Lemon Myrtle Research Articles

A low-cost, antimicrobial aloe-alginate hydrogel film containing Australian First Nations remedy ‘lemon myrtle oil’ (Backhousia citriodora) – Potential for incorporation into wound dressings

Chronic wounds pose a global public health challenge, particularly in remote settings where access to specialised wound care and dressings can be limited and cost-prohibitive. First Nations communities in Australia are at a significantly higher risk for developing chronic wounds and this risk further increases for people living in remote regions. There is an urgent need to develop inexpensive but effective wound dressings to improve wound outcomes. Over the past decade, sodium alginate (SA)-based hydrogel polymers have emerged as a cost-effective and biocompatible component in wound dressings, and many have been successfully commercialised. In this study, we have developed and evaluated various prototypes of SA-based hydrogels with the addition of another low-cost component, aloe vera (AV) to further tailor the physicochemical properties of the hydrogel. Since the presence of microbes is a major contributor to the pathophysiology of chronic wounds, we also evaluated the antimicrobial activity of lemon myrtle oil (LMO) (Backhousia citriodora) incorporated into the hydrogel, a remedy used traditionally by First Nations Australians. Novel formulations of AV-SA-LMO hydrogel prototypes in the absence and presence of lemon myrtle oil (at a concentration of 5 μg/mL) were assessed for their physicochemical and antimicrobial properties and compared to a commercially available hydrogel-based dressing. The addition of lemon myrtle oil imparted viscoelastic behaviour for improved processability of AV-SA-LMO hydrogel prototypes, while increasing protein adhesion, enhancing physical properties, and demonstrating antimicrobial activity against the common wound-infecting microbes Staphylococcus epidermidis and Candida albicans. Fourier transmission infrared (FTIR) spectra confirmed the molecular structures of the hydrogel prototypes as predicted. The prototypes also demonstrated biocompatibility with the HaCaT human keratinocyte cell line. This study has provided preliminary evidence that a 25:75 aloe vera:sodium alginate hydrogel with 5 μg/mL lemon myrtle oil has comparable physicochemical characteristics to a commercial hydrogel-based wound dressing and antimicrobial properties against S. epidermidis and C. albicans.

Phytochemical Composition and Toxicological Screening of Anise Myrtle and Lemon Myrtle Using Zebrafish Larvae.

Plants are an immense source of drugs, and 50% of modern pharmacopeia has a plant origin. With increasing life expectancy in humans, many age-related degenerative diseases converge on oxidative cellular stress pathways. This provides an opportunity to develop broad treatments by targeting the cause of common pathologic cell degeneration. Toxicological effects can be readily assessed in a live animal model system to establish potential fauna for clinical use. Here, we characterized and evaluated the antioxidant potential and toxicological effects of anise myrtle (Syzygium anisatum) and lemon myrtle (Backhousia citriodora) leaves. Using zebrafish larvae, a model for high-throughput pre-clinical in vivo toxicology screening, we identified safe levels of extract exposures for development of future therapeutics. The antioxidant capacity and toxicity were very similar in these two myrtles. The LC50-96h for anise myrtle was 284 mg/L, and for lemon myrtle, it was 270 mg/L. These measurements are comparable to ongoing studies we are performing using the same criteria in zebrafish, which allow for robust testing and prioritization of natural fauna for drug development.

Citral in lemon myrtle, lemongrass, litsea, and melissa essential oils suppress the growth and invasion of breast cancer cells

ObjectiveAlthough cancer therapy suppresses recurrence and prolongs life, it may be accompanied by strong side effects; thus, there is a strong demand for the development effective treatments with fewer side effects. Cancer therapy using plant-derived essential oils is attracting attention as one promising method. This study investigated the antitumor effects of essential oil volatiles on breast cancer cells and identifies four essential oils that display antitumor activity.MethodsBreast cancer cells were cultured in a 96-well plate, then one of twenty essential oils was added dropwise to the central well. The plate was incubated at 37 °C for 48 h and the effect of the volatile components of each essential oil on the surrounding breast cancer cell growth ability was examined using an MTT assay. Gas chromatography was used to investigate the concentration of the transpiration components that may affect cancer cells.ResultsOf the 20 essential oils, Lemongrass, Lemon myrtle, Litsea, and Melissa displayed strong anti-tumor effects. These essential oils inhibited the growth of nearby breast cancer cells, even when diluted more than 500-fold. The transpiration component of lemon Myrtle showed the strongest antitumor effect, but was the least cytotoxic to mononuclear cells in normal peripheral blood (PBMC). Each of these essential oils contained a very large amount of citral. The IC50 against breast cancer cells when citral was volatilized from each essential oil was 1.67 µL/mL for geranial and 1.31 µL/mL for neral. Volatilized citral alone showed strong anti-proliferation and infiltration-inhibiting effects.ConclusionThe transpiration components of Lemongrass, Lemon myrtle, Litsea, and Melissa are thought to inhibit breast cancer cell proliferation due to their high levels of citral.

