Terpenes: Effect of lipophilicity in enhancing transdermal delivery of alfuzosin hydrochloride

The Clinical Translation of α-humulene - A Scoping Review

α-humulene, a sesquiterpene found in essential oils of various plant species, has garnered interest due to its potential therapeutic applications. This scoping review aims to consolidate α-humulene's evidence base, informing clinical translation, and guiding future research directions. A scoping review was conducted of EMBASE, MEDLINE, and PubMed databases up to 14th July 2023. All studies describing original research on α-humulene extraction, as well as pre-clinical and clinical research, were included for review. Three hundred and forty articles were analysed. α-humulene yields ranged from negligible to 60.90% across plant species. In vitro experiments demonstrated cytotoxicity against adenocarcinomas (such as colorectal, pulmonary, breast, prostatic, lung, and ovarian), with varying responses in other cell models. Mechanistic insights revealed its involvement in mitochondrial dysfunction, diminished intracellular glutathione levels, and the induction of oxidative stress. In rodent studies, oral administration of α-humulene at 50 mg/kg reduced inflammation markers in paw oedema and ovalbumin-induced airway inflammation. Intraperitoneal administration of α-humulene (50 - 200 mg/kg) exhibited cannabimimetic properties through cannabinoid 1 and adenosine A2a receptors. α-humulene also exhibited a multitude of properties with potential scope for therapeutic utilisation. However, there is a paucity of studies that have successfully translated this research into clinical populations with the associated disease. Potential barriers to clinical translation were identified, including yield variability, limited isolation studies, and challenges associated with terpene bioavailability. Consequently, rigorous pharmacokinetic studies and further mechanistic investigations are warranted to effectively uncover the potential of α-humulene.

1,8-cineole (eucalyptol): A versatile phytochemical with therapeutic applications across multiple diseases

1,8-cineole (Eucalyptol), a naturally occurring compound derived from botanical sources such as eucalyptus, rosemary, and camphor laurel, has a long history of use in traditional medicine and exhibits an array of biological properties, including anti-inflammatory, antioxidant, antimicrobial, bronchodilatory, analgesic, and pro-apoptotic effects. Recent evidence has also indicated its potential role in managing conditions such as Alzheimer's disease, neuropathic pain, and cancer. This review spotlights the health advantages of 1,8-cineole, as demonstrated in clinical trials involving patients with respiratory disorders, including chronic obstructive pulmonary disease, asthma, bronchitis, and rhinosinusitis. In addition, we shed light on potential therapeutic applications of 1,8-cineole in various conditions, such as depression, epilepsy, peptic ulcer disease, diarrhea, cardiac-related heart diseases, and diabetes mellitus. A comprehensive understanding of 1,8-cineole's pharmacodynamics and safety aspects as well as developing effective formulations, might help to leverage its therapeutic value. This thorough review sets the stage for future research on diverse health benefits and potential uses of 1,8-cineole in tackling complex medical conditions.

Epicutaneous Sensitization to the Phytocannabinoid β-Caryophyllene Induces Pruritic Inflammation

In recent years, there has been increased accessibility to cannabis for recreational and medicinal use. Incidentally, there has been an increase in reports describing allergic reactions to cannabis including exacerbation of underlying asthma. Recently, multiple protein allergens were discovered in cannabis, yet these fail to explain allergic sensitization in many patients, particularly urticaria and angioedema. Cannabis has a rich chemical profile including cannabinoids and terpenes that possess immunomodulatory potential. We examined whether major cannabinoids of cannabis such as cannabidiol (CBD) and the bicyclic sesquiterpene beta-caryophyllene (β-CP) act as contact sensitizers. The repeated topical application of mice skin with β-CP at 10 mg/mL (50 µL) induced an itch response and dermatitis at 2 weeks in mice, which were sustained for the period of study. Histopathological analysis of skin tissues revealed significant edema and desquamation for β-CP at 10 mg/mL. For CBD and β-CP, we observed a dose-dependent increase in epidermal thickening with profound thickening observed for β-CP at 10 mg/mL. Significant trafficking of CD11b cells was observed in various compartments of the skin in response to treatment with β-CP in a concentration-dependent manner. Mast cell trafficking was restricted to β-CP (10 mg/mL). Mouse proteome profiler cytokine/chemokine array revealed upregulation of complement C5/5a (anaphylatoxin), soluble intracellular adhesion molecule-1 (sICAM-1) and IL-1 receptor antagonist (IL-1RA) in animals dosed with β-CP (10 mg/mL). Moreover, we observed a dose-dependent increase in serum IgE in animals dosed with β-CP. Treatment with β-CP (10 mg/mL) significantly reduced filaggrin expression, an indicator of barrier disruption. In contrast, treatment with CBD at all concentrations failed to evoke scratching and dermatitis in mice and did not result in increased serum IgE. Further, skin tissues were devoid of any remarkable features, although at 10 mg/mL CBD we did observe the accumulation of dermal CD11b cells in skin tissue sections. We also observed increased filaggrin staining in mice repeatedly dosed with CBD (10 mg/mL). Collectively, our studies indicate that repeated exposure to high concentrations of β-CP can induce dermatitis-like pathological outcomes in mice.

