In vivo activity of terpinen-4-ol, the main bioactive component of Melaleuca alternifolia Cheel (tea tree) oil against azole-susceptible and -resistant human pathogenic Candida species

Biomimetic Antifungal Materials: Countering the Challenge of Multidrug-Resistant Fungi

In light of rising public health threats like antifungal and antimicrobial resistance, alongside the slowdown in new antimicrobial development, biomimetics have shown promise as therapeutic agents. Multidrug-resistant fungi pose significant challenges as they quickly develop resistance, making traditional antifungals less effective. Developing new antifungals is also complicated by the need to target eukaryotic cells without harming the host. This review examines biomimetic antifungal materials that mimic natural biological mechanisms for targeted and efficient action. It covers a range of agents, including antifungal peptides, alginate-based antifungals, chitosan derivatives, nanoparticles, plant-derived polyphenols, and probiotic bacteria. These agents work through mechanisms such as disrupting cell membranes, generating reactive oxygen species, and inhibiting essential fungal processes. Despite their potential, challenges remain in terms of ensuring biocompatibility, optimizing delivery, and overcoming potential resistance. Production scalability and economic viability are also concerns. Future research should enhance the stability and efficacy of these materials, integrate multifunctional approaches, and develop sophisticated delivery systems. Interdisciplinary efforts are needed to understand interactions between these materials, fungal cells, and the host environment. Long-term health and environmental impacts, fungal resistance mechanisms, and standardized testing protocols require further study. In conclusion, while biomimetic antifungal materials represent a revolutionary approach to combating multidrug-resistant fungi, extensive research and development are needed to fully realize their potential.

A comprehensive review on the pharmacological prospects of Terpinen-4-ol: From nature to medicine and beyond

Owing to their extensive biological potential, essential oils (EOs) and their bioactive phytochemicals have gained attention from the scientific community. Within this domain, Terpinen-4-ol (T-4-ol), a bioactive monoterpene alcohol and the major constituent of tea tree oil (TTO), has made its way into translational research. Recent literature on T-4-ol strongly indicates its diverse pharmacological properties, including but not limited to antimicrobial, antivirulent, anti-oxidant, anti-inflammatory, anti-hypertensive, and anti-cancer effects. Hence, this review is the first to provide a comprehensive overview of the sources, bioavailability, safety, pharmaceutical delivery systems, and multifaceted biological properties of T-4-ol, emphasizing its medicinal potential for widescale application. The antibacterial and antifungal effectiveness of T-4-ol has been discussed, encompassing its role in combating a broad spectrum of bacterial and fungal pathogens. The review delves into the antivirulent prospects of T-4-ol, shedding light on its ability to attenuate virulence and mitigate bacterial pathogenesis. Scientific literature on the anti-oxidant and anti-inflammatory activity of T-4-ol highlighting its role in neutralizing reactive oxygen species and modulating inflammatory pathways has also been collated. Furthermore, the review elaborates on the cardioprotective and anti-hypertensive properties of T-4-ol and augments literature on its anti-cancer mechanism against various cancer cell lines. The review also provides in-depth knowledge of the pharmaceutical formulations of T-4-ol and recent knowledge about its application in clinical/field trials. The exploration of these diverse attributes positions T-4-ol as a promising candidate for further research and therapeutic repurposing in various biomedical applications.

Unveiling the phyto-restorative potential of ethereal distillates for atopic dermatitis: an advanced therapeutic approach

Atopic dermatitis is acknowledged as a vital inflammatory disorder associated with the integumentary system of the body and is characterized by the formation of thick reddish-grey scars and erythema formation on skin, prevalent amidst the populace. Numerous synthetic drugs are available for treatment like antihistamines, immunosuppressants, glucocorticoids etc., but contrarily, essential oil therapy is exclusively lime lighted to favour the purpose. The utilization of available engineered drugs, possess the marked adverse effects owing to prolonged duration of therapy and therefore, essential oils are explored well and proved to exhibit the anti-eczematic, anti-inflammatory and antipruritic properties. Ethereal distillates own the assorted and selective therapeutic properties attributable to presence of bioactive compounds liable to treat this torturous and integumentary disorder, likely lavender oil, patchouli oil, frankincense oil etc., have been found to exert their pharmacological actions by impeding the liberation and action of inflammatory mediators and immunological hyperactivities that are engaged in exacerbating this idiopathic illness. The current attempt provided the update with the aim to bring forth the naturally originated treatment that is pertinent to provide the invulnerable therapy by circumventing the noxious symptoms i.e. erythema formation and inflamed lesions.

Phytochemical analysis and allelopathic potential of essential oil of yarrow (Achillea spp.) ecotypes against redroot pigweed (Amaranthus retroflexus L.)

This study will contribute to the knowledge of plant allelopathy and its application in weed management, as well as to the valuation of medicinal and neglected plant species. An allelopathy experiment was conducted to introduce Achillea spp. as an effective species on the red root pigweed (Amaranthus retroflexus L.). The allelopathic effect of dry material from the flower, leaf and stem of Tanacetum polycephalum L. and 9 Achillea spp. (Achillea santolina L., A. millefolium L., A. nobilis L., A. conferta DC., A. vermicularis Trin., A. beibersteinii Afan., A. talagonica Boiss., A. tenuifolia Lam., A. aleppica DC.) applied to the soil on the growth of redroot pigweed seedling was tested. Five different ratios of aerial dry material of different species as residues (at 0, 10, 20, 40, and 50 g kg-1 dry weight) were used in the pots. Achillea residual had a significant effect on the growth of redroot pigweed. Achillea vermicolaris and A. aleppica were the most effective species at stopping the growth of redroot pigweed, reducing its dry matter by 90% at 0.07 and 0.02 g kg-1 dry weight, respectively. Based on the results of GC/MS analyses, 152 different compounds were found in the essential oil of Achillea spp. The possible relationship between allelochemicals and seedling investigation by partial least squares regression between effective doses for controlling redroot pigweed and allelochemical compounds of Achillea species. Result showed that cis-Menth-2-en-1-ol, α-Terpinyl, propionate and Bornyl acetate had the most effect on inhibiting the growth of redroot pigweed. Our research revealed that the Achillea genus has a lot of potential as a bioherbicide. This means that its leftovers or mulch could be used as a good cover crop to control redroot pigweed.

The potential role of plant secondary metabolites on antifungal and immunomodulatory effect

With the widespread use of antibiotic drugs worldwide and the global increase in the number of immunodeficient patients, fungal infections have become a serious threat to global public health security. Moreover, the evolution of fungal resistance to existing antifungal drugs is on the rise. To address these issues, the development of new antifungal drugs or fungal inhibitors needs to be targeted urgently. Plant secondary metabolites are characterized by a wide variety of chemical structures, low price, high availability, high antimicrobial activity, and few side effects. Therefore, plant secondary metabolites may be important resources for the identification and development of novel antifungal drugs. However, there are few studies to summarize those contents. In this review, the antifungal modes of action of plant secondary metabolites toward different types of fungi and fungal infections are covered, as well as highlighting immunomodulatory effects on the human body. This review of the literature should lay the foundation for research into new antifungal drugs and the discovery of new targets. KEY POINTS: • Immunocompromised patients who are infected the drug-resistant fungi are increasing. • Plant secondary metabolites toward various fungal targets are covered. • Plant secondary metabolites with immunomodulatory effect are verified in vivo.

