Screening of the antibacterial effects of a variety of essential oils on respiratory tract pathogens, using a modified dilution assay method

Antibacterial Effect of Eight Essential Oils against Bacteria Implicated in Bovine Mastitis and Characterization of Primary Action Mode of Thymus capitatus Essential Oil

During the current investigation, eight essential oils (EOs) were tested for their antimicrobial activity against six species, belonging to the genus of staphylococcus, multi-resistant to antibiotics (S. epidermidis, S. cohni, S. wareneri, S. scuiri, S. chromogenes, S. pasteuri), three methicillin-resistant Staphylococcus aureus strains (MRSA) and two strains of Escherichia coli, producing extended-spectrum β-lactamase (ESBL) responsible for bovine mastitis. Our results indicated that the antimicrobial activities of eight EOs varied significantly among the types of EOs and bacterial species. Thymus capitatus and Trachyspermum ammi EOs display important antibacterial activity against all tested strains, with the inhibition zone diameters situated between 20 and 45 mm, while EOs of Artemisia absinthium, Eucalyptus globulus, Eucalyptus camaldulensis, Myrtus communis and Mentha pulegium exerted an intermediate activity. For Cymbopogon citratus, this effect depends on bacteria species. In fact, an important effect was observed against S. warneri, S. epidermidis, S. cohenii, S. pasteuri and MRSA (EC 39+) strains. In addition, the important lytic effect was observed against MRSA strains, showing that Gram-positive bacteria were more sensitive to T. capitatus EO than Gram-negative ones. Concerning the characterization of the mode action of T. capitatus, experiments of kill-time, bacteriolytic, loss of salt tolerance and loss of cytoplasmic material showed that the used EO was able to destroy cell walls and membranes followed by the loss of vital intracellular materials. In addition, it inhibits the normal synthesis of DNA, causing the bacterial death of E. coli and MRSA strains. This study shows the potential of using of EOs, particularly T. capitaus, to inhibit the growth of Gram-positive and Gram-negative bacteria multi-resistant to antibiotics causing bovine mastitis.

Development of a Nanoemulgel for the Topical Application of Mupirocin

Mupirocin (MUP) is an effective topical antibiotic with poor skin permeability; however, its skin permeability can be improved by a nanoemulsion formulation based on eucalyptus oil or eucalyptol. Despite this improvement, the nanoemulsion has limitations, such as low viscosity, low spreadability, and poor retention on the skin. To overcome these limitations, the aim of this study was to develop a nanoemulgel formulation that would enhance its rheological behaviour and physicochemical properties. The MUP nanoemulgel was prepared by incorporating a preprepared MUP nanoemulsion into Carbopol gel at a concentration of 0.75% in a 1:1 ratio. The nanoemulgel formulations were characterised and evaluated for their physicochemical and mechanical strength properties, rheological behaviour, and in vitro skin permeation and deposition, as well as antibacterial studies. Both nanoemulgels exhibited stability at temperatures of 4 and 25 °C for a period of 3 months. They had a smooth, homogenous, and consistent appearance and displayed non-Newtonian pseudoplastic behaviour, with differences in their viscosity and spreadability. However, both nanoemulgels exhibited lower skin permeability compared to the marketed control. The local accumulation efficiency of MUP from nanoemulgel after 8 h was significantly higher than that of the control, although there was no significant difference after 24 h. Micro-CT scan imaging allowed visualisation of these findings and interpretation of the deposited drug spots within the layers of treated skin. While there were no significant differences in the antibacterial activities between the nanoemulgels and the control, the nanoemulgels demonstrated superiority over the control due to their lower content of MUP. These findings support the potential use of the nanoemulgel for targeting skin lesions where high skin deposition and low permeability are required, such as in the case of topical antibacterial agents.

Mechanistic Evidence of Andrographis paniculata (Burm. f.) Wall. ex Nees, Pelargonium sidoides DC., Echinacea Species and a Combination of Hedera helix L., Primula veris L./Primula elatior L. and Thymus vulgaris L./Thymus zygis L. in the Treatment of Acute, Uncomplicated Respiratory Tract Infections: A Systematic Literature Review and Expert Interviews

Reducing inappropriate antibiotic (AB) use by using effective non-antibiotic treatments is one strategy to prevent and reduce antimicrobial resistance (AMR). Andrographis paniculata (Burm. f.) Wall. ex Nees, Pelargonium sidoides DC., Echinacea species and a combination of ivy (Hedera helix L.), primrose (Primula veris L./Primula elatior L.) and thyme (Thymus vulgaris L./Thymus zygis L.) have promising clinical effects in uncomplicated, acute upper respiratory tract infections (URTI) treatment. However, mechanistic evidence of these herbal treatments is lacking. The objective of this Pstudy is to provide an overview of mechanistic evidence for these effects. Thirty-eight databases were searched. Included studies were mechanistic studies (in vitro, animal, and human studies and reviews) on these herbs; published before June 2021. Non-mechanistic studies or studies on combinations of herbs other than ivy/primrose/thyme were excluded. Furthermore, three experts in traditional, complementary and integrative healthcare (TCIH) research and pharmacognosy were interviewed to collect additional expert knowledge. The results show that A. paniculata acts through immunomodulation and antiviral activity, possibly supplemented by antibacterial and antipyretic effects. P. sidoides acts through antiviral, indirect antibacterial, immunomodulatory and expectorant effects. Echinacea species likely act through immunomodulation. The combination of ivy/primrose/thyme combines secretolytic and spasmolytic effects from ivy with antibacterial effects from thyme. Studies on primrose were lacking. This mechanistic evidence supports the difference-making evidence from clinical studies, contributes to evidence-based recommendations for their use in URTI treatment, and guides future mechanistic studies on URTI treatments.

Compounds from myrtle flowers as antibacterial agents and SARS-CoV-2 inhibitors: In-vitro and molecular docking studies

Plants and their related phytochemicals play a key role in the treatment of bacterial and viral infections, which inspire scientists to design and develop more efficient drugs starting from the phytochemical active scaffold. This work aims to characterize the chemical compounds of Myrtus communis essential oil (EO) from Algeria and to evaluate its in vitro antibacterial effect, as well as the in silico anti-SARS-CoV-2 activity. The chemical profile of hydrodistilled EO from myrtle flowers was determined using GC/MS analysis. The results showed qualitative and quantitative fluctuations and 54 compounds were identified including the main components: α-pinene (48.94%) and 1,8-cineole (28.3%) whereas other minor compounds were detected. The in vitro antibacterial activity of myrtle EO against Gram-negative bacteria was carried out by using the disc diffusion method. The best inhibition zone values ranged between 11 and 25 mm. The results revealed that Escherichia coli (25 mm), Klebsiella oxytoca (20 mm) and Serratia marcescens (20 mm) are the most susceptible strains to the EO which is endowed with a bactericidal effect. Furthermore, the antibacterial and anti-SARS-CoV-2 activities were investigated by the means of molecular docking (MD) study, in addition to ADME(Tox) analysis. The phytochemicals were docked against four targets: E. coli topoisomerase II DNA gyrase B (PDB: 1KZN), SARS-CoV-2 Main protease (PDB: 6LU7), Spike (PDB: 6ZLG) and angiotensin-converting enzyme II ACE2 (PDB: 1R42). The MD investigation revealed that 1,8-cineole could be the main phytochemical associated with the antibacterial activity of EO; s-cbz-cysteine, mayurone and methylxanthine were found the most promising phytochemicals against SARS-CoV-2; The ADME(Tox) analysis has shown their good druggability with no Lipinski's rule violation.