In vitro efficacy of essential oils against various Candida species

Candida species are responsible for the most common fungal infections worldwide. We studied the in vitro antifungal activity of a large panel of essential oils (EOs) against various Candida species. The EOs activity against Candida spp. was tested using a gradient microdilution assay ranging from 4% to 0.008% (v/v). After a preliminary screening including 31 EOs, seven selected EOs were tested against 13 clinical isolates and four reference strains belonging to six Candida species. Cinnamomum zeylanicum and Cymbopogon giganteus EOs exhibited the best antifungal activity against all clinical and reference strains, with MIC ranges of 0.015%–0.25% (v/v). EOs from Litsea citrata, Backhousia citriodora and Ocimum sanctum presented MIC ranges of 0.03%–0.5% (v/v). The antifungal efficacy of EOs was independent of the susceptibility of Candida strains to usual antifungal agents. These EOs could have a promising antifungal action.

LC-ESI-QTOF-MS/MS Identification and Characterization of Phenolic Compounds from Leaves of Australian Myrtles and Their Antioxidant Activities.

Phenolic compounds, present in plants, provide substantial health advantages, such as antioxidant and anti-inflammatory properties, which enhance cardiovascular and cognitive well-being. Australia is enriched with a wide range of plants with phytopharmacological potential, which needs to be fully elucidated. In this context, we analyzed leaves of aniseed myrtle (Syzygium anisatum), lemon myrtle (Backhousia citriodora), and cinnamon myrtle (Backhousia myrtifolia) for their complex phytochemical profile and antioxidant potential. LC-ESI-QTOF-MS/MS was applied for screening and characterizing these Australian myrtles' phenolic compounds and the structure-function relation of phenolic compounds. This study identified 145 and quantified/semi-quantified 27 phenolic compounds in these Australian myrtles. Furthermore, phenolic contents (total phenolic content (TPC), total condensed tannins (TCT), and total flavonoids (TFC)) and antioxidant potential of phenolic extracts from the leaves of Australian myrtles were quantified. Aniseed myrtle was quantified with the highest TPC (52.49 ± 3.55 mg GAE/g) and total antioxidant potential than other selected myrtles. Catechin, epicatechin, isovitexin, cinnamic acid, and quercetin were quantified as Australian myrtles' most abundant phenolic compounds. Moreover, chemometric analysis further validated the results. This study provides a new insight into the novel potent bioactive phenolic compounds from Australian myrtles that could be potentially useful for functional, nutraceutical, and therapeutic applications.

Dehydration Impact on Antioxidant Potential and Phenolic content of Backhousia citrodora leaves

The most popular method for food preservation is dehydration. In order to enhance the overall quality and prolong the longevity of herbal products, it is imperative to carefully choose optimal dehydration conditions. The dehydration of Backhousia citriodora, also known as lemon myrtle leaves (LML), was conducted via three distinct techniques: conventional dehydration at temperatures of 40, 50, and 60°C (referred to as CD40, CD50, and CD60, respectively); vacuum dehydration at the same temperature as conventional dehydration with a pressure of 50 mbar; and heat pump dehydration at a constant temperature of 45°C. The antioxidant capacities, specifically the radical scavenging activity (DPPH) and ferric reducing antioxidant power (FRAP), along with the total phenolic content (TPC), were evaluated. HPD samples came up second to VD samples in terms of TPC retention, DPPH activity, and FRAP test, whereas CD samples had the lowest biochemical content across all dehydration conditions. The TPC and antioxidant activity in the CD sample exhibited a substantial reduction as the dehydration temperature increased. After dehydration, the CD60 sample had the largest reduction in TPC, DPPH, and FRAP values. Maximising the retention of biochemical content is of utmost importance in post-harvest processing as it serves as an indicator of greater retention. Therefore, the selection of appropriate dehydration techniques and conditions is critical in achieving this objective.

