Citronellol, a monoterpene alcohol with promising pharmacological activities - A systematic review

Antimicrobial cyclodextrin-assisted electrospun fibers loaded with carvacrol, citronellol and cinnamic acid for wound healing

This work aimed to explore an alternative to the use of antibiotics for prevention and treatment of wounds infection caused by two common bacterial pathogens Staphylococcus aureus and Pseudomonas aeruginosa. For this purpose, three different essential oil components (EOCs), namely carvacrol, citronellol and cinnamic acid, were loaded into electrospun fibers of poly-ε-caprolactone (PCL) aided by alpha-cyclodextrin (αCD) and hydroxypropyl-β-cyclodextrin (HPβCD). Electrospun-fibers prepared with each EOC and their mixtures were screened for antimicrobial capability and characterized regarding morphological, mechanical, thermal, surface polarity, antibiofilm and antioxidant properties. αCD formed poly(pseudo)rotaxanes with PCL and weakly interacted with EOCs, while HPβCD facilitated EOC encapsulation and formation of homogeneous fibers (500-1000 nm diameter) without beads. PCL/HPβCD fibers with high concentration of EOCs (mainly carvacrol and cinnamic acid) showed strong antibiofilm (>3 log CFU reduction) and antioxidant activity (10-50% DPPH scavenging effects). Different performances were recorded for the EOCs and their mixtures; cinnamic acid migrated to fiber surface and was released faster. Fibers biocompatibility was verified using hemolysis tests and in ovo tissue integration and angiogenesis assays. Overall, HPβCD facilitates complete release of EOCs from the fibers to the aqueous medium, being an environment-friendly and cost-effective strategy for the treatment of infected wounds.

A Recyclable Electrochemical Reduction of Aldehydes and Ketones to Alcohols Using Water as the Hydrogen Source and Solvent

There are several challenging problems such as the usage of combustible and hazardous hydrogen sources and severe environmental pollution in the conventional reduction of aldehydes/ketones to alcohols. We report here a practical, safe, and green electrochemical reduction, which solves these problems to a large extent. Through an undivided cell, Zn(+) and Sn(-) as the electrode, tetrabutylammonium chloride (TBAC) as the electrolyte, water as the solvent and hydrogen source, a wide range of aldehydes and ketones are converted into the corresponding alcohols in mild conditions. Furthermore, the electrolytes and water can be recycled, and reductive deuteration can be achieved by simply using D2O as the solvent. Finally, the reduction can be smoothly scaled up to a kilogram level.

Cornstarch aerogels with thymol, citronellol, carvacrol, and eugenol prepared by supercritical CO2- assisted techniques for potential biomedical applications

This study focuses on the development of bioactive materials using environmentally friendly techniques, renewable, biocompatible, and biodegradable polysaccharide, as well as natural bioactive compounds (NBCs) found in plant extracts. First, cornstarch aerogels with a porosity of 86 % and a specific surface area of 225 m2/g were produced via supercritical CO2- assisted drying. Further, thymol, citronellol, carvacrol, and eugenol were incorporated into the aerogels by supercritical CO2- assisted impregnation, which allowed variation in loadings of NBCs (12.8-17.6 %). Interaction between cornstarch aerogels and NBCs determined impregnation rate, pore wall thickness (in the range 18-95 nm), liquid absorption capacity (from 265 to 569 %), dehydration mass loss, and release in phosphate-buffered saline. Controlled release of NBCs was maintained over a 3-day period. Moreover, impregnated aerogels showed a significant antioxidant effect with the highest value for DPPH radical inhibition of 25.5 % determined for the aerogels impregnated with eugenol. Notable antimicrobial activity against tested Gram-negative bacteria, Gram-positive bacteria, and fungi was also observed, being the highest for thymol-loaded aerogel with the diameter of the inhibition zones of up to 37.5 mm. This work shows a promising green approach for the production of bioactive two-component starch-based materials for potential applications in skin infection treatment.