Validation of Broth Macrodilution Volatilization Method for Testing of Essential Oils in Liquid and Vapor Phase: Chemical Composition, Cytotoxicity, and Antibacterial Effect of Indian Medicinal Plants against Pneumonia-Causing Pathogens

Essential oils (EOs) have great potential in inhalation therapy for the treatment of respiratory infections. However, innovative methods for evaluation of antimicrobial activity of their vapors are still needed. The current study reports validation of the broth macrodilution volatilization method for assessment of the antibacterial properties of EOs and shows the growth-inhibitory effect of Indian medicinal plants against pneumonia-causing bacteria in liquid and vapor phase. Among all samples tested, Trachyspermum ammi EO exhibits the strongest antibacterial effect against Haemophilus influenzae, with minimum inhibitory concentrations of 128 and 256 µg/mL in the liquid and vapor phases, respectively. Furthermore, Cyperus scariosus EO is found to be nontoxic to normal lung fibroblasts assessed by modified thiazolyl blue tetrazolium bromide assay. Chemical analysis performed using gas chromatography-mass spectrometry identified α-citral, cyperotundone, and thymol as the main constituents of Cymbopogon citratus, C. scariosus, and T. ammi EOs, respectively. In addition, β-cymene is identified as the major compound of T. ammi EO vapors when analyzed using solid-phase microextraction and gas-tight syringe sampling techniques. This study demonstrates the validity of the broth macrodilution volatilization method for antimicrobial screening of volatile compounds in the vapor phase and suggests the therapeutic potential of Indian medicinal plants in inhalation therapy.

The effect of irrigation with treated and untreated wastewater on the yield and chemical composition of essential oil of Mentha spicata L. and Rosmarinus officinalis L

Today, the lack of quality water supply has led to the tendency to use unconventional water to irrigate agricultural products. Considering the importance and application of essential oils of mint plants in various pharmaceutical, food, and health industries and also considering the approach of using unconventional waters in the cultivation of medicinal plants, the present study aimed to investigate and compare the chemical composition of essential oils of two species of Mentha spicata L. and Rosmarinus officinalis L. which was designed and implemented for the first time under the influence of different treatments of municipal and industrial wastewater. For this purpose, first R. officinalis cuttings and roots of M. spicata were prepared and after preparing and leveling the ground, in the spring of 2020, it was transferred to the planting site and planted in the form of creek and ridges. The treatments studied in this study included well water (WW), treated municipal wastewater (TMW), untreated municipal wastewater (UMW), treated industrial wastewater (TIW), and untreated industrial wastewater (UIW) in a randomized complete block design with four repeat runs. After watering the plants continuously for 3 months, the plant branches were collected and transferred to the laboratory for drying. After extracting the essential oil by water distillation (Clevenger) method, the analysis and identification of the compounds were performed by a chromatograph coupled with a mass spectrometer (GC/MS). The results showed that the highest and lowest yields of M. spicata belonged to the samples treated with UMW and WW, respectively. Also, R. officinalis essential oil irrigated with UMW and UIW had the highest and lowest yields, respectively. The number of essential oil compounds in of M. spicata was between 5 and 19 and in R. officinalis between 14 and 23 under different treatments. The results of the analysis of essential oil compounds showed that D-carvone (57.77-57.44%) and D-limonene (8.70-26.65%) for M. spicata and α-pinene (26.12-34.85%), 1,8-cineole (18.95-23.70%), and camphene (9.93-12.80%) for R. officinalis were predominant compounds in all studied treatments. The results show that UMW is a suitable and efficient treatment to have the best quantity of M. spicata essential oil and the best quality and quantity of R. officinalis essential oil.

Biosynthesis of Nanoparticles Using Plant Extracts and Essential Oils

Plant extracts and essential oils have a wide variety of molecules with potential application in different fields such as medicine, the food industry, and cosmetics. Furthermore, these plant derivatives are widely interested in human and animal health, including potent antitumor, antifungal, anti-inflammatory, and bactericidal activity. Given this diversity, different methodologies were needed to optimize the extraction, purification, and characterization of each class of biomolecules. In addition, these plant products can still be used in the synthesis of nanomaterials to reduce the undesirable effects of conventional synthesis routes based on hazardous/toxic chemical reagents and associate the properties of nanomaterials with those present in extracts and essential oils. Vegetable oils and extracts are chemically complex, and although they are already used in the synthesis of nanomaterials, limited studies have examined which molecules are effectively acting in the synthesis and stabilization of these nanostructures. Similarly, few studies have investigated whether the molecules coating the nanomaterials derived from these extracts and essential oils would bring benefits or somehow reduce their potential activity. This synergistic effect presents a promising field to be further explored. Thus, in this review article, we conducted a comprehensive review addressing the main groups of molecules present in plant extracts and essential oils, their extraction capacity, and available methodologies for their characterization. Moreover, we highlighted the potential of these plant products in the synthesis of different metallic nanomaterials and their antimicrobial capacity. Furthermore, we correlated the extract’s role in antimicrobial activity, considering the potential synergy between molecules from the plant product and the different metallic forms associated with nanomaterials.

A review of the bioactive components and pharmacological properties of Lavandula species

Lavandula species is a flowering plant that is common in Europe and across the Mediterranean. Lavender has many health benefits for humans. In addition to its use in herbal medicine, it is widely used in the fields of cosmetics, perfumes, foods, and aromatherapy. Google Scholar, PubMed, Scopus, and Web of Science were used to search for relevant material on the phytochemical ingredients, the pharmacologic effects of the ingredients, and the mechanism of action of the Lavandula species identified. These materials were reviewed in order to have access to important updates about the Lavandula species. Lavender as referred to in English contains essential oils, anthocyanins, phytosterols, sugars, minerals, coumaric acid, glycolic acid, valeric acid, ursolic acid, herniarins, coumarins, and tannins. It has been used to treat colic and chest ailments, worrisome headaches, and biliousness, and in cleaning wounds. It has antifungal, antibacterial, neurologic, antimicrobial, anti-parasitic, anti-diabetic, and analgesic effects among others. Lavandula species has prospects for various biological applications, especially with its dermatological application. Advances in drug development would enable characterization of various bioactive constituents; thus, its development and application can have a more positive impact on humanity. Here, we highlighted updated information on the history, distribution, traditional uses, phytochemical components, pharmacology, and various biological activities of Lavandula species.

