Air oxidation increases skin irritation from fragrance terpenes

Artificial intelligence-driven hydrogel microneedle patches integrating 5-fluorouracil inclusion complex-loaded flexible pegylated liposomes for enhanced non-melanoma skin cancer treatment

The current study focused on the development of crosslinked hydrogel microneedle patches (cHMNs) incorporating 5-FU-hydroxypropyl beta-cyclodextrin inclusion complex-loaded flexible PEGylated liposomes (5-FU-HPβCD-loaded FP-LPs) to enhance treatment efficacy and reduce drug toxicity. The research utilized artificial intelligence (AI) algorithms to design, optimize, and evaluate the cHMNs. Various AI models were assessed for accuracy, with metrics such as root mean square error and coefficient of determination guiding the selection of the most effective formulation. The physicochemical and mechanical properties, swelling behavior, in vitro skin permeation, and safety of the chosen cHMNs were tested. The results demonstrated that the 5-FU-HPβCD-loaded FP-LPs, stabilized with limonene, had an optimal particle size of 36.23 ± 2.42 nm, narrow size distribution, and zeta potential of -10.24 ± 0.37 mV, with high encapsulation efficiency. The cHMNs exhibited a conical needle shape with sufficient mechanical strength to penetrate the stratum corneum up to approximately 467.87 ± 65.12 μm. The system provided a high skin permeation rate of 41.78 ± 4.26 % and significant drug accumulation in the skin. Additionally, the formulation was proven safe in cell culture while effectively inhibiting cancer growth and promoting apoptosis. This study highlights the potential of AI-enhanced cHMNs for delivering 5-FU-HPβCD-loaded FP-LPs transdermally, offering a promising new treatment avenue for non-melanoma skin cancers.

The applications and mechanisms of Rosmarinus officinalis L. in the management of different wounds and UV-irradiated skin

Chronic wounds, especially non-healing wounds, significantly affect patients' quality of life and raise the costs of therapy. Wound healing is a complicated process involving interdependent stages, which may be impaired and delayed by infections with multi-drug resistant pathogens. Current medical strategies for wound healing, especially the treatment of non-healing wounds, exert limited therapeutic effects, thus become a dramatic challenge for modern medicine. There has been growing interest in exploring complementary approaches to enhance the wound healing process, and complementary therapy using herbs and their related products has gained increasing attention. Apart from skin wounds, dermal pathological changes caused by UV irradiation, may also benefit from such complementary therapy. The antimicrobial, anti-inflammatory, antioxidant, analgesic and collagen-promoting properties of extract from Rosmarinus officinalis L. (rosemary) have all been considered to contribute to the beneficial effects on different stages and multiple aspects of skin recovery after various wounds or UV irradiation. This review aims to summarize the applications and their underlying mechanisms of rosemary as part of the complementary therapy for injured and UV-irradiated skin based on the currently available evidence. The medicinal properties of rosemary and its application in wound dressing are first discussed, followed by summarization of its application in different types of wounds. A conclusion is reached and future directions are discussed. As research in this area continue to evolve, rosemary-derived products may become an integral part of holistic wound care strategies, offering a complementary approach to conventional treatments.

Toxicity of waterpipe tobacco smoking: the role of flavors, sweeteners, humectants, and charcoal

Waterpipe tobacco (WPT) smoking is a public health concern, particularly among youth and young adults. The global spread of WPT use has surged because the introduction of pre-packaged flavored and sweetened WPT, which is widely marketed as a safer tobacco alternative. Besides flavorants and sugars, WPT additives include humectants, which enhance the moisture and sweetness of WPT, act as solvents for flavors, and impart smoothness to the smoke, thus increasing appeal to users. In the United States, unlike cigarette tobacco flavoring (with the exception of menthol), there is no FDA product standard or policy in place prohibiting sales of flavored WPT. Research has shown that the numerous fruit, candy, and alcohol flavors added to WPT entice individuals to experience those flavors, putting them at an increased risk of exposure to WPT smoke-related toxicants. Additionally, burning charcoal briquettes-used as a heating source for WPT-contributes to the harmful health effects of WPT smoking. This review presents existing evidence on the potential toxicity resulting from humectants, sugars, and flavorants in WPT, and from the charcoal used to heat WPT. The review discusses relevant studies of inhalation toxicity in animal models and of biomarkers of exposure in humans. Current evidence suggests that more data are needed on toxicant emissions in WPT smoke to inform effective tobacco regulation to mitigate the adverse impact of WPT use on human health.

Exploration of D-limonene as a sex pheromone for males of Bactrocera minax (Diptera: Tephritidae)

BACKGROUND

Bactrocera minax is a devastating pest of citrus fruits. However, there have been no effective control measures before. Few reports on the sex pheromones of B. minax are available.