HPLC and GC/MS analysis of Prunus ulmifolia Franch. (syn. Aflatunia ulmifolia (Franch.) Vassilcz.) leaves growing in South-Eastern Kazakhstan

Prunus ulmifolia Franch. (Rosaceae) was investigated for its phytochemical composition from South-Eastern Kazakhstan for the first time. HPLC analysis confirmed rutin (0.88%) in ethanol extract, and the extract also exhibited antioxidant activity. The GC/MS analysis identified total 44 components from main groups e.g. oxygenated monoterpenes (51.06%), oxygenated sesquiterpenes (20.33%), non-terpene derivatives (18.71%), and sesquiterpene hydrocarbons (7.89%), and the maximum content was of acyclic alcoholic monoterpenoid citronellol (36.58%). The hierarchical cluster analysis (HCA) from previous reports and present study was used to demonstrate the variations between essential oil compositions in different Prunus species. It formed three main clusters, cluster I consisted of species with benzaldehyde as dominant component. Cluster II included plants with benzaldehyde as secondary component, and cluster III was of P. ulmifolia in which benzaldehyde was not detected. Further, the essential oil was assessed for cytotoxic and antimicrobial activities too, and it showed better cytotoxic but poor antimicrobial activities.

Enhancing collagen based nanoemulgel for effective topical delivery of Aceclofenac and Citronellol oil: Formulation, optimization, in-vitro evaluation, and in-vivo osteoarthritis study with a focus on HMGB-1/RAGE/NF-κB pathway, Klotho, and miR-499a

The majority of conventional osteoarthritis (OA) treatments are based on molecular adjustment of certain signaling pathways associated with osteoarthritis (OA) pathogenesis, however there is a significant need to search for more effective and safe treatments. This study centers around formulating Aceclofenac (ACF) with high bioavailability in combination with Citronellol oil and collagen. The optimal concentrations of Citronellol oil/D-Limonene oil, Tween 80, and Transcutol HP were determined using a pseudoternary phase diagram. The formulated nanoemulsions were studied for thermophysical stability. Thermodynamically stable formula were analyzed for droplet size, zeta potential, and in-vitro permeation. Then, collagen based nanoemulsion were prepared to capitalize on its efficacy in reducing osteoarthritis side effects and characterized for nano size properties. Formulae F10 and F10C were chosen as optimum nanosize formula. Hense, they were prepared and characterized as nanoemulgel dosage form. The nanoemulgel formulae F10NEG1 and F10CNEG1 showed reasonable viscosity and spreadability, with complete drug release after 4 h. These formulae were chosen for further In vivo anti-OA study. Collagen based ACF/citronellol emugel were able to modulate HMGB-1/RAGE/NF-κB pathway, mitigating the production of inflammatory cytokine TNF-α. They were also able to modulate Klotho and miR-499, reducing serum CTXII and COMP, by reducing the cartilage destruction. Histological investigations validated the efficacy, safety, and superiority of Aceclofenac in combination with Citronellol oil and collagen (F10CNEG1) over solo the treated group (F10NEG1 and blank). Hence, the findings of the current work encourage the use of this promising combined formula in treatment of OA patients.

Possible cerebroprotective effect of citronellal: molecular docking, MD simulation and in vivo investigations

This study focused on molecular docking, dynamic simulation, and in vivo approaches to examine the molecular interactions between citronellal (CT) and neurotoxic proteins. In silico studies of CT were performed using proteins involved in the pathophysiology of stroke, such as interleukin-6 (IL-6), interleukin-12 (IL-12), TNF-α, and nitric oxide synthase (NOS), to determine the binding affinity based on their interactions. The docking results of CT revealed that, among the targets, NOS had a better binding energy of -6.4 Kcal/mol. NOS showed good hydrophobic interactions: TYR A, 347; VAL A, 352; PRO A, 350; TYR A, 373 amino acids. Interactions with IL-6, TNF-α, and IL-12 resulted in lower binding affinities of -3.7, -3.9 and -3.1 Kcal/mol. Based on molecular dynamics simulations of 100 ns, the binding affinity of CT (-66.782 ± 7.309 kJ/mol) was well complemented, and NOS stability at the docked site was confirmed. In in vivo studies, cerebral stroke was induced by occlusion of the bilateral common carotid arteries for 30 min and reperfusion for 4 h. CT treatment protected the brain by decreasing cerebral infarction size, increasing GSH(p < 0.001***), decreasing MPO (p < 0.001***), MDA (p < 0.001***), NO production (p < 0.01**), and AChE (p < 0.001***) compared to stroke rats. Histopathological examination revealed that CT treatment reduced the severity of cerebral damage. The investigation concluded that CT strongly binds to NOS, as observed in molecular docking and dynamic simulation studies, which are involved in nitric oxide production, leading to cerebral damage, and CT treatment reduces NO production and oxidative stress parameters, and increases antioxidants via inhibition of NOS function.Communicated by Ramaswamy H. Sarma.

