was no significant difference between the concentrations of polyphenols in the six samples of commercial black tea bags, this may cause by the standardization of black tea production processes in various tea industries in Indonesia, but commercial black tea bags with the trademark TDT had polyphenol concentrations above the average is 43.63% w/w.

Increase in Plasma Oxidized Phosphatidylcholines (OxPCs) in Patients Presenting With ST-Elevation Myocardial Infarction (STEMI)

Objective: ST-segment Elevation Myocardial Infarction (STEMI) occurs as a result of acute occlusion of the coronary artery. Despite successful reperfusion using percutaneous coronary intervention (PCI), a large percentage of myocardial cells die after reperfusion which is recognized as ischemia/reperfusion injury (I/R). Oxidized phosphatidylcholines (OxPCs) are a group of oxidized lipids generated through non-enzymatic oxidation and have pro-inflammatory properties. This study aimed to examine the roles of OxPCs in a clinical setting of myocardial I/R.Methods: Blood samples were collected from STEMI patients at presentation prior to primary PCI (PPCI) (Isch) and at 4 time-points post-PPCI, including 2 h (R-2 h), 24 h (R-24 h), 48 h (R-48 h), and 30 days (R-30 d) post-PPCI. As controls, blood samples were collected from patients with non-obstructive coronary artery disease after diagnostic coronary angiography. Aspiration thrombectomy was also performed in selected STEMI patients. High-performance lipid chromatography-electrospray mass spectrometry (LC-MS/MS) was used for OxPCs analysis.Results: Twenty-two distinct OxPC species were identified and quantified in plasma samples in patients presenting with STEMI. These compounds were categorized as fragmented and non-fragmented species. Total levels of OxPCs did not significantly differ between Isch and control groups. However, total levels of fragmented OxPCs increased significantly in the ischemic period compared with controls (Isch: 4.79 ± 0.94, Control: 1.69 ± 0.19 ng/μl of plasma, P < 0.05). Concentrations of non-fragmented OxPCs had significant reductions during ischemia compared to the control group (Isch: 4.84 ± 0.30, Control: 6.6 ± 0.51 ng/μl, P < 0.05). Levels of total OxPCs in patients with STEMI were not significantly different during reperfusion periods. However, fragmented OxPCs levels were elevated at 48 h post-reperfusion and decreased at 30 days following MI, when compared to R-2 h and R-24 h time points (Isch: 4.79 ± 0.94, R-2 h: 5.33 ± 1.17, R-24 h: 5.20 ± 1.1, R-48 h: 4.18 ± 1.07, R-30 d: 1.87 ± 0.31 ng/μl, P < 0.05). Plasma levels of two fragmented OxPCs, namely, POVPC and PONPC were significantly correlated with peak creatine kinase (CK) levels (P < 0.05). As with plasma levels, the dominant OxPC species in coronary aspirated thrombus were fragmented OxPCs, which constituted 77% of total OxPC concentrations.Conclusion: Biologically active fragmented OxPC were elevated in patients presenting with STEMI when compared to controls. PONPC concentrations were subsequently increased after PPCI resulting in reperfusion. Moreover, levels of POVPC and PONPC were also associated with peak CK levels. Since these molecules are potent stimulators for cardiomyocyte cell death, therapeutics attenuating their activities can result in a novel therapeutic pathway for myocardial salvage for patients undergoing reperfusion therapy.

Accumulation and Transformation of Biogenic Amines and Gamma-Aminobutyric Acid (GABA) in Chickpea Sourdough

In general, sourdough fermentation leads to an improvement in the technological, nutritional, and sensory properties of bakery products. The use of non-conventional flours with a specific autochthonous microbiota may lead to the formation of secondary metabolites, which may even have undesirable physiological and toxicological effects. Chickpea flours from different suppliers have been used to produce sourdoughs by spontaneous and inoculated fermentations. The content of nutritionally undesirable biogenic amines (BA) and beneficial gamma-aminobutyric acid (GABA) was determined by chromatography. Fenugreek sprouts, which are a rich source of amine oxidases, were used to reduce the BA content in the sourdoughs. Spontaneous fermentation resulted in a high accumulation of cadaverine, putrescine, and tyramine for certain flours. The use of commercial starter cultures was not effective in reducing the accumulation of BA in all sourdoughs. The addition of fenugreek sprouts to the suspension of sourdough with pH raised to 6.5 resulted in a significant reduction in BA contents. Enzymatic oxidation was less efficient during kneading. Baking resulted in only a partial degradation of BA and GABA in the crust and not in the crumb. Therefore, it could be suggested to give more importance to the control of sourdough fermentation with regard to the formation of nutritionally undesirable BA and to exploit the possibilities of their degradation.

