Human metabolism of α-pinene and metabolite kinetics after oral administration

New metabolites of 2-ethylhexyl salicylate in human urine after simulated real-life dermal sunscreen application

2-Ethylhexyl salicylate (EHS) is an organic UV filter which is used in sunscreen and other personal care products. The dermal uptake of EHS was studied in several dermal-exposure experiments. This paper aims to coherently assess urine samples after dermal exposure for the biomarkers EHS, 5OH-EHS, 5oxo-EHS, and 5cx-EPS as well as further biomarkers of interest, specifically 4OH-EHS, 4oxo-EHS, 2OH-EHS, and 6OH-EHS, for the first time. Samples from 18 participants of a pre-existing dermal exposure study under real-life conditions were reassessed using a comprehensive LC-MS/MS method. EHS accounts for 34 % of the cumulative excretion of all analytes within 24 h after exposure, followed by 5OH-EHS (19 %), 5cx-EPS (18 %), 4OH-EHS (15 %) and 5oxo-EHS (11 %). Further metabolites were only quantified in minor amounts. EHS as the most prominent excretion parameter in this study demonstrates the missing first-pass effect after dermal absorption. Furthermore, the applied novel comprehensive analytical procedure revealed oxidation at the ω (5cx-EPS, 6OH-EHS), ω-1 (5OH-EHS, 5oxo-EHS), and ω-2 positions (4OH-EHS, 4oxo-EHS) in the main chain of the ethylhexyl group as well as oxidation in the side chain (2OH-EHS). The presented data are of high relevance for a reliable toxicological risk assessment of dermal exposure to EHS.

Antitumor activity of α-pinene in T-cell tumors

T-cell acute leukemia and lymphoma have a poor prognosis. Although new therapeutic agents have been developed, their therapeutic effects are suboptimal. α-Pinene, a monoterpene compound, has an antitumor effect on solid tumors; however, few comprehensive investigations have been conducted on its impact on hematologic malignancies. This report provides a comprehensive analysis of the potential benefits of using α-pinene as an antitumor agent for the treatment of T-cell tumors. We found that α-pinene inhibited the proliferation of hematologic malignancies, especially in T-cell tumor cell lines EL-4 and Molt-4, induced mitochondrial dysfunction and reactive oxygen species accumulation, and inhibited NF-κB p65 translocation into the nucleus, leading to robust apoptosis in EL-4 cells. Collectively, these findings suggest that α-pinene has potential as a therapeutic agent for T-cell malignancies, and further investigation is warranted.

Metabolomic evidence of independent biotransformation pathways for terpenes in two specialist mammalian herbivores (genus Neotoma)

Herbivory is common in mammals, yet our understanding of detoxification processes used by mammals to biotransform plant secondary compounds (PSCs) is limited. Specialist herbivores are thought to have evolved detoxification mechanisms that rely more heavily on energetically cheap Phase I biotransformation reactions to process high levels of PSCs in their diets. We explored this hypothesis by comparing the urinary metabolite patterns of two specialist herbivores (genus Neotoma). Neotoma stephensi is an obligate specialist on one-seeded juniper (Juniperus monosperma). Neotoma lepida is a generalist forager across its range, yet populations in the Great Basin specialize on Utah juniper (J. osteosperma). While both juniper species have high levels of terpenes, the terpene profiles and quantities differ between the two. Individuals from both woodrat species were fed diets of each juniper in a cross-over design. Urine, collected over a 24-h period, was extracted and analyzed in an untargeted metabolomics approach using both GC-MS and HPLC-MS/MS. The obligate specialist N. stephensi excreted a unique pattern of Phase I metabolites when fed its native juniper, while N. lepida excreted a unique pattern of Phase II metabolites when fed its native juniper. Both woodrat species utilized the Phase II metabolic pathway of glucuronidation more heavily when consuming the more chemically diverse J. osteosperma, and N. stephensi utilized less glucuronidation than N. lepida when consuming J. monosperma. These results are consistent with the hypothesis that obligate specialists may have evolved unique and efficient biotransformation mechanisms for dealing with PSCs in their diet.