An In Silico Approach to Exploring the Antinociceptive Biological Activities of Linalool and its Metabolites

Pain is characterized by the unpleasant sensory and emotional sensation associated with actual or potential tissue damage, whereas nociception refers to the mechanism by which noxious stimuli are transmitted from the periphery to the CNS. The main drugs used to treat pain are nonsteroidal anti-inflammatory drugs (NSAIDs) and opioid analgesics, which have side effects that limit their use. Therefore, in the search for new drugs with potential antinociceptive effects, essential oils have been studied, whose constituents (monoterpenes) are emerging as a new therapeutic possibility. Among them, linalool and its metabolites stand out. The present study aims to investigate the antinociceptive potential of linalool and its metabolites through a screening using an in silico approach. Molecular docking was used to evaluate possible interactions with important targets involved in antinociceptive activity, such as α2-adrenergic, GABAergic, muscarinic, opioid, adenosinergic, transient potential, and glutamatergic receptors. The compounds in the investigated series obtained negative energies for all enzymes, representing satisfactory interactions with the targets and highlighting the multi-target potential of the L4 metabolite. Linalool and its metabolites have a high likelihood of modulatory activity against the targets involved in nociception and are potential candidates for future drugs.

Antibacterial effect of ultrasound and β-citronellol against Listeria monocytogenes and its application in carrot preservation

This study investigated the antibacterial effects of ultrasound (US), β-citronellol (CT), and a combination of the two treatments on Listeria monocytogenes. Results showed that US or CT alone did not show apparent antibacterial effect (0.02-0.76 log CFU/mL reduction). The combined treatment showed obviously inactivate effect of L. monocytogenes, the populations of L. monocytogenes decreased by 8.93 log CFU/mL after US (253 W/cm2, 20 kHz) + 0.8 mg/mL CT treatment. US + CT treatment also had a significant (P < 0.05) antibacterial effect on isolates of L. monocytogenes from three different serotypes. In this study, the damage of US + CT on cell morphology had been observed using field emission scanning electron microscopy, while the damage to cell membranes by US + CT was observed by confocal laser scanning microscopy and flow cytometry. Meanwhile, the uptake of N-phenyl-l-naphthylamine and the absorbance at 260 and 280 nm also indicated that the combined treatment disrupted the permeability and integrity of L. monocytogenes membranes. Reactive oxygen species and malondialdehyde assays showed that US + CT exacerbated cellular oxidative stress and lipid peroxidation. In addition, the US + CT treatment reduced L. monocytogenes by 3.14-4.24 log CFU/g on the surface of carrots. Total phenolic and carotenoid contents in carrots were elevated after US + CT treatment. During storage, compared to control, US + CT did not significantly (P > 0.05) change the surface color of carrots but significantly (P < 0.05) decreased both hardness and weight, and has an impact on the sensory. This study showed that US + CT is a promising cleaning method that will provide new ideas for the preservation of fresh agricultural produce.

