Ethnobotanical uses, phytochemistry and bioactivities of Cymbopogon plants: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Cymbopogon (Poaceae) plants have been used for various purposes by many indigenous peoples in all continents. In particular, almost all species in the genus have traditionally been used as folk medicine to treat ailments. Traditional application records indicated that Cymbopogon might be used extensively to treat cold, dizziness, headache, loss of appetite, abdominal pain, rheumatism, diarrhea, whole grass for cold, sore throat, tracheitis and others.

AIMS OF THE REVIEW

Despite several research confirmed that Cymbopogon includes a range of active components, no review has been undertaken to consolidate information on its traditional uses, phytochemistry, pharmacology, and/or quality control. Thus this article aims to update a comprehensive review about the traditional uses, phytochemistry, pharmacology, cultivation techniques, economic benefits, trade, threats, and future conservation implications of Cymbopogon species. It may provide informative data for future development and further investigation of this important plant group.

MATERIALS AND METHODS

Traditional medicinal books and ethnomedicinal publications related to Cymbopogon from 1992 to 2023 were collated to investigate its ethnobotanical, phytochemical and pharmacological information. The online databases including Google Scholar, SciFinder, Web of Science, Scopus, Springer Link, PubMed, Wiley, China National Knowledge Infrastructure (CNKI), Baidu Scholar, and WanFang Database were screened.

RESULTS

Cymbopogon (Gramineae or Poaceae) plants have been grown worldwide. Traditional Chinese medicine and other medicinal systems believes that Cymbopogon has the effect of relieve a cough, analgesia, treating dizziness, traumatic injury and can relieve abdominal pain. A total of 153 compounds, including flavonoids, terpenoids, fatty acid and other compounds were isolated or identified from Cymbopogon species by phytochemical studies. The extracts or compounds from Cymbopogon have exhibited numerous biological activities such as antibacterial, antiinflammatory, antiviral, antineoplastic, antiarrhythmic, antidiabetic and other activities. The rich contents of citronellal, citronellol and geraniol found in Cymbopogon also provide significant nutritional benefits.

CONCLUSION

Based on their traditional uses, phytochemicals, and pharmacological activities, Cymbopogon plants are potential medicinal and edible resources with diverse pharmacological effects. Due to various advantages of this group, they possess huge application potential in food and pharmaceutical industries, and animal husbandry. Among them, citronella is very important in terms of economic development. Further comprehensive research to evaluate the medicinal properties of Cymbopogon species will be necessary for future development.

Synergism Between Essential Oils and Evaluation of Their Activities with a Focus on Malassezia furfur Control

Seborrheic dermatitis is a chronic inflammatory disease caused by Malassezia yeast species that affects the regions of the body where the sebaceous glands are present. The combined use of different essential oils (EOs) can increase their spectrum of action. Thus, the present study aimed to evaluate the action of EOs alone and in combination with each other on M. furfur, in planktonic and biofilm form, and their anti-inflammatory and mutagenic potential, in addition to the effects on the viability of cells lines. Of the 40 evaluated EOs, 22 showed activity against M. furfur at 0.5 - 2.0 mg/mL concentrations. Among the most active species, a blend of essential oils (BEOs) composed of Cymbopogon martini (Roxb.) Will. Watson (MIC = 0.5 mg/mL) and Mentha × piperita L. (MIC = 1.0 mg/mL) was selected, which showed a synergistic effect against yeast when evaluated through the checkerboard assay. The fungicidal activity was maintained by the addition of anti-inflammatory oil from Varronia curassavica Jacq. to BEOs. The BEOs also showed activity in the inhibition of biofilm formation and in the eradication of the biofilm formed by M. furfur, being superior to the action of fluconazole. Furthermore, it did not show mutagenic potential and did not interfere with the cell viability of both evaluated cell lines (HaCaT and BMDMs). TNF-α levels were reduced only by C. martini; however, this property was maintained when evaluating BEOs. BEOs had no effect on IL-8 levels. Thus, the BEOs may be indicated for alternative treatments against seborrheic dermatitis.

Antifungal activity and mechanism of palmarosa essential oil against pathogen Botrytis cinerea in the postharvest onions

AIMS

Botrytis cinerea is a pathogenic fungus that infests multiple crops, which causes a severe decrease in yield and generates substantial losses in the economy. Palmarosa essential oil (PEO) is a primary aromatic compound extracted from palmarosa that is commonly used for scent, medicine, and flavoring foods due to its diverse bioactive properties. In this study, we explored the antifungal activity and the main mechanism of action of PEO against B. cinerea. In addition, the components and control effects of PEO were also studied.