Geographical origin discrimination of lemon myrtle (Backhousia citriodora) leaf powder using near-infrared hyperspectral imaging

Lemon myrtle (LM), Backhousia citriodora, is a popular flavouring agent and herbal tea from Australia. To ensure traceability and consumer trust in global food supply chain, rapid and non-destructive tools are crucial. In this study, hyperspectral images were acquired from 91 L M samples sourced from three different origins (Malaysia, Queensland, and New South Wales (Australia)), within 950–2500 nm range. Classification models were developed using linear partial least squares-discriminant analysis (PLS-DA) with two approaches, pixel-based (trained by all spectral data points) and sample-based (trained by average spectrum). All models achieved classification accuracies above 96%. The sample-based PLS-DA model, trained by mean-centring transformed data, demonstrated the highest discriminatory performance. Both approaches show potential for LM origin classification, but the sample-based model is more suitable for automated and rapid industry applications due to its shorter calculation time. However, additional spectral data acquisition is necessary to improve the model and fully explore its capabilities and limitations.

Effect of Different Hydrophilic-lipophilic Balance (HLB) on Droplet Size, Polydispersity Index and Stability of Lemon Myrtle Nanoemulsion

Using mixed non-ionic surfactants Tween/Span, we determined the required hydrophilic-lipophilic balance (HLB) value on the oil in water nanoemulsion of lemon myrtle essential oil. In this study, Span 80 mixed with Tween 80, and Span 20 mixed with Tween 20 were used as mixed non-ionic surfactant. The droplet size, polydispersity index and stability of the lemon myrtle nanoemulsion at different HLB values were obtained over a period of 28 days. Both mixed surfactants have similar required HLB value at HLB 14 due to their smallest droplet size and lowest polydispersity index during the early nanoemulsion preparation. However, after a period of 28 days, nanoemulsion with Span 80-Tween 80 surfactant mixture was more stable compared to Span 20-Tween 20 surfactant mixture. Therefore, HLB 14 using Span 80-Tween 80 surfactant mixture has been selected as the required HLB for lemon myrtle nanoemulsion due to its stability and consistency of droplet size in 28 days.

Preparation, physicochemical characterisation and assessment of liquid and vapour phase antimicrobial activity of essential oil loaded lipid nanoparticles

Many essential oils have garnered attention as promising antimicrobials; however, their inherent volatility and susceptibility to degradation limit their effective utilisation. Encapsulation can address these limitations by entrapping the essential oils within protective matrices. In the current study, native Australian essential oils, Tasmanian mountain pepper (Tasmannia lanceolata) and lemon myrtle (Backhousia citriodora) and non-native thyme (Thymus vulgaris) were encapsulated in lipid nanoparticles (LNs) using high-pressure homogenisation. The morphology, size, stability and release properties of the LNs was assessed using cryo-TEM, DLS, turbiscanning and dialysis, respectively. The encapsulation efficiency of the LNs was determined using ultrafiltration and GC-FID analysis. The liquid and vapour phase antimicrobial activity and mode of action were determined using microdilution, inverted petri plate assays, and TEM, respectively. Stable spherical LNs (<200 nm size) with encapsulation efficiencies <88% and polydispersity index <0.2 were formulated. LNs generally showed higher antimicrobial activity than unencapsulated oils except for vapour phase activity which varied amongst the oils. Time-dependent cell membrane damage was confirmed using TEM. Essential oils exhibited a bi-phasic release profile from LNs characterised by initial burst release, followed by sustained release. In summary, encapsulation stabilised, promoted sustained release and enhanced the antimicrobial efficacy of the essential oils.

Efficacy of Lemon Myrtle Essential Oil as a Bio-Fungicide in Inhibiting Citrus Green Mould.

