Mānuka Oil-A Review of Antimicrobial and Other Medicinal Properties

Is aromatic plants environmental health engineering (APEHE) a leverage point of the earth system?

It is important to note that every ecological niche in an ecosystem is significant. This study aims to assess the importance of medicinal and aromatic plants (MAPs) in the ecosystem from multiple perspectives. A primary model of Aromatic Plants Environmental Health Engineering (APEHE) has been designed and constructed. The APEHE system was used to collect aerosol compounds, and it was experimentally verified that these compounds have the potential to impact human health by binding to AKT1 as the primary target, and MMP9 and TLR4 as secondary targets. These compounds may indirectly affect human immunity by reversing drug resistance in drug-resistant bacteria in the nasal cavity. This is mainly achieved through combined mutations in sdhA, scrA, and PEP. Our findings are based on Network pharmacology and molecular binding, drug-resistance rescue experiments, as well as combined transcriptomics and metabolomics experiments. It is suggested that APEHE may have direct or indirect effects on human health. We demonstrate APEHE's numerous potential benefits, such as attenuation and elimination of airborne microorganisms in the environment, enhancing carbon and nitrogen storage in terrestrial ecosystems, promoting the formation of low-level clouds and strengthening the virtuous cycle of Earth's ecosystems. APEHE also supports the development of transdisciplinary technologies, including terpene energy production. It facilitates the creation of a sustainable circular economy and provides additional economic advantages through urban optimisation, as well as fresh insights into areas such as the habitability of other planets. APEHE has the potential to serve as a leverage point for the Earth system. We have created a new research direction.

Natural Substances as Valuable Alternative for Improving Conventional Antifungal Chemotherapy: Lights and Shadows

Fungi are eukaryotic organisms with relatively few pathogenic members dangerous for humans, usually acting as opportunistic infections. In the last decades, several life-threatening fungal infections have risen mostly associated with the worldwide extension of chronic diseases and immunosuppression. The available antifungal therapies cannot combat this challenge because the arsenal of compounds is scarce and displays low selective action, significant adverse effects, and increasing resistance. A growing isolation of outbreaks triggered by fungal species formerly considered innocuous is being recorded. From ancient times, natural substances harvested from plants have been applied to folk medicine and some of them recently emerged as promising antifungals. The most used are briefly revised herein. Combinations of chemotherapeutic drugs with natural products to obtain more efficient and gentle treatments are also revised. Nevertheless, considerable research work is still necessary before their clinical use can be generally accepted. Many natural products have a highly complex chemical composition, with the active principles still partially unknown. Here, we survey the field underlying lights and shadows of both groups. More studies involving clinical strains are necessary, but we illustrate this matter by discussing the potential clinical applications of combined carnosic acid plus propolis formulations.

Medical-Grade Honey as a Potential New Therapy for Bacterial Vaginosis

The prevalence of bacterial vaginosis (BV) among women of reproductive age is 29%. BV arises from a vaginal imbalance marked by reduced levels of lactic acid-producing lactobacilli and an overgrowth of pathogenic anaerobes. The multifactorial nature of BV's pathogenesis complicates its treatment. Current antibiotic therapy exhibits a recurrence rate of about 60% within a year. Recurrence can be caused by antibiotic treatment failure (e.g., due to antimicrobial resistance), the persistence of residual infections (e.g., due to biofilm formation), and re-infection. Because of the high recurrence rates, alternative therapies are required. Medical-grade honey (MGH), known for its antimicrobial and wound healing properties in wound care, emerges as a potential novel therapy for BV. MGH exerts broad-spectrum antimicrobial activity, employing multiple mechanisms to eliminate the risk of resistance. For example, the low pH of MGH and the production of hydrogen peroxide benefit the microbiota and helps restore the natural vaginal balance. This is supported by in vitro studies demonstrating that MGH has an antibacterial effect on several pathogenic bacteria involved in the pathophysiology of BV, while lactobacilli and the vaginal microenvironment can be positively affected. In contrast to antibiotics, MGH exerts anti-biofilm activity, affects the microbiome as pre- and probiotic, and modulates the vaginal microenvironment through its anti-inflammatory, anti-oxidative, physicochemical, and immunomodulatory properties. More clinical research is required to confirm the positive effect of MGH on BV and to investigate the long-term cure rate.