Valorization of Bioactive Compounds from By-Products of Matricaria recutita White Ray Florets

In this research, we have reported the valorization possibilities of Matricaria recutita white ray florets using supercritical fluid extraction (SFE) with CO₂. Experiments were conducted at temperatures of 35-55 °C and separation pressures of 5-9 MPa to evaluate their impact on the chemical composition and biological activity of the extracts. The total obtained extraction yields varied from 9.76 to 18.21 g 100 g^-1 DW input. The greatest extraction yield obtained was at 9 MPa separation pressure and 55 °C in the separation tank. In all obtained extracts, the contents of total phenols, flavonoids, tannins, and sugars were determined. The influence of the supercritical CO₂ extraction conditions on the extract antioxidant capacity was evaluated using the quenching activity of 2,2-diphenyl-1-picrylhydrazyl (DPPH). The chemical composition of the extracts was identified using both gas and liquid chromatography-mass spectrometry methods, whereas analyses of major and minor elements as well as heavy metals by microwave plasma atomic emission spectrometer were provided. Moreover, extracts were compared with respect to their antimicrobial activity, as well as the cytotoxicity and phototoxicity of the extracts. The results revealed a considerable diversity in the phytochemical classes among all extracts investigated in the present study and showed that the Matricaria recutita white ray floret by-product possesses cytotoxic and proliferation-reducing activity in immortalized cell lines, as well as antimicrobial activity. To the best of our knowledge, this is the first paper presenting such comprehensive data on the chemical profile, antioxidant properties, and biological properties of SFE derived from Matricaria recutita white ray florets. For the first time, these effects have been studied in processing by-products, and the results generated in this study provide valuable preconditions for further studies in specific test systems to fully elucidate the mechanisms of action and potential applications, such as potential use in cosmetic formulations.

The effects of lavender oil and ice applications used in episiotomy care on episiotomy pain

Aim: The present study investigates the effects of lavender oil and ice applications on episiotomy pain and wound healing. Materials and Methods: This study was organized as a semi-randomized controlled type of research. A total of 96 term pregnant women who gave birth in the delivery service of Nazilli State Hospital and underwent episiotomy at birth, had a Visual Analog Skala (VAS) value greater than 3 and agreed to participate in the study were included in the study. The patient information form, the Visual Analog Scale, and the REEDA Scale were used for data collection. The research data was analyzed using number, percentage, the chi-square test, the Kruskal Wallis test, the Mann-Whitney U test, One-Way Anova test, Tukey HD test, and the Wilcoxon Signed Ranks test. Results: The mean VAS values of the groups before the application were 7.90±0.92 for the lavender group, 8.29±1.03 for the ice group, and 8.00±1.00 for the control group. In addition, it was found that there was a statistically significant difference between the VAS values between the groups after the application (p<0.05), and the mean VAS values in the intervention groups decreased (Lavender group 6.84±1.08, ice group 5.70±1.53). While there was no statistically significant difference in the mean REEDA recovery scores between the groups before the application (p=0.912), there was a statistically significant difference in the REEDA recovery scores of the intervention groups and the control group after the application (p=0.000). Conclusion: According to the findings of the study, lavender oil and ice applications used after labor reduce perineal pain and accelerate wound healing.

ROS-Induced DNA-Damage and Autophagy in Oral Squamous Cell Carcinoma by Usnea barbata Oil Extract-An In Vitro Study

Oxidative stress is associated with aging, cancers, and numerous metabolic and chronic disorders, and phenolic compounds are well known for their health-promoting role due to their free-radical scavenging activity. These phytochemicals could also exhibit pro-oxidant effects. Due to its bioactive phenolic secondary metabolites, Usnea barbata (L.) Weber ex. F.H. Wigg (U. barbata) displays anticancer and antioxidant activities and has been used as a phytomedicine for thousands of years. The present work aims to analyze the properties of U. barbata extract in canola oil (UBO). The UBO cytotoxicity on oral squamous cell carcinoma (OSCC) CLS-354 cell line and blood cell cultures was explored through complex flow cytometry analyses regarding apoptosis, reactive oxygen species (ROS) levels, the enzymatic activity of caspase 3/7, cell cycle, nuclear shrinkage (NS), autophagy (A), and synthesis of deoxyribonucleic acid (DNA). All these studies were concomitantly performed on canola oil (CNO) to evidence the interaction of lichen metabolites with the constituents of this green solvent used for extraction. The obtained data evidenced that UBO inhibited CLS-354 oral cancer cell proliferation through ROS generation (316.67 × 10⁴), determining higher levels of nuclear shrinkage (40.12%), cell cycle arrest in G0/G1 (92.51%; G0 is the differentiation phase, while during G1 phase occurs preparation for cell division), DNA fragmentation (2.97%), and autophagy (62.98%) than in blood cells. At a substantially higher ROS level in blood cells (5250.00 × 10⁴), the processes that lead to cell death-NS (30.05%), cell cycle arrest in G0/G1 (86.30%), DNA fragmentation (0.72%), and autophagy (39.37%)-are considerably lower than in CLS-354 oral cancer cells. Our work reveals the ROS-mediated anticancer potential of UBO through DNA damage and autophagy. Moreover, the present study suggests that UBO pharmacological potential could result from the synergism between lichen secondary metabolites and canola oil phytoconstituents.

Antimicrobial Formulation of Chrysopogon zizanioides Essential Oil in an Emulsified Lotion for Acne

Acne is a skin condition arising from excess sebum production and microbial overgrowth within the pilosebaceous unit. Several commercial essential oils have shown promising activity against acne-related pathogens. Due to their volatility and thermal instability, the formulation of essential oils into commercial products remains a pharmaceutical challenge. Thus, this study aimed to develop a viable anti-acne topical treatment as an oil-in-water emulsified lotion to overcome these challenges. Chrysopogon zizanioides (vetiver) displayed noteworthy antimicrobial activity with a mean minimum inhibitory concentration of 0.14 mg/mL against Cutibacterium acnes, Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus pyogenes. Emulsified lotions containing C. zizanioides were developed through the hydrophilic-lipophilic balance approach. At tested hydrophilic-lipophilic balance values of 8, 9, and 10, C. zizanioides emulsified lotions displayed maximum stability at hydrophilic-lipophilic balance 9 with a minimum change in mean droplet size and polydispersity index of 20.61 and 33.33%, respectively, over 84 days. The C. zizanioides emulsified lotion at optimum hydrophilic-lipophilic balance 9 completely inhibited the growth of C. acnes and killed S. aureus, S. epidermidis, and S. pyogenes within 24 h. Additionally, the lotion retained antimicrobial activity against these test micro-organisms over the 84-day stability test period. Thus, the C. zizanioides emulsified lotion demonstrated physical stability and antimicrobial efficiency, making it an ideal natural product anti-acne treatment.