Endothelial-dependent relaxation of α-pinene and two metabolites, myrtenol and verbenol, in isolated murine blood vessels

Epidemiological evidence shows that residential proximity to greenspaces is associated with lower risk of all-cause and cardiovascular mortality; however, the mechanism(s) underlying this link remains unclear. Plants emit biogenic volatile organic compounds such as α-pinene that could elicit beneficial cardiovascular effects. To explore the role of α-pinene more directly, we studied the metabolism and the vascular effects of α-pinene. We found that exposure of mice to α-pinene (1 ppm, 6 h) generated two phase I oxidation metabolites, cis- and trans-verbenol [(1R,2R,5R)-verbenol and (1 R,2S,5R)-verbenol)] and myrtenol [(1S,5R)-(+)-myrtenol] that were identified in urine by GC-MS. Precontracted naïve murine male and female aorta and superior mesenteric artery (SMA) were relaxed robustly (60% tension reduction) by increasing concentrations of α-pinene, myrtenol, and verbenol to 0.3 mM, whereas 1 mM α-pinene was vasotoxic. The SMA was six times more sensitive than the aorta to α-pinene. Both myrtenol and verbenol were equally potent and efficacious as parent α-pinene in male and female SMA. The sensitive portion of the α-pinene-, myrtenol-, and verbenol-induced relaxations in male SMA was mediated by 1) endothelium, 2) eNOS-derived NO, and 3) guanylyl cyclase (GC) activity. Moreover, α-pinene activated the transient receptor potential ankyrin-1 (TRPA1) channel whereas the metabolites did not. Endothelial-derived NO regulates blood flow, blood pressure, and thrombosis, and it is plausible that inhaled (and ingested) α-pinene (or its metabolites) augments NO release to mediate the cardiovascular benefits of exposure to greenness.NEW & NOTEWORTHY A common plant-derived biogenic volatile organic compound, α-pinene, and two of its metabolites, myrtenol and verbenol, stimulate vasorelaxation in murine superior mesenteric artery. Both α-pinene- and its metabolites induce vasorelaxation by activation of the endothelium, nitric oxide, and guanylyl cyclase. α-Pinene also activates the transient receptor potential ankyrin-1. Positive associations between greenness exposure and human cardiovascular health may be a result of the vascular action of α-pinene and its metabolites, a novel consideration.

Human Metabolism and Urinary Elimination Kinetics of the Fragrance Geraniol after Oral Dosage

Geraniol is a fragrance with a characteristic rose-like smell, naturally occurring in terpene oil and also chemically synthesized on a large scale. Geraniol is widely used in consumer products such as cosmetics, personal care products, and household cleaners and as an additive in foods. An experimental study in human volunteers was carried out to investigate the metabolism and elimination kinetics of geraniol. Three subjects were orally exposed to geraniol in two different dosages (25 or 250 mg). In each case, one pre-exposure urine sample and all urine voids for 72 h after exposure were collected separately. The geraniol metabolites Hildebrandt acid, geranic acid, 3-hydroxycitronellic acid, and 8-carboxygeraniol were analyzed in every sample after enzymatic hydrolysis and liquid-liquid extraction using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Maximum urinary concentrations of the metabolites were measured between 1 and 5 h after oral dosing, and elimination half-lives were determined to be about 2-4 h. The predominant metabolite found in urine was Hildebrandt acid with 34.4 ± 5.6% of the ingested dose, followed by geranic acid (12.7 ± 5.6%), 3-hydroxycitronellic acid (2.2 ± 0.4%), and 8-carboxygeraniol (0.19 ± 0.09%). In total, the four metabolites determined represent 41.7-55.5% of the ingested dose. Only 8-carboxygeraniol is, however, a specific metabolite, while the other three target analytes are also formed from other terpenes like citral. Within this study, conversion factors were calculated, which allow for a rough estimate of the total geraniol uptake by back-calculation from metabolite concentrations of spot urine samples. Taking the conversion factor for all four metabolites into account, a mean daily uptake of geraniol of 1.43 mg was estimated from 41 urine samples of occupationally nonexposed adults. The metabolites Hildebrandt acid, geranic acid, 3-hydroxycitronellic acid, and 8-carboxygeraniol in urine are suitable biomarkers of exposure for geraniol and can be used for human biomonitoring studies.