RESULTS

In this study, nine of the volatile compounds in adult females were identified using headspace solid-phase microextraction (HS-SPME) in combination with gas chromatography-mass spectrometry (GC-MS). Among them, d-limonene, caprolactam, 2-Nitro-1H-imidazole, and creatinine could evoke antennal responses in males. Field bioassays showed that only d-limonene could lure male flies, with a relative lure rate of 78.18% in all tested samples, which was significantly higher than that of paraffin oil control, while all volatile compounds did not have any lure effective to female flies. Moreover, d-limonene was diluted with paraffin oil into differential concentrations, the lure effect on males was better at 100, 500, and 800 μL d-limonene mL-1 than pure d-limonene (1000 μL mL-1 ). The relative male lure rate of d-limonene at 100 μL mL-1 was 85.88%, which was significantly higher than that of food-baits (14.12%) on day 3. However, d-limonene was unattractive to female and male Bactrocera dorsalis and Zeugodacus tau. Further kinetic analysis showed that female adults released d-limonene around 15-day post eclosion. Electroantennography 1 results showed that 500 μL mL-1 d-limonene evoked the strongest responses to antennae of 10- to 25-day-old male flies.

CONCLUSION

Our results indicated that d-limonene could be a sex pheromone from female flies of B. minax, and it could be used as a male-specific sex attractant for B. minax. © 2023 Society of Chemical Industry.

Patch testing hydroperoxides of limonene and linalool in consecutive patients-Results of the IVDK 2018-2020

BACKGROUND

Hydroperoxides of limonene (Lim-OOHs) and linalool (Lin-OOHs) are potent contact sensitizers.

OBJECTIVES

To investigate the prevalence of positive patch test (PT) reactions to Lim-OOHs and Lin-OOHs in consecutive patients, their demographic factors and concomitant reactions.

METHODS

Between 7/2018 and 12/2020, Lim-OOHs 0.3% pet. and Lin-OOHs 1% pet. were patch tested in 5511 consecutive patients. We assessed PT reactivity and analysed data from patients with either positive or negative PTs to Lim-OOHs and Lin-OOHs.

RESULTS

Positive PT results to Lim-OOHs (n = 170, 3.1%) and Lin-OOHs (n = 483, 8.8%) were frequent. Most of the positive reactions were weak (LimOOHs n = 134/LinOOHs n = 429), and even more frequently, doubtful (n = 252/n = 578) or irritant reactions (n = 81/n = 178) were documented. PT reactivity to Lim-OOHs and Lin-OOHs was increased in patients with irritant reactions to sodium lauryl sulphate (SLS). The proportion of leg dermatitis and concomitant positive reactions to fragrances and essential oils was increased in patients with reactivity to these hydroperoxides.

CONCLUSION

The observed reaction pattern suggests that both test preparations display an irritant potential with an increased risk of false positive reactions. Preparations should be chemically monitored in order to reduce irritancy. Mindful interpretation of PT results and aimed patch testing of lower concentrations is recommended.

Contact allergy to oxidized linalool and oxidized limonene: Patch testing in consecutive patients with dermatitis

BACKGROUND

Contact allergy to oxidized (ox.) linalool and ox. limonene has been reported to have a high prevalence, raising the question of inclusion into the baseline series. However, several important issues should be clarified and further investigated before inclusion can be warranted.

OBJECTIVES

To report the trends of ox. terpenes allergy in patients with dermatitis, features of the patch test reactions, and clinical characteristics of the patients.

METHODS

A retrospective analysis of 5773 patients was performed. All patients were patch tested with baseline series, individual ingredients of fragrance mix I and II, ox. linalool, and ox. limonene from 2013 to 2020.

RESULTS

The prevalence rates of contact allergy to ox. linalool and ox. limonene were 7.0% and 5.1%, respectively. Significantly increasing trends of contact allergy were observed. More than 95% of contact allergy cases were identified on Day 3/4. Patients with contact allergy to ox. linalool and ox. limonene were significantly younger than those with contact allergy to other fragrances and were predominantly female. Strong reactions were associated with older age and multiple fragrance allergies.

CONCLUSIONS

Contact allergy to ox. linalool and ox. limonene is becoming increasingly important, and findings show intriguing features. More studies concerning the clinical relevance before recommending these substances for screening are required.

One hundred years of allergic contact dermatitis due to oxidized terpenes: What we can learn from old research on turpentine allergy

Although in recent years the focus on sensitizing terpene oxidation products has been on oxidized limonene and linalool, the autoxidation of terpenes in relation to allergic contact dermatitis is not new and dates back to the early part of the 20th century with the use of turpentine causing occupational contact dermatitis in painters. This review is written in a way as to allow us to get closer to the work of the scientists in earlier days, to participate in the successes, and also to observe the weak points. The researchers concluded that the main culprit in Scandinavian turpentine was Δ³ -carene hydroperoxides. This explains its high sensitizing effect compared with French turpentine which is of the Iberian type with no or only traces of Δ³ -carene. Historical exposure to turpentine showed that ending the industrial exposure stopped the occupational skin sensitization. Patch test studies demonstrated that monoterpene hydroperoxides, far from being an obsolete source of contact allergy solely related to turpentine, is a common cause of contact allergy in the population. A hundred years of extensive chemical and clinical studies worldwide should be sufficient to meet the evidence requirement regarding allergic contact dermatitis caused by terpenes. HIGHLIGHTS: The autoxidation of terpenes in relation to allergic contact dermatitis is not new and dates back to the early part of the 20th century with the use of turpentine. The main culprit in Scandinavian turpentine was Δ³ -carene hydroperoxides. This explains its high sensitizing effect compared with French turpentine with no or only traces of Δ³ -carene. Recent patch test studies demonstrated that monoterpene hydroperoxides, far from being an obsolete source of contact allergy solely related to turpentine, is a common cause of contact allergy in the population.