Dietary Polyphenol, Gut Microbiota, and Health Benefits

Polyphenols, which are probably the most important secondary metabolites produced by plants, have attracted tremendous attention due to their health-promoting effects, including their antioxidant, anti-inflammatory, antibacterial, anti-adipogenic, and neuro-protective activities, as well as health properties. However, due to their complicated structures and high molecular weights, a large proportion of dietary polyphenols remain unabsorbed along the gastrointestinal tract, while in the large intestine they are biotransformed into bioactive, low-molecular-weight phenolic metabolites through the residing gut microbiota. Dietary polyphenols can modulate the composition of intestinal microbes, and in turn, gut microbes catabolize polyphenols to release bioactive metabolites. To better investigate the health benefits of dietary polyphenols, this review provides a summary of their modulation through in vitro and in vivo evidence (animal models and humans), as well as their possible actions through intestinal barrier function and gut microbes. This review aims to provide a basis for better understanding the relationship between dietary polyphenols, gut microbiota, and host health.

Ultrastructural Damages to H1N1 Influenza Virus Caused by Vapor Essential Oils

Influenza viruses are transmitted from human to human via airborne droplets and can be transferred through contaminated environmental surfaces. Some works have demonstrated the efficacy of essential oils (EOs) as antimicrobial and antiviral agents, but most of them examined the liquid phases, which are generally toxic for oral applications. In our study, we describe the antiviral activity of Citrus bergamia, Melaleuca alternifolia, Illicium verum and Eucalyptus globulus vapor EOs against influenza virus type A. In the vapor phase, C. bergamia and M. alternifolia strongly reduced viral cytopathic effect without exerting any cytotoxicity. The E. globulus vapor EO reduced viral infection by 78% with no cytotoxicity, while I. verum was not effective. Furthermore, we characterized the EOs and their vapor phase by the head-space gas chromatography–mass spectrometry technique, observing that the major component found in each liquid EO is the same one of the corresponding vapor phases, with the exception of M. alternifolia. To deepen the mechanism of action, the morphological integrity of virus particles was checked by negative staining transmission electron microscopy, showing that they interfere with the lipid bilayer of the viral envelope, leading to the decomposition of membranes. We speculated that the most abundant components of the vapor EOs might directly interfere with influenza virus envelope structures or mask viral structures important for early steps of viral infection.

Natural Occurring Phenolic Derivatives from Mauritia flexuosa (Buriti) Stems and Their Potential Antibacterial Activity against Methicillin-Resistant Staphylococcus aureus (MRSA)

Mauritia flexuosa Linnaeus filius (buriti or aguage; Arecaceae) is a palm used by traditional medicine in Brazil to treat dysentery and diarrhea. Our group showed that the soluble dichloromethane (CH₂ Cl₂ ) fraction from EtOH extract from M. flexuosa stems inhibited the growth of methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) and it is rich in phenolic compounds. This study aimed to isolate new phenolic compounds from CH₂ Cl₂ fraction from M. flexuosa stems with in vitro antibacterial activity. The crude CH₂ Cl₂ fraction was fractionated by gel permeation chromatography (GPC) followed by semi-preparative RP-HPLC. The antibacterial activity was evaluated using the broth microdilution method against MSSA (ATCC 29213) and MRSA (clinical isolate 155). All compounds were also tested against Gram-negative (Escherichia coli; ATCC 35218) bacteria and two fungi species (Candida albicans; ATCC 14053 and Trichophyton rubrum; ATCC MYA 4438). The chemical structures of isolated compounds were determined by analysis and comparison with literature data of their NMR and HRMS spectra and optical activity. The chemical investigation yielded seven aromatic compounds, of which four, (2S,15S)-2,15-dimethyl-2,15-dioxa-1,8(1,4)-dibenzenacyclotetradecaphane (1), (2S,5S)-1-(4-hydroxyphenyl)hexane-2,5-diol (3), bruguierol E (4), and buritin (5) were previously unreported and three are known compounds identified as 6-(4'-hydroxyphenyl) hexan-2-one (2), (+)-(2R,3R)-dihydrokaempferol (6), and (+)-(2R)-naringenin (7). Compounds 1 and 7 showed antibacterial activity against MRSA and MSSA with minimum inhibitory concentrations (MICs) of between 62.5 and 31.3 μg/mL, respectively. Our preliminary findings support that CH₂ Cl₂ fraction from buriti, a typical species of flooded areas of Brazilian savanna, and its aromatic phenolic compounds are active against MSSA and MRSA contributing with understanding about the traditional use of this species.

Synergistic Effect of Polyphenol-Rich Complex of Plant and Green Propolis Extracts with Antibiotics against Respiratory Infections Causing Bacteria

Bacterial infections are a prevalent complication after primary viral respiratory infections and are associated with high morbidity and mortality. Antibiotics are widely used against bacterial respiratory pathogens; however, the rise in antibiotic-resistant strains urges us to search for new antimicrobial compounds, including ones that act synergistically with antibiotics. In this study, the minimal inhibitory (MIC) and minimal bactericidal (MBC) concentrations of a polyphenol-rich complex of green propolis, Tabebuia avellanedae bark, and Olea europaea leaf extracts against Staphylococcus aureus, Haemophilus influenzae, and Klebsiella pneumoniae were determined, followed by an analysis of the synergistic effect with clarithromycin, azithromycin, and amoxiclav (875/125 mg amoxicillin/clavulanic acid). A combination of extracts showed activity against all three bacterial strains, with MIC values ranging from 0.78 to 12.5 mg/mL and MBC values from 1.56 to 12.5 mg/mL. The extracts showed synergistic activity with azithromycin and clarithromycin against S. aureus, with clarithromycin against K. pneumoniae, and with all three tested antibiotics against H. influenzae. Synergy with clarithromycin was additionally evaluated in a time-kill assay where the synergistic effects against S. aureus and K. pneumoniae were seen within the first 6 h of incubation. The results show the potential of polyphenol-rich extracts in enhancing the efficacy of antibiotic therapy and indicate their potential to be used in the management of respiratory infections.

Self-stick membrane based on grafted gum Arabic as active food packaging for cheese using cinnamon extract

Encapsulation of volatile essential oils has been investigated to provide an active food packaging (AFP) material with more control over their fast release and pungent smell. In this work, Gum Arabic-based adhesive membrane was developed as a self-stick AFP material, delivering cinnamon essential oil (CEO) in vapor phase. Gum Arabic (GA) was grafted with butyl acrylate (BA) and hydroxyethyl methacrylate [GA-g-poly(BA-HEMA)]. Adhesive membrane was characterized by means of spectral, physicochemical and rheological analysis. GA-adhesive membrane made of 5% wt/v GA, 3.5 m mol HEMA, and 87 m mol BA with 21 N/m tack are loaded with 4, 8 and 10% v/v of CEO and used for antimicrobial bioassays. GA-g-poly(BA-HEMA) membrane prolonged CEO release up to 2 days. 8%v/v CEO showed superior activities against both Gram negative and positive bacteria. Shelf-life of cheese samples, packed with the self-stick membranes loaded with cinnamon extract, has extended from 3 to 8 weeks. Cheese samples that inoculated with shiga toxin producing E. coli O157:H7 and packed in plastic boxes with the self-stick AFP (4, 8 and 10 % CEO), showed significant reduction in the total bacteria counts.