Mode of Antifungal Action of Daito-Gettou (Alpinia zerumbet var. exelsa) Essential Oil against Aspergillus brasiliensis

Plant-derived essential oils (EOs) are used in medicines, disinfectants, and aromatherapy products. Information on the antifungal activity of EO of Alpinia zerumbet var. exelsa (known as Daito-gettou) found in Kitadaito Island, Okinawa, is limited. Therefore, we aimed to evaluate the antifungal activity of EOs obtained via steam distillation of leaves of Daito-gettou, which is a hybrid of A. zerumbet and A. uraiensis. Daito-gettou EO showed antifungal activity (minimum inhibitory concentration = 0.4%) against Aspergillus brasiliensis NBRC 9455, which was comparable to that of A. zerumbet found in the Okinawa main island. Gas chromatography/mass spectrometry revealed that the main components of Daito-gettou EOs are γ-terpinene, terpinen-4-ol, 1,8-cineole, 3-carene, and p-cymene. Terpinen-4-ol content (MIC = 0.075%) was 17.24%, suggesting that the antifungal activity of Daito-gettou EO was mainly attributable to this component. Daito-gettou EO and terpinen-4-ol inhibited mycelial growth. Moreover, calorimetric observations of fungal growth in the presence of Daito-gettou EO showed a characteristic pattern with no change in the initial growth rate and only a delay in growth. As this pattern is similar to that of amphotericin B, it implies that the action mode of Daito-gettou EO and terpinen-4-ol may be fungicidal. Further studies on the molecular mechanisms of action are needed for validation.

Chemical Composition and Antimicrobial Potential of a Plant-Based Substance for the Treatment of Seborrheic Dermatitis

Seborrheic dermatitis (SD) is the most prevalent dermatological disease, occurring in up to 50% of newborns, children, and adults around the world. The antibacterial and antifungal resistance contributed to the search for new natural substances and the development of a novel substance based on Melaleuca alternifolia (M. alternifolia) leaf oil (TTO), 1,8-cineole (eucalyptol), and α-(-)-bisabolol. Thus, this work aimed to determine the chemical composition of the novel plant-based substance and to evaluate its antimicrobial activity against standard microorganisms involved in the pathogenesis of SD. Moreover, the chemical composition of the substance was analyzed by gas chromatography coupled with mass spectrometry (GC/MS). Staphylococcus epidermidis (S. epidermidis), Staphylococcus aureus (S. aureus), Micrococcus luteus (M. luteus), and Candida albicans (C. albicans) were used for antimicrobial and antifungal assays by means of the broth microdilution method to determine the minimal inhibitory concentration (MIC). Finally, the substance’s ability to inhibit Malassezia furfur (M. furfur) was evaluated. Eighteen compounds from different chemical groups were identified by GC/MS. The major biologically active compounds of the substance were terpinen-4-ol (20.88%), 1,8-cineole (22.28%), (-)-α-bisabolol (25.73%), and o-cymene (8.16%). The results showed that the substance has a synergistic antimicrobial and antifungal activity, while S. epidermidis and C. albicans strains were the most susceptible. Furthermore, the substance inhibited M. furfur, which is a main pathogen involved in the pathogenesis of SD and clinical manifestations. It can be concluded that the novel plant-based substance has a promising potential against M. furfur and scalp commensal bacteria and may be helpful for the development of new drugs for treatment of dandruff and SD.

Recent Advances in Using Natural Antibacterial Additives in Bioactive Wound Dressings

Wound care is a global health issue with a financial burden of up to US $96.8 billion annually in the USA alone. Chronic non-healing wounds which show delayed and incomplete healing are especially problematic. Although there are more than 3000 dressing types in the wound management market, new developments in more efficient wound dressings will require innovative approaches such as embedding antibacterial additives into wound-dressing materials. The lack of novel antibacterial agents and the misuse of current antibiotics have caused an increase in antimicrobial resistance (AMR) which is estimated to cause 10 million deaths by 2050 worldwide. These ongoing challenges clearly indicate an urgent need for developing new antibacterial additives in wound dressings targeting microbial pathogens. Natural products and their derivatives have long been a significant source of pharmaceuticals against AMR. Scrutinising the data of newly approved drugs has identified plants as one of the biggest and most important sources in the development of novel antibacterial drugs. Some of the plant-based antibacterial additives, such as essential oils and plant extracts, have been previously used in wound dressings; however, there is another source of plant-derived antibacterial additives, i.e., those produced by symbiotic endophytic fungi, that show great potential in wound dressing applications. Endophytes represent a novel, natural, and sustainable source of bioactive compounds for therapeutic applications, including as efficient antibacterial additives for chronic wound dressings. This review examines and appraises recent developments in bioactive wound dressings that incorporate natural products as antibacterial agents as well as advances in endophyte research that show great potential in treating chronic wounds.

In Vitro and In Vivo Evaluation of a Nano-Tool Appended Oilmix (Clove and Tea Tree Oil) Thermosensitive Gel for Vaginal Candidiasis

The main objective of the proposed work was the development of a thermosensitive gel (containing clove and tea tree oil) for the management of vaginal candidiasis. Both oils have been recommended to be used separately in a topical formulation for vaginal candidiasis. Incorporating two natural ingredients (clove and tea tree oil) into a product give it a broad antimicrobial spectrum and analgesic properties. The two oils were mixed together at a 3:1 ratio and converted into o/w nanoemulsion using the aqueous titration method and plotting pseudo ternary phase diagrams. Further transformations resulted in a gel with thermosensitive properties. To determine the final formulation's potential for further clinical investigation, in vitro analyses (viscosity measurement, MTT assay, mucoadhesion, ex vivo permeation) and in vivo studies (fungal clearance kinetics in an animal model) were conducted. The current effort leveraged the potential of tea tree and clove oils as formulation ingredients and natural therapeutic agents for vaginal infections. Its synergy generated a stable and effective thermosensitive gel that can be utilized for recurrent candidiasis and other infections.

Comparative Study of Antibacterial, Antibiofilm, Antiswarming and Antiquorum Sensing Activities of Origanum vulgare Essential Oil and Terpinene-4-ol against Pathogenic Bacteria

Essential oils from aromatic and medicinal plants have many bioactive compounds known for their important biological activities mainly their antibacterial effects. Here we evaluated qualitatively and quantitatively the biofilm formation capability of pathogenic bacterial strains (n = 8). Then, we investigated the antibacterial, antibiofilm, antiquorum-sensing, and antiswarming efficacy of Origanum vulgare essential oil (EO) and terpinene-4-ol. Our results revealed that EO exhibited a more potent inhibitory effect against the tested strains. While the terpinene-4-ol was found to be more effective against developed Staphylococcus aureus biofilm. Regarding the anti quorum-sensing activity, we noticed that O. vulgare displayed better inhibition percentages in violacein production even at a low concentration (MIC/4). Additionally, this EO showed better inhibition of Pseudomonas aeruginosa PAO1 migration in comparison with the terpinene-4-ol. Our findings revealed that using pure O. vulgare EO demonstrated better competitive effects against pathogenic bacteria with a different mode of action when compared to the terpinene-4-ol. Hence, exploration and development of efficient anti-infection agents from natural resources such as full EOs represent promising tools in anti-infective therapy.