Association of exposures to serum terpenes with the prevalence of dyslipidemia: a population-based analysis

This study sought to examine hitherto unresearched relationships between serum terpenes and the prevalence of dyslipidemia. Serum terpenes such as limonene, α-pinene, and β-pinene from the 2013-2014 National Health and Nutrition Examination Survey (NHANES) were used as independent variables in this cross-sectional study. Continuous lipid variables included total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), non-HDL-C, triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), residual cholesterol (RC), and apolipoprotein B (Apo B). Binary lipid variables (elevated TC, ≥5.18 mmol/L; lowered HDL-C, <1.04 mmol/L in men, and <1.30 mmol/L in women; elevated non-HDL-C, ≥4.2 mmol/L; elevated TG, ≥1.7 mmol/L; elevated LDL-C, ≥3.37 mmol/L; elevated RC, ≥1.0 mmol/L; and elevated Apo B, ≥1.3 g/L) suggest dyslipidemia. The relationships between the mixture of serum terpenes with lipid variables were investigated using weighted quantile sum (WQS) regression and Bayesian kernel machine regression (BKMR). The study for TC, HDL-C, and non-HDL-C included a total of 1,528 people, whereas the analysis for TG, LDL-C, RC, and Apo B comprised 714 participants. The mean age of the overall participants was 47.69 years, and 48.77% were male. We found that tertiles of serum terpene were positively associated with binary (elevated TC, non-HDL-C, TG, LDL-C, RC, Apo B, and lowered HDL-C) and continuous (TC, non-HDL-C, TG, LDL-C, RC, and Apo B, but not HDL-C) serum lipid variables. WQS regression and BKMR analysis revealed that the mixture of serum terpenes was linked with the prevalence of dyslipidemia. According to our data, the prevalence of dyslipidemia was correlated with serum concentrations of three terpenes both separately and collectively.

Theoretical Study of Hydroxylation of α- and β-Pinene by a Cytochrome P450 Monooxygenase Model

Previous studies on biocatalytic transformations of pinenes by cytochrome P450 (CYP) enzymes reveal the formation of different oxygenated products from a single substrate due to the multistate reactivity of CYP and the many reactive sites in the pinene scaffold. Up until now, the detailed mechanism of these biocatalytic transformations of pinenes have not been reported. Hereby, we report a systematic theoretical study of the plausible hydrogen abstraction and hydroxylation reactions of α- and β-pinenes by CYP using the density functional theory (DFT) method. All DFT calculations in this study were based on B3LYP/LAN computational methodology using the Gaussian09 software. We used the B3LYP functional with corrections for dispersive forces, BSSE, and anharmonicity to study the mechanism and thermodynamic properties of these reactions using a bare model (without CYP) and a pinene-CYP model. According to the potential energy surface and Boltzmann distribution for radical conformers, the major reaction products of CYP-catalyzed hydrogen abstraction from β-pinene are the doublet trans (53.4%) and doublet cis (46.1%) radical conformer at delta site. The formation of doublet cis/trans hydroxylated products released a total Gibbs free energy of about 48 kcal/mol. As for alpha pinene, the most stable radicals were trans-doublet (86.4%) and cis-doublet (13.6%) at epsilon sites, and their hydroxylation products released a total of ~50 kcal/mol Gibbs free energy. Our results highlight the likely C-H abstraction and oxygen rebounding sites accounting for the multi-state of CYP (doublet, quartet, and sextet spin states) and the formation of different conformers due to the presence of cis/trans allylic hydrogen in α-pinene and β-pinene molecules.