In vitro evaluation of the antimicrobial properties of terpinen-4-ol on apical periodontitis-associated bacteria

Manuka oil and tea tree oil are essential oils with known antibacterial properties that are believed to be caused by one main component: terpinen-4-ol. Terpinen-4-ol has potent antibacterial activity against caries-related microorganisms. However, few studies have investigated the antimicrobial effects of terpinen-4-ol on bacteria in apical periodontitis. Thus, the objective of the present study was to evaluate the antibacterial and antibiofilm potential of terpinen-4-ol against Enterococcus faecalis, Porphyromonas gingivalis, Prevotella intermedia, and Fusobacterium nucleatum, which have all been detected in apical periodontitis. The minimum inhibitory and minimum bactericidal concentrations of terpinen-4-ol were determined to assess its activity against biofilms. The minimum inhibitory concentration of terpinen-4-ol was 0.25% against E. faecalis and F. nucleatum, 0.05% against P. gingivalis, and 0.1% against P. intermedia. The minimum bactericidal concentration of terpinen-4-ol was 1.0% against E. faecalis, 0.2% against P. gingivalis and P. intermedia, and 0.5% against F. nucleatum. In the biofilm evaluations, all terpinen-4-ol-treated bacteria had significant reductions in biofilm viability compared with controls in experiments assessing attachment inhibitory activity. Furthermore, structural alterations and decreased bacterial cell clumping were observed under scanning electron microscopy, and significantly decreased cell survival was noted using fluorescence microscopy. Together, these results suggest that terpinen-4-ol is a potential antibacterial agent with bactericidal properties, and can also act on established biofilms.

TLC-Bioautography-Guided Isolation and Assessment of Antibacterial Compounds from Manuka (Leptospermum scoparium) Leaf and Branch Extracts

A rapid procedure for the targeted isolation of antibacterial compounds from Manuka (Leptospermum scoparium) leaf and branch extracts was described in this paper. Antibacterial compounds from three different Manuka samples collected from New Zealand and China were compared. The active compounds were targeted by TLC-bioautography against S. aureus and were identified by HR-ESI-MS, and -MS/MS analysis in conjunction with Compound Discoverer 3.3. The major antibacterial component, grandiflorone, was identified, along with 20 β-triketones, flavonoids, and phloroglucinol derivatives. To verify the software identification, grandiflorone underwent purification via column chromatography, and its structure was elucidated through NMR analysis, ultimately confirming its identity as grandiflorone. This study successfully demonstrated that the leaves and branches remaining after Manuka essential oil distillation serve as excellent source for extracting grandiflorone. Additionally, we proposed an improved TLC-bioautography protocol for evaluating the antibacterial efficacy on solid surfaces, which is suitable for both S. aureus and E. coli. The minimum effective dose (MED) of grandiflorone was observed to be 0.29-0.59 μg/cm2 against S. aureus and 2.34-4.68 μg/cm2 against E. coli, respectively. Furthermore, the synthetic plant growth retardant, paclobutrazol, was isolated from the samples obtained in China. It is hypothesized that this compound may disrupt the synthesis pathway of triketones, consequently diminishing the antibacterial efficacy of Chinese Manuka extract in comparison to that of New Zealand.

