Neonicotinoid’s resistance monitoring, diagnostic mechanisms and cytochrome P450 expression in green peach aphid [Myzus persicae (Sulzer) (Hemiptera: Aphididae)]

Green peach aphid [Myzus persicae (Sulzer) (Hemiptera: Aphididae)] is a significant pest with a known history of insecticide resistance. Neonicotinoids could manage this pest; however, their frequent use led to the evolution of resistance in field populations of M. persicae. Toxicity data for neonicotinoid insecticides synergized with pipernyl butoxide (PBO) in a field population (FP) were collected and compared to a laboratory susceptible clone (SC) of aphids. The enhanced expression of metabolic resistance-related cytochrome P450 gene CYP6CY3 and an arginine-threonine substitution were detected in FP, causing a single point mutation (R81T) at β1 subunit of nicotinic acetylcholine receptor (nAChR) within D loop. High level of resistance to imidacloprid was developed in FP with 101-fold resistance ratio and moderate resistance level (10.9-fold) to acetamiprid. The results of PBO synergized bioassay suggested that cytochrome P450 enzymes were involved in the resistance to neonicotinoids. The mRNA transcriptional level of CYP6CY3 gene was significantly higher (3.74 fold) in FP compared to SC. The R81T mutation associated with neonicotinoid resistance had 26% resistant allele frequency in FP. Both P450 enzymes and R81T mutation of nAChR were found in field-evolved neonicotinoid resistance. It is concluded that field-evolved resistance in green peach aphid could be managed by using appropriate synergists such as PBO.

1,3-Butadiene: a ubiquitous environmental mutagen and its associations with diseases

Abstract1,3-Butadiene (BD) is a petrochemical manufactured in high volumes. It is a human carcinogen and can induce lymphohematopoietic cancers, particularly leukemia, in occupationally-exposed workers. BD is an air pollutant with the major environmental sources being automobile exhaust and tobacco smoke. It is one of the major constituents and is considered the most carcinogenic compound in cigarette smoke. The BD concentrations in urban areas usually vary between 0.01 and 3.3 μg/m3 but can be significantly higher in some microenvironments. For BD exposure of the general population, microenvironments, particularly indoor microenvironments, are the primary determinant and environmental tobacco smoke is the main contributor. BD has high cancer risk and has been ranked the second or the third in the environmental pollutants monitored in most urban areas, with the cancer risks exceeding 10-5. Mutagenicity/carcinogenicity of BD is mediated by its genotoxic metabolites but the specific metabolite(s) responsible for the effects in humans have not been determined. BD can be bioactivated to yield three mutagenic epoxide metabolites by cytochrome P450 enzymes, or potentially be biotransformed into a mutagenic chlorohydrin by myeloperoxidase, a peroxidase almost specifically present in neutrophils and monocytes. Several urinary BD biomarkers have been developed, among which N-acetyl-S-(4-hydroxy-2-buten-1-yl)-L-cysteine is the most sensitive and is suitable for biomonitoring BD exposure in the general population. Exposure to BD has been associated with leukemia, cardiovascular disease, and possibly reproductive effects, and may be associated with several cancers, autism, and asthma in children. Collectively, BD is a ubiquitous pollutant that has been associated with a range of adverse health effects and diseases with children being a subpopulation with potentially greater susceptibility. Its adverse effects on human health may have been underestimated and more studies are needed.

Association between genetic polymorphisms in cytochrome P450 enzymes and survivals in women with breast cancer receiving adjuvant endocrine therapy: a systematic review and meta-analysis

Tamoxifen is commonly prescribed for preventing recurrence in patients with breast cancer. However, the responses of the patients on tamoxifen treatment are variable. Cytochrome P450 genetic variants have been reported to have a significant impact on the clinical outcomes of tamoxifen treatment but no tangible conclusion can be made up till now. The present review attempts to provide a comprehensive review on the associative relationship between genetic polymorphisms in cytochrome P450 enzymes and survival in breast cancer patients on adjuvant tamoxifen therapy. The literature search was conducted using five databases, resulting in the inclusion of 58 studies in the review. An appraisal of the reporting quality of the included studies was conducted using the assessment tool from the Effective Public Health Practice Project (EPHPP). Meta-analyses were performed on CYP2D6 studies using Review Manager 5.3 software. For other studies, descriptive analyses were performed. The results of meta-analyses demonstrated that shorter overall survival, disease-free survival and relapse-free survival were found in the patients with decreased metabolisers when compared to normal metabolisers. The findings also showed that varying and conflicting results were reported by the included studies. The possible explanations for the variable results are discussed in this review.