Citrus Essential Oils in Aromatherapy: Therapeutic Effects and Mechanisms

Citrus is one of the main fruit crops cultivated in tropical and subtropical regions worldwide. Approximately half (40-47%) of the fruit mass is inedible and discarded as waste after processing, which causes pollution to the environment. Essential oils (EOs) are aromatic compounds found in significant quantities in oil sacs or oil glands present in the leaves, flowers, and fruit peels (mainly the flavedo part). Citrus EO is a complex mixture of ~400 compounds and has been found to be useful in aromatic infusions for personal health care, perfumes, pharmaceuticals, color enhancers in foods and beverages, and aromatherapy. The citrus EOs possess a pleasant scent, and impart relaxing, calming, mood-uplifting, and cheer-enhancing effects. In aromatherapy, it is applied either in message oils or in diffusion sprays for homes and vehicle sittings. The diffusion creates a fresh feeling and enhances relaxation from stress and anxiety and helps uplifting mood and boosting emotional and physical energy. This review presents a comprehensive outlook on the composition, properties, characterization, and mechanism of action of the citrus EOs in various health-related issues, with a focus on its antioxidant properties.

Stability Study, Quantification Method and Pharmacokinetics Investigation of a Coumarin-Monoterpene Conjugate Possessing Antiviral Properties against Respiratory Syncytial Virus

The stability of a new coumarin derivative, agent K-142, bearing α-pinene residue and possessing antiviral activity against respiratory syncytial virus (RSV) was studied in whole mice blood in vitro, and a method for its quantification in this matrix was developed and validated. The sample preparation method was precipitation of whole blood with a mixture of 0.2 M ZnSO₄ with MeOH (2:8 v/v) containing 2-adamantylamine hydrochloride as an internal standard (IS). Analysis was carried out by HPLC-MS/MS using reversed phase chromatography and a triple quadrupole mass spectrometer 6500 QTRAP (SCIEX) in multiple reaction monitoring (MRM) mode. The transitions 351.2 → 217.1 Da and 152.2 → 93.1/107.2 Da were monitored for K-142 and the IS, respectively. The method was validated in terms of selectivity, calibration curve, LLOQ, accuracy and precision, stability, recovery and carry over. The developed method was used for a pharmacokinetics study of the compound after its oral administration to mice at a dose of 20 mg/kg.

Metabolic conversion of β-pinene to β-ionone in rats

Exposure to or ingestion of turpentine can alter the scent of urine, conferring it a flowery, violet-like scent. Turpentine's effect on urine was initially noticed after its use either as medicine or as a preservative in winemaking. Regardless of the source of exposure, the phenomenon requires metabolic conversion of turpentine component(s) to ionone, the molecule mainly responsible for the scent of violets.The purpose of this study was to identify the presence of ionone in the urine of rats that received β-pinene, and thus to demonstrate that the postulated conversion occurs.We treated rats intraperitoneally with normal saline (negative control), β-ionone (positive control), low-dose β-pinene (1/3 of LD50), and high-dose β-pinene (1/2 of LD50). Urine samples were collected up to 72 h after administration of the compounds, followed by gas chromatography/mass spectrometry identification of the presence of ionone.β-Ionone was found in the urine of rats exposed to both low and high doses of β-pinene. In contrast, α-ionone appears unlikely to have been formed in rats exposed to either low or high doses of β-pinene. β-pinene was converted to β-ionone, followed by partial excretion in the urine of rats. β-Ionone is a minor metabolite of β-pinene.