Synergistic antimicrobial interaction of plant essential oils and extracts against foodborne pathogens

Essential oils (EOs) and plant extracts have demonstrated inhibitory activity against a wide range of pathogenic bacteria. In this study, the chemical composition of manuka, kanuka, peppermint, thyme, lavender, and feijoa leaf and peel EOs and feijoa peel and leaf extracts were analyzed, and their antimicrobial activity against Escherichia coli, Salmonella enterica Typhimurium, Staphylococcus aureus, Bacillus cereus, and Listeria monocytogenes were determined. The results showed that the major compounds varied among different EOs and extracts, with menthol in peppermint EO, thymol and carvacrol in thyme EO, linalool in lavender EO, β-caryophyllene in feijoa EO, and flavones in feijoa extract being the most prevalent. The study found that while EOs/extracts had antimicrobial activity alone, no individual EO/extract was highly effective against all tested species. Therefore, their combinations were tested to identify those that could broaden the spectrum of activity and act synergistically. The checkerboard method was applied to assess the possible synergism between the paired combinations of EOs/extract. The peppermint/thyme, peppermint/lavender, and peppermint/feijoa peel extract combinations exhibited a synergistic effect against E. coli and L. monocytogenes, with the peppermint/thyme and peppermint/feijoa peel extract combinations being the most effective against all five pathogens. Time-to-kill kinetics assays demonstrated that peppermint/thyme and peppermint/feijoa peel extract combinations achieved complete eradication of E. coli within 10-30 min and L. monocytogenes within 4-6 h. This study provides a promising approach to developing a natural alternative for food preservation using synergistic combinations of EOs/extracts, which could potentially reduce the required dosage and broaden their application in food products as natural preservatives.

Antimicrobial function of yeast against pathogenic and spoilage microorganisms via either antagonism or encapsulation: A review

Contaminations of pathogenic and spoilage microbes on foods are threatening food safety and quality, highlighting the importance of developing antimicrobial agents. According to different working mechanisms, the antimicrobial activities of yeast-based agents were summarized from two aspects: antagonism and encapsulation. Antagonistic yeasts are usually applied as biocontrol agents for the preservation of fruits and vegetables via inactivating spoilage microbes, usually phytopathogens. This review systematically summarized various species of antagonistic yeasts, potential combinations to improve the antimicrobial efficiency, and the antagonistic mechanisms. The wide applications of the antagonistic yeasts are significantly limited by undesirable antimicrobial efficiency, poor environmental resistance, and a narrow antimicrobial spectrum. Another strategy for achieving effective antimicrobial activity is to encapsulate various chemical antimicrobial agents into a yeast-based carrier that has been previously inactivated. This is accomplished by immersing the dead yeast cells with porous structure in an antimicrobial suspension and applying high vacuum pressure to allow the agents to diffuse inside the yeast cells. Typical antimicrobial agents encapsulated in the yeast carriers have been reviewed, including chlorine-based biocides, antimicrobial essential oils, and photosensitizers. Benefiting from the existence of the inactive yeast carrier, the antimicrobial efficiencies and functional durability of the encapsulated antimicrobial agents, such as chlorine-based agents, essential oils, and photosensitizers, are significantly improved compared with the unencapsulated ones.

The efficacy of honey or olive oil on the severity of oral mucositis and pain compared to placebo (standard care) in children with leukemia receiving intensive chemotherapy: A randomized controlled trial (RCT)

BACKGROUND

Oral mucositis (OM) is a significant complication occurring in approximately 40 to 80% of patients receiving chemotherapy regimens. Although a wide variety of agents have been tested to prevent OM or reduce its severity, none have provided conclusive evidence.

OBJECTIVES

To determine the efficacy of honey or olive oil on the severity and OM pain in children with leukemia and suffering from OM compared to placebo (standard care) and, to assess which of the two interventions is more beneficial.

METHODS

A single blind randomized controlled study (RCT) was used to evaluate the effect of Manuka honey or olive oil, in the treatment of chemotherapy-related OM in 42 children with leukemia. The primary outcome was the severity of mucositis, using the World Health Organization (WHO) scale and the secondary outcome was the pain assessed using the Visual analogue scale (VAS).

RESULTS

Children who received the honey had less severe OM (assessed on the (WHO) scale), p = 0.00 and less pain (assessed on the VAS scale), p = 0.00, compared to the control group. Children who received the olive oil had less pain than the control group, p = 0.00), although not lower than the honey group.