METHODS AND RESULTS

The antifungal assay was tested using the mycelial growth rate method and colony morphology. The constituents of PEO were identified according to gas chromatography/mass spectrometry (GC-MS). The main mechanism of action of PEO was evaluated by measuring representative indicators, which consist of cell contents leakage, excess reactive oxygen species (ROS), and other related indicators. The results indicated that at a concentration of 0.60 ml l-1, PEO exhibits strong antifungal activity against B. cinerea. The PEO mainly included 13 compounds, of which citronellol (44.67%), benzyl benzoate (14.66%), and acetyl cedrene (9.63%) might be the main antifungal ingredients. The study elucidated the main mechanism of action of PEO against B. cinerea, which involved the disruption of cell membrane structure, resulting in altered the cell membrane permeability, leakage of cell contents, and accumulation of excess ROS.

CONCLUSIONS

PEO is a satisfactory biological control agent that inhibits B. cinerea in postharvest onions. PEO (0.60 ml l-1) exhibited strong antifungal activity by disrupting the cell membrane structure, altering cell membrane permeability, leading to the cell contents leakage, accumulation of excess ROS and increased level of Malondialdehyde (MDA) compared to the control group.

Geraniol Suppresses Oxidative Stress, Inflammation, and Interstitial Collagenase to Protect against Inflammatory Arthritis

Geraniol (GER) is a plant-derived acyclic isoprenoid monoterpene that has displayed anti-inflammatory effects in numerous in vivo and in vitro models. This study was therefore designed to evaluate the antiarthritic potential of GER in complete Freund's adjuvant (CFA)-induced inflammatory arthritis (IA) model in rats. IA was induced by intraplantar injection of CFA (0.1 mL), and a week after CFA administration, rats were treated with various doses of methotrexate (MTX; 1 mg/kg) or GER (25, 50, and 100 mg/kg). Treatments were given on every alternate day, and animals were sacrificed on the 35th day. Paw volume, histopathological, hematological, radiographic, and qPCR analyses were performed to analyze the severity of the disease. GER significantly reduced paw edema after 35 days of treatment, and these results were comparable to the MTX-treated group. GER-treated animals displayed a perfect joint structure with minimal inflammation and no signs of cartilage or bone damage. Moreover, GER restored red blood cell and hemoglobin levels, normalized erythrocyte sedimentation rate, platelet, and c-reactive protein values, and also attenuated the levels of rheumatoid factor. RT-qPCR analysis demonstrated that GER decreased mRNA expression of pro-inflammatory cytokines like tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta. GER also down-regulated the transcript levels of cyclooxygenase-2 (COX-2), microsomal prostaglandin E synthase-1, prostaglandin D2 synthase, and interstitial collagenase (MMP-1). Molecular docking of GER with COX-2, TNF-α, and MMP-1 also revealed that the antiarthritic effects of GER could be due to its direct interactions with these mediators. Based on our findings, it is conceivable that the antiarthritic effects of GER could be attributed to downregulation of pro-inflammatory mediators and protease like MMP-1.

Antipruritic effects of geraniol on acute and chronic itch via modulating spinal GABA/GRPR signaling

BACKGROUND AND PURPOSE

Itch (pruritus) is a common unpleasant feeling, often accompanied by the urge of scratching the skin. It is the main symptom of many systemic and skin diseases, which can seriously affect the patient's quality of life. Geraniol (GE; trans-3,7-dimethyl-2,6-octadien-1-ol) is a natural monoterpene with diverse effects, including anti-inflammatory, antioxidant, neuroprotective, anti-nociceptive, and anticancer properties. The study aims to examine the effects of GE on acute and chronic itch, and explore the underlying mechanisms.

METHODS

Acute itch was investigated by using Chloroquine and compound 48/80 induced model, followed by manifestation of diphenylcyclopropenone (DCP)-induced allergic contact dermatitis and the acetone-ether-water (AEW)-induced dry skin model in mice. The scratching behavior, skin thickness, c-Fos expression, and GRPR protein expression in the spinal cord were subsequently monitored and evaluated by behavioral tests as well as pharmacological and pharmacogenetic technologies.

RESULTS

Dose-dependent intraperitoneal injection of GE alleviated the acute itch, induced by chloroquine and compound 48/80, as well as increased the spinal c-Fos expression. Intrathecal administration of GE suppressed the GABAA receptor inhibitor bicuculline-induced itch, GRP-induced itch, and the GABAergic neuron inhibition-induced itch. Furthermore, the subeffective dose of bicuculline blocked the anti-pruritic effect of GE on the chloroquine and compound 48/80 induced acute itch. GE also attenuated DCP and AEW-induced chronic itch, as well as the increase of spinal GRPR expression in DCP mice.

CONCLUSION AND IMPLICATIONS

GE alleviates both acute and chronic itch via modulating the spinal GABA/GRPR signaling in mice. Findings of this study reveal that GE may provide promising therapeutic options for itch management. Also, considering the pivotal role of essential oils in aromatherapy, GE has great application potential in aromatherapy for treating skin diseases, and especially the skin with severe pruritus.