Virtual screening of functional foods and dissecting their roles in modulating gene functions to support post COVID-19 complications

COVID‐19 has become the focal point since 2019 after the outbreak of coronavirus disease. Many drugs are being tested and used to treat coronavirus infections; different kinds of vaccines are also introduced as preventive measure. Alternative therapeutics are as well incorporated into the health guidelines of some countries. This research aimed to look into the underlying mechanisms of functional foods and how they may improve the long‐term post COVID‐19 cardiovascular, diabetic, and respiratory complications through their bioactive compounds. The potentiality of nine functional foods for post COVID‐19 complications was investigated through computational approaches. A total of 266 bioactive compounds of these foods were searched via extensive literature reviewing. Three highly associated targets namely troponin I interacting kinase (TNNI3K), dipeptidyl peptidase 4 (DPP‐4), and transforming growth factor beta 1 (TGF‐β1) were selected for cardiovascular, diabetes, and respiratory disorders, respectively, after COVID‐19 infections. Best docked compounds were further analyzed by network pharmacological tools to explore their interactions with complication‐related genes (MAPK1 and HSP90AA1 for cardiovascular, PPARG and TNF‐alpha for diabetes, and AKT‐1 for respiratory disorders). Seventy‐one suggested compounds out of one‐hundred and thirty‐nine (139) docked compounds in network pharmacology recommended 169 Gene Ontology (GO) items and 99 Kyoto Encyclopedia of Genes and Genomes signaling pathways preferably AKT signaling pathway, MAPK signaling pathway, ACE2 receptor signaling pathway, insulin signaling pathway, and PPAR signaling pathway. Among the chosen functional foods, black cumin, fenugreek, garlic, ginger, turmeric, bitter melon, and Indian pennywort were found to modulate the actions. Results demonstrate that aforesaid functional foods have attenuating roles to manage post COVID‐19 complications.

Metabolomic Profiles of Essential Oils from Selected Rosa Varieties and Their Antimicrobial Activities

This study aimed to analyze the essential oils of the aerial parts (A) and flowers (F) of Rosa banksiae var. banksiae Ait. (RBW), Rosa polyantha Thunb. "orange fairy" (RPO) and Rosa polyantha Thunb. "white fairy" (RPW), family Rosaceae, and perform multivariate data analyses and antimicrobial activity evaluations. The essential oil analyses were performed by GC/FID and GC/MS. Principal component analysis (PCA), hierarchical cluster analysis (HCA), and clustered heat map were used for the multivariate analyses. The antimicrobial activity was evaluated by the well-diffusion method against four bacteria and four fungi. Two hundred fifty-three compounds were identified from the six oil samples. The major components in RBW-A, RPO-A, and RPW-A were n-undecane (14.40, 19.36, and 9.21%) n-dodecane (14.54, 22.13, and 8.39%), and yomogi alcohol (8.41, 10.53, and 6.28%), respectively, whereas RBW-F, RPO-F and RPW-F contained n-heptadecane (16.70%), n-undecane (7.98%), and β-phellandrene (22.78%), respectively. The tested essential oils showed moderate antifungal activity against Aspergillus fumigatus compared to amphotericin B. PCA and HCA revealed five main clusters. The six samples carried close chemical profiles and can be regarded as fruitful sources of safe antifungal agents.

Three chemotypes of thyme (Thymus vulgaris L.) essential oil and their main compounds affect differently the IL-6 and TNFα cytokine secretions of BV-2 microglia by modulating the NF-κB and C/EBPβ signalling pathways

BACKGROUND

The essential oils possess both antimicrobial and anti-inflammatory effects, therefore they can provide an effective treatment against infections. Essential oils are widely used as supportive ingredients in many diseases, especially in the acute and chronic diseases of the respiratory tract. Neuroinflammation is responsible for several diseases of the central nervous system. Some plant-derived bioactive molecules have been shown to have role in attenuating neuroinflammation by regulating microglia, the immune cells of the CNS.

METHODS

In this study, the anti-inflammatory effect of three chemotypes of thyme essential oil and their main compounds (geraniol, thujanol and linalool) were examined on lipopolysaccharide-induced BV-2 microglia. Three different experimental setups were used, LPS pretreatment, essential oil pretreatment and co-treatments of LPS and essential oils in order to determine whether essential oils are able to prevent inflammation and can decrease it. The concentrations of the secreted tumour necrosis factor α (TNFα) and interleukin-6 (IL-6) proinflammatory cytokines were measured and we analysed by Western blot the activity of the cell signalling pathways, NF-κB and CCAAT-enhancer binding protein β (C/EBPβ) regulating TNFα and IL-6 proinflammatory cytokine expressions in BV-2 cells.

RESULTS

Our results showed definite alterations in the effects of essential oil chemotypes and their main compounds at the different experimental setups. Considering the changes of IL-6 and TNFα secretions the best reduction of inflammatory cytokines could be reached by the pretreatment with the essential oils. In addition, the main compounds exerted better effects than essential oil chemotypes in case of LPS pretreatment. At the essential oil pretreatment experiment, the effect of linalool and geraniol was outstanding but there was no major difference between the actions of chemotypes and standards. Main compounds could be seen to have large inhibitory effects on certain cell signalling components related to the activation of the expression of proinflammatory cytokines.

CONCLUSION

Thyme essential oils are good candidates to use in prevention of neuroinflammation and related neurodegeneration, but the exact ratio of the components has to be selected carefully.

Osteopathic manipulative treatment and the Spanish flu: a historical literature review

Context

The Spanish flu pandemic of 1918 was approached with a variety of management techniques available at that time, including osteopathic care in addition to standard medical care.

Objective

To analyze the osteopathic manipulative treatment (OMT) techniques used for the management of patients affected by the Spanish flu according to four themes: the principles and procedures used, frequency and length of OMT, reported side effects, and advice for patients.

Methods

A structured review of the literature was performed by hand-searching texts at the Museum of Osteopathic Medicine International Center for Osteopathic History in Kirksville, Missouri, and online via PubMed (National Library of Medicine), ScienceDirect (Elsevier), and Google Scholar (Google, Inc). The literature search was carried out between February and March 2020. Three keywords were selected from the medical subject headings database of the National Library of Medicine: manipulation, osteopathic; influenza pandemic, 1918-1919; epidemics. Articles were then reviewed for relevance by screening for articles published between 1900 and 1940 that contained at least 1 of the following keywords in their title: Spanish influenza, flu, epidemic, grippe, pneumonia, or osteopathic management/treatment. All articles that provided information about OMT and advice met the inclusion criteria. Articles that did not report descriptions of manipulative intervention were excluded.

Results

Our search yielded 63 articles: 23 from the hand-search and 40 from the electronic search. No electronic source was selected for the review because none met inclusion criteria. A total of 16 articles from the hand-searched set met inclusion criteria and were analyzed according to the four main themes stated in the objective. The range of OMT approaches reported to be administered to patients with Spanish flu suggests that early osteopathic physicians treated patients with this disease using OMT in addition to offering advice on healthy lifestyle behaviors.

Conclusion

Conclusions from this study are limited by the historical and descriptive nature of the data gathered, which lacked the rigor of modern-day scientific studies. However, this review could lead to future research inquiries on the effectiveness of these approaches. Osteopathic physicians and osteopaths should embrace their historical osteopathic heritage by continuing the work of our predecessors and combining their hands-on experience and osteopathic principles with modern medical treatment and rigorous scientific standards.