Use of Chemical Hair Straighteners and Fecundability in a North American Preconception Cohort

Chemical hair straighteners ("relaxers") are used by millions of North Americans, particularly women of color. Hair relaxers may contain endocrine-disrupting compounds, which can harm fertility. We evaluated the association between hair relaxer use and fecundability among 11,274 participants from Pregnancy Study Online (PRESTO), a North American preconception cohort study. During 2014-2022, participants completed a baseline questionnaire in which they reported their history of relaxer use and completed follow-up questionnaires every 8 weeks for 12 months or until pregnancy, whichever came first. We used multivariable-adjusted proportional probabilities regression models to estimate fecundability ratios (FRs) and 95% confidence intervals (CIs). Relative to never use, fecundability was lower among current (FR = 0.81, 95% CI: 0.64, 1.03) and former (FR = 0.89, 95% CI: 0.81, 0.98) users of hair relaxers. FRs for first use of hair relaxers at ages <10, 10-19, and ≥20 years were 0.73 (95% CI: 0.55, 0.96), 0.93 (95% CI: 0.83, 1.04), and 0.85 (95% CI: 0.74, 0.98), respectively. Fecundability was lowest among those with longer durations of use (≥10 years vs. never: FR = 0.71, 95% CI: 0.54, 0.91) and more frequent use (≥5 times/year vs. never: FR = 0.82, 95% CI: 0.60, 1.11), but associations were nonmonotonic. In this preconception cohort study, use of chemical hair straighteners was associated with slightly reduced fecundability.

The Potential of Pharmaceutical Hydrogels in the Formulation of Topical Administration Hormone Drugs

Hormones have attracted considerable interest in recent years due to their potential use in treatment of many diseases. Their ability to have a multidirectional effect leads to searching for new and increasingly effective drugs and therapies. Limitations in formulating drug forms containing hormones are mainly due to their low enzymatic stability, short half-life and limited bioavailability. One of the solutions may be to develop a hydrogel as a potential hormone carrier, for epidermal and transdermal application. This review discusses the main research directions in developing this drug formulation. The factors determining the action of hormones as drugs are presented. An analysis of hydrogel substrates and permeation enhancers that have the potential to enhance the efficacy of hormones applied to the skin is reviewed.

Using Chitosan-Coated Polymeric Nanoparticles-Thermosensitive Hydrogels in association with Limonene as Skin Drug Delivery Strategy

Topical delivery of local anesthetics (LAs) is commonly used to decrease painful sensations, block pain throughout procedures, and alleviate pain after surgery. Dermal and/or transdermal delivery of LAs has other advantages, such as sustained drug delivery and decreased systemic adverse effects. This study reports the development of poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles coated with chitosan for the sustained release and topicality of benzocaine (BZC) and topical delivery. BZC PLGA nanoparticles or nonencapsulated drugs were further incorporated into Poloxamer hydrogels (Pluronic™ F-127). The nanoparticles showed a mean diameter of 380 ± 4 nm, positive zeta potential after coating with chitosan (23.3 ± 1.7 mV), and high encapsulation efficiency (96.7 ± 0.02%). Cellular viability greater than 70% for both fibroblasts and keratinocytes was observed after treatment with nanoparticles, which is in accordance with the preconized guidelines for biomedical devices and delivery systems. Both the nanoparticles and hydrogels were able to modulate BZC delivery and increase drug permeation when compared to the nonencapsulated drug. Furthermore, the incorporation of limonene into hydrogels containing BZC-loaded nanoparticles increased the BZC permeation rates. Non-Newtonian and pseudoplastic behaviors were observed for all hydrogel nanoformulations with or without nanoparticles. These results demonstrate that the hydrogel-nanoparticle hybrids could be a promising delivery system for prolonged local anesthetic therapy.