The peppermint breath test benchmark for PTR-MS and SIFT-MS

A major challenge for breath research is the lack of standardization in sampling and analysis. To address this, a test that utilizes a standardized intervention and a defined study protocol has been proposed to explore disparities in breath research across different analytical platforms and to provide benchmark values for comparison. Specifically, thePeppermint Experimentinvolves the targeted analysis in exhaled breath of volatile constituents of peppermint oil after ingestion of the encapsulated oil. Data from thePeppermint Experimentperformed by proton transfer reaction mass spectrometry (PTR-MS) and selected ion flow tube mass spectrometry (SIFT-MS) are presented and discussed herein, including the product ions associated with the key peppermint volatiles, namely limonene,α- andβ-pinene, 1,8-cineole, menthol, menthone and menthofuran. The breath washout profiles of these compounds from 65 individuals were collected, comprising datasets from five PTR-MS and two SIFT-MS instruments. The washout profiles of these volatiles were evaluated by comparing the log-fold change over time of the product ion intensities associated with each volatile. Benchmark values were calculated from the lower 95% confidence interval of the linear time-to-washout regression analysis for all datasets combined. Benchmark washout values from PTR-MS analysis were 353 min for the sum of monoterpenes and 1,8-cineole (identical product ions), 173 min for menthol, 330 min for menthofuran, and 218 min for menthone; from SIFT-MS analysis values were 228 min for the sum of monoterpenes, 281 min for the sum of monoterpenes and 1,8-cineole, and 370 min for menthone plus 1,8-cineole. Large inter- and intra-dataset variations were observed, whereby the latter suggests that biological variability plays a key role in how the compounds are absorbed, metabolized and excreted from the body via breath. This variability seems large compared to the influence of sampling and analytical procedures, but further investigations are recommended to clarify the effects of these factors.

Neuroprotective effect of α-pinene self-emulsifying nanoformulation against 6-OHDA induced neurotoxicity on human SH-SY5Y cells and its in vivo validation for anti-Parkinson's effect

Oxidative stress (OS) is involved in the multifaceted pathogenic paradigm of neurodegenerative diseases like Parkinson's disease (PD). Monoterpenes like α-pinene (ALP) is considered to be a therapeutically potent antioxidant agent able to attenuate and scavenge various reactive oxygen species and reactive nitrogen species. The present study aimed to evaluate the in vitro and in vivo neuroprotective effect of α-pinene self-emulsifying nanoformulation (ALP-SENF) for PD. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay was done to evaluate the neurotoxic dose of the ALP-SENF; however, the neuroprotective effect was assessed by 6-hydroxydopamine (6-OHDA) induced neurotoxicity model on SH-SY5Y taking NAC (N-acetyl-l-cysteine) as standard. The in vivo anti-Parkinson's activity of the ALP-SENF was compared with that of the plain ALP suspension by using reserpine antagonism and haloperidol-induced Parkinsonism model in rats. Various behavioral tests and biochemical antioxidant enzymes were estimated. The in vitro results revealed that treatment with ALP-SENF at a concentration of 100 and 200 µM was found to show significant neuronal SH-SY5Y cell viability against 50 µM 6-OHDA. ALP-SENF treated animals have seen significant neurobehavioral improvement. Furthermore, the levels of antioxidative enzymes in biochemical test reveals a marked enhancement in the expression of antioxidant enzymes that significantly attenuated the OS induced neurodegeneration. Due to the mechanisms of their antioxidant action, it was probably due to the scavenging of free radicals and the expression of antioxidant enzymes. It also improved neurobehavioral changes induced by reserpine and haloperidol.

Monoterpenes: current knowledge on food source, metabolism, and health effects

Monoterpenes, volatile metabolites produced by plants, are involved in the taste and aroma perception of fruits and vegetables and have been used for centuries in gastronomy, as food preservatives and for therapeutic purposes. Biological activities such as antimicrobial, analgesic and anti-inflammatory are well-established for some of these molecules. More recently, the ability of monoterpenes to regulate energy metabolism, and exert antidiabetic, anti-obesity and gut microbiota modulation activities have been described. Despite their promising health effects, the lack of reliable quantification of monoterpenes in food, hindered the investigation of their role as dietary bioactive compounds in epidemiological studies. Moreover, only few studies have documented the biotransformation of these compounds and identified the monoterpene metabolites with biological activity. This review presents up-to-date knowledge about the occurrence of monoterpenes in food, their bioavailability and potential role in the modulation of intermediate metabolism and inflammation, focusing on novel findings of molecular mechanisms, underlining research gaps and new avenues to be explored.

