ABSTRACT
The highly strained cubylmethyl radical undergoes one of the fastest radical rearrangements known (reported k = 2.9 × 1010 s-1 at 25 °C) through scission of two bonds of the cube. The rearrangement has previously been used as a mechanistic probe to detect radical-based pathways in enzyme-catalyzed C-H oxidations. This paper reports the discovery of highly selective cytochrome P450-catalyzed methylcubane oxidations which notionally proceed via cubylmethyl radical intermediates yet are remarkably free of rearrangement. The bacterial cytochrome P450 CYP101B1 from Novosphingobium aromaticivorans DSM 12444 is found to hydroxylate the methyl group of a range of methylcubane substrates containing a regio-directing carbonyl functionality at C-4. Unlike other reported P450-catalyzed methylcubane oxidations, the designed methylcubanes are hydroxylated with high efficiency and selectivity, giving cubylmethanols in yields of up to 93%. The lack of cubane core ring-opening implies that the cubylmethyl radicals formed during these CYP101B1-catalyzed hydroxylations must have very short lifetimes, of just a few picoseconds, which are too short for them to manifest the side reactivity characteristic of a fully equilibrated P450 intermediate. We propose that the apparent ultrafast radical rebound can be explained by a mechanism in which C-H abstraction and C-O bond formation are merged into a dynamically coupled process, effectively bypassing a discrete radical intermediate. Related dynamical phenomena can be proposed to predict how P450s may achieve various other modes of reactivity by controlling the formation and fate of radical intermediates. In principle, dynamical ideas and two-state reactivity are each individually able to explain apparent ultrashort radical lifetimes in P450 catalysis, but they are best considered together.
ABSTRACT
The cytochrome P450 monooxygenase CYP101B1, from a Novosphingobium bacterium is able to bind and oxidise aromatic substrates but at a lower activity and efficiency than norisoprenoids and monoterpenoid esters. Histidineâ 85 of CYP101B1 aligns with tyrosineâ 96 of CYP101A1, which, in the latter enzyme forms the only hydrophilic interaction with its substrate, camphor. The histidine residue of CYP101B1 was mutated to phenylalanine with the aim of improving the activity of the enzyme for hydrophobic substrates. The H85F mutant lowered the binding affinity and activity of the enzyme for ß-ionone and altered the oxidation selectivity. This variant also showed enhanced affinity and activity towards alkylbenzenes, styrenes and methylnaphthalenes. For example the rate of product formation for acenaphthene oxidation was improved sixfold to 245â nmol per nmol CYP per min. Certain disubstituted naphthalenes and substrates, such as phenylcyclohexane and biphenyls, were oxidised with lower activity by the H85F variant. Variants at H85 (A and G) designed to introduce additional space into the active site so as to accommodate these larger substrates did not improve the oxidation activity. As the H85F mutant of CYP101B1 improved the oxidation of hydrophobic substrates, this residue is likely to be in the substrate binding pocket or the access channel of the enzyme. The side chain of the histidine might interact with the carbonyl groups of the favoured norisoprenoid substrates of CYP101B1.
Subject(s)
Cytochrome P-450 Enzyme System/genetics , Cytochrome P-450 Enzyme System/metabolism , Hydrocarbons, Aromatic/chemistry , Hydrocarbons, Aromatic/metabolism , Mutation , Sphingomonadaceae/enzymology , Hydrophobic and Hydrophilic Interactions , Molecular Structure , Oxidation-ReductionABSTRACT
Present study investigates 39 brands of candies, chocolate, and litchis, purchased from Dhaka City, Bangladesh, for their moisture content, sulphated ash value, heavy metal, and bacterial contamination. All the brands showed moisture content (0.64%-4.775%) within the BSTI range, but sulphated ash values (18.80%-25.72%) were beyond the accepted value. Pb, Cd, Ni, and Cr ranged from 0.24-2.40 µg/g, 0.071-0.44 µg/g, 0.38-48.10 µg/g, and 0.50-12.79 µg/g, respectively, in the tested brands. Most of the brands contained Pb and Cd beyond the acceptable limits of WHO/FDA. Pb (2.24-2586.75 µg/g) was found in high concentration in the packaging of most brands, and Ni and Cd ranged from 2.10-108.05 µg/g and 1.68-45 µg/g, respectively. Bacterial presence was found in 15 brands, and 4 of them had a total aerobic bacterial count of >1 log CFU/g. Consumption of such contaminated confectionaries holds significant public health risks, specially in children, and demands necessary precautionary steps.