Emerging Insights into the Applicability of Essential Oils in the Management of Acne Vulgaris

The occurrence of pustules, comedones, nodules, and cysts defines acne vulgaris, a prevalent chronic inflammatory dermatological condition. In the past few decades, essential oils extracted from varied natural sources have acquired recognition due to their potential medicinal applications in acne therapy. However, there is not yet sufficient medical data to fully characterize this interaction. Multiple factors contribute to the development of acne vulgaris, including excessive sebaceous production, inflammatory processes, hyperkeratinization, and infection with Cutibacterium acnes. Essential oils, including oregano, lavender, lemon grass, myrtle, lemon, thyme, eucalyptus, rosemary, and tea tree, have been found to possess anti-inflammatory, antioxidant, and antimicrobial properties, which may target the multifactorial causes of acne. Analytical methods for determining antioxidant potential (i.e., total phenolic content, diphenyl-1-picrylhydrazyl free radical scavenging assay, reducing power assay, ferrous ion chelating activity, thiobarbituric acid reactive species assay, β-carotene bleaching assay, etc.) are essential for the evaluation of these essential oils, and their method optimization is crucial. Further studies could include the development of novel acne treatments incorporating essential oils and an assessment of their efficacy in large clinical trials. In addition, further research is necessary to ascertain the mechanisms of action of essential oils and their optimal doses and safety profiles for optimal implementation in the management of acne vulgaris.

Geraniol improves passive avoidance memory and hippocampal synaptic plasticity deficits in a rat model of Alzheimer's disease

Alzheimer's disease (AD) is the most progressive and irreversible neurodegenerative disease that leads to synaptic loss and cognitive decline. The present study was designed to evaluate the effects of geraniol (GR), a valuable acyclic monoterpene alcohol, with protective and therapeutic effects, on passive avoidance memory, hippocampal synaptic plasticity, and amyloid-beta (Aβ) plaques formation in an AD rat model induced by intracerebroventricular (ICV) microinjection of Aβ_1-40. Seventy male Wistar rats were randomly into sham, control, control-GR (100 mg/kg; P.O. (orally), AD, GR-AD (100 mg/kg; P.O.; pretreatment), AD-GR (100 mg/kg; P.O.; treatment), and GR-AD-GR (100 mg/kg; P.O.; pretreatment & treatment). Administration of GR was continued for four consecutive weeks. Training for the passive avoidance test was carried out on the 36^th day and a memory retention test was performed 24 h later. On day 38, hippocampal synaptic plasticity (long-term potentiation; LTP) was recorded in perforant path-dentate gyrus (PP-DG) synapses to assess field excitatory postsynaptic potentials (fEPSPs) slope and population spike (PS) amplitude. Subsequently, Aβ plaques were identified in the hippocampus by Congo red staining. The results showed that Aβ microinjection increased passive avoidance memory impairment, suppressed of hippocampal LTP induction, and enhanced of Aβ plaque formation in the hippocampus. Interestingly, oral administration of GR improved passive avoidance memory deficit, ameliorated hippocampal LTP impairment, and reduced Aβ plaque accumulation in the Aβ-infused rats. The results suggest that GR mitigates Aβ-induced passive avoidance memory impairment, possibly through alleviation of hippocampal synaptic dysfunction and inhibition of Aβ plaque formation.

Underutilized Plant Cymbopogan martinii Derived Essential Oil Is Excellent Source of Bioactives with Diverse Biological Activities

Cymbopogan martinii, also known as Palmarosa, is an underutilized plant of tropical region. Due to outstanding antioxidant potential it has been used as a part of conventional medicine and beauty product. Regardless of its importance, complete pharmacological and phytochemical studies are still in its early stages. In the current study, Palmarosa essential oil (PRO) was extracted from Cymbopogan martinii and was evaluated for its phytochemicals, antimicrobial and antifungal, anti-inflammatory and anti-diabetic and protection from UV rays. Oil from fresh leaves was extracted and analysed for presence of phytochemicals (Tannin, Flavonoids, and Phenolics). Various antioxidant activities like DPPH (1,1-diphenyl-2-picrylhydrazyl), ABTS (2,2-azinobis-3-ethylbenzothiazoline-6-sulphonic acid), Nitric oxide radical, Hydroxyl radical, iron reducing, iron cheating activity were performed. Antibacterial, anti-inflammatory, Antidiabetic, membrane integrity assay, and UV-absorption assay was also performed. Antifungal activity against "Aspergillosis" and "Mucormycosis" causing fungal strains was also evaluated. High concentration of polyphenolics like Tannin, Flavonoid, phenolics were revealed through phytochemical analysis. GC-FID revealed the presence of Geraniol, major component of Palmarosa oil and other bioactive compound in PRO. PRO showed high anti-inflammatory and anti-diabetic potential and can be used as an Antidiabetic agent due to inhibitory effect on α-amylase activity. Further study revealed that PRO inhibits α-amylase in competitive manner. Hence from the results obtained it is confirmed that the PRO possesses considerable amount of bioactive compounds and can be used in pharmaceutical, food and cosmetic industries.