Development and Validation of an Analytical Method for Quantitation of Alpha-Pinene Oxide in Rodent Blood and Mammary Gland by GC-MS

Alpha-pinene is a monoterpene found in the oil of coniferous trees and has a wide variety of applications. Alpha pinene oxide is a potential reactive metabolite of alpha-pinene in rodents. The objective of this work is to validate a gas chromatography-mass spectrometry method to quantitate alpha pinene oxide in rat and mouse blood and mammary gland in support of studies investigating the toxicity and toxicokinetic behavior of alpha-pinene. The method was validated in male Sprague Dawley rat blood over the concentration range 5 to 250 ng/mL. Matrix standard curves were linear (r ≥ 0.99), and accuracy (percent relative error %RE) was ≤ ±15% for standards at all levels. Intra- and inter-day precision (% relative standard deviation, RSD) and accuracy (%RE) were evaluated at three concentration levels (10, 50, and 200 ng/mL) and were ≤ 6.3% and ≤ ±5.4%, respectively. The limit of detection, determined from the SD of the limit of quantitation (5 ng/mL), was 1.06 ng/mL. Standards as high as 25,000 ng/mL could be accurately quantified after diluting into the validated range (%RE ≤ ±7.1%; RSD ≤5.8%). Alpha pinene oxide was stable in rat blood for at least 70 days in frozen storage (-80 °C). Alpha pinene oxide could accurately be quantified in male and female Hsd:Sprague Dawley®SD® rat and B6C3F1 mouse blood (mean %RE ≤ ±5.3%; %RSD ≤7.8%) and female B6C3F1 and SD rat mammary gland (mean %RE ≤ ±14.6%; %RSD ≤8.1%) using primary matrix standard curve. These results demonstrate that the method is suitable for the analysis of alpha pinene oxide in rodent blood and mammary gland generated from toxicokinetic and toxicology studies.

Quantitative determination of urinary metabolites of geraniol by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS)

Geraniol is a fragrance which occurs in natural terpene oil or is chemically synthesized on a large scale. It is used in a wide variety of consumer products such as perfumes, deodorants, household products and cosmetics. Hence, not only industry workers in the production of geraniol, but also consumers can come into contact with the substance. Human biomonitoring (HBM), i.e. the analytical determination of substances and their metabolites in human biological material, is a key element in the analysis and assessment of the distribution and intensity of occupational and environmental exposure of humans. Therefore, a procedure for the quantitative determination of the urinary metabolites Hildebrandt acid, geranic acid, 3-hydroxycitronellic acid and 8-carboxygeraniol as potential biomarkers of geraniol exposure was developed and validated. The method is based on ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) after enzymatic hydrolysis and liquid-liquid extraction (LLE) of the target analytes. The limit of quantification (LOQ) is 1.5 μg L^-1 for 8-carboxygeraniol, 2.7 μg L^-1 each for Hildebrandt acid and geranic acid, and 1.8 μg L^-1 for 3-hydroxycitronellic acid. The method was applied to urine samples of 41 persons without occupational exposure to geraniol. Hildebrandt acid and geranic acid were detected in all samples, 8-carboxygeraniol in 83% and 3-hydroxycitronellic acid in 81% of the samples. Hildebrandt acid (median: 313 μg L^-1, range: 37-1966 μg L^-1) was the most abundant metabolite, followed by geranic acid (93 μg L^-1; 9-477 μg L^-1), 3-hydroxycitronellic acid (18 μg L^-1; <LOQ to 70 μg L^-1) and 8-carboxygeraniol (9 μg L^-1; <LOQ to 46 μg L^-1). Hildebrandt acid, geranic acid and 3-hydroxycitronellic acid apparently represent larger relative fractions of the eliminated metabolites, but they are not strictly specific for geraniol since they are metabolites of other terpenes as well, such as citral. In contrast, geraniol seems to be the only parent compound for 8-carboxygeraniol, which makes this metabolite a promising candidate for specific human biomonitoring and risk assessment.