CONCLUSION

Manuka honey or olive oil can be used as alternative therapies by nurses to children with leukemia and suffering from OM, especially in low and middle-income countries where more expensive therapies may not be available or economical.

PRACTICE IMPLICATIONS

Pediatric nurses may recommend Manuka honey to treat OM in children with leukemia as it is safe and inexpensive compared to other treatment modalities.

Antimicrobial Activity of Some Medicinal Herbs to the Treatment of Cutaneous and Mucocutaneous Infections: Preliminary Research

(1) Background: Superficial, including cutaneous and mucocutaneous infections are a current public health problem with universal distribution. One of the main concerns, in the present/future, is fungal/bacterial infections by resistant microorganisms. This study aimed to verify if decoctions of coptidis (Coptis chinensis, Ranunculaceae family), neem (Azadirachta indica, Meliaceae family), and their essential oils (EOs), as well as the EO of manuka (Leptospermum scoparium, Myrtaceae family) have antimicrobial activity against prevalent species of microorganisms responsible for superficial infections. (2) Methods: The antimicrobial activity was determined by the minimum inhibitory concentration (MIC), using broth microdilution method, and minimum lethal concentration (MLC) was determined from subculture of MIC plates. (3) Results: C. chinensis EO and decoction demonstrated some antifungal action against the yeasts and dermatophytes tested. Greatest bactericidal effect against Propionibacterium acnes and some action against Staphylococcus aureus was observed. For A. indica only EO proved activity against dermatophytes and P. acnes. L. scoparium EO showed the broadest antimicrobial spectrum with activity against bacteria, yeasts, and dermatophytes showing greater activity against P. acnes and S. aureus. (4) Conclusions: C. chinensis (EO/decoction), EOs of L. scoparium and A. indica proved in vitro efficacy against fungal, bacterial, or mixed agents of superficial infections, either by sensitive or resistant strains.

Investigating the Antibacterial Properties of Prospective Scabicides

Scabies is a dermatological disease found worldwide. Mainly in tropical regions, it is also the cause of significant morbidity and mortality due to its association with potentially severe secondary bacterial infections. Current treatment strategies for scabies do not consider the role of opportunistic bacteria, and here we investigate whether current and emerging scabicides can offer any anti-bacterial protection. Using the broth microdilution method, we examined antimicrobial potential of the current scabicide ivermectin and emerging scabies treatments: abametapir, mānuka oil, and its individual β-triketones. Our results demonstrate that the two novel scabicides abametapir and mānuka oil have antimicrobial properties against common scabies-associated bacteria, specifically Staphylococcus aureus, Streptococcus pyogenes, Streptococcus dysgalactiae subsp. equisimilis and Acinetobacter baumannii. The current scabicide ivermectin offers some antimicrobial activity and is capable of inhibiting the growth aforementioned bacteria. This research is important as it could help to inform future best treatment options of scabies, and scabies-related impetigo.

Antifungal Potential of Some Herb Decoctions and Essential Oils on Candida Species

(1) Background: Candidiasis is a fungal infectious disease caused by opportunistic Candida species. The incidence of candidiasis has improved, due to prolonged antibiotic therapy and an increased number of immunocompromised patients. The purpose of this study was to evaluate if decoctions and essential oil (EO) of neem (Azadirachta indica, Meliaceae family), coptidis (Coptis chinensis, Ranunculaceae family), magnolia (Magnolia officinalis, Magnoliaceae family), scutellaria (Scutellaria barbata, Lamiaceae family), and the EO of manuka (Leptospermum scoparium, Myrtaceae family), have antifungal activity in vitro against some clinically prevalent species of Candida. (2) Methods: The antifungal activity was studied by the determination of the minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC) against five Candida strains. The effect in dimorphic transition of Candida albicans was also evaluated for the two plants with higher antimicrobial behavior. (3) Results: C. chinensis decoction and EO and L. scoparium EO exhibited antifungal activity in Candida spp. In addition to the fact that both C. chinensis decoction and EO proved strong antifungal activity, L. scoparium EO also displayed a relevant inhibitory effect on the dimorphic transition. (4) Conclusions: The results provided support for the potential use of C. chinensis and L. scoparium in the treatment of infections by Candida spp.