Gaafar AR, Nafidi HA, Bourhia M. Mechanistic Evaluation of Antiarthritic Effects of Citronellol in CFA-Induced Arthritic Rats

Rheumatoid arthritis (RA) is an autoimmune disease characterized by systemic inflammation, joint tissue damage, pain, and synovitis. It leads to deformity of joints, disability, and even premature death. Markers of inflammation are highly expressed in synovium fluid and serum of arthritic patients and play an important role in the pathophysiology of RA. These transcription factors promote the fabrication of type I interferons and inflammatory cytokines. In RA, degradation of synovial cartilage and bone results from stimulation of proinflammatory cytokines. Citronellol (Ct), a monoterpene alcohol, is found in citrus fruits and essential oils of many aromatic plants. It possesses numerous pharmacological properties such as antioxidant activity and potential antinociceptive and anti-inflammatory effects. Keeping in view the significant anti-inflammatory role of Ct, a trial of 28 days was conducted. Ct was administered orally at three different doses (25, 50, and 100) mg/kg in Freund's adjuvant-induced arthritic rats, and the results were compared with piroxicam, chosen as the standard drug. The antiarthritic activity of the compound was evaluated through measurements of arthritic scoring and plethysmometry before and after treatment. The blood biochemical and hematological parameters and histopathological analyses were performed. Additionally, qPCR was conducted to analyze the mRNA expression levels of TNF-α, IL-1β, NF-κB, MMP3, IL-6, and IL-4 in the blood. ELISA was performed to evaluate the levels of PGE2. The results demonstrated that Ct showed significant results at all doses, but the highest dose proved to be most significant in terms of decreasing arthritic scoring and paw edema, indicating the antiarthritic potential of Ct. Furthermore, the compound was found to downregulate all the proinflammatory cytokines (TNF-α, IL-1β, NF-κB, MMP3, and IL-6) and upregulate the anti-inflammatory cytokine (IL-4). The levels of PGE2 were also reduced which further supported the antiarthritic effects of Ct and validated it as a potential antiarthritic candidate.

The Ethnopharmacology, Phytochemistry and Bioactivities of the Corymbia Genus (Myrtaceae)

Plants have been vital to human survival for aeons, especially for their unique medicinal properties. Trees of the Eucalyptus genus are well known for their medicinal properties; however, little is known of the ethnopharmacology and bioactivities of their close relatives in the Corymbia genus. Given the current lack of widespread knowledge of the Corymbia genus, this review aims to provide the first summary of the ethnopharmacology, phytochemistry and bioactivities of this genus. The Scopus, Web of Science, PubMed and Google Scholar databases were searched to identify research articles on the biological activities, phytochemistry and ethnomedical uses of Corymbia species. Of the 115 Corymbia species known, 14 species were found to have ethnomedical uses for the leaves, kino and/or bark. Analysis of the references obtained for these 14 Corymbia spp. revealed that the essential oils, crude extracts and compounds isolated from these species possess an array of biological activities including anti-bacterial, anti-fungal, anti-protozoal, anti-viral, larvicidal, insecticidal, acaricidal, anti-inflammatory, anti-oxidant, anti-cancer and anti-diabetic activities, highlighting the potential for this under-studied genus to provide lead compounds and treatments for a host of medical conditions.

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.

Citronellol-Based Long-Lasting Antibacterial Cotton Fabrics without Bacterial Resistance

Antibacterial cotton helps prevent the growth and spread of harmful microorganisms, reduces the risk of infection, and has a prolonged service life by reducing bacterial degradation. However, most antibacterial agents used are toxic to humans and the environment. Citronellol-poly(N,N-dimethyl ethyl methacrylate) (CD), a highly effective antibacterial polymer, is synthesized from natural herbal essential oils (EOs). CD exhibited efficient, rapid bactericidal activity against Gram-positive, Gram-negative, and drug-resistant bacteria. Citronellol's environmental benignity makes CDs less hemolytic. Notably, negligible drug resistance developed after 15 bacterial subcultures. The CD-treated cotton fabric displayed better antibacterial performance than AAA-grade antibacterial fabric, even after repeated washing. This study extends the practical application of EOs to antibacterial surfaces and fabrics, which is promising for use in personal care products and medical settings.