Quantification of Seven Terpenes in Human Serum by Headspace Solid-Phase Microextraction-Gas Chromatography-Tandem Mass Spectrometry

Terpenes are a class of volatile organic hydrocarbons commonly produced by vegetation and released into the atmosphere. These compounds are responsible for the scents of pine forests, citrus fruits, and some flowers. Human terpene exposure can come from inhalation, diet, smoking, and more recently, using e-cigarettes. Terpenes are present in tobacco smoke and are used as flavor chemicals in e-liquids. The health effects of terpenes are not widely known, though several studies have suggested that they may prove useful in future medical applications. We have developed a novel, high-throughput method of quantifying seven terpenes (α-pinene, β-pinene, β-myrcene, 3-carene, limonene, β-caryophyllene, and α-humulene) in human serum to aid human-exposure investigations. This method employs headspace sampling using solid-phase microextraction (SPME) coupled to gas chromatography-tandem mass spectrometry to detect and quantify five monoterpenes and two sesquiterpenes in the low parts-per-trillion to low parts-per-billion range. The intraday and interday variability (percent error) of the method are ≤2 and ≤11%, respectively. In addition, this method showed excellent recovery in human serum (between 80 and 120% for all analytes). The assay precision ranges between 4.0 and 11%. Limits of detection ranged between 0.032 and 0.162 μg/L. Using serum cotinine values to classify tobacco use showed that smokers have higher serum concentrations of six terpenes compared to nonusers. Terpene concentrations were 14-78% higher in smokers than nonusers. Our method can provide essential biomonitoring data to establish baseline exposure levels for terpenes in humans.

The Relative Content and Distribution of Absorbed Volatile Organic Compounds in Rats Administered Asari Radix et Rhizoma Are Different between Powder- and Decoction-Treated Groups

Asari Radix et Rhizoma (ARR) is an important traditional Chinese medicine. Volatile organic compounds (VOCs) are the main active constituents of ARR. Research on the metabolite profile of VOCs and the difference of absorbed constituents in vivo after an administration of ARR decoction and powder will be helpful to understand the pharmacological activity and safety of ARR. In this study, headspace solid-phase microextraction gas chromatography mass spectrometry (HS-SPME-GC-MS) was applied to profile the VOCs from ARR in rats in vivo. A total of 153 VOCs were tentatively identified; 101 were original constituents of ARR (98 in the powder-treated group and 43 in the decoction-treated group) and 15 were metabolites, and their metabolic reactions were mainly oxidation and reduction, with only two cases of methylation and esterification, and 37 unclassified compounds were identified only in the ARR-treated group. Of the 153 VOCs identified, 131 were reported in rats after oral administration of ARR for the first time, containing 79 original constituents, 15 metabolites, and 37 unclassified compounds. In the powder-treated group, methyleugenol, safrole, 3,5-dimethoxytoluene (3,5-DMT), 2,3,5-trimethoxytoluene (2,3,5-TMT), and 3,4,5-trimethoxytoluene (3,4,5-TMT) were the main absorbed constituents, the relative contents of which were significantly higher compared to the decoction-treated group, especially methyleugenol, safrole, and 3,5-DMT. In the decoction-treated group, 3,4,5-TMT, 2,3,5-TMT, kakuol, and eugenol were the main constituents with a higher content and wider distribution. The results of this study provide a reference for evaluating the efficacy and safety of ARR.