The Role of Insect Cytochrome P450s in Mediating Insecticide Resistance

In many organisms, cytochrome P450 enzymes are the primary detoxifying enzymes. Enhanced P450 activity can be mediated by the emergence of new genes, increased transcription due to mutations in the promoter regions, changes in enzyme structures and functions due to mutations in protein-coding regions, or changes in post-translational modifications; all of these changes are subject to insecticide selection pressure. Multiple signalling pathways and key effector molecules are involved in the regulation of insect P450s. Increased P450 activity is a key mechanism inducing insect resistance. Hence, downregulation of selected P450s is a promising strategy to overcome this resistance. Insect P450 inhibitors that act as insecticide synergists, RNA interference to induce P450 gene silencing, and the use of transgenic insects and crops are examples of strategies utilized to overcome resistance. This article reviews the latest advances in studies related to insect P450s-mediated agrochemical resistance, with focuses on the regulatory mechanisms and associated pest management strategies. Future investigations on the comprehensive regulatory pathways of P450-mediated detoxification, identification of key effectors, and downregulation strategies for P450s will ecologically, economically, and practically improve pest management.

Evaluation of Pharmacogenomics Testing of Cytochrome P450 Enzymes in the Military Health System From 2015 to 2020

ABSTRACT Pharmacogenomics (PGx) plays a fundamental role in personalized medicine, providing an evidence-based treatment approach centered on the relationship between genomic variations and their effect on drug metabolism. Cytochrome P450 (CYP450) enzymes are responsible for the metabolism of most clinically prescribed drugs and a major source of variability in drug pharmacokinetics and pharmacodynamics. To assess the prevalence of PGx testing within the Military Health System (MHS), testing of specific CYP450 enzymes was evaluated. Data were retrospectively obtained from the Military Health System Management Analysis and Reporting Tool (M2) database. Patient demographics were identified for each test, along with TRICARE status, military treatment facility, clinic, and National Provider Identifier. A total of 929 patients received 1,833 PGx tests, predominantly composed of active duty/guard service members (N = 460; 49.5%), with highest testing rates in the army (51.5%). An even distribution in testing was observed among gender, with the highest rates in Caucasians (41.7%). Of the CYP enzymes assessed, CYP2C19 and CYP2D6 accounted for 87.8% of all PGx CYP testing. The majority of patients were tested in psychiatry clinics (N = 496; 53.4%) and primary care clinics (N = 233; 25.1%), accounting for 56.4% and 24.8% of all tests, respectively. Testing was found to be provider driven, suggesting a lack of a standardized approach to PGx and its application in patient care within the MHS. We initially recommend targeted education and revising testing labels to be more uniform and informative. Long-term recommendations include establishing pharmacy-driven protocols and point-of-care PGx testing to optimize patient outcomes.

Metabolism of Phytochemicals

Several phytochemicals have been developed as medicinal compounds. Extensive research has recently been conducted on phytochemicals such as curcumin, resveratrol, catechin, gallic acid, humulone, quercetin, rutin, diosgenin, allicin, gingerenone-A, caffeic acid, ellagic acid, kaempferol, isorhamnetin, chlorogenic acid, and others. All of these phytochemicals are metabolized in the biological system. To study the metabolic pathways of phytochemicals, studies are done using both in vitro and in vivo techniques. Metabolism is critical in determining phytochemical bioavailability, pharmacokinetics, and effectiveness. Metabolism can occur in organs such as the intestine, liver, gut, and spleen. The metabolic process is aided by a variety of enzymes, including cytochrome P450 enzymes found in the organs. This study outlines a few phytochemicals metabolic pathways. Tannic acid, ellagic acid, curcumin, quercetin, and resveratrol are selected and explained as examples.