Computer-aided drug design combined network pharmacology to explore anti-SARS-CoV-2 or anti-inflammatory targets and mechanisms of Qingfei Paidu Decoction for COVID-19

Introduction

Coronavirus Disease-2019 (COVID-19) is an infectious disease caused by SARS-CoV-2. Severe cases of COVID-19 are characterized by an intense inflammatory process that may ultimately lead to organ failure and patient death. Qingfei Paidu Decoction (QFPD), a traditional Chines e medicine (TCM) formula, is widely used in China as anti-SARS-CoV-2 and anti-inflammatory. However, the potential targets and mechanisms for QFPD to exert anti-SARS-CoV-2 or anti-inflammatory effects remain unclear.

Methods

In this study, Computer-Aided Drug Design was performed to identify the antiviral or anti-inflammatory components in QFPD and their targets using Discovery Studio 2020 software. We then investigated the mechanisms associated with QFPD for treating COVID-19 with the help of multiple network pharmacology approaches.

Results and discussion

By overlapping the targets of QFPD and COVID-19, we discovered 8 common targets (RBP4, IL1RN, TTR, FYN, SFTPD, TP53, SRPK1, and AKT1) of 62 active components in QFPD. These may represent potential targets for QFPD to exert anti-SARS-CoV-2 or anti-inflammatory effects. The result showed that QFPD might have therapeutic effects on COVID-19 by regulating viral infection, immune and inflammation-related pathways. Our work will promote the development of new drugs for COVID-19.

Acute and Subacute Toxicity Study of Essential Oil of Cymbopogon Martini in Mice

Background

Local Ethiopians regularly use Cymbopogon martini for cosmetic purposes. The plant's safety, however, is not supported by any solid facts. This investigation aimed to evaluate the acute and subacute toxicities of C. martini essential oil in mice.

Methods

The essential oil was analyzed using GC-MS. The approach outlined by Chinedu et al., 2013 has been used to calculate the median lethal dose. According to organization for economic cooperation and development (OECD) 407 standard, a 28-day repeated dose oral toxicity study was carried out on female mice. Three groups of ten experimental mice each were distributed at random. Group I received the same saline volume and was considered the control. Groups II and III were treated with doses of C. martini of 500 mg/kg and 1000 mg/kg, respectively, of body weight. Hematological and biochemical markers were assessed. The liver and kidney were taken out after the sacrifice using sodium pentobarbital for pathological analysis.

Results

Geraniol (40.89%) was the predominant component in the essential oil composition of C. martini with cyclofenchene (13.91%), myrcene (9.34%), 2, 4, 6, octatriene, 2, 6, dimethyl (8.20%), and ocimene (5.93%) being present in small amounts. The LD₅₀ of C. martini essential oil was discovered to be greater than 5000 mg/kg body weight. During a 4-week follow-up period, mice treated with C. martini, the essential oil, at doses of 500 mg/kg or 1000 mg/kg body weight showed no evidence of toxicity or mortality. Biochemical and hematological parameters were not significantly altered in mice treated with the essential oil of C. martini compared with the control group. Histopathological evaluation of the liver and kidney did not exhibit any adverse results.

Conclusions

The essential oil of C. martini from Ethiopia is considered relatively safe and nontoxic.

p-Menthadienols-rich essential oil from Cymbopogon martini ameliorates skin inflammation

Cymbopogon martini variety sofia, commonly known as ginger-grass, is an important aromatic crop used by the perfumery, medicinal and cosmetic industries worldwide. This study explores the chemical and possible pharmacological profile of hydro-distilled essential oil of C. martini variety sofia against skin inflammation. The essential oil extracted by the hydrodistillation process was analyzed by gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance spectroscopy (NMR) to identify its constituents, and was coded as CMA-01 for further in vitro and in vivo pharmacological study related to skin inflammation. The chemical fingerprint revealed that CMA-01 oil has (E)-p-mentha-2,8-dien-1-ol (21.0%), (E)-p-mentha-1(7),8-dien-2-ol (18.1%), (Z)-p-mentha-1(7),8-dien-2-ol (17.4%), (Z)-p-mentha-2,8-dien-1-ol (9.0%), limonene (7.7%), and (E)-carveol (5.7%) as major components. The pre-treatment of CMA-01 showed significant inhibition of pro-inflammatory markers in activated HaCat cells without cytotoxic effect. The in vivo study revealed the ameliorative impact of CMA-01 against skin inflammation induced by TPA in mouse ears as evidenced by a reduction of ear edema, pro-inflammatory mediators (IL-6, TNF-α), oxidative stress markers (malondialdehyde and nitric-oxide) and histological changes in ear tissues without any skin irritation response on rabbit skin. These findings suggest the suitability of CMA-01 as a valuable therapeutic candidate for the treatment of skin inflammation.