Identification of a promising inhibitor from Illicium verum (star anise) against the main protease of SARS-CoV-2: insights from the computational study

SARS-CoV-2, the causing agent of coronavirus disease (COVID-19), first broke out in Wuhan and rapidly spread worldwide, resulting in a global health emergency. The lack of specific drugs against the coronavirus has made its spread challenging to control. The main protease (M^pro) is a key enzyme of SARS-CoV-2 used as a key target in drug discovery against the coronavirus. Medicines derived from plant phytoconstituents have been widely exploited to treat various diseases. The present study has evaluated the potential of Illicium verum (star anise) phytoconstituents against M^pro by implementing a computational approach. We performed molecular docking and molecular dynamics simulation study with a set of 60 compounds to identify their potential to inhibit the main protease (M^pro) of SARS-CoV-2. DFT study and post dynamics free energy calculations were also performed to strengthen the findings. The identified four compounds by docking study exhibited the highest potential compared to other selected phytoconstituents. Further, density functional theory (DFT) calculation, molecular dynamics simulation and post dynamics MM-GBSA energy calculation predicted Verimol-G as a potential compound, which formed stable interactions through the catalytic dyad residues. The HOMO orbital energy (-0.250038) from DFT and the post dynamics binding free energy calculation (-73.33 Kcal/mol) correlate, suggesting Verimol-G is the best inhibitor compared to the other phytoconstituents. This compound also complies with the ADME properties of drug likeliness. Thus, based on a computational study, we suggest that Verimol G may be developed as a potential inhibitor against the main protease to combat COVID-19.Communicated by Ramaswamy H. Sarma.

The Biological Activity of Tea Tree Oil and Hemp Seed Oil

The interest in hemp seed oil (HSO) and tea tree oil (TTO) in the medical and food industries is increasing. The current study compares their bioactivity to other plant oils, mainly focusing on hemp seed oils (HSOs) with various cannabidiol (CBD) contents. A DPPH assay was employed to evaluate the antioxidant activity. The antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Salmonella enteritidis was evaluated using time–kill, minimum inhibition concentration (MIC), and Kirby–Bauer disk diffusion methods. Tea tree oil showed significantly higher antimicrobial activity against S. enteritidis compared to E. coli and S. aureus (p < 0.05). The antioxitant activity range (lowest to highest) was sesame < vetiver < rosehip < tea tree < organic hemp < pure hemp < 5% CBD < vitamin C. Tea tree oil and 5% CBD showed antioxidant activity at IC50 of 64.45 μg/mL and 11.21 μg/mL, respectively. The opposing antimicrobial and antioxidant results for TTO and HSO indicate that these activities arise from different components within the oil compositions.

Essential Oils as a Good Weapon against Drug-Resistant Candida auris

Candida auris is a recently found Candida species, mainly associated with nosocomial outbreaks in intensive care hospital settings, and unlike other Candida species, it can be transmitted through person-to-person or by contact with surfaces. C. auris is described as resistant to first-line antifungals and, consequently, associated with high mortality. Nowadays, essential oils (EOs) are known to be effective against fungal and bacterial infections. This work aimed to evaluate the effect of four EOs (tea tree, niaouli, white thyme and cajeput) against C. auris. The EO’s effect on C. auris planktonic growth was evaluated by the minimum inhibitory concentration determination and by the agar disc diffusion method. Then, the same effect was evaluated on biofilm by colony-forming units’ enumeration. The results showed that EOs were able to inhibit the C. auris planktonic growth, with an MIC50 between 0.78 and 1.56% and halos of 20–21 mm for white thyme and tea tree and 13–14 mm for cajeput and niaouli. In addition, the EOs were also able to completely inhibit biofilm formation. Moreover, white thyme and cajeput completely eradicate pre-formed biofilms, while tea tree and niaouli significantly reduce it. Thus, this work demonstrates that EOs are a possible therapeutic alternative and a future perspective for the hard fight against C. auris.

Terpinen-4-ol, the Main Bioactive Component of Tea Tree Oil, as an Innovative Antimicrobial Agent against Legionella pneumophila

Legionella pneumophila (Lp), responsible for a severe pneumonia called Legionnaires’ disease, represents an important health burden in Europe. Prevention and control of Lp contamination in warm water systems is still a great challenge often due to the failure in disinfection procedures. The aim of this study was to evaluate the in vitro activity of Terpinen-4-ol (T-4-ol) as potential agent for Lp control, in comparison with the essential oil of Melaleuca alternifolia (tea tree) (TTO. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of T-4-ol were determined by broth micro-dilution and a micro-atmosphere diffusion method to investigate the anti-Lp effects of T-4-ol and TTO vapors. Scanning Electron Microscopy (SEM) was adopted to highlight the morphological changes and Lp damage following T-4-ol and TTO treatments. The greatest antimicrobial activity against Lp was shown by T-4-ol with a MIC range of 0.06–0.125% v/v and MBC range of 0.25–0.5% v/v. The TTO and T-4-ol MIC and MBC decreased with increasing temperature (36 °C to 45 ± 1 °C), and temperature also significantly influenced the efficacy of TTO and T-4-ol vapors. The time-killing assay showed an exponential trend of T-4-ol bactericidal activity at 0.5% v/v against Lp. SEM observations revealed a concentration- and temperature- dependent effect of T-4-ol and TTO on cell surface morphology with alterations. These findings suggest that T-4-ol is active against Lp and further studies may address the potential effectiveness of T-4-ol for control of water systems.

Prevalence of endocrine disorders among children exposed to Lavender Essential Oil and Tea Tree Essential Oils

Background

Lavender essential oil and tea tree essential oil have become popular ingredients in personal care and household products in recent decades. Questions regarding the safety of these oils in pediatric populations have been raised, proposing a link between these essential oils and endocrine disruption in children, specifically prepubertal gynecomastia. To date, no epidemiological studies have been conducted to evaluate this proposed link.

Methods

This is a cross sectional study conducted among parents of children in the United States to identify the prevalence of endocrine disruption in children aged 2-15 years old. This study also evaluates the potential for a relationship between the exposure of lavender essential oil and tea tree essential oil products and endocrine disrupting outcomes.

Results

In 556 children with a mean age of 6.33 (SD = 3.92), prevalence of endocrine disruption was .016 (SD = 0.13). No cases of prepubertal gynecomastia were identified in either group, and prevalence of precocious puberty, delayed puberty, growth hormone deficiency, and hypothyroidism were all consistent with population norms. Total risk of endocrine disorders among those exposed (0.0194) did not differ from the risk of those unexposed (0.0069). The risk ratio was 2.796 (95% CI: 0.352, 22.163, P = .458).

Conclusion

Children who were regularly exposed to lavender or tea tree essential oils experienced the same risk of endocrine disorders as those who were not exposed.