Ubiquity, Hazardous Effects, and Risk Assessment of Fragrances in Consumer Products

Purpose of review

The main aims of fragrances are to create pleasing scents or to mask unpleasant odors. We hereby review their main exposure sources, presumed benefits, and unwanted effects, with special attention to allergic contact dermatitis (prevalence, regulatory environment, risk assessment methodology, and preventive measures).

Recent findings

Fragrances elicit positive emotions and presumably have therapeutic benefits related to stress reduction and memory enhancement. However, they also cause detrimental health or environmental effects including contact dermatitis (irritant and/or allergic), non-eczematous contact reactions, photosensitivity, photo-allergy, and immediate contact reactions, which can negatively impact the quality of life. Fragrances are the most frequent chemicals causing contact dermatitis. Their main sources are cosmetics, household products, industrial substances, food flavorings, oral hygiene products, and topical medications. It is difficult for sensitized patients to avoid contact with fragrances, due to their ubiquity and because manufacturers are not willing to volunteer information regarding fragrance ingredients.

Summary

The treatment of contact dermatitis relies on allergens avoidance which does not “cure” the disease (sensitization persists for life) but prevents disabling illness. The patient should understand that avoiding perfume means to avoid all scented goods and not just perfumes.

Labeling fragrances is key in primary prevention (by giving the healthy individual the chance to make an informed choice to avoid risky substances), diagnosis (by helping the practitioner to plan and interpret patch tests), secondary prevention, and prognosis (by allowing the sensitized patient to follow the avoidance instructions). However, only 26 fragrances are mandatory to be declared in cosmetics. The vague labeling of other fragrance ingredients as “perfume” or “fragrance” hampers the diagnostic and preventive approaches. Therefore, in our opinion, declaration should be mandatory for all fragrance ingredients as well as straightforward so most consumers can understand it. Moreover, legislation should be improved to prevent inappropriately high exposures by forbidding stronger allergens, restricting maximum concentrations in the finished product or fields of application, delivering information regarding the risks to the general public, and controlling the compliance of manufacturers with the regulations. Besides, manufacturers should share information regarding the composition in the final products and provide physicians with samples of all fragrance chemicals whenever needed for patch test investigations.

Skin sensitization to fragrance hydroperoxides: interplay between dendritic cells, keratinocytes and free radicals

BACKGROUND

Skin sensitization to hydroperoxides (R-OOHs) of the commonly used fragrance terpenes limonene, linalool and citronellol is frequently reported. R-OOHs are believed to initiate the process leading to sensitization and allergic contact dermatitis through mechanisms involving radical intermediates. Thus, radical intermediates, keratinocytes and dendritic cells (DCs) may act in concert to initiate the process.

OBJECTIVES

To evaluate individual DC activation profiles by R-OOHs in the context of keratinocytes with regard to frequency, specificity and magnitude of upregulation.

METHODS

We used 2D and 3D cocultures with keratinocytes/reconstructed human epidermis (RHE) and DCs to evaluate cell surface levels of the costimulatory molecules CD86, CD80 and the adhesion molecule CD54 on cocultured DCs. Analysis of radical formation from limonene hydroperoxides in RHE was performed using electron paramagnetic resonance combined with the spin trapping technique.

RESULTS

R-OOHs induce donor-dependent DC activation. Major differences were found between the limonene-OOHs. Limonene-1-OOH was stronger with respect to both frequency and magnitude of response. Using a 3D coculture model, no DC activation was detected after topical application of 0·2% limonene-OOHs (20 µg cm^-2 ), while 1·2% limonene-1-OOH or 2% limonene-2-OOH induced DC activation. Furthermore, we demonstrated differences in the carbon and oxygen radicals formed from the limonene-OOHs using RHE, mimicking what may happen in vivo.

CONCLUSIONS

We report clear individual differences in DC maturation induced by the most important hydroperoxides. Response rates and magnitude of response both indicate that very small structural alterations in the hydroperoxides are translated into specific DC responses. In addition, we provide more insight into the amounts of hydroperoxides that can activate DCs and induce sensitization.