Acaricidal and Repellent Effects of Essential Oils against Ticks: A Review

Tick control is a priority in order to prevent the transmission of vector-borne diseases. Industrial chemical acaricides and repellents have been the most efficient tools against hard ticks for a long time. However, the appearance of resistances has meant the declining effectiveness of the chemicals available on the market. The trend today is to develop alternative control methods using natural products to replace nonefficient pesticides and to preserve the efficient ones, hoping to delay resistance development. Traditional in vitro evaluation of acaricidal activity or resistance to synthetic pesticides have been reviewed and they mainly focus on just one species, the one host tick (Rhipicephalus (Boophilus) microplus (Acari: Ixodidae)). Recent reports have called for the standardization of natural product components, extraction techniques, and experimental design to fully discover their acaricidal potential. This study reviews the main variables used in the bibliography about the efficiency of natural products against ticks, and it proposes a unification of variables relating to ticks, practical development of bioassays, and estimation of ixodicidal activity.

Insights into the mechanism of Cymbopogan martinii essential oil in topical therapy of acne vulgaris

Aim: The present study investigated the essential oil of Cymbopogan martinii (palmarosa oil; PRO) as a potential topical therapy in acne vulgaris. Materials & methods: GC-MS profiling and biocompatibility studies of PRO were undertaken. The antimicrobial potential was assessed against Cutibacterium acnes. anti-inflammatory, antityrosinase activity and lipid peroxidation were also evaluated. Results: Geraniol was identified as the major phytoconstituent, and the oil was found to be safe for topical application. The minimum inhibitory concentration and minimum bactericidal concentration values were noted as 16 μl/ml. PRO reduced the cytokine levels of TNF-α, IL-12 and IL-8 and inhibited tyrosinase. A low concentration of the oil (up to 0.5 μl/ml) produced malondialdehyde levels equivalent to that of untreated cells. Conclusion: PRO may prove useful as a natural topical agent in the management of acne.

Geraniol improved memory impairment and neurotoxicity induced by zinc oxide nanoparticles in male wistar rats through its antioxidant effect

AIMS

Zinc oxide nanoparticles (ZnO-NPs) are currently applied in food and pharmaceutical industries whose neurotoxic effect on the central nervous system (CNS) is a major concern. Considering the pharmacological properties (antioxidant, anti-inflammatory) of the geraniol (GE), we aimed to investigate the efficacy of geraniol on ZnO-NPs neurotoxicity.

MATERIALS AND METHODS

We used 32 male Wistar rats, randomly assigned to four groups (n = 8): Control, GE (daily received 100 mg/kg of GE by gavage), ZnO-NPs (received intraperitoneal injection of 75 mg/kg of ZnO-NPs twice a week), and ZnO-NPs + GE (received both GE and ZnO-NPs at same doses above during 4 weeks). Morris water maze (MWM) and Y-maze tasks were done to evaluate learning and memory function. Biochemical assays were done to measure total antioxidant capacity (TAC), malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPX) and ZnO-NPs bioaccumulation. Nissl and H&E staining were performed for histological evaluations.

KEY FINDINGS

The results of behavioral study revealed that GE improved learning and memory impairment induced by ZnO-NPs. Moreover, neuroprotective effect of GE significantly decreased pathological parameters such as necrosis and gliosis, and consequently increased the number of nerve cells in the cortex and different hippocampal areas. Furthermore, biochemical studies demonstrated that GE significantly increased antioxidant indices (namely, TAC, SOD, and GPX) and reduced oxidative stress marker (MDA) and Zn bioaccumulation in ZnO-NPs treated animals.

SIGNIFICANCE

Our results provide experimental evidence to further investigate the precise mechanisms underlying the geraniol as a promising therapeutic approach for improvement of cognitive function and neurotoxicity induce by ZnO-NPs.

Review of Antimicrobial and Other Health Effects in 5 Essential Oil Producing Grass Species

The warm season essential oil producing grass species including lemongrass (Cymbopogon citratus), palmarosa grass (C. martini), geranium grass (C. schoenanthus), vetiver grass (Chrysopogon zizanioides), and scented top grass (Capillipedium parviflorum) are used worldwide for their cosmetic and health properties. A discussion providing evidence from literature reviews about the potential uses of these grass species for antimicrobial and other health uses are presented. These species could be used as new therapies for treating microbial infections. The purpose of this study is to discuss in detail, evidence from literature reviews supporting potential health uses and to provide some discussion regarding some agronomic traits for these essential oil producing species.

Anti-inflammatory and analgesic properties of Moroccan medicinal plants: Phytochemistry, in vitro and in vivo investigations, mechanism insights, clinical evidences and perspectives

Moroccan medicinal plants exhibit several pharmacological properties such as antimicrobial, anticancer, antidiabetic, analgesic, and anti-inflammatory effects, which are related to the presence of numerous bioactive compounds, including phenolic acids, flavonoids, and terpenoids. In the present review, we systematically evaluate previously published reports on the anti-inflammatory and analgesic effects of Moroccan medicinal plants. The in vitro investigations revealed that Moroccan medicinal plants inhibit several enzymes related to inflammatory processes, whereas in vivo studies noted significant anti-inflammatory and analgesic effects as demonstrated using different experimental models. Various bioactive compounds exhibiting in vitro and in vivo anti-inflammatory and analgesic effects, with diverse mechanisms of action, have been identified. Some plants and their bioactive compounds reveal specific secondary metabolites that possess important anti-inflammatory effects in clinical investigations. Our review proposes the potential applications of Moroccan medicinal plants as sources of anti-inflammatory and analgesic agents.