Meta-analysis of the antifungal activities of three essential oils as alternative therapies in dermatophytosis infections

Aims

This work examines the available scientific evidence about the efficiency of essential oils (EO) as an alternative therapy to traditional treatment of fungal infections, including onychomycosis, assessing the effect of the three EO most frequently studied for their antifungal activity (thyme, cinnamon and tea tree EO) against three causative agents of fungal diseases in humans: Trichophyton rubrum, Trichophyton mentagrophytes complex and Candida albicans.

Methods and Results

The PRISMA statement protocol was followed to conduct a bibliographical search and 54 articles that met all the inclusion criteria were retrieved. Differences were observed in the MIC and MFC values depending on the micro‐organism strain and the EO used. The lowest MIC were observed with Cinnamomum zeylanicum EO (0.013–1120 μl ml⁻¹) against the three micro‐organisms. For MFC, the lowest value was found for Thymus vulgaris EO (4.2 μl ml⁻¹) against Trichophyton rubrum.

Conclusions

The antifungal effects of EO could be a very promising solution to overcome the therapeutic shortcomings of antimycotic medication. More experiments are needed to examine the properties of these oils to devise effective and nonaggressive therapies for treatment of dermatophytosis.

Significance and Impact of Study

The results indicate that EO remain good candidates for future treatments and could provide a solution for failed medications and/or adverse reactions to current pharmacological treatments.

Synergistic effects of carvacrol, α-terpinene, γ-terpinene, ρ-cymene and linalool against Gardnerella species

Bacterial vaginosis (BV) is the most common vaginal infection affecting women worldwide. This infection is characterized by the loss of the dominant Lactobacillus community in the vaginal microbiota and an increase of anaerobic bacteria, that leads to the formation of a polymicrobial biofilm, mostly composed of Gardnerella spp. Treatment of BV is normally performed using broad-spectrum antibiotics, such as metronidazole and clindamycin. However, the high levels of recurrence of infection after treatment cessation have led to a demand for new therapeutic alternatives. Thymbra capitata essential oils (EOs) are known to have a wide spectrum of biological properties, including antibacterial activity. Thus, herein, we characterized two EOs of T. capitata and tested their antimicrobial activity as well as some of their main components, aiming to assess possible synergistic effects. Our findings showed that carvacrol and ρ-cymene established a strong synergistic antimicrobial effect against planktonic cultures of Gardnerella spp. On biofilm, carvacrol and linalool at sub-MIC concentrations proved more efficient in eliminating biofilm cells, while showing no cytotoxicity observed in a reconstituted human vaginal epithelium. The antibiofilm potential of the EOs and compounds was highlighted by the fact cells were not able to recover culturability after exposure to fresh medium.

Chemical and Biological Characterization of Melaleuca alternifolia Essential Oil

The essential oil of Melaleuca alternifolia, commonly known as tea tree oil, has many beneficial properties due to its bioactive compounds. The aim of this research was to characterize the tea tree essential oil (TTEO) from Slovakia and its biological properties, which are specific to the chemical composition of essential oil. Gas chromatography/mass spectroscopy revealed that terpinen-4-ol was dominant with a content of 40.3%. γ-Terpinene, 1,8-cineole, and p-cymene were identified in contents of 11.7%, 7.0%, and 6.2%, respectively. Antioxidant activity was determined at 41.6% radical inhibition, which was equivalent to 447 μg Trolox to 1 mL sample. Antimicrobial activity was observed by the disk diffusion method against Gram-positive (G⁺), Gram-negative (G^-) bacteria and against yeasts, where the best antimicrobial activity was against Enterococcus faecalis and Candida albicans with an inhibition zone of 10.67 mm. The minimum inhibitory concentration showed better susceptibility by G⁺ and G^- planktonic cells, while yeast species and biofilm-forming bacteria strains were more resistant. Antibiofilm activity was observed against Pseudomonas fluorescens and Salmonella enterica by MALDI-TOF, where degradation of the protein spectra after the addition of essential oil was obtained. Good biological properties of tea tree essential oil allow its use in the food industry or in medicine as an antioxidant and antimicrobial agent.

Solid lipid nanoparticles and nanostructured lipid carrier-based nanotherapeutics for the treatment of psoriasis

INTRODUCTION

Psoriasis is an auto-immune inflammatory skin disease affecting people worldwide. Its topical therapy via different nanoformulations prevents the long-term side-effects of conventional formulations. Nanocarriers, especially solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs), pose extra benefits in topical drug delivery due to their lipid constituents. Although both natural and synthetic anti-psoriatic drugs have been successfully incorporated in these nanoformulations, yet further studies including dual drug-loadings are being carried out for assessing their efficacy.

AREAS COVERED

This review aims at describing the different aspects of SLNs and NLCs in psoriasis, including their skin permeation behavior and the various drug molecules incorporated. The recent studies with single- and dual drug-loaded SLNs and NLCs have also been discussed in the review.

EXPERT OPINION

SLNs and NLCs have been very effective in mitigating psoriasis when compared to commercial formulations. They have also shown promising results when loaded with two drugs, thus overcoming drawbacks of traditional combination therapy. Therefore, various drug/antibody/siRNA combinations can be selected in the upcoming research works to evaluate their synergistic performance against psoriasis. However, the conclusions drawn so far are only based on the pre-clinical studies and hence further investigations are required to obtain their clinical trial outcomes.

Chemical Profiles of Herbal Compress and Their Persistence Affected by Steaming and Storage Time

The steamed herbal compress is one of the well-known traditional medicines used to relieve pain and stress and to promote emotional and physical well-being. Although it has several therapeutic benefits due to its chemical compounds, there are insufficient reports on the effect of steaming of the herbal compress to promote the release of active compounds and its shelf life. Hence, this study aims at analysing the effect of various steaming processes and storage conditions on the chemical composition of most commonly used herbs such as kaffir lime, lemongrass, plai, soap pod, tamarind, and turmeric. The herbs were extracted with solid-liquid and Soxhlet-mediated extraction using 95% ethanol, hexane, and water as solvents. The analysis of chemical profiles of herbs indicated that Soxhlet extraction is the best extraction procedure based on the extraction yield and abundance of eluted compounds. The herbs were then steam-processed according to the traditional practice of using herbal compress with water alone, and water in combination with 5% ethanol or 5% coconut oil to analyse the effect of steaming. The results indicated that a steaming process can promote the release of bioactive compounds from herbs. The effect of storage was also investigated by storing herbs for 1 day and 7 days at 4°C. The finding suggested that storage has resulted in changes in the bioactive composition of herbs pointing to the necessity of modifying storage conditions to eliminate the loss of beneficial compounds. Thus, this study can be helpful for product development to improve the quality of products by modifying their steaming or storage conditions.