R, Rocha P, López Rodilla JM. Chemical Composition and Antibacterial Activity of Lippia multiflora Moldenke Essential Oil from Different Regions of Angola

The purpose of the study was to determine the chemical composition and antibacterial activity of Lippia multiflora Moldenke essential oils (EOs) collected in different regions of Angola. Antibacterial activity was evaluated using the agar wells technique and vapour phase test. Analysis of the oils by GC/MS identified thirty-five components representing 67.5 to 100% of the total oils. Monoterpene hydrocarbons were the most prevalent compounds, followed by oxygenated monoterpenes. The content of the compounds varied according to the samples. The main components were Limonene, Piperitenone, Neral, Citral, Elemol, p-cymene, Transtagetone, and Artemisia ketone. Only one of the eleven samples contained Verbenone as the majority compound. In the vapour phase test, a single oil was the most effective against all the pathogens studied. The principal component analysis (PCA) and hierarchical cluster analysis (HCA) of components of the selected EOs and inhibition zone diameter values of agar wells technique allowed us to identify a variability between the plants from the two provinces, but also intraspecific variability between sub-groups within a population. Each group of essential oils constituted a chemotype responsible for their bacterial inhibition capacity. The results presented here suggest that Angolan Lippia multiflora Moldenke has antibacterial properties and could be a potential source of antimicrobial agents for the pharmaceutical and food industry.

Health-Promoting Capacities of In Vitro and Cultivated Goji (Lycium chinense Mill.) Fruit and Leaves; Polyphenols, Antimicrobial Activity, Macro- and Microelements and Heavy Metals

There is a growing interest among the public in fruit with a positive impact on human health. Two goji berry cultivars (‘No. 1’ and ‘New Big’) were propagated in vitro, grown in an orchard and then evaluated for macro- and microelements and harmful heavy metals (i.e., Pb, Ni, and Cd). The leaves and fruit were also assessed for nutritional value, polyphenols and the antimicrobial activity of the leaves. ‘New Big’ was characterized by a higher content of macro elements in the leaves (in vitro and orchard) and a higher content of microelements in the fruit. The harmful substances content was below the minimum value. Furthermore, neither the fruit nor the leaves contained cadmium. This study also indicated that leaves had a higher content of polyphenols compared to the fruit. The fruits were characterized by their health-promoting capacities, while the leaves were characterized by their antibacterial activity. Among the Gram-positive bacteria, the most sensitive strain was Bacillus subtilis, and among the Gram-negative bacteria, it was Proteus vulgaris. Taking into consideration the Recommended Daily Allowance (RDA) for minerals, goji berries can be declared to be a source of Cu, Fe, Mn, Zn and P.

Odoriferous Therapy: A Review Identifying Essential Oils against Pathogens of the Respiratory Tract

This review explores the body of scientific information available on the antimicrobial properties of essential oils against pathogens responsible for respiratory infections and critically compares this to what is recommended in the Layman's aroma-therapeutic literature. Essential oils are predominantly indicated for the treatment of respiratory infections caused by bacteria or viruses (total 79.0 %), the efficacy of which has not been confirmed through clinical trials. When used in combination, they are often blended for presumed holistic synergistic effects. Of the essential oils recommended, all show some degree of antioxidant activity, 50.0 % demonstrate anti-inflammatory effects and 83.3 % of the essential oils showed antihistaminic activity. Of the essential oils reviewed, 43.8 % are considered non-toxic while the remaining essential oils are considered slightly to moderately toxic (43.7 %) or the toxicity is unknown (12.5 %). Recommendations are made for further research into essential oil combinations.

New SiO2/Caffeic Acid Hybrid Materials: Synthesis, Spectroscopic Characterization, and Bioactivity

The sol–gel route represents a valuable technique to obtain functional materials, in which organic and inorganic members are closely connected. Herein, four hybrid materials, containing caffeic acid entrapped in a silica matrix at 5, 10, 15, and 20 wt.%, were synthesized and characterized through Fourier-Transform Infrared (FT-IR) and Ultraviolet-Visible (UV–Vis) spectroscopy. FT-IR analysis was also performed to evaluate the ability to induce the hydroxyapatite nucleation. Despite some structural changes occurring on the phenol molecular skeleton, hybrid materials showed scavenging properties vs. 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and 2,2′-azinobis-(3-ethylbenzothiazolin-6-sulfonic acid) radical cation (ABTS•⁺), which was dependent on the tested dose and on the caffeic acid wt.%. The SiO₂/caffeic acid materials are proposed as valuable antibacterial agents against Escherichia coli and Enterococcus faecalis.

In Vitro Evaluation of Antioxidant, Anti-Inflammatory, Antimicrobial and Wound Healing Potential of Thymus Sipyleus Boiss. Subsp. Rosulans (Borbas) Jalas

Thymus sipyleus Boiss. subsp. rosulans (Borbas) Jalas (TS) is a commonly used plant in the treatment of various complaints, including skin wounds in Turkish folk medicine. Despite the widespread traditional use of TS, there is not any scientific report confirming the effectiveness of this plant on the healing process. This research aimed to investigate the effects of different extracts obtained from TS on biological events during wound healing, on a cellular basis. In this context, proliferative activities of the extracts, as well as the effects on wound closure and hydroxyproline synthesis, were determined. In addition to wound healing properties, the antioxidant, antibacterial and anti-inflammatory activities of the extracts were evaluated. Decoction (D) and infusion (I) extracts contained the highest amount of phenolic content and showed the most potent activity against DPPH radical. All extracts exhibited complete protection against the damage induced by hydrogen peroxide (H₂O₂) by increasing cell viability compared to only H₂O₂-treated groups, both in co-treatment and pre-treatment protocols. None of the extracts exhibited cytotoxic activity, and most of the extracts from the TS stimulated fibroblast proliferation and migration. All TS extracts exert anti-inflammatory activity by suppressing the overproduction of tumor necrosis factor-alpha (TNF-α) and nitric oxide (NO). The most pronounced activity on hydroxyproline synthesis was observed in D extract. In summary, it was observed that TS extracts can promote the healing process by enhancing fibroblast migration, proliferation and collagen synthesis as well as suppressing pro-inflammatory cytokines. The obtained data in this work support the traditional use of TS as a valuable plant-based compound for the treatment of wounds.