Aceclofenac/Citronellol Oil Nanoemulsion Repurposing Study: Formulation, In Vitro Characterization, and In Silico Evaluation of Their Antiproliferative and Pro-Apoptotic Activity against Melanoma Cell Line

Aceclofenac (ACF) is a widely used non-steroidal anti-inflammatory drug (NSAID) known for its effectiveness in treating pain and inflammation. Recent studies have demonstrated that ACF possesses antiproliferative properties, inhibiting the growth of cancer cells in various cancer cell lines. Citronellol, a monoterpenoid alcohol found in essential oils, exhibits antioxidant properties and activities such as inhibiting cell growth and acetylcholinesterase inhibition. In this study, the objective was to formulate and evaluate an aceclofenac/citronellol oil nanoemulsion for its antiproliferative effects on melanoma. The optimal concentrations of citronellol oil, Tween 80, and Transcutol HP were determined using a pseudoternary phase diagram. The formulated nanoemulsions were characterized for droplet size, zeta potential, thermophysical stability, and in vitro release. The selected formula (F1) consisted of citronellol oil (1 gm%), Tween 80 (4 gm%), and Transcutol HP (1 gm%). F1 exhibited a spherical appearance with high drug content, small droplet size, and acceptable negative zeta potential. The amorphous state of the drug in the nanoemulsion was confirmed by Differential Scanning Calorimetry, while FTIR analysis indicated its homogenous solubility. The nanoemulsion showed significant antiproliferative activity, with a lower IC50 value compared to aceclofenac or citronellol alone. Flow cytometric analysis revealed cell cycle arrest and increased apoptosis induced by the nanoemulsion. In silico studies provided insights into the molecular mechanism underlying the observed antitumor activity. In conclusion, the developed aceclofenac/citronellol oil nanoemulsion exhibited potent cytotoxicity and pro-apoptotic effects, suggesting its potential as a repurposed antiproliferative agent for melanoma treatment. In a future plan, further animal model research for validation is suggested.

The dual face of microglia (M1/M2) as a potential target in the protective effect of nutraceuticals against neurodegenerative diseases

The pathophysiology of different neurodegenerative illnesses is significantly influenced by the polarization regulation of microglia and macrophages. Traditional classifications of macrophage phenotypes include the pro-inflammatory M1 and the anti-inflammatory M2 phenotypes. Numerous studies demonstrated dynamic non-coding RNA modifications, which are catalyzed by microglia-induced neuroinflammation. Different nutraceuticals focus on the polarization of M1/M2 phenotypes of microglia and macrophages, offering a potent defense against neurodegeneration. Caeminaxin A, curcumin, aromatic-turmerone, myricetin, aurantiamide, 3,6'-disinapoylsucrose, and resveratrol reduced M1 microglial inflammatory markers while increased M2 indicators in Alzheimer's disease. Amyloid beta-induced microglial M1 activation was suppressed by andrographolide, sulforaphane, triptolide, xanthoceraside, piperlongumine, and novel plant extracts which also prevented microglia-mediated necroptosis and apoptosis. Asarone, galangin, baicalein, and a-mangostin reduced oxidative stress and pro-inflammatory cytokines, such as interleukin (IL)-1, IL-6, and tumor necrosis factor-alpha in M1-activated microglia in Parkinson's disease. Additionally, myrcene, icariin, and tenuigenin prevented the nod-like receptor family pyrin domain-containing 3 inflammasome and microglial neurotoxicity, while a-cyperone, citronellol, nobiletin, and taurine prevented NADPH oxidase 2 and nuclear factor kappa B activation. Furthermore, other nutraceuticals like plantamajoside, swertiamarin, urolithin A, kurarinone, Daphne genkwa flower, and Boswellia serrata extracts showed promising neuroprotection in treating Parkinson's disease. In Huntington's disease, elderberry, curcumin, iresine celosia, Schisandra chinensis, gintonin, and pomiferin showed promising results against microglial activation and improved patient symptoms. Meanwhile, linolenic acid, resveratrol, Huperzia serrata, icariin, and baicalein protected against activated macrophages and microglia in experimental autoimmune encephalomyelitis and multiple sclerosis. Additionally, emodin, esters of gallic and rosmarinic acids, Agathisflavone, and sinomenine offered promising multiple sclerosis treatments. This review highlights the therapeutic potential of using nutraceuticals to treat neurodegenerative diseases involving microglial-related pathways.