•

Anti-inflammatory and analgesic effects of Moroccan medicinal plants were highlighted.

•

Chemical nature of Moroccan medicinal plants with anti-inflammatory and analgesic effects was reported.

•

Insights into anti-inflammatory mechanisms of bioactive compounds were highlighted.

•

Toxicological investigations of Moroccan medicinal plants were reviewed.

Chemometric Screening of Fourteen Essential Oils for Their Composition and Biological Properties

Essential oils (EOs) obtained from aromatic plants are widely used worldwide, especially in cosmetic and food products due to their aroma and biological properties and health benefits. Some EOs have significant antimicrobial and antioxidant activities, and thus could effectively increase the shelf lives of foodstuff and beverages. In this study, fourteen essential oils (clove, eucalyptus, fennel, lavender, oregano, palmarosa, pepper, star anise, tea tree, turmeric, Chinese yin yang, Japanese yin yang, and ylang ylang) from different medicinal plant families were screened by gas-chromatography-mass spectrometry (GC-MS) for their different chemical profiles and bioassays were performed to assess their antifungal and antioxidant activities. The results obtained were assessed by principal component analysis (PCA). PCA distinguished six groups characterized by different terpene chemotypes. Amongst the EOs studied, the clove EO showed the strongest antioxidant activity characterized by an EC50 of 0.36 µL/mL. The oregano EO had the greatest antiyeast activity characterized by a minimal inhibitory concentration of 10 µL/mL. In conclusion, clove and oregano EOs are strong antifungal and antioxidant agents, respectively, with great potential in the food industry to avoid spoilage and to increase shelf life.

Identification of essential oils with activity against stationary phase Staphylococcus aureus

Background

Staphylococcus aureus is the most dominant human pathogen, responsible for a variety of chronic and severe infections. There is mounting evidence that persisters are associated with treatment failure and relapse of persistent infections. While some essential oils were reported to have antimicrobial activity against growing S. aureus, activity of essential oils against the stationary phase S. aureus enriched in persisters has not been investigated.

Methods

In this study, we evaluated the activity of 143 essential oils against both growing and stationary phase S. aureus by minimum inhibitory concentration (MIC) testing and by colony forming unit assay.

Results

We identified 39 essential oils (Oregano, Cinnamon bark, Thyme white, Bandit “Thieves”, Lemongrass (Cymbopogon flexuosus), Sandalwood oil, Health shield, Allspice, Amyris, Palmarosa, Cinnamon leaf, Clove bud, Citronella, Geranium bourbon, Marjoram, Peppermint, Lemongrass, Cornmint, Elemi, Ho wood, Head ease, Lemon eucalyptus, Litsea cubeba, Myrrh, Parsley seed, Coriander oil, Dillweed, Hyssop, Neroli, Rosewood oil, Tea tree, Cajeput, Clove bud, Lavender, Sleep tight, Vetiver, Palo santo, Sage oil, Yarrow) at 0.5% (v/v) concentration, 10 essential oils (Cinnamon bark, Oregano, Thyme white, Bandit “Thieves”, Lemongrass, Sandalwood oil, Health shield, Allspice, Amyris, Palmarosa at 0.25% (v/v) concentration, and 7 essential oils (Oregano, Cinnamon bark, Thyme white, Lemongrass, Allspice, Amyris, Palmarosa at 0.125% (v/v) concentration to have high activity against stationary phase S. aureus with no visible growth on agar plates after five-day exposure. Among the 10 essential oils which showed high activity at 0.25% (v/v) concentration, 9 (Oregano, Cinnamon bark, Thyme white, Bandit “Thieves”, Lemongrass, Health shield, Allspice, Palmarosa, Amyris showed higher activity than the known persister drug tosufloxacin, while Sandalwood oil had activity at a higher concentration. In Oregano essential oil combination studies with antibiotics, Oregano plus tosufloxacin (or levofloxacin, ciprofloxacin) and rifampin completely eradicated stationary phase S. aureus cells, but had no apparent enhancement for linezolid, vancomycin, sulfamethoxazole, trimethoprim, azithromycin or gentamicin.

Conclusions

Our findings indicate that some essential oils have excellent activity against both growing and stationary phase S. aureus. Further studies are needed to identify the active components, evaluate safety, pharmacokinetics, and their activity to eradicate S. aureus infections in vivo.