ABSTRACT
This study aimed to investigate antibiotic residues such as oxytetracycline, ciprofloxacin, enrofloxacin and levofloxacin, in both pasteurised and raw cow's milk. A method using high-performance liquid chromatography with a UV detector (HPLC-UV) was developed and validated following International Conference on Harmonization (ICH) guidelines for simultaneous detection and quantification of these residues. The technique demonstrated linearity, with r2 values ranging from 0.999 to 1.00 within the 1.3-15.0 µg ml-1 range for each antibiotic. Thirty cow's milk samples, raw and pasteurised, from Dhaka's local markets were analysed, revealing the presence of enrofloxacin and levofloxacin, while oxytetracycline was absent in all samples. Notably, pasteurised milk samples contained enrofloxacin, levofloxacin and oxytetracycline, with groups P6 and P7 exceeding the Maximum Residue Limit for enrofloxacin, levofloxacin and ciprofloxacin (121 µg l-1). This study emphasises antibiotic residues in milk, with a validated method holding promise for routine analysis in industries requiring simultaneous quantitation of multiple antibiotics.
ABSTRACT
Background and Objectives: Prescription errors can inadvertently compromise the effectiveness and increase the risk of adverse events. This study aims to compare prescription patterns and errors between government and private hospitals in Dhaka, Bangladesh, by evaluating the World Health Organization (WHO) prescription indicators, polypharmacy, and omission errors. Methods: Between September 2021 and November 2021, a total of 399 prescriptions were collected from outpatient departments of various government and private hospitals from patients or their attendants. The data were analyzed using the statistical package STATA 15. Chi-square and Fisher's exact test were employed to determine associations (p < 0.05) among various types of categorical data. Results: Of the collected prescriptions, 48% (n = 192) were from government, while 52% (n = 207) were from private hospitals. The mean number of medicines per prescription was 5.16 for government and 5.87 for private hospitals. Generic names were absent (0%) in both types of hospitals. Antibiotics were present in 34.37% of prescriptions from government and 51.69% from private hospitals. Moreover, injection were found in 17.70% of government and 18.35% of private hospitals' prescriptions. Government hospitals adhered to 67.97% of the essential drug list, whereas private hospitals adhered to 80.42%. Associations between hospital types were observed in missing age, and comorbidities, while no association was found in inscription mistakes. Missing dates and signatures were also associated with hospital types. Polypharmacy was observed in 49.47% of government hospitals and 71.01% of private hospitals. Additionally, polypharmacy in females, pediatrics, geriatrics, and missing comorbidity were also associated with hospital types (p < 0.05). Conclusion: Both government and private hospitals exhibited similar deviations from the WHO prescribing indicators. While government hospitals showed more omission errors, private hospitals exhibited higher rates of polypharmacy. Physicians in both types of hospitals should be vigilant about omission errors, maintain the WHO prescribing indicators, and minimize polypharmacy.
ABSTRACT
Crinum asiaticum L. (Amaryllidaceae) is a perennial bulbous herb, locally utilized for possessing multifaceted pharmacological properties including anticancer, immune-stimulating, analgesic, antiviral, antimalarial, antibacterial and antifungal, in addition to its popularity as an aesthetic plant. Separation of MeOH extract of C. asiaticum leaves yielded three known compounds as cycloneolitsol (1), hippeastrine (2) and ß-sitosterol (3). Among these, compounds 1 and 2 were subjected to the cytotoxic assay and found that they induced mild effect against HCT116, Huh7 and DU145 cell lines with the IC50 values from 73.76 to 132.53 µM. When tested for TRAIL-resistance abrogating activity, 1 (100 µM) along with TRAIL (100 ng/mL) showed moderate activity in AGS cells producing 25 % more inhibition than the agent alone. Whereas 2 (20 and 30 µM) in combination with TRAIL (100 ng/mL) exhibited strong activity in abrogating TRAIL-resistance and caused 34 % and 36 % more inhibition in AGS cells, respectively. The in-silico studies of compound 2 revealed high docking hits with the TRAIL-associated anti-apoptotic proteins which give a justification for the regulatory interactions to induce such abrogating activity. It is still recommended to conduct further investigations to understand their exact molecular mechanism.
ABSTRACT
Background and Aims: To reduce death rates for critical patients hospitalized in intensive care units (ICUs), coronavirus (COVID-19) lacks proven and efficient treatment methods. This cross-sectional study aims to evaluate how physicians treat severe and suspected COVID-19 patients in the ICU department in the absence of an established approach, as well as assess the rational use of the medication in the ICU department. Methods: Between June 16, 2021, and December 10, 2022, a total of 428 prescriptions were randomly gathered, including both suspected (yellow zone) and confirmed (red zone) COVID-19 patients. For data management, Microsoft Excel 2021 was utilized, while STATA 17 provided statistical analysis. To find associations between patients' admission status and demographic details, exploratory and bivariate analyses were conducted. Results: Of the 428 patients admitted to the ICU, 228 (53.27%) were in the yellow zone and 200 (46.73%) were in the verified COVID-19 red zone. The majority of patients were male (54.44%), and the age range from 41 to 60 was the most common (41.82%). No significant deviation was detected to the yellow and red groups' prescription patterns. A total of 4001 medicines (mean 9.35/patient) were prescribed. Antiulcerants, antibiotics, respiratory, analgesics, anticoagulants, vitamins and minerals, steroids, cardiovascular, antidiabetic drugs, antivirals, antihistamines, muscle relaxants, and antifungal treatments were widely prescribed drugs. Enoxaparin (67.06%) appeared as the most prescribed medicine, followed by montelukast (60.51%), paracetamol (58.41%), and dexamethasone (51.64%). Conclusion: The prescription patterns for the yellow and red groups were comparable and mostly included symptomatic treatment. Respiratory drugs constituted the most frequent therapeutic class. Polypharmacy should be taken under considerations. In ICU settings, the outcomes emphasize the need of correct diagnosis, cautious antibiotic usage, suitable therapy, and attentive monitoring.