Development of an Effective and Economic Biosensor for Diabetic Blood Monitoring Based on MWCNTs, Artificial Redox Mediator Ferrocene, Nafion Polymer and a Local Extracted and Purified Glucose Oxidase Enzyme from Penicillium Notatum F-158 Fungus

Enhancement of the properties of glucose oxidase (GOx) enzyme is still receiving attention due to its extensive applications. Eight different fungal strains were isolated from soil and orange fruit samples for inexpensive GOx production. Penicillium notatum F-158 (P. notatum) strain produced a remarkable amount of GOx. Its culture condition was optimized for optimum GOx production. GOx was purified and its activity, stability and kinetic parameters were studied. An effective biosensor {GCE/[MWCNTs–Fc–GOx(FAD)–NF]} based on layer by layer immbolization of MWCNTs, aritificial ferrocene (Fc) redox mediator, extracted P. notatum GOx enzyme and nafion polymer (NF) on glassy carbon electrode (GCE) surface was developed for glucose determination. Fc acts as an electron relay between enzyme and MWCNTs/GCE. The synergy of MWCNTs and Fc enhances the electrocatalytic action of Fc to the enzymatic oxidation of glucose. Low potential (+0.3V) of Fc applied in amperometric measurements avoids interference of the main electroactive substances present in the real plasma samples. This biosensor showed broad linear ranges {2.80×10-4 to 14.99×10-3 M} and low detection limit (8.68×10-6 M) for glucose determination. The achieved glucose concentrations in six plasma samples are consistent with normal values in human blood indicating that such biosensor could be used clinically.

Changes in Browning Degree and Reducibility of Polyphenols during Autoxidation and Enzymatic Oxidation

In the present study, the browning degree and reducing power of browning products of catechin (CT), epicatechin (EC), caffeic acid (CA), and chlorogenic acid (CGA) in autoxidation and enzymatic oxidation were investigated. Influencing factors were considered, such as pH, substrate species and composition, and eugenol. Results show that polyphenols’ autoxidation was intensified in an alkaline environment, but the reducing power was not improved. Products of enzymatic oxidation at a neutral pH have higher reducing power than autoxidation. In enzymatic oxidation, the browning degree of mixed substrates was higher than that of a single polyphenol. The reducing power of flavonoid mixed solution (CT and EC) was higher than those of phenolic acids’ (CA and CGA) in autoxidation and enzymatic oxidation. Eugenol activity studies have shown that eugenol could increase autoxidation browning but inhibit enzymatic browning. Activity test and molecular docking results show that eugenol could inhibit tyrosinase.

Use of Immobilized Enzyme In Granular Activated Carbon And Chitosan Beads For Phenol Removal From Effluents

Tyrosinase enzyme present in a crude extract was immobilized in granular activated carbon (GAC) and activated chitosan beads (ACB). It was possible to immobilize up to 70.0 % of the enzymes in GAC in the conditions of 10.0 g of support, 15.7 rad/s of agitation and 90 minutes of contact time, and 100.0 % of enzymes in ACB when using 5 g of support, agitation of 15.7 rad/s and contact time of 120 minutes. In enzymatic oxidation tests, tyrosinase immobilized in GAC was able to achieve a final phenol concentration below the limit required by Brazilian law, 0.5 mg/L for phenol solutions with an initial concentration up to 20.0 mg/L while the enzyme immobilized in ACB was able to adapt solutions with initial concentrations of phenol up to 40.0 mg /L. It was possible to reuse the enzyme immobilized in GAC 2 times, maintaining the same phenol removal efficiency, while the enzyme immobilized in ACB maintained up to 98.0 % of its efficiency in 5 cycles of enzymatic oxidation of solutions with 10.0 mg/L of phenol initially. It was possible to maintain the same phenol removal efficiency as immobilized enzymes when stored for up to 2 weeks.