Preparation and Characterization of Blank and Nerolidol-Loaded Chitosan–Alginate Nanoparticles

Recently, there has been a growing interest in using natural products as treatment alternatives in several diseases. Nerolidol is a natural product which has been shown to have protective effects in several conditions. The low water solubility of nerolidol and many other natural products limits their delivery to the body. In this research, a drug delivery system composed of alginate and chitosan was fabricated and loaded with nerolidol to enhance its water solubility. The chitosan–alginate nanoparticles were fabricated using a new method including the tween 80 pre-gelation, followed by poly-ionic crosslinking between chitosan negative and alginate positive groups. Several characterization techniques were used to validate the fabricated nanoparticles. The molecular interactions between the chitosan, alginate, and nerolidol molecules were confirmed using the Fourier transform infrared spectroscopy. The ultraviolet spectroscopy showed an absorbance peak of the blank nanoparticles at 200 nm and for the pure nerolidol at 280 nm. Using both scanning and transmission electron microscopy, the nanoparticles were found to be spherical in shape with an average size of 12 nm and 35 nm for the blank chitosan–alginate nanoparticles and the nerolidol-loaded chitosan–alginate nanoparticles, respectively. The nanoparticles were also shown to have a loading capacity of 51.7% and an encapsulation efficiency of 87%. A controlled release profile of the loaded drug for up to 28 h using an in vitro model was also observed, which is more efficient than the free form of nerolidol. In conclusion, chitosan–alginate nanoparticles and nerolidol loaded chitosan–alginate nanoparticles were successfully fabricated and characterized to show potential encapsulation and delivery using an in vitro model.

Bioactive properties of the aromatic molecules of spearmint (Mentha spicata L.) essential oil: a review

Spearmint belongs to the genus Mentha in the family Labiateae (Lamiaceae), which is wildly cultivated worldwide for its remarkable aroma and commercial value. The aromatic molecules of spearmint essential oil,...

Development of a novel nanoemulgel formulation containing cumin essential oil as skin permeation enhancer

Essential oils have been proposed as promising non-toxic transdermal permeation enhancers. Their use is limited because of their low water solubility. The use of nanotechnology-based strategies is one of the ways to overcome this limitation. This study aimed to explore the transdermal permeation enhancing capability of cumin essential oil in nanoemulgel systems containing diclofenac sodium. Cumin essential oil nanoemulsion was produced by high-pressure homogenization technique. The formulation was optimized by changing HLB values in a range of 9.65–16.7 using different surfactant mixtures, namely, Tween 20, Tween 80, and Span 80. Preparations were characterized by polydispersity index, droplet size, and zeta potential. Nanoemulsion with concentrations of 2 and 4% essential oil was incorporated into 0.75% Carbopol gel matrix to make nanoemulgel formulation, and its permeation enhancing effect was performed through Franz diffusion cells. Antinociceptive activities of the formulations were measured in thermal (tail-flick) and chemical (formalin) models of nociception in mice. Characterization exhibited that at HLB value of 9.65, the smallest particle size (82.20 ± 5.82 nm) was formed. By increasing the essential oil percentage in the nanoemulgel from 1 to 2%, the permeation of diclofenac increased from 28.39 ± 1.23 to 34.75 ± 1.07 µg/cm² at 24 h. The value of permeation from the simple gel (21.18 ± 2.51 µg/cm²) and the marketed product (22.97 ± 1.92 µg/cm²) was lower than the formulations containing essential oil. Nanoemulgel of diclofenac containing essential oil showed stronger antinociceptive effects in formalin and tail-flick tests than simple diclofenac gel and marketed formulation. In conclusion, the study proved that nanoemulgel formulation containing cumin essential oil could be considered as a promising skin enhancer to enhance the therapeutic effect of drugs.

Evaluation of the antioxidant, antibacterial, and antibiofilm activity of the sesquiterpene nerolidol

The aim of this study was to evaluate the antioxidant, antibacterial, and antibiofilm activities of nerolidol. The antioxidant activity of nerolidol was determined using the total antioxidant activity method. Antibacterial activity was performed using the microdilution method to determine the minimum inhibitory concentration (MIC) against seven standard strains of the ATCC and four bacterial clinical isolates with a resistance profile, following the Clinical and Laboratory Standards Institute (CLSI). The antibiofilm activity of nerolidol was performed using the crystal violet method. The results of the antioxidant test revealed a total antioxidant activity of 93.94%. Nerolidol inhibited the growth of Staphylococcus aureus (MIC = 1 mg/mL), Streptococcus mutans (MIC = 4 mg/mL), Pseudomonas aeruginosa (MIC = 0.5 mg/mL), and Klebsiella pneumoniae (MIC = 0.5 mg/mL). For clinical isolates, nerolidol showed an inhibitory potential against multidrug-resistant P. aeruginosa, K. pneumoniae carbapenemase (MIC = 0.5 mg/mL), methicillin-susceptible S. aureus (MIC = 2 mg/mL), and methicillin-resistant S. aureus (MIC = 2 mg/mL). Nerolidol showed similar antibacterial activity against ATCC strains and hospital clinical isolates with resistance profile, suggesting that even though these strains are resistant to antibiotics, they are still sensitive to nerolidol. Nerolidol exerted a dose-dependent effect on the inhibition of biofilm formation, even at subinhibitory concentrations. Nerolidol inhibited bacterial biofilms of ATCC strains at a rate ranging from 51 to 98%, at concentrations ranging from 0.5 to 4 mg/mL. For clinical bacterial isolates, biofilm inhibition ranged from 6 to 60%. Therefore, the present study showed the antioxidant, antibacterial, and antibiofilm properties of nerolidol.