Screening and testing potential inhibitors of sulphide gas production by sulphate-reducing bacteria

Sulphate-reducing bacteria are commonly associated with biological causes of oil well souring. Biosulphetogenesis can directly affect oil quality and storage due to the accumulation of sulphides. In addition, these microorganisms can create bio-incrustation that can clog pipes. Sulphite reductase (SIR) is the enzyme responsible for converting ion sulphite into sulphide and several substances may interfere or control such activity. This interference can hinder growth of the sulphate-reducing bacteria and, consequently, it reduces sulphide accumulation in situ. This work focuses on molecular modelling techniques along with in vitro experiments in order to investigate the potential of two essential oils and one vegetable oil as main inhibitors of sulphite reductase activity. Docking simulation identified several substances present in Rosmarinus officinalis, Tea tree and Neem extractable oils as potential inhibitors of SIR. Substances present in Neem vegetable oil are the most potent inhibitors, followed by Rosmarinus officinalis and Tea tree essential oils. The Neem oil mixture showed a superior effectiveness in intracellular SIR inhibitory effects.

Natural substances to potentiate canonical glioblastoma chemotherapy

Glioblastoma multiforme (GBM) is the most frequent primary malignant brain tumour prevalent in humans, that exhibits aggressive cell proliferation and rapid invasion of normal brain tissue. Despite aggressive therapeutic approaches consisting of maximum safe surgical resection followed by radio-chemotherapy with temozolomide (TMZ), more than 95% of GBM patients die within 5 years after diagnosis. In most cases, the therapy is not able to counteract the growth and invasiveness of the tumour, which relapses after an interval of time that varies from patient to patient. An increasing number of evidence indicates that natural substances exhibited effective anti-tumour functions and might be successfully used in the treatment of GBM. This review summarizes some natural substances: lactoferrin, hispolon, aloe-emodin and tea tree oil; all these show a growth inhibition and synergistic effect when together with TMZ, (the most commonly used alkylating drug for the treatment of glioblastoma) were administered to U87MG glioblastoma cell line in vitro and in murine animal model. U87MG cell growth was monitored by daily cell count after treatments with the substances mentioned above and growth analysis showed that all drugs significantly decrease proliferation of U87MG in a time- and dose-dependent manner. FACS analysis demonstrates a block of cell cycle in S, G2/M or G0/G1 phases. These substances mediate multiple processes including apoptosis by releasing the inducing factor: PARP. Natural compounds, in combination with conventional chemotherapy TMZ, are a powerful approach to improve the effectiveness of brain cancer treatment.

Effects of dietary marjoram, Origanum majorana extract on growth performance, hematological, antioxidant, humoral and mucosal immune responses, and resistance of common carp, Cyprinus carpio against Aeromonas hydrophila

The present study aimed to investigate the potential effects of dietary marjoram extract on growth performance, health, and disease resistance in common carp, Cyprinus carpio. To this purpose, the fish were assigned into four treatments and fed by diets supplemented with 0 (control), 100, 200, and 400 mg marjoram extract kg^-1 over eight weeks and then challenged with Aeromonas hydrophila. According to the results, 200 mg kg^-1 dietary marjoram extract inclusion showed the highest final weight, weight gain, and specific growth rate, and lowest feed conversion ratio (FCR). White blood cell number, Red blood cells, hematocrit, hemoglobin, mean corpuscular volume and mean corpuscular hemoglobin were markedly increased particularly at 200 mg kg^-1 treatment. Marjoram extract significantly increased plasma superoxide dismutase activity and decreased malondialdehyde level compared to the control treatment. Plasma complement and lysozyme activities and total immunoglobulin levels, mucosal complement, lysozyme and alkaline phosphatase activities and immunoglobulin levels were significantly increased compared to the control group. The lowest post-challenge survival rate was observed in the control treatment, whereas the highest value was related to the 200 mg kg^-1 marjoram treatment. In conclusion, the present study demonstrated that, marjoram extract is a suitable feed supplements for common carp, as it stimulates the fish growth, antioxidant, and immune systems, which suppress the fish mortality during Aeromonas septicemia. According to the results, 200 mg marjoram extract kg^-1 is recommended for carp feed formulation.

Volatile Compounds of Lemon and Grapefruit IntegroPectin

An HS-SPME GC-MS analysis of the volatile compounds adsorbed at the outer surface of lemon and grapefruit pectins obtained via the hydrodynamic cavitation of industrial waste streams of lemon and grapefruit peels in water suggests important new findings en route to understanding the powerful and broad biological activity of these new pectic materials. In agreement with the ultralow degree of esterification of these pectins, the high amount of highly bioactive α-terpineol and terpinen-4-ol points to limonene (and linalool) decomposition catalyzed by residual citric acid in the citrus waste peel residue of the juice industrial production.

Inhibitory Activity of Essential Oils against Vibrio campbellii and Vibrio parahaemolyticus

Vibriosis, caused by Vibrio strains, is an important bacterial disease and capable of causing significant high mortality in aquatic animals. Essential oils (EOs) have been considered as an alternative approach for the treatment of aquatic bacterial diseases. In this study, we evaluated the antibacterial activity of essential oils (n = 22) or essential oil components (EOCs, n = 12) against Vibrio strains belonging to the harveyi clade. It was verified by three different approaches, e.g., (i) a bacterial growth assay, comparing Vibrio growth with or without EO(C)s at various concentrations; (ii) a vapor-phase-mediated susceptibility assay, comparing the effect of EO(C)s on bacterial growth through the vapor phase; and (iii) a quorum sensing-inhibitory assay, based on specific inhibition of quorum sensing-regulated bioluminescence. The results showed that, in the bacterial growth assay, EOs of Melaleuca alternifolia and Litsea citrata at 0.0001%, Eucalyptus citriodora at 0.01% can inhibit the growth of Vibrio campbellii BB120. These EOs can also prevent the growth of V. parahaemolyticus strains but need to be present at a higher concentration (0.1%). Moreover, in the vapor-phase-mediated susceptibility assay, EOs of M. alternifolia, L. citrata and E. citriodora can inhibit the growth of V. campbellii BB120 through their vapor phase. However, V. parahaemolyticus strains (CAIM170, LMG2850 and MO904) cannot be inhibited by these EOs. Additionally, in the quorum sensing-inhibitory assay, EOs of Mentha pulegium, Cuminum cyminum, Zingiber officinalis, and E. citriodora, all at 0.001%, have quorum sensing-inhibitory activity in V. campbellii BB120. Taken together, our study provides substantial evidence that usage of the major components, individually or in combination, of the tested commercial EOs (extracted from M. alternifolia, L. citrata, and E. citriodora) could be a promising approach to control V. campbellii BB120.

Microbial metabolomics and network analysis reveal fungistatic effect of basil (Ocimum basilicum) oil on Candida albicans

ETHNOPHARMACOLOGICAL RELEVANCE

Fungal infections remain a serious problem worldwide that require effective therapeutic strategies. Essential oil of basil (Ocimum basilicum L., BEO) being traditionally used extensively for the treatment of bacterial and fungal infection has a long history. However, the potential mechanism of action was still obscure, especially from the metabolic perspective.

MATERIALS AND METHODS

The fungistatic effect of BEO on Candida albicans (C. albicans) was evaluated by measurement of minimum inhibitory concentration (MIC) and morphological analysis. A high-coverage microbial metabolomics approach was utilized to identify the alterations of intracellular metabolites of C. albicans at mid-logarithmic growth phase in response to the subinhibitory concentration of BEO, by using gas chromatography coupled to time-of-fight mass spectrometry (GC-TOFMS). Following the metabolic fingerprinting, systematic network analysis was performed to illustrate the potential mechanism of BEO involved in the suppression of C. albicans.