The effectiveness of lemon myrtle (LM) (Backhousia citriodora) essential oil (EO) was investigated to combat Penicillium digitatum by in vitro agar diffusion and vapour assay and in artificially infected oranges. The main constituent of LM EO was revealed as citral when analysed in gas chromatography-mass spectrometry. Pure citral was also included in the experiment for comparison. The in vitro fungal growth was significantly inhibited by LM EO at 1, 2, 3, 4 and 5 μL per disc while complete growth inhibition by both the pure citral and LM EO occurred at 4 and 5 μL per disc. Inoculated fruits treated by dipping in 1000 μL L-1 LM EO solutions for 5, 10, 15, 30 and 120 s showed significantly lower fungal wounds compared to control. While longer dipping times led to some rind injuries, fruits with a 5 and 10 s dip were found free from any injury. The evaluation after dipping and storage confirmed that the fruits maintained the sensory attributes and were not compromised by the incorporation of the essential oil. The results of this study indicate that LM EO can be a promising alternative to synthetic fungicides for preserving the quality of citrus fruits during storage.

Essential oil of lemon myrtle (Backhousia citriodora) induces S-phase cell cycle arrest and apoptosis in HepG2 cells

Ethnopharmacological relevanceLemon myrtle (Backhousia citriodora F.Muell.) leaves, whether fresh or dried, are used traditionally in folk medicine to treat wounds, cancers, skin infections, and other infectious conditions. However, the targets and mechanisms related to anti-cancer effect of lemon myrtle are unavailable. In our study, we found that the essential oil of lemon myrtle (LMEO) showed anti-cancer activity in vitro, and we initially explored its mechanism of action. Materials and methodsWe analyzed the chemical compositions of LMEO by GC-MS. We tested the cytotoxicity of LMEO on various cancer cell lines using the MTT assay. Network pharmacology was used also to analyze the targets of LMEO. Moreover, the mechanisms of LMEO were investigated through scratch assay, flow cytometry analysis, and western blot in the HepG2 liver cancer cell line. ResultsLMEO showed cytotoxicity on various cancer cell lines with values of IC50 40.90 ± 2.23 (liver cancer HepG2 cell line), 58.60 ± 6.76 (human neuroblastoma SH-SY5Y cell line), 68.91 ± 4.62 (human colon cancer HT-29 cell line) and 57.57 ± 7.61 μg/mL (human non-small cell lung cancer A549 cell line), respectively. The major cytotoxic chemical constituent in LMEO was identified as citrals, which accounted for 74.9% of the content. Network pharmacological analysis suggested that apurinic/apyrimidinic endodeoxyribonuclease 1 (APEX1), androgen receptor (AR), cyclin-dependent kinases 1 (CDK1), nuclear factor erythroid 2-related factor 2 (Nrf-2), fatty acid synthase (FASN), epithelial growth factor receptor (EGFR), estrogen receptor 1 (ERα) and cyclin-dependent kinases 4 (CDK4) are potential cytotoxic targets of LMEO. These targets are closely related to cell migration, cycle and apoptosis. Notley, the p53 protein had the highest confidence to co-associate with the eight common targets, which was further confirmed by scratch assay, flow cytometry analysis, and western blot in the HepG2 liver cancer cell line. LMEO significantly inhibited the migration of HepG2 cells in time-dependent and dose-dependent manner. Moreover, LMEO caused a S-phase blocking on HepG2 cells and promoted apoptosis in the meanwhile. Western blot results indicated that p53 protein, Cyclin A2 and Bax proteins were up-regulated, while Cyclin E1 and Bcl-2 proteins were down-regulated. ConclusionLMEO showed cytotoxicity in various cancer cell lines in vitro. Pharmacological networks showed LMEO to have multi-component and multi-targeting effects that are related to inhibit migration of HepG2 cells, and affect cell cycle S-phase arrest and apoptosis through modulation of p53 protein.

The antimicrobial efficacy of native Australian essential oils in liquid and vapour phase against foodborne pathogens and spoilage microorganisms