Volatile organic compounds in feminine hygiene products sold in the US market: A survey of products and health risks

Feminine hygiene products (FHPs) are used on highly permeable and sensitive vaginal and vulvar tissues by many women. These products contain a variety of chemicals, and few regulations require disclosure of their ingredients. The objectives of this study are to identify volatile organic compounds (VOCs) that may be present in these products and to evaluate the potential for exposure and health risk associated with product use. We collected 79 commercially available FHPs, including washes, tampons, menstrual pads, wipes, sprays, powders and moisturizers, and analyzed their composition using purge and trap sampling, thermal desorption, gas chromatography and mass spectroscopy. Exposures and risks were modeled using reasonable upper bound exposure scenarios. The highest VOC concentrations (as total target VOCs) were found in washes, sprays and powders, with median concentrations from 25,000 to 34,000 ng/g. Benzene (maximum: 3,604 ng/g) was detected in 83% of the collected products, and 1,4-dioxane (maximum: 24,354 ng/g) in 50% of the products. VOC composition depended on the FHP type, manufacturer and brand. Products labeled as "organic," "natural," or "for sensitive skin" did not necessarily have lower VOC concentrations. For most FHPs, calculated risks were low; however, menstrual pads had hazard ratios of up to 11, sprays and powders had hazard ratios of up to 2.2 and excess cancer risks of up to 2.1 × 10^-6, and washes had excess cancer risks of up to 3.3 × 10^-6. Our data suggest that all tested FHPs contained some toxic VOCs, and that risks of using some products should be addressed. We recommend the elimination of toxic ingredients and the disclosure of all chemicals that are used in these products.

Patch testing with purified and oxidized citronellol

BACKGROUND

Citronellol is a commonly used fragrance terpene included in fragrance mix II. As with many other fragrance terpenes, citronellol is susceptible to autoxidation. Citronellol hydroperoxides are formed in large amounts and are the only oxidation products identified as sensitizers in oxidized citronellol.

AIM

To compare frequencies of contact allergy to purified and oxidized citronellol and to investigate the pattern of concomitant reactions to fragrance markers of the baseline series, oxidized linalool, and oxidized limonene.

METHODS

A total of 658 dermatitis patients were patch tested with purified and oxidized citronellol at 2.0%, 4.0%, 6.0%, and 1.0%, 2.0%, 4.0%, 6.0% petrolatum, respectively. The irritant properties of purified and oxidized citronellol were studied before patch testing.

RESULTS

Few irritant reactions were observed in the pretest. Purified citronellol detected positive reactions in 0.15%-0.31% of patients, while oxidized citronellol detected positive reactions in 0.61%-4.5%. Among patients reacting to oxidized citronellol, 34%-50% showed concomitant reactions to fragrance markers of the baseline series and 75%-91% to oxidized linalool or oxidized limonene.

CONCLUSION

Oxidized citronellol detects more cases of contact allergy than purified citronellol, and these cases are not all detected using fragrance mix II. Patch testing with oxidized citronellol will add to the tools in the diagnosis of fragrance allergy.

Novel (‒)-carvone derivatives as potential anticonvulsant and analgesic agents

Novel hydrazones based on (‒)-carvone were synthesized via condensation of terpenoid with 4-R-phenoxyacetic acid hydrazides. The structure of target compounds was established by FT-IR, Raman, ¹H-NMR and ¹³C-NMR spectral analysis, FAB/ESI mass spectrometry. (‒)-Carvone hydrazones were proven to exist as Z/E geometrical isomers about C = N bond using ion mobility-tandem mass spectrometry (IM-MS/MS). Single crystal X-ray diffraction study was applied to determine molecular and crystal structure of compound 3e. Hydrazones 3a-3e were evaluated as potential anticonvulsant agents after their oral administration against maximal electroshock (MES) and pentylenetetrazole (PTZ)-induced seizures in mice. Analgesic activity of compounds was investigated by topical application on models of capsaicin and AITC-induced pain. The present findings indicate that (‒)-carvone derivatives afforded seizure protection both at short (1 h) and long (24 h) time period by blocking electroshock- and chemical-induced convulsions. Hydrazones binding to TRPA1/TRPV1 ion channels was proposed as possible mechanism explaining significant analgesic effect of compounds.

Use of Natural Components Derived from Oil Seed Plants for Treatment of Inflammatory Skin Diseases

The incidence of inflammatory skin diseases is increasing, so the search for relevant therapeutics is of major concern. Plants are rich in phytochemicals which can alleviate many symptoms. In this review, we concentrate on compounds found in the seeds of widely cultivated plants, regularly used for oil production. The oils from these plants are often used to alleviate the symptoms of inflammatory diseases through synergetic action of unsaturated fatty acids and other phytochemicals most commonly derived from the terpenoid pathway. The knowledge of the chemical composition of oil seeds and the understanding of the mechanisms of action of single components should allow for a more tailored approach for the treatment for many diseases. In many cases, these seeds could serve as an efficient material for the isolation of pure phytochemicals. Here we present the content of phytochemicals, assumed to be responsible for healing properties of plant oils in a widely cultivated oil seed plants and review the proposed mechanism of action for fatty acids, selected mono-, sesqui-, di- and triterpenes, carotenoids, tocopherol and polyphenols.