RESULTS

The damage in cellular membranes of C. albicans treated by BEO above MIC was observed on the scanning electron microscope (SEM) micrographs. Metabolomics results showed that, among 140 intracellular metabolites identified by comparison with reference standards, thirty-four had significantly changed abundances under 0.2 MIC of BEO treatment, mainly involving in central carbon metabolism (glycolysis/gluconeogenesis, pentose phosphate pathway and TCA cycle), amino acids, polyamines and lipids metabolism. Pathway and network analyses further found that fifteen ingredients of BEO mainly terpenoids and phenyl-propanoids, potentially participated in the metabolic regulation and may be responsible for the suppression of C. albicans.

CONCLUSIONS

The findings highlighted that integrated microbial metabolomics and network analyses could provide a methodological support in understanding the functional mechanisms of natural antimicrobial agents and contribute to drug discovery.

The sensitivity of Demodex canis (Acari: Demodicidae) to the essential oil of Melaleuca alternifolia - an in vitro study

The essential oil of the Melaleuca alternifolia (Maiden & Betche) (tea tree oil) has been effective in previous studies, in the treatment of infestation by Demodex mites in humans. The present study aimed at evaluating the in vitro acaricidal effect of this herbal medicine on Demodex canis. For the parasitological examination, samples were collected from a dog's skin and examined using optical microscopy. Only samples with intact mites and with evident movement of chelicerae and tarsi were selected. Twenty-one samples were tested with the oil, in seven different concentrations: 100%; 50%; 25%; 12.5%; 6.25%; 5.0% and 3.13%. Three samples were tested with the positive control amitraz, and three with the negative control neutral shampoo. The interval between the time the solution was added and the moment the movement of the last mite ceased defined the survival time in the sample. By comparing the times at different concentrations and controls, the results showed that the higher the concentration of the oil, the more quickly its lethal effect occurred, and that the survival times in the controls were longer than in the different concentrations of melaleuca oil.

Chemical Composition of a Supercritical Fluid (Sfe-CO2) Extract from Baeckea frutescens L. Leaves and Its Bioactivity Against Two Pathogenic Fungi Isolated from the Tea Plant (Camellia sinensis (L.) O. Kuntze)

Colletotrichum gloeosporioides and Pseudopestalotiopsis camelliae-sinensis are the two most important tea plant (Camellia sinensis L.) pathogenic fungi. Interest in natural plant extracts as alternatives to synthetic chemical fungicides to control plant pathogens is growing. In this study, the volatile fraction of Baeckea frutescens L. was extracted by supercritical fluid extraction (SFE-CO₂), and its chemical composition was analyzed, and investigated for its antifungal activity against C. gloeosporioides and P. camelliae. The major constituents of the volatile fraction were β-caryophyllene (28.05%), α-caryophyllene (24.02%), δ-cadinene (6.29%) and eucalyptol (5.46%) in B. frutescens SFE-CO₂ extracts. The terpineol, linalool, terpinen-4-ol and eucalyptol showed strong contact antifungal activity against P. camelliae and C. gloeosporioides with median inhibitory concentration (MIC₅₀) in the range of 0.69 μL/mL to 2.79 μL/mL and 0.62 μL/mL to 2.18 μL/mL, respectively. Additionally, the volatile fraction had high fumigation antifungal activity against P. camelliae and C. gloeosporioides with an inhibition rate between 20.87% and 92.91%. Terpineol presented the highest antifungal activity in the contact and fumigation toxicity assays. Terpineol, linalool, terpinen-4-ol and eucalyptol were associated with the most active chemical compounds in the volatile fraction against the fungi. The results suggest that B. frutescens SFE-CO₂ extracts are potential ingredients to develop a natural fungicide for control of tea plant pathogens.

Essential Oils: An Impending Substitute of Synthetic Antimicrobial Agents to Overcome Antimicrobial Resistance

Antimicrobial resistance (AMR) is an emerging problem in the world that has a significant impact on our society. AMR made conventional drugs futile against microorganisms and diseases untreatable. Plant-derived medicines are considered to be safe alternatives as compared to synthetic drugs. Active ingredients and the mixtures of these natural medicines have been used for centuries, due to their easy availability, low cost, and negligible side effects. Essential oils (EOs) are the secondary metabolites that are produced by aromatic plants to protect them from microorganisms. However, these EOs and their constituents have shown good fighting potential against drug-resistant pathogens. These oils have been proved extremely effective antimicrobial agents in comparison to antibiotics. Also, the combination of synthetic drugs with EOs or their components improve their efficacy. So, EOs can be established as an alternative to synthetic antimicrobial agents to eradicate tough form of infectious microorganisms. EO's can interact with multiple target sites, like the destruction of cytoplasm membrane or inhibition of protein synthesis and efflux pump, etc. The purpose of this review is to provide information about the antimicrobial activity of EOs attained from different plants, their combination with synthetic antimicrobials. In addition, mechanism of antimicrobial activity of several EOs and their constituents was reported.

Microsponge Based Gel of Tea Tree Oil for Dermatological Microbial Infections

Objective:

Tea Tree Oil (TTO), derived from Melaleuca alternifolia possesses broad spectrum antimicrobial potential. However, its therapeutic utility is impaired due to its high volatility, poor aqueous solubility and low stability in the presence of light, oxygen and temperature. The present study was attempted to investigate Ethyl Cellulose (EC) microsponges (MSs) as topical carriers for TTO to circumvent above mentioned limitations.

Methods:

TTO MSs were prepared using quasi emulsion solvent diffusion technique. The effect of formulation variables on the production yield, entrapment efficiency, particle size and drug release of MSs was investigated. The optimized MSs were dispersed into Carbopol 934 gel and evaluated for drug release, skin irritation, antibacterial activity and photostability.

Results:

Scanning electron microscopy revealed spherical and porous nature of TTO microsponges. The optimized MSs possessed particle size of 36.98 μm, percent entrapment efficiency of 93.12% and percent cumulative drug release of 79.18%, respectively. MS-loaded gels were found nonirritant. In addition, TTO loaded MS gels exhibited good stability. Antimicrobial effect of TTO MS gel showed broader zones of inhibition in comparison to TTO gel.

Conclusion:

The findings of our study suggest that MS loaded gel could prove alternative to conventional antibacterial formulations for dermatological microbial infections.