ABSTRACT
Context: The rational prescription leads to a healthy and good-quality life of a patient. Irrational, inappropriate, and unnecessary prescriptions are major therapeutic issues in Bangladesh, which can cause severe consequences. Aim: This cross-sectional study was conducted to evaluate the prescription patterns and errors as well as to review the most frequently prescribed drug classes among outpatients at a secondary hospital in Pabna, a district of Bangladesh. Methods: A total of 400 prescriptions were reviewed from March 2019 to May 2019. In this study, statistical data analysis was implemented by IBM SPSS Statistics V22 and data revealed in frequencies, mean, and percentage. Spearman's rank correlation coefficient was calculated to show the correlation between bivariate coded variables. Results: The results revealed that majority of the prescription were prescribed for females (73.5%) where proton-pump inhibitors (PPIs), analgesics, vitamins, and single antibiotics were most frequently prescribed medicine for the female patients compared to male patients. Almost half of the collected prescription contained four medicines (47%). Maximum number of prescriptions contained two (30.5%) essential drugs and among 1402 medicines of 400 prescriptions, antiulcerants were most frequently prescribed medicine (23.32%) where esomeprazole was highly prescribed generic drug (44.75%). Moreover, Spearman's rank correlation coefficient suggested that PPIs and analgesics were frequently prescribed medicines at a time for the patients (0.182). According to the age group, the study also got some significant variations in prescribing pattern. However, most common prescription errors were prescriber's name not mentioned (100%), diagnosis not mentioned (96.75%), dose not indicated (15.41%), and wrong drug name (0.36%). Conclusion: Findings of the current study represent the existing prescribing trends of different therapeutic classes of drugs and common prescription errors in a secondary health facility of Bangladesh. From this study, it is observed that physicians prescribed rationally in some cases but need to ensure rationality in all prescriptions. Continuous monitoring of drug use, development of prescribing guidelines, and training are recommended to ensure and implement good-quality prescribing practices for promoting the rational and cost-effective use of drugs.
ABSTRACT
Dengue, a mosquito transmitted febrile viral disease, is a serious public health concern in Bangladesh. Despite significant number of incidences and reported deaths each year, there are inadequate number of studies relating the temporal trends of the clinical parameters as well as socio-demographic factors with the clinical course of the disease. Therefore, this study aims to associate the clinical parameters, demographic and behavioral factors of the dengue patients admitted in a tertiary care hospital in Dhaka, Bangladesh during the 2019 outbreak of dengue with the clinical course of the disease. Data were collected from the 336 confirmed dengue in-patients and analyzed using SPSS 26.0 software. Majority of the patients were male (2.2 times higher than female) who required longer time to recover compared to females (p < 0.01), urban resident (54.35%) and belonged to the age group of 18-40 years (73.33%). Dengue fever (90.77%) and dengue hemorrhagic fever (5.95%) were reported in most of the dengue patients while fever (98%) was the most frequently observed symptom. A significantly positive association was found between patient's age and number of manifested symptoms (p = 0.013). Average duration of stay in the hospital was 4.9 days (SD = 1.652) and patient's recovery time was positively correlated with delayed hospitalization (p < 0.01). Additionally, recovery time was negatively correlated with initial blood pressure (both systolic (p = 0.001, and diastolic (p = 0.023)) and platelet count (p = 0.003) of the patients recorded on the first day of hospitalization. Finally, a statistical model was developed which predicted that, hospital stay could be positively associated with an increasing trend of temperature, systolic blood pressure and reduced platelets count. Findings of this study may be beneficial to better understand the clinical course of the disease, identify the potential risk factors and ensure improved patient management during future dengue outbreaks.
Subject(s)
Dengue , Adolescent , Adult , Animals , Bangladesh/epidemiology , Dengue/diagnosis , Female , Humans , Incidence , Male , Retrospective Studies , Tertiary Care Centers , Young AdultABSTRACT
The cytochrome P450 monooxygenase CYP101B1 from Novosphingobium aromaticivorans selectively hydroxylated methylene C-H bonds in cycloalkyl rings. Cycloketones and cycloalkyl esters containing C6, C8, C10 and C12 rings were oxidised with high selectively on the opposite side of the ring to the carbonyl substituent. Cyclodecanone was oxidised to oxabicycloundecanol derivatives in equilibrium with the hydroxycyclodecanones.