The characterization of flavored hookahs aroma profile and in response to heating as analyzed via headspace solid-phase microextraction (SPME) and chemometrics

Flavors profiling in flavored hookah tobacco is an issue of increasing scrutiny for the health sector owing to its adverse effects on humans, especially being heated to produce smoke. This study aims at tackling the components involved in the flavored hookah tobacco from a chemical and biological point of view. Detecting individual flavor compounds, within a complex hookah tobacco matrix was accomplished using headspace solid phase microextraction (SPME). A total of 114 volatiles were identified in 13 flavored hookah tobacco products, with esters amounting for the major component up to 40%. Whereas oxygenated monoterpenes presented another major volatile class, contributing up to 23%, including (E)-anethole. Superheating flavored hookah tobacco at 190 °C resulted in the release of a mixture of phenol derivatives and polycyclic aromatic compounds that are indicative of coal tar, a major component produced during hookah tobacco usage with potential health hazards. This study provides the first comprehensive volatile profile of hookah tobacco products from different origins identifying chemical components involved in flavors. It is expected to serve as informative grounds for the better understanding of hookah tobacco production and usage. The information presented is also expected to raise awareness on the health risks of hookah tobacco smoking.

Contact sensitization to hydroperoxides of limonene and linalool: Results of consecutive patch testing and clinical relevance

Background

Hydroperoxides of limonene and linalool are potent sensitizers.

Objectives

To investigate the prevalence of contact allergy to both hydroperoxides of limonene and hydroperoxides of linalool, to report clinical relevance, and to investigate patient demographics.

Methods

A total of 821 patients (35.6% male, mean age 42.4 years ± 17.8 years) were consecutively patch tested with our departmental baseline series and our fragrance series, including hydroperoxides of limonene 0.3% pet. and hydroperoxides of linalool 1.0% pet. The clinical relevance was assessed for all positive reactions.

Results

Positive patch test reactions to hydroperoxides of limonene and to hydroperoxides of linalool were observed in 77 patients (9.4%, 95% confidence interval [CI]: 7.4%‐11.4%) and in 96 patients (11.7%, 95%CI: 9.5%‐13.9%), respectively; 38 of these patients (4.6%, 95%CI: 3.2%‐6.0%) reacted to both. Most reactions were considered to be possibly or probably clinically relevant (66.3% and 68.8%, respectively), and a small proportion were deemed to be of certain clinical relevance (18.2% and 19.8%, respectively).

Conclusion

As compared with previous studies, high numbers of positive reactions to both hydroperoxides of limonene and hydroperoxides of linalool were observed, the majority of which were clinically relevant, supporting their inclusion in the European baseline series.

Biological Activities and Safety of Citrus spp. Essential Oils

Citrus fruits have been a commercially important crop for thousands of years. In addition, Citrus essential oils are valuable in the perfume, food, and beverage industries, and have also enjoyed use as aromatherapy and medicinal agents. This review summarizes the important biological activities and safety considerations of the essential oils of sweet orange (Citrus sinensis), bitter orange (Citrus aurantium), neroli (Citrus aurantium), orange petitgrain (Citrus aurantium), mandarin (Citrus reticulata), lemon (Citrus limon), lime (Citrus aurantifolia), grapefruit (Citrus × paradisi), bergamot (Citrus bergamia), Yuzu (Citrus junos), and kumquat (Citrus japonica).

Rosemary Essential Oil-Loaded Lipid Nanoparticles: In Vivo Topical Activity from Gel Vehicles

Although rosemary essential oil (EO) shows many biological activities, its topical benefits have not been clearly demonstrated. In this work, we assessed the effects on skin hydration and elasticity of rosemary EO after topical application via gel vehicles in human volunteers. To improve its topical efficacy, rosemary EO was loaded into lipid nanoparticles (NLCs) consisting of cetyl palmitate as a solid lipid, and non-ionic surfactants. Such NLCs were prepared using different ratios of EO/solid lipid and those containing EO 3% w/w and cetyl pamitate 7% w/w were selected for in vivo studies, showing the best technological properties (small particle size, low polydispersity index and good stability). Gels containing free EO or EO-loaded NLCs were applied on the hand skin surface of ten healthy volunteers twice a day for one week. Skin hydration and elasticity changes were recorded using the instrument Soft Plus. Gels containing EO-loaded NLCs showed a significant increase in skin hydration in comparison with gels containing free EO. Skin elasticity increased, as well, although to a lesser extent. The results of this study point out the usefulness of rosemary EO-loaded NLCs for the treatment of cutaneous alterations involving loss of skin hydration and elasticity.

Determination of Volatile Flavour Profiles of Citrus spp. Fruits by SDE-GC-MS and Enantiomeric Composition of Chiral Compounds by MDGC-MS

INTRODUCTION

Citrus fruits are known to have characteristic enantiomeric key compounds biosynthesised by highly stereoselective enzymatic mechanisms. In the past, evaluation of the enantiomeric ratios of chiral compounds in fruits has been applied as an effective indicator of adulteration by the addition of synthetic compounds or natural components of different botanical origin.