Antibiofilm efficacy of tea tree oil and of its main component terpinen-4-ol against Candida albicans

Candida infection is an important cause of morbidity and mortality in immunocompromised patients. The increase in its incidence has been associated with resistance to antimicrobial therapy and biofilm formation. The aim of this study was to evaluate the efficacy of tea tree oil (TTO) and its main component - terpinen-4-ol - against resistant Candida albicans strains (genotypes A and B) identified by molecular typing and against C. albicans ATCC 90028 and SC 5314 reference strains in planktonic and biofilm cultures. The minimum inhibitory concentration, minimum fungicidal concentration, and rate of biofilm development were used to evaluate antifungal activity. Results were obtained from analysis of the biofilm using the cell proliferation assay 2,3-Bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) and confocal laser scanning microscopy (CLSM). Terpinen-4-ol and TTO inhibited C. albicans growth. CLSM confirmed that 17.92 mg/mL of TTO and 8.86 mg/mL of terpinen-4-ol applied for 60 s (rinse simulation) interfered with biofilm formation. Hence, this in vitro study revealed that natural substances such as TTO and terpinen-4-ol present promising results for the treatment of oral candidiasis.

Star anise (Illicium verum): Chemical compounds, antiviral properties, and clinical relevance

Medicinal herbs are one of the imperative sources of drugs all over the world. Star anise (Illicium verum), an evergreen, medium-sized tree with star-shaped fruit, is an important herb with wide distribution throughout southwestern parts of the Asian continent. Besides its use as spice in culinary, star anise is one of the vital ingredients of the Chinese medicinal herbs and is widely known for its antiviral effects. It is also the source of the precursor molecule, shikimic acid, which is used in the manufacture of oseltamivir (Tamiflu®), an antiviral medication for influenza A and influenza B. Besides, several other molecules with numerous biological benefits including the antiviral effects have been reported from the same plant. Except the antiviral potential, star anise possesses a number of other potentials such as antioxidant, antimicrobial, antifungal, anthelmintic, insecticidal, secretolytic, antinociceptive, anti-inflammatory, gastroprotective, sedative properties, expectorant and spasmolytic, and estrogenic effects. This review aimed to integrate the information on the customary attributes of the plant star anise with a specific prominence on its antiviral properties and the phytochemical constituents along with its clinical aptness.

Determination of phenolic compounds by MALDI-TOF and essential oil composition by GC-MS during three development stages of Origanum majorana L

This study aimed to investigate the effect of the maturation process of sweet marjoram (Origanum majorana L.) on essential oil composition, the phenolic profile of ethanolic extract and their antioxidant capacities. The essential oil composition was studied at three stages of maturity by GC-MS. Thirty compounds were detected representing 100% of the total essential oil. p-Menth-1-en-4-ol was the major compound (37.15-76.94%) followed by cyclohexanol-3,3,5 trimethyl (5.41-15.99%) and α-terpineol (0.94-11.34%). During the maturation process, an accumulation of oxygenated monoterpenes was observed. The phenolic composition was studied using matrix-assisted laser desorption/ionization time of flight. The analysis showed the presence of short flavonoid monomers at all stages of maturation. The antioxidant capacity of ethanolic extracts and essential oils was evaluated using the DPPH assay, iron chelating power and reducing power assay. The highest phenolic content and antioxidant capacity were found at flowering stage. These findings on essential oil composition, phenolic profile and antioxidant capacity of O. majorana at three different stages of development provide more information on how these secondary metabolites are accumulated.

Dietary Tea Tree (Melaleuca alternifolia) Oil Supplementation Improves Growth Performance, Cecal Microflora, Immunity, and Antioxidant Capacity of Partridge Shank Chickens

The aim of this study was to investigate the effects of tea tree oil (TTO) supplementation on the growth performance, cecal microflora composition, immunity, and antioxidant status of Partridge Shank chickens. A total of 144 one-day-old chicks were allocated into three treatments with six replicates of eight chicks each and fed with a basal diet supplemented with 0 (Control group), 500, and 1000 mg/kg TTO for 50 days. Compared with the control group, the broilers fed with the basal diet supplemented with 1000 mg/kg TTO exhibited an increase in average daily gain from 22 to 50 days (P=0.035) and in both relative thymus weight (P<0.001) and Lactobacillus colonies in the cecal contents (P=0.045) at 50 days of age, but a reduction in the feed/gain ratio during 1 to 50 days (P=0.048). Additionally, dietary TTO supplementation, irrespective of dosage, increased the relative spleen weight (P=0.003) and total antioxidant capacity in the jejunum (P=0.049) and ileum (P=0.001) at 21 days, but decreased the malondialdehyde content in the ileum at both 21 (P=0.003) and 50 days (P<0.001) and in the jejunum at 50 days (P=0.012). The results suggested that TTO supplementation could improve the growth performance, cecal microflora composition, immunity, and antioxidant capacity of Partridge Shank chickens.

Terpene Derivatives as a Potential Agent against Antimicrobial Resistance (AMR) Pathogens

The evolution of antimicrobial resistance (AMR) in pathogens has prompted extensive research to find alternative therapeutics. Plants rich with natural secondary metabolites are one of the go-to reservoirs for discovery of potential resources to alleviate this problem. Terpenes and their derivatives comprising of hydrocarbons, are usually found in essential oils (EOs). They have been reported to have potent antimicrobial activity, exhibiting bacteriostatic and bactericidal effects against tested pathogens. This brief review discusses the activity of terpenes and derivatives against pathogenic bacteria, describing the potential of the activity against AMR followed by the possible mechanism exerted by each terpene class. Finally, ongoing research and possible improvisation to the usage of terpenes and terpenoids in therapeutic practice against AMR are discussed.

The influence of terpinen-4-ol and eucalyptol - The essential oil components - on fungi and plant sterol monolayers

Antifungal and herbicidal activity of terpenes, being the components of the essential oils, is directly related to the incorporation of these compounds into cellular membranes. Thus, the differences in the lipid composition of various pathogenic membranes may be the factor determining the activity of these molecules. One of the class of lipids, which form the membrane environment are sterols. The aim of this work was to compare the effect of two terpenes: terpinen-4-ol and eucalyptol on the monolayers formed by ergosterol and β - sitosterol, which are the components of fungi and plant membranes, respectively. The modifications in the sterol monolayer properties were investigated in the surface pressure-area measurements and penetration studies as well as in a micrometer scale (Brewster angle microscopy experiments) and in nanoscale (GIXD technique). It was evidenced that although at higher surface pressure the terpene molecules are in part removed from the interface, they are able to substantially modify the condensation, morphology and molecular organization of the sterol film. It was also found that the incorporation of terpenes into sterol films is comparable for both sterols, however, β - sitosterol monolayers properties are affected more strongly than ergosterol films. Finally, the analysis of the results of the studies performed on model membrane systems and the results of antimicrobial studies reported in literature, enabled us to suggest that the activity of terpenes depends on the membrane composition and that the sterol concentration may be important from the point of view of antifungal effect of terpinen-4-ol and eucalyptol.