Forest Volatile Organic Compounds and Their Effects on Human Health: A State-of-the-Art Review

The aim of this research work is to analyze the chemistry and diversity of forest VOCs (volatile organic compounds) and to outline their evidence-based effects on health. This research work was designed as a narrative overview of the scientific literature. Inhaling forest VOCs like limonene and pinene can result in useful antioxidant and anti-inflammatory effects on the airways, and the pharmacological activity of some terpenes absorbed through inhalation may be also beneficial to promote brain functions by decreasing mental fatigue, inducing relaxation, and improving cognitive performance and mood. The tree composition can markedly influence the concentration of specific VOCs in the forest air, which also exhibits cyclic diurnal variations. Moreover, beneficial psychological and physiological effects of visiting a forest cannot be solely attributed to VOC inhalation but are due to a global and integrated stimulation of the five senses, induced by all specific characteristics of the natural environment, with the visual component probably playing a fundamental role in the overall effect. Globally, these findings can have useful implications for individual wellbeing, public health, and landscape design. Further clinical and environmental studies are advised, since the majority of the existing evidence is derived from laboratory findings.

In-vivo biotransformation of citrus functional components and their effects on health

Citrus, one of the most popular fruits worldwide, contains various functional components, including flavonoids, dietary fibers (DFs), essential oils (EOs), synephrines, limonoids, and carotenoids. The functional components of citrus attract special attention due to their health-promoting effects. Food components undergo complex biotransformation by host itself and the gut microbiota after oral intake, which alters their bioaccessibility, bioavailability, and bioactivity in the host body. To better understand the health effects of citrus fruits, it is important to understand the in-vivo biotransformation of citrus functional components. We reviewed the biotransformation of citrus functional components (flavonoids, DFs, EOs, synephrines, limonoids, and carotenoids) in the body from their intake to excretion. In addition, we described the importance of biotransformation in terms of health effects. This review would facilitate mechanistic understanding of the health-promoting effect of citrus and its functional components, and also provide guidance for the development of health-promoting foods based on citrus and its functional components.

Jayaweera S, A. Dias D, Sharopov F, Taheri Y, Martins N, Baghalpour N, C. Cho W, Sharifi-Rad J. Therapeutic Potential of α- and β-Pinene: A Miracle Gift of Nature

α- and β-pinene are well-known representatives of the monoterpenes group, and are found in many plants' essential oils. A wide range of pharmacological activities have been reported, including antibiotic resistance modulation, anticoagulant, antitumor, antimicrobial, antimalarial, antioxidant, anti-inflammatory, anti-Leishmania, and analgesic effects. This article aims to summarize the most prominent effects of α- and β-pinene, namely their cytogenetic, gastroprotective, anxiolytic, cytoprotective, anticonvulsant, and neuroprotective effects, as well as their effects against H2O2-stimulated oxidative stress, pancreatitis, stress-stimulated hyperthermia, and pulpal pain. Finally, we will also discuss the bioavailability, administration, as well as their biological activity and clinical applications.

FEMA GRAS assessment of natural flavor complexes: Citrus-derived flavoring ingredients

In 2015, the Expert Panel of the Flavor and Extract Manufacturers Association (FEMA) initiated a re-evaluation of the safety of over 250 natural flavor complexes (NFCs) used as flavoring ingredients. This publication is the first in a series and summarizes the evaluation of 54 Citrus-derived NFCs using the procedure outlined in Smith et al. (2005) and updated in Cohen et al. (2018) to evaluate the safety of naturally-occurring mixtures for their intended use as flavoring ingredients. The procedure relies on a complete chemical characterization of each NFC intended for commerce and organization of each NFC's chemical constituents into well-defined congeneric groups. The safety of the NFC is evaluated using the well-established and conservative threshold of toxicological concern (TTC) concept in addition to data on absorption, metabolism and toxicology of members of the congeneric groups and the NFC under evaluation. As a result of the application of the procedure, 54 natural flavor complexes derived from botanicals of the Citrus genus were affirmed as generally recognized as safe (GRAS) under their conditions of intended use as flavoring ingredients based on an evaluation of each NFC and the constituents and congeneric groups therein.