OBJECTIVE

To analyse the volatile flavour compounds of Citrus junos Sieb. ex Tanaka (yuzu), Citrus limon BURM. f. (lemon) and Citrus aurantifolia Christm. Swingle (lime), and determine the enantiomeric ratios of their chiral compounds for discrimination and authentication of extracted oils.

METHODOLOGY

Volatile flavour compounds of the fruits of the three Citrus species were extracted by simultaneous distillation extraction and analysed by gas chromatography-mass spectrometry. The enantiomeric composition (ee%) of chiral camphene, sabinene, limonene and β-phellandrene was analysed by heart-cutting multidimensional gas chromatography-mass spectrometry.

RESULTS

Sixty-seven (C. junos), 77 (C. limon) and 110 (C. aurantifolia) volatile compounds were identified with limonene, γ-terpinene and linalool as the major compounds. Stereochemical analysis (ee%) revealed 1S,4R-(-) camphene (94.74, 98.67, 98.82), R-(+)-limonene (90.53, 92.97, 99.85) and S-(+)-β-phellandrene (98.69, 97.15, 92.13) in oil samples from all three species; R-(+)-sabinene (88.08) in C. junos; and S-(-)-sabinene (81.99, 79.74) in C. limon and C. aurantifolia, respectively.

CONCLUSION

The enantiomeric composition and excess ratios of the chiral compounds could be used as reliable indicators of genuineness and quality assurance of the oils derived from the Citrus fruit species. Copyright © 2017 John Wiley & Sons, Ltd.

Natural Terpenes as Penetration Enhancers for Transdermal Drug Delivery

The greatest hindrance for transdermal drug delivery (TDD) is the barrier property of skin, especially the stratum corneum (SC). Various methodologies have been investigated and developed to enhance the penetration of drugs through the skin. Among them, the most popular approach is the application of penetration enhancers (PEs), including natural terpenes, a very safe and effective class of PEs. In the present paper, we focused on terpenes as skin PEs for TDD. The mechanism of their action, the factors affecting their penetration enhancement effect, as well as their possible skin toxicity were discussed. Terpenes abundant in nature have great potential in the development of PEs. Compared to synthetic PEs, natural terpenes have been proved to possess higher enhancement activity. Interaction with SC intercellular lipids is the main mechanism of action for terpenes. The key factor affecting the enhancement effect is the lipophilicity of both terpenes and drug molecules. In addition, a lot of terpenes have also been proved to be much less toxic compared to azone, the classic synthetic PE. In summary, terpenes may be preferred over the chemically synthesized compounds as safe and effective PEs to promote the percutaneous absorption of drugs.

Fragrance allergic contact dermatitis

Fragrances are a common cause of allergic contact dermatitis in Europe and in North America. They can affect individuals at any age and elicit a spectrum of reactions from contact urticaria to systemic contact dermatitis. Growing recognition of the widespread use of fragrances in modern society has fueled attempts to prevent sensitization through improved allergen identification, labeling, and consumer education. This review provides an overview and update on fragrance allergy. Part 1 discusses the epidemiology and evaluation of suspected fragrance allergy. Part 2 reviews screening methods, emerging fragrance allergens, and management of patients with fragrance contact allergy. This review concludes by examining recent legislation on fragrances and suggesting potential additions to screening series to help prevent and detect fragrance allergy.

Air-oxidized linalool elicits eczema in allergic patients - a repeated open application test study

BACKGROUND

Linalool is a commonly used fragrance terpene that forms potent sensitizers upon oxidation. In a recent multicentre study, we found that 7% of 2900 patients showed positive patch test reactions to oxidized linalool at 6.0%. No elicitation studies have been performed.

OBJECTIVE

To identify threshold concentrations for elicitation of allergic contact dermatitis caused by oxidized linalool in allergic individuals with repeated exposures.

METHODS

Repeated open application tests were performed in 6 participants previously diagnosed with contact allergy to oxidized linalool. Creams containing 3.0%, 1.0% and 0.30% oxidized linalool (corresponding to 0.56%, 0.19% and 0.056% linalool hydroperoxides, respectively) and 'fine fragrance' containing 1.0%, 0.30% and 0.10% oxidized linalool (corresponding to 0.19%, 0.056% and 0.019% linalool hydroperoxides, respectively) were used twice daily for up to 3 weeks. Patch testing with a dilution series of oxidized linalool was performed.

RESULTS

Five of 6 participants reacted to the cream containing 3% oxidized linalool. With 1% oxidized linalool, a reaction was seen in 3 (cream) and 4 (fine fragrance) participants, respectively. With 0.3% oxidized linalool, 2 (cream) and 1 (fine fragrance) participants reacted.

CONCLUSION

Repeated exposure to low concentrations of oxidized linalool can elicit allergic contact dermatitis in previously sensitized individuals.