Volatile molecules for COVID-19: A possible pharmacological strategy?

COVID-19 is a novel coronavirus disease with a higher incidence of bilateral pneumonia and pleural effusion. The high pulmonary tropism and contagiousness of the virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), have stimulated new approaches to combat its widespread diffusion. In developing new pharmacological strategies, the chemical characteristic of volatility can add therapeutic value to the hypothetical drug candidate. Volatile molecules are characterized by a high vapor pressure and are consequently easily exhaled by the lungs after ingestion. This feature could be exploited from a pharmacological point of view, reaching the site of action in an uncommon way but allowing for drug delivery. In this way, a hypothetical molecule for COVID-19 should have a balance between its lung exhalation characteristics and both antiviral and anti-inflammatory pharmacological action. Here, the feasibility, advantages, and disadvantages of a therapy based on oral administration of possible volatile drugs for COVID-19 will be discussed. Both aerosolized antiviral therapy and oral intake of volatile molecules are briefly reviewed, and an evaluation of 1,8-cineole is provided in view of a possible clinical use and also for asymptomatic COVID-19.

Composition and Antibacterial Effect of Mint Flavorings in Candies and Food Supplements

Mint flavorings are widely used in confections, beverages, and dairy products. For the first time, mint flavoring composition of mint candies and food supplements (n = 45), originating from 16 countries, as well as their antibacterial properties, was analyzed. The flavorings were isolated by Marcusson's type micro-apparatus and analyzed by GC-MS. The total content of the mint flavoring hydrodistilled extracts was in the range of 0.01 - 0.9%. The most abundant compounds identified in the extracts were limonene, 1,8-cineole, menthone, menthofuran, isomenthone, menthol and its isomers, menthyl acetate. The antimicrobial activity of 13 reference substances and 10 selected mint flavoring hydrodistilled extracts was tested on Escherichia coli and Staphylococcus aureus by broth dilution method. Linalool acetate and (-)-carvone, as most active against both bacteria, had the lowest MIC₉₀ values. (+)-Menthyl acetate, (-)-menthyl acetate, and limonene showed no antimicrobial activity. Three of the tested extracts had antimicrobial activity against E. coli and 8 extracts against S. aureus. Their summary antimicrobial activity was not always in concordance with the activities of respective reference substances.

Chemical composition, anti-nociceptive and anti-inflammatory activities of essential oil of Bougainvillea glabra

ETHNOPHARMACOLOGICAL RELEVANCE

Bougainvillea glabra is widely used in Nigeria for the treatment of inflammatory-related conditions, and as remedy for pain ailments.

AIM OF THE STUDY

Considering the lack of scientific studies focused on chemical constituents and pharmacological activity of B. glabra essential oil, this work was designed to characterize the volatile compounds and evaluate the anti-inflammatory and anti-nociceptive properties ascribed to this plant species.

MATERIALS AND METHODS

The essential oil was extracted from the leaf of B. glabra by hydrodistillation in an all glass Clevenger-type apparatus and characterized by gas chromatography (GC-FID) and gas chromatography-mass spectrometry (GC-MS) on HP-5 column. The anti-inflammatory property of the essential was established by measurement of carrageenan induced rat paw edema while the anti-nociceptive activity was determined by hot plate test, according to established procedures.

RESULTS

The essential oil was obtained in a yield of 0.08% (v/w) calculated on dry weight basis. A total of 11 compounds representing 96.2% of the oil contents were identified by GC/MS. The main constituents of the essential oil were (E)-nerolidol (31.4%), (E)-β-ionone (10.3%) and linalool (10.1%). The anti-nociceptive property of the essential oil was statistically significant p < 0.001 at all doses of when compared to the control while exhibiting an activity in tandem with the standard drug. For the 1st and 2nd h, at doses of 100 and 200 mg/kg, the anti-inflammatory activity was statistically very significant (p < 0.001), while at 3rd h the activity declined (p < 0.01) at a dose of 200 mg. The activity was non-significant at the 4th h experimental duration.