Foodborne pathogens and spoilage microorganisms are a source of concern for public health and the food industry. Considering the problem of antimicrobial resistance in microbes, controlling these microorganisms using synthetic antimicrobials is challenging, thus, essential oils are a potential natural alternative. Previous studies have predominantly focussed on the antimicrobial activity of essential oils in the liquid phase. However, in this work we report on the in vitro antimicrobial activity of the liquid and vapour phases of essential oils from native Australian plants Tasmanian mountain pepper (Tasmannia lanceolata), lemon myrtle (Backhousia citriodora), as well as the common herb thyme (Thymus vulgaris) against 11 common food spoilage and pathogenic bacteria and fungi. Initial screening was conducted using the disc diffusion assay. The minimum inhibitory concentration (MIC) of the oils was determined using the broth microdilution assay. The vapour phase antimicrobial activity of the oils was assessed using an inverted petri plate assay and the vapour phase MIC (V-MIC) was quantified using a vapour diffusion assay. GC-MS was adopted to elucidate the compositional profile of the oil in liquid phase. Two extraction methods, namely solid-phase microextraction (HS-SPME) and gas tight syringe headspace sampling (HS) coupled with GC-MS were used for profiling the composition of the volatiles. The findings of this study confirmed the antimicrobial activity of the oils in both liquid and vapour phases, with lemon myrtle and thyme generally showing stronger antimicrobial activity than Tasmanian mountain pepper. The activity in liquid phase was generally higher than the volatiles. However, lemon myrtle and Tasmanian mountain pepper berry volatiles were more effective against Aspergillus niger and Saccharomyces cerevisiae, respectively, relative to the liquid phase highlighting their potential as vapour phase antifungals. In the liquid and gas phases, the major compounds in lemon myrtle were Z-citral (neral) and E-citral (geranial). Polygodial and thymol were the major compounds in Tasmanian mountain pepper and thyme in the liquid phase, respectively. However, the main compounds in their volatiles were p-cymene and γ-terpinene. In conclusion, our research indicates the essential oils' potent vapour phase activity, highlighting their potential application in gaseous diffusion-dependent food applications such as active antimicrobial food packaging.

Optimization of electrochemical pre-treatment for essential oil extraction from lemon myrtle (B. citriodora) leaves by response surface methodology

Optimization of electrochemical pre-treatment for essential oil extraction from lemon myrtle (B. citriodora) leaves by response surface methodology

Antimicrobial and antioxidant AIE chitosan-based films incorporating a Pickering emulsion of lemon myrtle (Backhousia citriodora) essential oil

Films based on chitosan (CS) and Lemon Myrtle ( Backhousia citriodora ) essential oil (LEO) were prepared that exhibited novel dose-dependent fluorescent patterns owing to aggregation-induced emission (AIE) effects. Specifically, chitosan-coated alkali lignin (CS@AL) colloid particles were obtained by a facile one-pot ultrasonication, and were used to prepare LEO-loaded Pickering emulsions (CS@ALPE). Different amounts of CS@ALPE were incorporated into CS-based film-forming solutions. The composite (CS@ALPE-CS) films contained LEO/CS (w/w) ratios around 0%, 5.9%, 14.8%, 29.6% and 59.2% after solution casting. The microstructures, optical properties, water affinity, mechanical attributes, fluorescent characteristics, as well as antimicrobial and antioxidant efficacies of CS@ALPE-CS films were assessed for multifunctional food packaging. 0.5% (w/v) of CS@AL particles (pH ∼4.3 to 4.6) enabled stabilization of CS@ALPE (φ = 0.4) for at least 35 days. Adding CS@ALPE with appropriate LEO/CS (w/w) ratios modified the properties of the composite films. The 0.5CS@ALPE-CS film (with LEO/CS (w/w) around 29.6%) was the most promising candidate for multifunctional packaging considering its optimal optical properties, resistance to moisture and mechanical stress, characteristic fluorescent attributes along with antimicrobial and antioxidant activities. A schematic illustration of a dose-dependent AIE fluorescence pattern correlating to the relative contents of CS@ALPE to CS within CS@ALPE-CS films. • Emulsions of lemon myrtle essential oil stabilized by chitosan-coated lignin. • Facile one-pot scheme for chitosan-based films incorporating the essential oil. • Films with improved UV-shielding, antimicrobial and antioxidant properties. • Reactions between chitosan and essential oil yielded Schiff base products. • Correlations between fluorescence emission spectra and essential oil content.

Chemical Composition, Antioxidant, Antibacterial, and Antibiofilm Activities of Backhousia citriodora Essential Oil.