Essential oils loaded in nanosystems: a developing strategy for a successful therapeutic approach

Essential oils are complex blends of a variety of volatile molecules such as terpenoids, phenol-derived aromatic components, and aliphatic components having a strong interest in pharmaceutical, sanitary, cosmetic, agricultural, and food industries. Since the middle ages, essential oils have been widely used for bactericidal, virucidal, fungicidal, antiparasitical, insecticidal, and other medicinal properties such as analgesic, sedative, anti-inflammatory, spasmolytic, and locally anaesthetic remedies. In this review their nanoencapsulation in drug delivery systems has been proposed for their capability of decreasing volatility, improving the stability, water solubility, and efficacy of essential oil-based formulations, by maintenance of therapeutic efficacy. Two categories of nanocarriers can be proposed: polymeric nanoparticulate formulations, extensively studied with significant improvement of the essential oil antimicrobial activity, and lipid carriers, including liposomes, solid lipid nanoparticles, nanostructured lipid particles, and nano- and microemulsions. Furthermore, molecular complexes such as cyclodextrin inclusion complexes also represent a valid strategy to increase water solubility and stability and bioavailability and decrease volatility of essential oils.

Safety evaluation and risk assessment of d-Limonene

d-Limonene, a major constituent of citrus oils, is a monoterpene widely used as a flavor/fragrance additive in cosmetics, foods, and industrial solvents as it possesses a pleasant lemon-like odor. d-Limonene has been designated as a chemical with low toxicity based upon lethal dose (LD50) and repeated-dose toxicity studies when administered orally to animals. However, skin irritation or sensitizing potential was reported following widespread use of this agent in various consumer products. In experimental animals and humans, oxidation products or metabolites of d-limonene were shown to act as skin irritants. Carcinogenic effects have also been observed in male rats, but the mode of action (MOA) is considered irrelevant for humans as the protein α(2u)-globulin responsible for this effect in rodents is absent in humans. Thus, the liver was identified as a critical target organ following oral administration of d-limonene. Other than the adverse dermal effects noted in humans, other notable toxic effects of d-limonene have not been reported. The reference dose (RfD), the no-observed-adverse-effect level (NOAEL), and the systemic exposure dose (SED) were determined and found to be 2.5 mg/kg/d, 250 mg/kg//d, and 1.48 mg/kg/d, respectively. Consequently, the margin of exposure (MOE = NOAEL/SED) of 169 was derived based upon the data, and the hazard index (HI = SED/RfD) for d-limonene is 0.592. Taking into consideration conservative estimation, d-limonene appears to exert no serious risk for human exposure. Based on adverse effects and risk assessments, d-limonene may be regarded as a safe ingredient. However, the potential occurrence of skin irritation necessitates regulation of this chemical as an ingredient in cosmetics. In conclusion, the use of d-limonene in cosmetics is safe under the current regulatory guidelines for cosmetics.

Evaluation of selected quality parameters to monitor essential oil alteration during storage

Several analytical methods including high-performance liquid chromatography (HPLC) were applied on essential oils to establish a set of suitable quality parameters for monitoring changes during storage. For this purpose, 7 essential oils derived from various plant families were exposed to possible worst-case conditions for up to 3 mo at 38 °C under cool white light in the presence of atmospheric oxygen. After storage and immediate freezing at -80 °C to stop further alterations until analysis, individual physicochemical parameters were assessed and are discussed with regard to the precision of the respective method as well as suitability to monitor aging processes. To determine conductivity and pH values, a work-up of essential oils by water extraction was established. Conductivity, peroxide value as well as pH turned out to be suitable parameters to picture alterations. Additionally, HPLC fingerprints were monitored by diode array detection to track underlying chemical changes in essential oil composition.

PRACTICAL APPLICATION

This study evaluates a set of analytical parameters to track changes during essential oil storage. On this basis, quality alterations can be monitored.

Efficacy of plant-derived and synthetic compounds on clothing as repellents against Ixodes scapularis and Amblyomma americanum (Acari: Ixodidae)

We conducted field trials to compare the relative repellent activity of two natural product compounds (nootkatone and carvacrol) with commercially available plant-derived (EcoSMART organic insect repellent) and permethrin-based (Repel Permanone) repellents against adult Ixodes scapularis Say and Amblyomma americanum (L.) (Acari: Ixodidae) by using treated coveralls. One day after treatment, nootkatone and carvacrol provided 100% repellency of I. scapularis adults, with nootkatone maintaining complete protection through 3 d, whereas carvacrol showed steadily declining repellency against I. scapularis during the 7-d course of the trials. Nootkatone was at least as effective against host-seeking A. americanum as against I. scapularis through 3 d. Carvacrol provided little protection against A. americanum adults. Both natural compounds performed well initially in comparison with the commercial products. After 7 d, nootkatone was the most effective against both species followed in order of activity by Permanone, EcoSMART, and carvacrol. Nootkatone seems to have offer considerable potential as a clothing repellent against both I. scapularis and A. americanum.