Anti-Haemophilus Activity of Selected Essential Oils Detected by TLC-Direct Bioautography and Biofilm Inhibition

Essential oils (EOs) are becoming increasingly popular in medical applications because of their antimicrobial effect. Direct bioautography (DB) combined with thin layer chromatography (TLC) is a screening method for the detection of antimicrobial compounds in plant extracts, for example, in EOs. Due to their lipophilic character, the common microbiological assays (etc. disk diffusion) could not provide reliable results. The aim of this study was the evaluation of antibacterial and anti-biofilm properties of the EO of cinnamon bark, clove, peppermint, thyme, and their main components against Haemophilus influenzae and H. parainfluenzae. Oil in water (O/W) type Pickering nano-emulsions stabilized with silica nanoparticles from each oil were prepared to increase their water-solubility. Samples with Tween80 surfactant and absolute ethanol were also used. Results showed that H. influenzae was more sensitive to the EOs than H. parainfluenzae (except for cinnamon bark oil). In thin layer chromatography-direct bioautography (TLC-DB) the ethanolic solutions of thyme oil presented the best activity against H. influenzae, while cinnamon oil was the most active against H. parainfluenzae. Pickering nano-emulsion of cinnamon oil inhibited the biofilm formation of H. parainfluenzae (76.35%) more efficiently than samples with Tween80 surfactant or absolute ethanol. In conclusion, Pickering nano-emulsion of EOs could inhibit the biofilm production effectively.

Antibacterial Properties of Polyphenols: Characterization and QSAR (Quantitative Structure-Activity Relationship) Models

Besides their established antioxidant activity, many phenolic compounds may exhibit significant antibacterial activity. Here, the effect of a large dataset of 35 polyphenols on the growth of 6 foodborne pathogenic or food-spoiling bacterial strains, three Gram-positive ones (Staphylococcus aureus, Bacillus subtilis, and Listeria monocytogenes) and three Gram-negative ones (Escherichia coli, Pseudomonas aeruginosa, and Salmonella Enteritidis), have been characterized. As expected, the effects of phenolic compounds were highly heterogeneous ranging from bacterial growth stimulation to antibacterial activity and depended on bacterial strains. The effect on bacterial growth of each of the polyphenols was expressed as relative Bacterial Load Difference (BLD) between a culture with and without (control) polyphenols at a 1 g L-1 concentration after 24 h incubation at 37°C. Reliable Quantitative Structure-Activity Relationship (QSAR) models were developed (regardless of polyphenol class or the mechanism of action involved) to predict BLD for E. coli, S. Enteritidis, S. aureus, and B. subtilis, unlike for L. monocytogenes and P. aeruginosa. L. monocytogenes was generally sensitive to polyphenols whereas P. aeruginosa was not. No satisfactory models predicting the BLD of P. aeruginosa and L. monocytogenes were obtained due to their specific and quite constant behavior toward polyphenols. The main descriptors involved in reliable QSAR models were the lipophilicity and the electronic and charge properties of the polyphenols. The models developed for the two Gram-negative bacteria (E. coli, S. Enteritidis) were comparable suggesting similar mechanisms of toxic action. This was not clearly observed for the two Gram-positive bacteria (S. aureus and B. subtilis). Interestingly, a preliminary evaluation by Microbial Adhesion To Solvents (MATS) measurements of surface properties of the two Gram-negative bacteria for which QSAR models were based on similar physico-chemical descriptors, revealed that MATS results were also quite similar. Moreover, the MATS results of the two Gram-positive bacterial strains S. aureus and B. subtilis for which QSARs were not based on similar physico-chemical descriptors also strongly differed. These observations suggest that the antibacterial activity of most of polyphenols likely depends on interactions between polyphenols and bacterial cells surface, although the surface properties of the bacterial strains should be further investigated with other techniques than MATS.

Antibacterial and Cytotoxic Activity of Nepeta Cataria L., N. Cataria Var. Citriodora (Beck.) Balb. and Melissa Officinalis L. Essential Oils

The aim of the present study was to investigate the susceptibility of bacteria that play a role in respiratory tract and skin infections to the essential oils of catnip (Nepeta cataria), lemon catnip (N. cataria var. citriodora) and lemon balm (Melissa officinalis) with regard to their chemical composition. In addition, we wanted to assess whether antibiotic-resistant and -sensitive strains differ in their susceptibility to the oils and if there are cross resistances between standard antibiotics and essential oils. To evaluate the safety of topical application, cytotoxicity of the oils was studied in human keratinocyte and bronchial epithelial cell lines and irritation threshold concentrations were determined in ovo using the HET-CAM-test. The composition of the essential oils was analyzed by GC and GC-MS. Their MICs and MBCs were determined by a broth microdilution method against both reference strains from culture collections and clinical isolates with different susceptibility to standard antibiotics. Cytotoxicity was assessed by the MTT assay. Except for P. aeruginosa (MIC ≥2%), all reference strains tested were susceptible to catnip and lemon balm oils with MIC values ranging from 0.016 % to 0.25% (v/v). The clinical isolates were as susceptible to the oils (± 1 serial dilution) as the corresponding reference strains, regardless of their origin and resistance to standard antibiotics. The oils were cytotoxic to both keratinocytes and bronchial epithelial cells at CC50 values from 0.0012% to 0.015% (v/v). Lemon balm oil, whose main components were monoterpene aldehydes, exhibited the highest antibacterial and cytotoxic activity, followed by lemon catnip oil, which contained mainly monoterpene alcohols, and catnip oil, which was characterized by nepetalactones. Our results provide a rationale for the use of catnip, lemon catnip and lemon balm oils in the complementary topical treatment of respiratory tract infections, as the oils show a high antibacterial activity against respiratory tract pathogens, including clinical isolates with reduced susceptibility to standard antibiotics. However, cytotoxicity must be considered in topical therapy.

Plant antimicrobial polyphenols as potential natural food preservatives

BACKGROUND

The growing demand for natural food preservatives in the last decade has promoted investigations on their application for preserving perishable foods. In this context, the present review is focused on discussing the prospective application of plant extracts containing phenolics or isolated plant phenolics as natural antimicrobials in foods. Plant essential oils are outside the scope of this review since utilization of their antimicrobial activity for food preservation has been extensively reviewed.

RESULTS

Although the exact antimicrobial mechanisms of action of phenolic compounds are not yet fully understood, it is commonly acknowledged that they have diverse sites of action at the cellular level. Antimicrobial phenolics can be added directly to the formulation of perishable food products or incorporated into food-contact materials to release them in the immediate zone of perishable foods. Edible coatings or active food packaging materials can thus be used as carriers of plant bioactive compounds.

CONCLUSION

These materials could be an interesting delivery system to improve the stability of phenolics in foods and to improve the shelf life of perishable foods. This review will thus provide an overview of current knowledge of the antimicrobial activity of phenolic-rich plant extracts and of the promises and limits of their exploitation for the preservation of perishable foods. © 2018 Society of Chemical Industry.

Chitosan-Stabilized Ag Nanoparticles with Superior Biocompatibility and Their Synergistic Antibacterial Effect in Mixtures with Essential Oils

Silver nanoparticles (AgNPs) are considered a promising alternative to the use of antibiotics in fighting multidrug-resistant pathogens. However, their use in medical application is hindered by the public concern regarding the toxicity of metallic nanoparticles. In this study, rationally designed AgNP were produced, in order to balance the antibacterial activity and toxicity. A facile, environmentally friendly synthesis was used for the electrochemical fabrication of AgNPs. Chitosan was employed as the capping agent, both for the stabilization and to improve the biocompatibility. Size, morphology, composition, capping layer, and stability of the synthesized nanoparticles were characterized. The in vitro biocompatibility and antimicrobial activities of AgNPs against common Gram-negative and Gram-positive bacteria were evaluated. The results revealed that chitosan-stabilized AgNPs were nontoxic to normal fibroblasts, even at high concentrations, compared to bare nanoparticles, while significant antibacterial activity was recorded. The silver colloidal dispersion was further mixed with essential oils (EO) to increase the biological activity. Synergistic effects at some AgNP–EO ratios were observed, as demonstrated by the fractionary inhibitory concentration values. Our results reveal that the synergistic action of both polymer-stabilized AgNPs and essential oils could provide a significant efficiency against a large variety of microorganisms, with minimal side effects.