CONCLUSIONS

This is first report on the chemical constituents and biological activity of essential oil of B. glabra from Nigeria. Overall, the results herein presented sustain and strengthen the anti-nociceptive and anti-inflammatory properties traditionally ascribed to B. glabra.

Solid-in-oil nanodispersions for transdermal drug delivery systems

Transdermal administration of drugs has advantages over conventional oral administration or administration using injection equipment. The route of administration reduces the opportunity for drug evacuation before systemic circulation, and enables long-lasting drug administration at a modest body concentration. In addition, the skin is an attractive route for vaccination, because there are many immune cells in the skin. Recently, solid-in-oil nanodisperison (S/O) technique has demonstrated to deliver cosmetic and pharmaceutical bioactives efficiently through the skin. S/O nanodispersions are nanosized drug carriers designed to overcome the skin barrier. This review discusses the rationale for preparation of efficient and stable S/O nanodispersions, as well as application examples in cosmetic and pharmaceutical materials including vaccines. Drug administration using a patch is user-friendly, and may improve patient compliance. The technique is a potent transcutaneous immunization method without needles.

Nerolidol: A Sesquiterpene Alcohol with Multi-Faceted Pharmacological and Biological Activities

Nerolidol (3,7,11-trimethyl-1,6,10-dodecatrien-3-ol) is a naturally occurring sesquiterpene alcohol that is present in various plants with a floral odor. It is synthesized as an intermediate in the production of (3E)-4,8-dimethy-1,3,7-nonatriene (DMNT), a herbivore-induced volatile that protects plants from herbivore damage. Chemically, nerolidol exists in two geometric isomers, a trans and a cis form. The usage of nerolidol is widespread across different industries. It has been widely used in cosmetics (e.g., shampoos and perfumes) and in non-cosmetic products (e.g., detergents and cleansers). In fact, U.S. Food and Drug Administration (FDA) has also permitted the use of nerolidol as a food flavoring agent. The fact that nerolidol is a common ingredient in many products has attracted researchers to explore more medicinal properties of nerolidol that may exert beneficial effect on human health. Therefore, the aim of this review is to compile and consolidate the data on the various pharmacological and biological activities displayed by nerolidol. Furthermore, this review also includes pharmacokinetic and toxicological studies of nerolidol. In summary, the various pharmacological and biological activities demonstrated in this review highlight the prospects of nerolidol as a promising chemical or drug candidate in the field of agriculture and medicine.

Investigating transdermal delivery of vitamin D3

Transdermal delivery of therapeutic amounts of vitamin D3 is proposed to overcome its variable oral bioavailability, especially for people who suffer from fat malabsorption. The main challenge for this delivery route is to overcome the barrier properties of skin, especially for very lipophilic compounds such as vitamin D3. In this study, the effect of different penetration enhancers, such as oleic acid, dodecylamine, ethanol, oleic acid in propylene glycol, isopropyl myristate, octyldodecanol, and oleyl alcohol in propylene glycol were evaluated in vitro for their effectiveness in delivering vitamin D3 through polyamide filter, polydimethylsiloxane membrane, and porcine skin. A diffusion cell was used to study the transdermal permeability of vitamin D3. Ointment formulations of vitamin D3 were prepared containing the most widely used penetration enhancers, oleic acid, and dodecylamine. The ointment containing oleic acid as chemical penetration enhancer did not improve delivery compared to control. On the other hand, the formulation containing dodecylamine as a penetration enhancer did improve the transdermal delivery of vitamin D3. However, statistical significance and an amount high enough for nutritional supplementation purposes were reached only when the skin was pretreated with 50% ethanol. In these conditions, the ointment delivered an amount of 760-ng vitamin D3 per cm(2) of skin. The research shows promise that transdermal delivery could be an effective administration route for vitamin D3 when ethanol and dodecylamine are used as penetration enhancers.

Formulation optimization of arecoline patches

The response surface methodology (RSM) including polynomial equations has been used to design an optimal patch formulation with appropriate adhesion and flux. The patch formulations were composed of different polymers, including Eudragit RS 100 (ERS), Eudragit RL 100 (ERL) and polyvinylpyrrolidone K30 (PVP), plasticizers (PEG 400), and drug. In addition, using terpenes as enhancers could increase the flux of the drug. Menthol showed the highest enhancement effect on the flux of arecoline.