Nerolidol and Farnesol Inhibit Some Cytochrome P450 Activities but Did Not Affect Other Xenobiotic-Metabolizing Enzymes in Rat and Human Hepatic Subcellular Fractions

Neuroprotective mechanism of trans,trans-Farnesol in an ICV-STZ-induced rat model of Alzheimer's pathology

BACKGROUND

Alzheimer's disease (AD) is a prominent cause of dementia, resulting in neurodegeneration and memory impairment. This condition imposes a considerable public health burden on both patients and their families due to the patients' functional impairments as well as the psychological and financial constraints. It has been well demonstrated that its aetiology involves proteinopathy, mitochondriopathies, and enhanced reactive oxygen species (ROS) generation, which are some of the key features of AD brains that further result in oxidative stress, excitotoxicity, autophagy, and mitochondrial dysfunction.

OBJECTIVE

The current investigation was created with the aim of elucidating the neurological defence mechanism of trans,trans-Farnesol (TF) against intracerebroventricular-streptozotocin (ICV-STZ)-induced Alzheimer-like symptoms and related pathologies in rodents.

MATERIALS AND METHODS

The current investigation involved male SD rats receiving TF (25-100 mg/kg, per oral) consecutively for 21 days in ICV-STZ-treated animals. An in silico study was carried out to explore the possible interaction between TF and NADH dehydrogenase and succinate dehydrogenase. Further, various behavioural (Morris water maze and novel object recognition test), biochemical (oxidants and anti-oxidant markers), activities of mitochondrial enzyme complexes and acetylcholinesterase (AChE), pro-inflammatory (tumor necrosis factor-alpha; TNF-α) levels, and histopathological studies were evaluated in specific brain regions.

RESULTS

Rats administered ICV-STZ followed by treatment with TF (25, 50, and 100 mg/kg) for 21 days had significantly better mental performance (reduced escape latency to access platform, extended time spent in target quadrant, and improved differential index) in the Morris water maze test and new object recognition test models when compared to control (ICV-STZ)-treated groups. Further, TF treatment significantly restored redox proportion, anti-oxidant levels, regained mitochondrial capacities, attenuated altered AChE action, levels of TNF-α, and histopathological alterations in certain brain regions in comparison with control. In in silico analysis, TF caused greater interaction with NADH dehydrogenase and succinate dehydrogenase.

CONCLUSION

The current work demonstrates the neuroprotective ability of TF in an experimental model with AD-like pathologies. The study further suggests that the neuroprotective impacts of TF may be related to its effects on TNF-α levels, oxidative stress pathways, and mitochondrial complex capabilities.

CYP1A inhibitors: Recent progress, current challenges, and future perspectives

Mammalian cytochrome P450 1A (CYP1A) are key phase I xenobiotic-metabolizing enzymes that play a distinctive role in metabolic activation or metabolic clearance of a variety of procarcinogens, drugs, and endogenous substances. Human CYP1A subfamily contains two members (hCYP1A1 and hCYP1A2), which are known to catalyze the oxidative activation of some environmental procarcinogens into carcinogenic species. Increasing evidence has demonstrated that CYP1A inhibitor therapies are promising strategies for cancer chemoprevention or overcoming CYP1A-associated drug toxicity and resistance. Herein, we reviewed recent advances in the discovery and characterization of hCYP1A inhibitors, from the discovery approaches to structural features and biomedical applications of hCYP1A inhibitors. The inhibition potentials, inhibition modes, and inhibition constants of all reported hCYP1A inhibitors are comprehensively summarized. Meanwhile, the structural features and structure-activity relationships of different classes of hCYP1A1 and hCYP1A2 inhibitors are analyzed and discussed in depth. Furthermore, the major challenges and future directions for this field are presented and highlighted. Collectively, the information and knowledge presented here will strongly facilitate the researchers to discover and develop more efficacious CYP1A inhibitors for specific purposes, such as chemo-preventive agents or as tool molecules in hCYP1A-related fundamental studies.

beta-caryophyllene oxide and trans-nerolidol affect enzyme activity of CYP3A4 - in vitro and in silico studies

Evaluation of possible interactions with enzymes of drug metabolism is an important part of studies on safety and, in general, on the properties of any drug or biologically active compound. Here, focus is given on interactions of three sesquiterpenes (beta-caryophyllene oxide (CAO), trans-nerolidol (tNER) and farnesol (FAR)) with CYP3A4. To determine the CYP3A4 activity, specific substrates testosterone (TES) and midazolam (MDZ) were used. In human liver microsomes, the CAO inhibited the MDZ 1´-hydroxylation by mixed type inhibition and K(i) 46.6 microM; TES 6beta-hydroxylation was inhibited more strongly by tNER by the same mechanism and with K(i) of 32.5 microM. Results indicated a possibility of different mode of interaction of both compounds within the active site of CYP3A4 and this was why the molecular docking study was done. The docking experiments showed that the studied sesquiterpenes (CAO and tNER) bound to the CYP3A4 active site cause a significant decrease of binding affinity of substrates tested which corresponded well to the inhibition studies. The inhibition observed, however, most probably does not pose a real harm to microsomal drug metabolism as the levels of sesquiterpenes in plasma (assuming the use of these compounds as spices or flavoring additives) does not usually exceed micromolar range. Hence, the interaction of drugs metabolized by CYP3A4 with sesquiterpenes is less probable.

Sesquiterpenes Are Agonists of the Pregnane X Receptor but Do Not Induce the Expression of Phase I Drug-Metabolizing Enzymes in the Human Liver

Sesquiterpenes, the main components of plant essential oils, are bioactive compounds with numerous health-beneficial activities. Sesquiterpenes can interact with concomitantly administered drugs due to the modulation of drug-metabolizing enzymes (DMEs). The aim of this study was to evaluate the modulatory effects of six sesquiterpenes (farnesol, cis-nerolidol, trans-nerolidol, α-humulene, β-caryophyllene, and caryophyllene oxide) on the expression of four phase I DMEs (cytochrome P450 3A4 and 2C, carbonyl reductase 1, and aldo-keto reductase 1C) at both the mRNA and protein levels. For this purpose, human precision-cut liver slices (PCLS) prepared from 10 patients and transfected HepG2 cells were used. Western blotting, quantitative real-time PCR and reporter gene assays were employed in the analyses. In the reporter gene assays, all sesquiterpenes significantly induced cytochrome P450 3A4 expression via pregnane X receptor interaction. However in PCLS, their effects on the expression of all the tested DMEs at the mRNA and protein levels were mild or none. High inter-individual variabilities in the basal levels as well as in modulatory efficacy of the tested sesquiterpenes were observed, indicating a high probability of marked differences in the effects of these compounds among the general population. Nevertheless, it seems unlikely that the studied sesquiterpenes would remarkably influence the bioavailability and efficacy of concomitantly administered drugs.