Antibacterial activity evaluation of selected essential oils in liquid and vapor phase on respiratory tract pathogens

BACKGROUND

The increasing number of multidrug-resistant bacteria and the fact of antibiotic resistance is leading to a continuous need for discovering alternative treatments against infections, e.g. in the case of respiratory tract diseases. Essential oils (EOs), because of their volatility, can easily reach both the upper and lower parts of the respiratory tract via inhalation. Therefore, the aim of the present study was the antibacterial evaluation of clove, cinnamon bark, eucalyptus, thyme, scots pine, peppermint, and citronella EOs against respiratory tract pathogens such as Streptococcus pneumoniae, S. mutans, S. pyogenes, Haemophilus influenzae, H. parainfluenzae, and Moraxella catarrhalis. Furthermore, we wanted to compare the antibacterial effect of these EOs in two different test systems to provide data for the development of an appropriate product formulation.

METHODS

Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined with in vitro vapor phase test (VPT) and broth macrodilution test (BDT). The chemical and percentage compositions of the EOs were determined by GC-MS and GC-FID analysis.

RESULTS

Among the EOs, thyme was the most effective against S. mutans (MIC: 0.04 mg/mL in BDT, but cinnamon bark and clove oils also presented high inhibition in liquid medium with MIC values of 0.06 mg/mL and 0.1 mg/mL against S. pneumoniae and S. pyogenes, respectively. M. catarrhalis was the most sensitive to thyme EO (MIC: 0.09 mg/mL). Cinnamon bark EO was the most effective against Haemophilus spp. (MIC: 0.06 mg/mL). In the VPT, cinnamon bark was the most effective oil against all investigated pathogens with MIC values in the range of 15.62-90 μl/L. Surprisingly, the eucalyptus and scots pine showed weak activity against the test bacteria in both test systems.

CONCLUSIONS

The EO of thyme, clove and cinnamon bark may provide promising antibacterial activity against respiratory tract pathogens either in liquid medium or in vapor phase. However, their effect is lower than that of the reference antibiotics. The combination of EOs and antibiotics may be beneficial in the alternative treatment of respiratory tract diseases. In vivo studies are necessary to calculate the effective dose of EOs in patients and determine their possible side effects and toxicity.

Medicinal Plants of the Family Lamiaceae in Pain Therapy: A Review

Recently, numerous side effects of synthetic drugs have lead to using medicinal plants as a reliable source of new therapy. Pain is a global public health problem with a high impact on life quality and a huge economic implication, becoming one of the most important enemies in modern medicine. The medicinal use of plants as analgesic or antinociceptive drugs in traditional therapy is estimated to be about 80% of the world population. The Lamiaceae family, one of the most important herbal families, incorporates a wide variety of plants with biological and medical applications. In this study, the analgesic activity, possible active compounds of Lamiaceae genus, and also the possible mechanism of actions of these plants are presented. The data highlighted in this review paper provide valuable scientific information for the specific implications of Lamiaceae plants in pain modulation that might be used for isolation of potentially active compounds from some of these medicinal plants in future and formulation of commercial therapeutic agents.

Antibacterial Activity of Emulsified Pomelo (Citrus grandis Osbeck) Peel Oil and Water-Soluble Chitosan on Staphylococcus aureus and Escherichia coli

This study utilized pomelo steam distillation to isolate pomelo peel essential oil. The constituents were then analyzed through gas chromatography-mass spectrometry (GC-MS), and the antibacterial activity of the essential oil emulsions at different homogenizer speed conditions and concentrations of water-soluble chitosan (degree of acetylation, DA = 54.8%) against S. aureus and E. coli was examined. Analysis of the essential oil composition identified a total of 33 compounds with the main constituent, limonene accounting for 87.5% (940.07 mg/g) of the total. The pomelo peel oil was emulsified through homogenization at 24,000 rpm, resulting in a minimal inhibitory concentration (MIC) for E. coli that was 1.9 times lower than that of the essential oil without homogenization. In addition, a mixture of 0.4% essential oil emulsion and 0.03% water-soluble chitosan had the strongest synergetic antibacterial effect on S. aureus and E. coli at pH 7.4. In comparison with chitosan alone, the MIC value of this mixture was significantly 2.4 and 2.5 times lower. Hence, this study suggests using a mixture of emulsified pomelo peel oil and water-soluble chitosan to develop a novel natural food preservative, and that the processability of food, as well as the economic value of the byproducts of the Taiwan Matou pomelo and chitosan, could be increased.

Effect of Angelica glauca essential oil on allergic airway changes induced by histamine and ovalbumin in experimental animals

Objective:

Angelica glauca Edgew (Apiaceae) is used in traditional medicine for treatment of several diseases including bronchial asthma. The present investigation was aimed to evaluate broncho-relaxant activity of A. glauca essential oil in histamine and ovalbumin (OVA)-induced broncho constriction in experimental animals.

Materials and Methods:

Airway was induced using histamine aerosol in guinea pigs (n = 24) and OVA aerosol in albino mice (n = 24). The number of inflammatory cells, namely, absolute eosinophils count in blood, total immunoglobulin E (IgE) in serum, eosinophils, and neutrophils in bronchoalveolar lavage fluid (BALF) and histopathological examination of lung tissues were investigated in A. glauca oil and dexamethasone-treated groups. A. glauca oil 200 μL/kg was given orally, and dexamethasone 2 mg/kg was given intraperitoneal. Both the treatments were repeated daily for 7 days. Results were analyzed by one-way ANOVA, and P ≤ 0.05 was considered statistically significant.

Results:

Treatment with A. glauca essential oil significantly (P < 0.001) increased the time of preconvulsive dyspnea in histamine-induced guinea pigs. Oral treatment of A. glauca oil significantly (P < 0.001) decreased absolute blood eosinophil count (from 325 ± 3.69 to 200 ± 3.05 cells/mm³), serum level of IgE (from 6.10 ± 0.05 to 0.70 ± 0.08 IU/L), and the number of eosinophils (from 11.0% ±1.41% to 3.0% ±0.51%), neutrophils (from 13.0% ±1.12% to 5.0% ±1.39%) in BALF. Histopathological changes observed in lungs of untreated group were marked suppressed by treatment with A. glauca oil.

Conclusion:

The essential oil of A. glauca has bronchorelaxation in both histamine and OVA-induced bronchoconstriction in animals. The traditional use of A. glauca against asthma could be attributed to its bronchodilator property as observed in the present study.