Brine Shrimp Toxicity of Essential Oils from Musa spp

Essential oils of seven Musa spp.’s fruits namely, Musa acuminata colla ‘gros michel’ (PE), Musa acuminata colla ‘lakatan’ (PB), Musa acuminata colla ‘sucrier’ (PM), Musa acuminata × balbisiana ‘horn plantain’ (PT), Musa acuminata × balbisiana colla ‘saba’ (PN), Musa acuminata colla 'inarnibal' (PO) and Musa acuminata colla ‘red’ (PJ) were extracted by hydrodistillation method using Clevenger apparatus. The essential oils were analysed using GC-FID and identified using Kovat Indeces compared with published information. PE gave the highest yields of oils compared to the other species with yield of 0.43% and 0.28% for its peels and flesh, respectively. The most abundant groups present in most of the essential oils are ester and alcohol groups. The brine shrimp toxicity of PT, PM, PN and PO essential oils were tested and showed toxicity against brine shrimp in dose dependent manner. It can be concluded that the essential oils showed some biological activities which may be a potent medicine in curing tumor. This study implies that the presence of ester and alcohol groups are a good marker for the biological activities of plants. Further studies should focus on the potential of the essential oils of Musa spp. as an antitumor medicine.

Citronellal prevents endothelial dysfunction and atherosclerosis in rats

BACKGROUND

Atherosclerosis is a chronical inflammatory disease in arterial walls, which is involved in oxidative stress and endothelial dysfunction. Aromatherapy is one of the complementary therapies that use essential oils as the major therapeutic agents to treat several diseases. Citronellal (CT) is a monoterpene predominantly formed by the secondary metabolism of plants, producing antithrombotic, antiplatelet, and antihypertensive activities.

AIM

The aim of the present study is to explore whether aromatherapy with CT improves endothelial function to prevent the formation of atherosclerotic plaque in vivo.

METHODS

An AS model in carotid artery was induced by balloon injury and vitamin D3 injection in rats fed with a high-fat diet. The size of the carotid atherosclerotic plaque was determined by ultrasound, oil red, and hematoxylin-eosin staining. Endothelial function was assessed by measuring acetylcholine-induced vessel relaxation in an organ chamber.

RESULTS

Administrations of CT (50, 100, and 150 mg/kg) as well as lovastatin dramatically reduced the size of carotid atherosclerotic plaque in rats in a dose-dependent manner, compared with atherosclerotic rats fed with a high-fat diet plus balloon injury and vitamin D3. Mechanically, CT improved endothelial dysfunction, increased cell migration, and suppressed oxidative stress and inflammation in vascular endothelium in rats feeding on the high-fat diet plus balloon injury. Further, CT downregulated the protein levels of sodium-hydrogen exchanger 1 in rats with atherosclerosis.

CONCLUSION

CT improves endothelial dysfunction and prevents the growth of atherosclerosis in rats by reducing oxidative stress. Clinically, CT is potentially considered as a medicine to treat patients with atherosclerosis.

The impact of Cymbopogon martinii essential oil on Cutibacterium (formerly Propionibacterium) acnes strains and its interaction with keratinocytes

OBJECTIVES

The human skin microbiota is mainly composed of bacteria belonging to the genera Staphylococcus, Cutibacterium, Micrococcus and Corynebacterium, but on the skin of the face and back, ca. 50% of the total microbiota is represented by the bacterium Cutibacterium acnes. The aim of this research was to evaluate the impact of C. martini EO and its major compound, geraniol, on C. acnes.

METHODS

The minimum inhibitory concentration against C. acnes strains, phenotypic changes and responses of the proteome was determined. In addition, was assessed the effect of compounds in RNA-binding assay, on C. acnes-exposed keratinocytes and on the C. acnes type distribution on shoulder skin.

KEY FINDINGS

The range of the MIC was 0.7 to 1.6 mg/ml for the three main C. acnes types. There were no cytotoxic effects of compounds in the absence or presence of C. acnes; after 7 days of exposure to C. martini EO, we could not detect a major shift of the C. acnes types on shoulder skin that was found to be dominated by C. acnes strains of types II and IA2.

CONCLUSIONS

Our work gives novel insight into the skin microbiota-interacting properties of C. martini EO.

Geraniol as a novel antivirulence agent against bacillary dysentery-causing Shigella sonnei

Antimicrobial resistance has emerged as a major challenge to modern medicine and it has become urgent to seek alternative approaches to treat infections caused by fast-evolving multi-resistant clones of bacillary dysentery-causing Shigella sonnei. Here, we show that geraniol, a natural substance present in the essential oils of plants such as rose and lemongrass, can reduce S. sonnei proliferation inside host cells and protect Galleria mellonella larvae from killing by S. sonnei infection. We present evidence that geraniol competitively inhibits the catalytic activity of the master virulence regulator, DsbA, a periplasmic disulphide bond oxidoreductase required for Shigella survival in the host cell cytosol. Our observations suggest that geraniol holds a great therapeutic potential that should be further exploited.

The in vitro antimicrobial evaluation of commercially essential oils and their combinations against acne

OBJECTIVE

The study investigated the efficacy of commercial essential oil combinations against the two pathogens responsible for acne with the aim to identify synergy and favourable oils to possibly use in a blend.