Antifungal effect of (R) and (S)-citronellal enantiomers and their predictive mechanism of action on Candida albicans from voriconazole-resistant onychomycoses

Onychomycosis is the most common disease affecting the nail unit and accounts for at least 50% of all nail diseases. In addition, Candida albicans is responsible for approximately 70% of onychomycoses caused by yeasts. This study investigated the antifungal effect of (R) and (S)-citronellal enantiomers, as well as its predictive mechanism of action on C. albicans from voriconazole-resistant onychomycoses. For this purpose, in vitro broth microdilution and molecular docking techniques were applied in a predictive and complementary manner to the mechanisms of action. The main results of this study indicate that C. albicans was resistant to voriconazole and sensitive to the enantiomers (R) and (S)-citronellal at a dose of 256 and 32 µg/mL respectively. In addition, there was an increase in the minimum inhibitory concentration (MIC) of the enantiomers in the presence of sorbitol and ergosterol, indicating that these molecules possibly affect the integrity of the cell wall and cell membrane of C. albicans. Molecular docking with key biosynthesis proteins and maintenance of the fungal cell wall and plasma membrane demonstrated the possibility of (R) and (S)-citronellal interacting with two important enzymes: 1,3-β-glucan synthase and lanosterol 14α-demethylase. Therefore, the findings of this study indicate that the (R) and (S)-citronellal enantiomers are fungicidal on C. albicans from onychomycoses and probably these substances cause damage to the cell wall and cell membrane of these micro-organisms possibly by interacting with enzymes in the biosynthesis of these fungal structures.

Biosynthesis and the Transcriptional Regulation of Terpenoids in Tea Plants (Camellia sinensis)

Terpenes, especially volatile terpenes, are important components of tea aroma due to their unique scents. They are also widely used in the cosmetic and medical industries. In addition, terpene emission can be induced by herbivory, wounding, light, low temperature, and other stress conditions, leading to plant defense responses and plant-plant interactions. The transcriptional levels of important core genes (including HMGR, DXS, and TPS) involved in terpenoid biosynthesis are up- or downregulated by the MYB, MYC, NAC, ERF, WRKY, and bHLH transcription factors. These regulators can bind to corresponding cis-elements in the promoter regions of the corresponding genes, and some of them interact with other transcription factors to form a complex. Recently, several key terpene synthesis genes and important transcription factors involved in terpene biosynthesis have been isolated and functionally identified from tea plants. In this work, we focus on the research progress on the transcriptional regulation of terpenes in tea plants (Camellia sinensis) and thoroughly detail the biosynthesis of terpene compounds, the terpene biosynthesis-related genes, the transcription factors involved in terpene biosynthesis, and their importance. Furthermore, we review the potential strategies used in studying the specific transcriptional regulation functions of candidate transcription factors that have been discriminated to date.

Elaboration and general evaluation of chitosan-based films containing terpene alcohols-rich essential oils

Recently, the scientific community is interested in the synthesis of biodegradable and bioactive packaging to replace oil-based ones. Therefore, the present study aims to elaborate an active and biodegradable material using chitosan (CS-film) combined with pelargonium, tea tree, marjoram, and thyme essential oils (EOs), and then evaluate their different properties and biological activities. The obtained data showed an augmentation in CS-film thickness and opacity following the addition of EOs ranging from 17 ± 3 to 42 ± 2 μm and from 1.53 ± 0.04 to 2.67 ± 0.09, respectively. Furthermore, a significant decrease in the water vapor transmission rate and moisture content parameters was recorded as regards the treated CS-films. On the other hand, the treatment with EOs engenders random modifications in the physicochemical and mechanical characteristics of the material. Concerning the biological activities, the treated CS-films scavenged around 60% of DPPH radical while the control CS-film exhibited a negligible antioxidant activity. Finally, the CS-films containing pelargonium and thyme EOs exhibited the strongest antibiofilm-forming activity against Escherichia coli, Enterococcus hirae, Staphylococcus aureus, and Pseudomonas aeruginosa with values of inhibition greater than 70%. These encouraging results verify the effectiveness of CS-films containing EOs such as pelargonium and thyme EOs as biodegradable and bioactive packaging.