The essential oil of Backhousia citriodora, commonly known as lemon myrtle oil, possesses various beneficial properties due to its richness in bioactive compounds. This study aimed to characterize the chemical profile of the essential oil isolated from leaves of Backhousia citriodora (BCEO) and its biological properties, including antioxidant, antibacterial, and antibiofilm activities. Using gas chromatography–mass spectrometry, 21 compounds were identified in BCEO, representing 98.50% of the total oil content. The isomers of citral, geranial (52.13%), and neral (37.65%) were detected as the main constituents. The evaluation of DPPH radical scavenging activity and ferric reducing antioxidant power showed that BCEO exhibited strong antioxidant activity at IC50 of 42.57 μg/mL and EC50 of 20.03 μg/mL, respectively. The antibacterial activity results showed that BCEO exhibited stronger antibacterial activity against Gram-positive bacteria (Staphylococcus aureus and Staphylococcus epidermidis) than against Gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae). For the agar disk diffusion method, S. epidermidis was the most sensitive to BCEO with an inhibition zone diameter of 50.17 mm, followed by S. aureus (31.13 mm), E. coli (20.33 mm), and K. pneumoniae (12.67 mm). The results from the microdilution method showed that BCEO exhibited the highest activity against S. epidermidis and S. aureus, with the minimal inhibitory concentration (MIC) value of 6.25 μL/mL. BCEO acts as a potent antibiofilm agent with dual actions, inhibiting (85.10% to 96.44%) and eradicating (70.92% to 90.73%) of the biofilms formed by the four tested bacteria strains, compared with streptomycin (biofilm inhibition, 67.65% to 94.29% and biofilm eradication, 49.97% to 89.73%). This study highlights that BCEO can potentially be a natural antioxidant agent, antibacterial agent, and antibiofilm agent that could be applied in the pharmaceutical and food industries. To the best of the authors’ knowledge, this is the first report, on the antibiofilm activity of BCEO against four common nosocomial pathogens.

Formulation, characterization, and stability of food grade oil‐in‐water nanoemulsions of essential oils of Tasmannia lanceolata, Backhousia citriodora and Syzygium anisatum

AbstractOil‐in‐water nanoemulsions were formulated using sunflower oil mixed with each of the essential oils of Tasmannia lanceolata (Tasmanian pepper leaf [TPL]), Backhousia citriodora (lemon myrtle [LM]) and Syzygium anisatum (anise myrtle [AM]) and stabilized with Tween 80 using ultrasonication. An oil‐surfactant ratio of 3:1 was found to produce the lowest emulsion droplet sizes of 96.6 nm for LM, 122.2 nm for AM and 131.8 nm for TPL. Increase in surfactant concentration above 10r resulted in larger droplet sizes, 165.8–2,647.2 nm for LM (radius, r = .82), 153.7–2,573.5 nm for AM (r = .93) and 157.4–2,621.6 nm for TPL (r = .83). Sonication for 3 min produced smaller droplet size; however, sonication for 9 min resulted in increase of droplet size by 1.48, 1.43 and 1.47 times for oils of LM (r = .82), AM (r = .93) and TPL (r = .83), respectively. A positive correlation was found between sonication amplitude (20–50%) and droplet size for nanoemulsions of LM (r = .93), AM (r = .98) and TPL (r = .95). TPL and LM nanoemulsions showed broad‐ spectrum antimicrobial activities against yeasts and bacteria. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) against weak‐acid resistant yeasts were between 0.001–0.003 and 0.002–0.007 mg/ml for nanoemulsion of TPL and between 0.003–0.014 mg/ml and 0.005–0.027 for nanoemulsion of LM, respectively. The stability and antimicrobial activity of TPL and LM essential oil nanoemulsions confirm their potential for application as food preservatives especially in beverage products that are commonly spoiled by weak‐acid resistant yeasts.

Effect of different drying methods and conditions on drying performance and volatile retention of Backhousia citriodora (lemon myrtle) leaves