Allergic contact dermatitis: epidemiology, molecular mechanisms, in vitro methods and regulatory aspects. Current knowledge assembled at an international workshop at BfR, Germany

Contact allergies are complex diseases, and one of the important challenges for public health and immunology. The German ‘Federal Institute for Risk Assessment’ hosted an ‘International Workshop on Contact Dermatitis’. The scope of the workshop was to discuss new discoveries and developments in the field of contact dermatitis. This included the epidemiology and molecular biology of contact allergy, as well as the development of new in vitro methods. Furthermore, it considered regulatory aspects aiming to reduce exposure to contact sensitisers. An estimated 15–20% of the general population suffers from contact allergy. Workplace exposure, age, sex, use of consumer products and genetic predispositions were identified as the most important risk factors. Research highlights included: advances in understanding of immune responses to contact sensitisers, the importance of autoxidation or enzyme-mediated oxidation for the activation of chemicals, the mechanisms through which hapten-protein conjugates are formed and the development of novel in vitro strategies for the identification of skin-sensitising chemicals. Dendritic cell cultures and structure-activity relationships are being developed to identify potential contact allergens. However, the local lymph node assay (LLNA) presently remains the validated method of choice for hazard identification and characterisation. At the workshop the use of the LLNA for regulatory purposes and for quantitative risk assessment was also discussed.

Top 10 botanical ingredients in 2010 anti-aging creams

New developments in the realm of skin rejuvenation such as phytotherapy are at an astounding increasing pace in the cosmeceutical market. Yet, many of these products that are classified as cosmeceuticals are tested less vigorously and do not have to be approved by the Food and Drug Administration to establish efficacy and safety. Thus, as clinicians, we must ask the question, "Is there science-based evidence to validate the mechanism of these new treatments?" We assessed the top anti-aging creams currently on the market specifically evaluating their botanical ingredients. Some of the most common botanicals that are hot off the market are: Rosmarinus officinalis, Vitis vinifera (grape seed extract), Citronellol, Limonene, Oenothera biennis (evening primrose), Glycyrrhiza glabra (licorice extract), Aframomum angustifolium seed extract, Diosgenin (wild yam), N6 furfuryladenine (kinetin), and Ergothioneine. Through researching each of these botanical ingredients, we have concluded that randomized controlled trials are still needed in this area, but there is promise in some of these ingredients and science to validate them.

Contact allergens and irritants in household washing and cleaning products

BACKGROUND

Household cleaning products often contain potential allergens and irritants but allergic contact dermatitis from these products in general consumers is rarely reported in the literature.

OBJECTIVES

The purpose of this study was to evaluate the presence of irritants and allergens as indicated on the labels or on the product information found on the website of household cleaning products marketed in Italy.

MATERIAL/METHODS

We examined the labels and the product information of 291 liquid household washing and cleaning products, including 43 washing-up liquids, 63 laundry detergents, 61 fabric conditioners, 47 spray detergents, and 77 hard surface cleaning products. We obtained the data from the product information found on the websites for 263 products and directly on the product packages for 28 products. For each product we specifically recorded the presence of surfactants, preservatives, and fragrances listed in Annex III of Directive 76/768/EEC.

RESULTS

The websites of two Italian brands do not respect EU regulations as they provide product information only with bar codes of the products. Preservatives and fragrances are the main allergens declared in the label of household cleaning products with methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) listed in 35.7% and limonene in 43.6% of the products. Surfactants were listed in 16.5% of the studied products.

CONCLUSIONS

Our study shows that household cleaning products in Italian market contain several allergens, particularly preservatives and fragrances. For consumers, at least in Italy, it may not be easy to retrieve product information from the website for two widely sold brands. The information had to be taken from the actual package.

Linalool--a significant contact sensitizer after air exposure

BACKGROUND

Linalool is a widely used fragrance terpene. Pure linalool is not allergenic or a very weak allergen, but autoxidizes on air exposure and the oxidation products can cause contact allergy. Oxidized (ox.) linalool has previously been patch tested at a concentration of 2.0% in petrolatum (pet.) in 1511 patients, and 1.3% positive patch test reactions were observed.

OBJECTIVE

To investigate the optimal patch test concentration for detection of contact allergy to ox. linalool.

METHODS

Four concentrations of ox. linalool (2.0%, 4.0%, 6.0%, 11.0% pet.) were tested in 3418 consecutive dermatitis patients.

RESULTS

Ox. linalool 2.0%, 4.0%, 6.0%, and 11.0% pet. detected positive patch test reactions in 0.83%, 3.2%, 5.3%, and 7.2% of the tested patients, respectively. The doubtful reactions increased with rising concentrations but relatively less, giving 5.1%, 6.4%, and 7.3% doubtful reactions, respectively, for ox. linalool 4.0%, 6.0%, and 11.0% pet. Few irritative reactions were seen.

CONCLUSIONS

Raising the patch test concentration for ox. linalool gave a better detection of contact allergy, as many as 5-7% positive patch test reactions were detected. We suggest a patch test concentration of ox. linalool 6.0% pet. for future patch testing, giving a dose per unit area of 2.4 mg/cm(2) when 20 mg test substance is tested in small Finn Chambers.