Chemical profiling, biostatic and biocidal dynamics of Origanum vulgare L. essential oil

Origanum vulgare L. (Lamiaceae) is a widespread flavoring culinary and medicinal herb. The present study aimed at investigating the antimicrobial activity of Origanum vulgare (OV) essential oil (EO) through illustrating its biostatic, biocidal and the dynamics of the biocidal activity against 11 different microorganisms. GC/MS of OV EO allowed the identification of 32 compounds representing 99.94% of the oil. The two major identified compounds were terpinen-4-ol (38.35%) and trans-sabinene hydrate (10.06%). Different methods were employed to illustrate the biostatic activity of OV EO. Results of the biostatic studies on OV EO using agar and broth dilution methods showed that Staphylococcus aureus (S. aureus) was the most sensitive organism; with a Minimum inhibitor concentration (MIC) 1.18 mg/ml. Agar diffusion method showed that the highest activity was observed against Bordetella bronchiseptica (Br. bronchiseptica), Saccharomyces cerevisiae (S. cerevisiae), Bacillus subtilis (B. subtilus) and Staphylococcus epidermidis (S. epidermidis) with inhibition zones 38 ± 1.5, 29.5 ± 0.8, 26.9 ± 0.9 and 26.9 ± 1.1 mm, respectively. Studying the dynamics of 1% v/v OV essential oil emulsion over a period of 6 h revealed that Escherichia coli (E. coli), B. subtilis, S. epidermidis and S. cerevisiae had the fastest response. Also increasing concentrations of OV oil emulsion increased the rate of cell killing and the duration of growth lag phase increased correspondingly. These data indicated that OV EO produces a concentration and time-dependent antimicrobial activity.

Interactions between Terpinen-4-ol and Nystatin on biofilm of Candida albicans and Candida tropicalis

The aim of this study was to evaluate the antifungal activity of Terpinen-4-ol associated with nystatin, on single and mixed species biofilms formed by Candida albicans and Candida tropicalis, as well as the effect of terpinen-4-ol on adhesion in oral cells and the enzymatic activity. The minimum inhibitory concentrations and minimum fungicide concentrations of terpinen-4-ol and nystatin on Candida albicans and Candida tropicalis were determined using the microdilution broth method, along with their synergistic activity ("checkerboard" method). Single and mixed species biofilms were prepared using the static microtiter plate model and quantified by colony forming units (CFU/mL). The effect of Terpinen-4-ol in adhesion of Candida albicans and Candida tropicalis in coculture with oral keratinocytes (NOK Si) was evaluated, as well as the enzymatic activity by measuring the size of the precipitation zone, after the growth agar to phospholipase, protease and hemolysin. Terpinen-4-ol (4.53 mg mL-1) and nystatin (0.008 mg mL-1) were able to inhibit biofilms growth, and a synergistic antifungal effect was showed with the drug association, reducing the inhibitory concentration of nystatin up to 8 times in single biofilm of Candida albicans, and 2 times in mixed species biofilm. A small decrease in the adhesion of Candida tropicalis in NOK Si cells was showed after treatment with terpinen-4-ol, and nystatin had a greater effect for both species. For enzymatic activity, the drugs showed no action. The effect potentiated by the combination of terpinen-4-ol and nystatin and the reduction of adhesion provide evidence of its potential as an anti-fungal agent.

Essential oils from Piper aduncum inflorescences and leaves: chemical composition and antifungal activity against Sclerotinia sclerotiorum

Even though essential oils from Piper aduncum (Piperaceae) have different biological activities, little is known about their application to agricultural areas. White mold is a plant disease caused by the phytopathogen Sclerotinia sclerotiorum, which needs to be controlled by alternative measures. This study aimed at evaluating the effect of essential oils from P. aduncum leaves (PL-EO) and inflorescences (PI-EO) on the mycelial growth of S. sclerotiorum. Essential oils from P. aduncum were obtained by hydrodistillation by a Clevenger-type apparatus while their chemical composition was analyzed by GC-MS and GC-FID. Piperitone (23.4 %), myristicin (12.4 %), terpinen-4-ol (12.3 %), β-caryophyllene (7.2 %), α-humulene (6.9 %), germacrene-D (6.9 %) and dillapiol (6.3 %) were the main constituents found in oils from P. aduncum. The in vitro antifungal activity showed that PI-EO dose above 30 µL inhibited mycelial growth in 100 %, whereas PL-EO at 50 µL inhibited it in 98.74 %. This is the first report of the chemical composition of PI-EO and results suggest that the essential oils under evaluation have high potential to control the phytopathogenic fungus S. sclerotiorum.

Studies on the Behavior of Eucalyptol and Terpinen-4-ol-Natural Food Additives and Ecological Pesticides-in Model Lipid Membranes

Effective application of the essential oils requires detailed exploration of their mechanism of action and the origin of diverse activity of their components. In this work, the influence of eucalyptol and terpinen-4-ol on artificial membranes was studied to verify whether the differences in the activity of these compounds are related to their effect on membranes. The properties of monolayers formed from structurally different lipids in the presence of terpenes were examined based on the results of the surface pressure-area measurements, penetration studies, and Brewster angle microscopy experiments. Both compounds were able to incorporate into the membrane and alter lipid/lipid interactions, making the monolayer less stable and more fluid. These effects were determined by monolayer composition (but not by its condensation per se) and the resulting rheological properties and were stronger in the presence of terpinen-4-ol. These findings confirm the hypothesis that differences in the antimicrobial potency of these terpenes are membrane-related, and membrane composition may determine their selectivity.

Nanoparticles as safe and effective delivery systems of antifungal agents: Achievements and challenges

Invasive fungal infections are becoming a major health concern in several groups of patients leading to severe morbidity and mortality. Moreover, cutaneous fungal infections are a major cause of visits to outpatient dermatology clinics. Despite the availability of several effective agents in the antifungal drug arena, their therapeutic outcome is less than optimal due to limitations related to drug physicochemical properties and toxicity. For instance, poor aqueous solubility limits the formulation options and efficacy of several azole antifungal drugs while toxicity limits the benefits of many other drugs. Nanoparticles hold great promise to overcome these limitations due to their ability to enhance drug aqueous solubility, bioavailability and antifungal efficacy. Further, drug incorporation into nanoparticles could greatly reduce its toxicity. Despite these interesting nanoparticle features, there are only few marketed nanoparticle-based antifungal drug formulations. This review sheds light on different classes of nanoparticles used in antifungal drug delivery, such as lipid-based vesicles, polymeric micelles, solid lipid nanoparticles, nanostructured lipid carriers, nanoemulsions and dendrimers with emphasis on their advantages and limitations. Translation of these nanoformulations from the lab to the clinic could be facilitated by focusing the research on overcoming problems related to nanoparticle stability, drug loading and high cost of production and standardization.

Differential Gene Expression Network in Terpenoid Synthesis of Antrodia cinnamomea in Mycelia and Fruiting Bodies

Antodia cinnamomea, a precious brown-rot fungus endemic to Taiwan, has pharmaceutical applications due to its diverse array of metabolites. The terpenoids found in A. cinnamomea contribute to its most important bioactivities. We identified several terpenoid compounds in A. cinnamomea and revealed that their content in mycelium and fruiting body were significantly different. Using next-generation sequencing and an in-house transcriptome database, we identified several terpene synthase (TPS) candidates. After sequence analysis and functional characterization, 10 out of 12 candidates were found to have single or multiple terpene synthesis functions. Most of the terpenoid compounds were found to confer important bioactivities. RT-PCR results showed a positive correlation between terpene synthase expression pattern and terpenoid content. In addition, we identified several modification enzyme candidates that may be involved in the postmodification of terpenoid compounds with a genomic DNA scaffold, and a putative genetic network.