The effect of different drying methods i.e., oven (OD), vacuum (VD), and heat pump assisted (HPD) drying on lemon myrtle leaf (LML) as well as the retention of volatiles in the dried product was investigated. Following a constant rate period, each method entered the falling rate period, whereby drying was governed by internal diffusion. The moisture diffusivity (Deff), calculated using Fick’s second law, was found to fall in the range of 8.07 × 10-10 to 4.35 × 10-9 m2/s across the varying drying methods and conditions. The activation energy (Ea), calculated using the Arrhenius equation, was 13.42, 45.41, and 72.85 kJ/mol for HPD, VD, and OD, respectively. Essential oils (EO) were obtained from dried LML through the simultaneous distillation and extraction (SDE) method, and thereafter, the EO was analysed using gas chromatography-mass spectrometry (GC-MS). Citral, an important volatile in LML, was among the EO components identified. Commonly found in its cis- and trans- forms, citral retention differed between the drying methods. The highest retention of volatiles was observed in the HPD method, followed by VD and OD. As high citral content is indicative of successful post-harvest processing, and given its ability to retain such volatiles in dried LML, HPD is therefore the most suitable drying method for LML drying. HPD can also be applied for the preservation of various agricultural products especially heat-sensitive herbs. The waste heat recovery ability attracts agropreneurs’ attention on adapting HPD into their industry. The versatile feature of this controlled dryer not only ensures good quality herb products, but is also economical, efficient, and time-saving.

Identification of phytochemical inhibitors of SARS-CoV-2 protease 3CLpro from selected medicinal plants as per molecular docking, bond energies and amino acid binding energies

Recent worldwide outbreak of SARS-COV-2 pandemic has increased the thirst to discover and introduce antiviral drugs to combat it. The bioactive compounds from plant sources, especially terpenoid have protease inhibition activities so these may be much effective for the control of viral epidemics and may reduce the burden on health care system worldwide. Present study aims the use of terpenoid from selected plant source through bioinformatics tools for the inhibition of SARS-COV-2. This study is based on descriptive analysis. The Protein Data Bank and PubChem database were used for the analysis of SARS-COV-2 protease and plant source terpenoids. Molecular docking by using molegro virtual docker (MVD) software was carried out. The findings of study are based on the inhibitory actions of different plant sourced terpenoid against SARS-COV-2. As per the available resources and complementary analysis these phytochemicals have capacity to inhibit 3CLpro protease. The study reports that (3,3-dimethylally) isoflavone (Glycine max), licoleafol (Glycyrrhiza uralensis), myricitrin (Myrica cerifera), thymoquinone (Nigella sativa), bilobalide, ginkgolide A (Ginkgo biloba), Salvinorin A (Salvia divinorum), citral (Backhousia citriodora) and prephenazine (drug) showed high activity against SARS-COV-2 protease 3CLpro. The drug like and ADMET properties revealed that these compounds can safely be used as drugs. Cross structural analysis by using bioinformatics study concludes that these plant source terpenoid compounds can be effectively used as antiprotease drugs for SARS-COV-2 in future.

Lemon myrtle (Backhousia citriodora) leaf extract on biofilm formation of Pseudomonas aeruginosa

This study includes 10 samples isolated from a different source. This research paper was to study the antibacterial activity and antibiofilm activity of an alcoholic extract of Lemon Myrtle (Backhousia citriodora) leaves, against 10 clinical isolates of Pseudomonas aerogenoza. Isolates were diagnosed by the VITEK-2 compact system and (PCR). The capacity of isolates to produce biofilm was tested by using the Microtiter plate technique (96 wells). The results showed that isolates were able to form a biofilm, also the ability of Backhousia citriodora was been effective on bacteria and biofilm formation.

Lemon myrtle and lemon scented tea tree essential oils as potential inhibitors of green mould on citrus fruits

ABSTRACT This study examined the ability of essential oils (EOs) obtained from the Australian native plants, lemon myrtle (Backhousia citriodora) (LM) and lemon scented tea tree (Leptospermum petersonii) (LSTT) to inhibit the in vivo growth of Penicillium digitatum in citrus fruits. The main constituent of LM and LSTT EOs was citral at 85 and 64%, respectively. Citral was included for comparison. Oranges dipped for 120 sec in EO solutions showed less fungal wastage compared to control with efficacy being LM > pure citral > LSTT, with 1000 μL L−1 LM EO the optimal treatment. The greater response of LM over LSTT EO was attributed to its higher concentration of citral but the greater effect over citral suggested some minor constituent(s) of LM EO also had antifungal activity. While the 120 sec dips caused severe rind injury, a 30 sec dip in 1000 µL L−1 LM EO generated only slight injury and inhibited fungal wastage in Valencia and Navel oranges, mandarins and lemons. A 10 sec dip did not cause rind injury but was less effective for mould inhibition. The findings suggest LM EO as an alternative to synthetic fungicides to inhibit wastage in citrus during storage, particularly for organic produce.