Diversity of Monofloral Honey Based on the Antimicrobial and Antioxidant Potential

This study aimed to investigate the antioxidant profile and the antimicrobial activity of four different types of monofloral honey (manuka (MH), brassica rapeseed (BH), acacia (AH), and linden honey (LH)) against some bacterial/fungal ATCC strains and some multidrug-resistant strains isolated from chronic otitis in dogs. For the characterisation of the antioxidant profile of each honey, we extracted the honey samples by hydroalcoholic extraction and analysed them in terms of total polyphenols (TPC), total flavonoids (TFC), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) using the spectrophotometric method. The antimicrobial activity was determined using the microdilution method at concentrations of 10%, 15%, and 20%, with the results expressed in OD (optical density) calculated as BIR% (bacterial inhibition rate)/MIR% (mycelial inhibition rate). The antioxidant characterisation of the analysed honey samples showed the highest antioxidant activity and concentrations of TPC and TFC in MH, followed by LH. MH was proven to be the most effective on most clinical isolates concerning the antimicrobial activity in comparison with BH, AH, and LH. Except for B. cepacia and P. vulgaris, all the clinical isolates were sensitive to the antibacterial activity of honey. Regarding the ATCC strains, MH 10% was the most effective in inhibiting all the strains tested except for P. aeruginosa. In conclusion, the efficacy classification in our study was MH > BH > AH > LH.

Enhancement of Biofunctionalization by Loading Manuka Oil on TiO2 Nanotubes

Metallic implants (mesh) for guided bone regeneration can result in foreign body reactions with surrounding tissues, infection, and inflammatory reactions caused by micro-organisms in the oral cavity after implantation. This study aimed to reduce the possibility of surgical failure caused by microbial infection by loading antibacterial manuka oil in a biocompatible nanostructure surface on Ti and to induce stable bone regeneration in the bone defect. The manuka oil from New Zealand consisted of a rich β-triketone chemotype, leptospermone, which showed strong inhibitory effects against several bacteria, even at very low oil concentrations. The TiO₂ nanotubular layer formed by anodization effectively enhanced the surface hydrophilicity, bioactivity, and fast initial bone regeneration. A concentration of manuka oil in the range of 0.02% to less than 1% can have a synergistic effect on antibacterial activity and excellent biocompatibility. A manuka oil coating (especially with a concentration of 0.5%) on the TiO₂ nanotube layer can be expected not only to prevent stenosis of the connective tissue around the mesh and inflammation by microbial infection but also to be effective in stable and rapid bone regeneration.

Intolerable Burden of Impetigo in Endemic Settings: A Review of the Current State of Play and Future Directions for Alternative Treatments

Impetigo (school sores) is a common superficial bacterial skin infection affecting around 162 million children worldwide, with the highest burden in Australian Aboriginal children. While impetigo itself is treatable, if left untreated, it can lead to life-threatening conditions, such as chronic heart and kidney diseases. Topical antibiotics are often considered the treatment of choice for impetigo, but the clinical efficacy of these treatments is declining at an alarming rate due to the rapid emergence and spread of resistant bacteria. In remote settings in Australia, topical antibiotics are no longer used for impetigo due to the troubling rise of antimicrobial resistance, demanding the use of oral and injectable antibiotic therapies. However, widespread use of these agents not only contributes to existing resistance, but also associated with adverse consequences for individuals and communities. These underscore the urgent need to reinvigorate the antibiotic discovery and alternative impetigo therapies in these settings. This review discusses the current impetigo treatment challenges in endemic settings in Australia and explores potential alternative antimicrobial therapies. The goals are to promote intensified research programs to facilitate effective use of currently available treatments, as well as developing new alternatives for impetigo.