The Oxidation Cascade of a Rare Multifunctional P450 Enzyme Involved in Asperterpenoid A Biosynthesis

The cytochrome P450 enzymes (P450s or CYPs) are heme-containing enzymes which catalyze a wide range of oxidation reactions in nature. In our previous study, a rare multifunctional P450 AstB was found, which can dually oxidize two methyl groups (C-19 and C-21) of preasperterpenoid A to asperterpenoid A with 3-carboxyl and 11-hydroxymethyl groups. However, the oxidation order of C-19 and C-21 catalyzed by AstB is unclear. In order to reveal this oxidation order, probable pathways catalyzed by AstB were proposed, and the oxidation order of C-19 and C-21 was obtained by quantum chemistry calculations. The potential intermediates (three new asperterpenoids D–F, 1–3) were obtained through the chemical investigation on the extract of the transformant strain and chemical conversions, which were used as the standards to detect their existences in the extract of the transformant strain with HPLC-MS. Combined with the quantum chemistry calculation and the HPLC-MS analysis, the catalyzed order of AstB in asperterpenoid A biosynthesis was revealed. Furthermore, the mPTPB inhibition of obtained asperterpenoids was evaluated, and the results showed that 3-carboxyl and the oxidation station of C-21 would be the key factors for mPTPB inhibition of asperterpenoids.

Genomic analysis of Elsinoë arachidis reveals its potential pathogenic mechanism and the biosynthesis pathway of elsinochrome toxin

Elsinochromes (ESCs) are virulence factors produced by Elsinoë arachidis which is the cause of peanut scab. However, the biosynthesis pathway of ESCs in E. arachidis has not been elucidated and the potential pathogenic mechanism of E. arachidis is poorly understood. In this study, we report a high-quality genome sequence of E. arachidis. The size of the E. arachidis genome is 33.18Mb, which is comparable to the Ascomycota genome (average 36.91 Mb), encoding 9174 predicted genes. The self-detoxification family including transporters and cytochrome P450 enzymes were analysis, candidate effectors and cell wall degrading enzymes were investigated as the pathogenicity genes by using PHI and CAZy databases. Additionally, the E. arachidis genome contains 24 secondary metabolism gene clusters, in which ESCB1 was identified as the core gene of ESC biosynthesis. Taken together, the genome sequence of E. arachidis provides a new route to explore its potential pathogenic mechanism and the biosynthesis pathway of ESCs.

In Silico Taste, Cytochrome and Toxicity Prediction Study of Major Chamomile Constituents

Chamomile is an ancient herb used for various medications. It contains many bioactive constituents such as volatile oils, terpenoids, flavonoids, lactones, acid esters, glycosides and others. By reviewing many references, a confliction appeared of using Chamomile preparations to treat primary teeth eruption symptoms as a therapy administered by pediatric dentist or pediatrician. In this study, thirteen bioactive constituents (α-bisabolol (B), chamazulene (C), umbelliferone (U), apigenin (A), apigetrin (AT), apiin (AI), luteolin (L), quercetin (Q), quercimertrin (QT), rutin (R), α-cadinene (CD), α-farnesene (F), and matricarin (M) were subject to computational predication through various online websites to predicate their taste, activity towards several CYP450 enzymes and their action as Hepatotoxic, carcinogenic, immunotoxic, mutagenic, and cytotoxic compounds. Our calculations revealed several points such as high value of taste predication indicated that Chamomile constituents under study were with sour taste, did not classify as individual fatal compound Class (GHS) 1 or 2, 44.87% of them showed inhibition character toward specific cytochrome P450 enzyme while 43.59% were non- inhibition character, more than (0.5) probability predication of various cytochrome P450 enzymes gave a positive activity that may affect liver functions. Also, hepatotoxicity, carcinogenicity, immunotoxicity, mutagenicity, and cytotoxicity predictions were more than (0.5), unsaturated Chamomile constituent (Farnesene, F) had highest immune – and mutagenic properties whilst the disaccharide flavonoid (Rutin, R) had the highest Carcino- immunogenic response. According to the above notes, our conclusion is to use minimum concentration of Chamomile preparation for less period of time and lowest repeating intake that ensure effective treatment of teething symptoms under supervision of pediatricians with minimum side effect.