MATERIALS AND METHODS

Antimicrobial activity was assessed using the minimum inhibitory concentration (MIC) assay against Staphylococcus epidermidis (ATCC 2223) and Propionibacterium acnes (ATCC 11827), and the fractional inhibitory concentration index (ΣFIC) was calculated. Combinations displaying synergistic interactions were further investigated at varied ratios and the results plotted on isobolograms.

RESULTS

From the 408 combinations investigated, 167 combinations were identified as displaying noteworthy antimicrobial activity (MIC value ≤1.00 mg mL-1 ). Thirteen synergistic interactions were observed against S. epidermidis, and three synergistic combinations were observed against P. acnes. It was found that not one of the synergistic interactions identified were based on the combinations recommended in the layman's aroma-therapeutic literature. Synergy was evident rather from leads based on antimicrobial activity from previous studies, thus emphasizing the importance of scientific validation. Leptospermum scoparium J.R.Forst. and G.Forst (manuka) was the essential oil mostly involved in synergistic interactions (four) against S. epidermidis. Cananga odorata (Lam.) Hook.f. and Thomson (ylang ylang) essential oil was also frequently involved in synergy where synergistic interactions could be observed against both pathogens. The combination with the lowest MIC value against both acne pathogens was Vetiveria zizanioides Stapf (vetiver) with Cinnamomum verum J.Presl (cinnamon bark) (MIC values 0.19-0.25 mg mL-1 ). Pogostemon patchouli Benth. (patchouli), V. zizanioides, C. verum and Santalum spp. (sandalwood) could be identified as the oils that contributed the most noteworthy antimicrobial activity towards the combinations. The different chemotypes of the essential oils used in the combinations predominantly resulted in similar antimicrobial activity.

CONCLUSIONS

The investigated essential oil combinations resulted in at least 50% of the combinations displaying noteworthy antimicrobial activity. Most of the synergistic interactions do not necessarily correspond to the recommended layman's aroma-therapeutic literature, which highlights a need for scientific validation of essential oil antimicrobial activity. No antagonism was observed.

Essential Oils as Immunomodulators: Some Examples

Essential oils (EOs) exhibit a wide range of pharmacological properties, which have been reported over the years in various studies. The aim of this literature review is to present the latest findings of the immunomodulatory effects of EOs. From 2008 to 2016in vivo- and/orin vitro-studies, most of which were published in the last couple of years, have been selected based on their topic relevance, namely immunomodulatory, anti-inflammatory, antileishmanial, antiallergic, and anticancer effects of various EOs. These findings show modulation of pro- and anti-inflammatory cytokines, antiproliferative, chemotactic properties and also exert antiparasitic effects by inhibiting the pro, axenic and intramacrophagic amastigote forms of Leishmania parasites or by modulating the TH1 and TH2 immune responses. Furthermore, the EOs of some plants show the ability to reduce the mast cell degranulation and improve the airway inflammation and mucus obstruction in the cases of immediate hypersensitivity in murine models. Additionally, the cytotoxicity of some EOs against human melanoma, hepatoma, lung, prostate and breast cancer cell lines proposed their potential antitumor effect by an increased immunosuppressive (cytostatic) activity.

Essential oil of Cymbopogon citratus (lemongrass) and geraniol, but not citral, promote gastric healing activity in mice

Cymbopogon citratus, popularly known as lemongrass, is used for the treatment of gastric, nervous and hypertensive disorders, in addition to its use in the food and pharmaceutical industries. This study evaluated the gastroprotective and gastric healing effect of essential oil of C. citratus (EOCC), citral and geraniol at doses of 1-100 mg/kg (p.o) on acute ethanol-induced ulcer and chronic acetic acid-induced ulcer. Histological and histochemical evaluation was also performed, as well as the in vitro evaluation of the effects of these phytochemicals on H⁺/K⁺-ATPase activity. In the ethanol-induced gastric ulcer, the minimum effective oral dose of EOCC, citral and geraniol were 10, 100 and 3 mg/kg, reducing the ulcer area by 51.67%, 96.57% and 55.74%, respectively, compared to vehicle group (25.82 ± 3.59 mm²). Moreover, EOCC (10 mg/kg, p.o) and geraniol (3 mg/kg), but not citral (100 mg/kg), accelerated the gastric healing process by 34.52 and 80.57%, compared to acetic-acid ulcerated group treated with vehicle (36.04 ± 1.03 mm²). These healing effects were confirmed histologically by the contraction of the ulcer base and by the enhancement on mucin staining in slices of ulcer site from mice treated with EOCC or geraniol. Interestingly, EOCC and citral at 100 μg/ml inhibited the H⁺/ K⁺-ATPase activity by 28.26% and 44.36%, whereas geraniol did not change this parameter. Together, these findings confirm the gastroprotective and healing gastric ulcer effects of essential oil from aerial parts of C. citratus and added the information that geraniol, but not citral, promotes healing effects on installed ulcers.