A review of citrus plants as functional foods and dietary supplements for human health, with an emphasis on meta-analyses, clinical trials, and their chemical composition

Fruits, flowers, leaves, essential oils, hydrosols, and juices of citrus spp. Are utilized to prepare various forms of food products. Along with their nutritional values, in the health industry, different parts of the plants of the citrus genus have been used as supplements or remedies to prevent or control diseases. This review focused on reported meta-analyses and clinical trials on the health benefits of citrus plants as functional foods. Also, chemical compounds of various citrus species were reviewed. The following information sources were used for data collection: Google Scholar, the Web of Science, Scopus, and PubMed. Various keywords, including "citrus AND chemical compounds," "citrus AND phytochemicals," "citrus species," "citrus AND meta-analysis," "nutritional and therapeutical values of citrus spp.," "clinical trials AND citrus," "clinical trials AND Rutaceae," "health benefits of citrus spp.," "citrus edible or non-edible applications," and scientific names of the citrus plants were utilized to collect data for the review. The scientific name and common name of all twenty-eight citrus species, along with any of the above keywords, were also searched in the mentioned databases. Scientific papers and data sources were sought to review and discuss the citrus plant's nutritional and therapeutic importance. Several meta-analyses and clinical trials have reported beneficial effects of citrus spices on a variety of cancer risks, cardiovascular risk factors, neurologic disorders, urinary tract conditions, and gastrointestinal tract conditions. They have shown anxiolytic, antimicrobial, and pain-alleviating effects. Some of them can be helpful in managing obesity and cardiovascular risk factors.

Essential Oil from Coriandrum sativum: A review on Its Phytochemistry and Biological Activity

Essential oils are hydrophobic liquids produced as secondary metabolites by specialized secretory tissues in the leaves, seeds, flowers, bark and wood of the plant, and they play an important ecological role in plants. Essential oils have been used in various traditional healing systems due to their pharmaceutical properties, and are reported to be a suitable replacement for chemical and synthetic drugs that come with adverse side effects. Thus, currently, various plant sources for essential oil production have been explored. Coriander essential oil, obtained from the leaf and seed oil of Coriandrum sativum, has been reported to have various biological activities. Apart from its application in food preservation, the oil has many pharmacological properties, including allelopathic properties. The present review discusses the phytochemical composition of the seed and leaf oil of coriander and the variation of the essential oil across various germplasms, accessions, at different growth stages and across various regions. Furthermore, the study explores various extraction and quantification methods for coriander essential oils. The study also provides detailed information on various pharmacological properties of essential oils, such as antimicrobial, anthelmintic, insecticidal, allelopathic, antioxidant, antidiabetic, anticonvulsive, antidepressant, and hepatoprotective properties, as well as playing a major role in maintaining good digestive health. Coriander essential oil is one of the most promising alternatives in the food and pharmaceutical industries.

Citronellol Prevents 6-OHDA-Induced Oxidative Stress, Mitochondrial Dysfunction, and Apoptosis in Parkinson Disease Model of SH-SY5Y Cells via Modulating ROS-NO, MAPK/ERK, and PI3K/Akt Signaling Pathways

Parkinson disease is a neurodegenerative disorder distinguished by dopaminergic shortage in the striatum and the accumulation of α-synuclein neuronal aggregates in the brains of patients. Since, there is no accurate treatment available for Parkinson disease, researches are designed to alleviate the pathognomonic symptoms such as neuroinflammation, oxidative stress, mitochondrial dysfunction, and apoptosis. Accordingly, a number of compounds have been reported to inhibit these pathognomonic symptoms. In this study, we have assessed the neuroprotective potential of citronellol against 6-OHDA-induced neurotoxicity in SH-SY5Y cells. The results found that citronellol treatment effectively hindered the cell death caused by 6-OHDA and thereby maintaining the cell viability in SH-SY5Y cells at 50 µg/mL concentration. As expected, the citronellol treatment significantly reduced the 6-OHDA-induced secretion of inflammatory factors (IL-1β, IL-6, and TNF-α), which was obtained through ELISA technique. Similarly, citronellol hindered the 6-OHDA-induced oxidative stress by lowering the intracellular ROS and NO level and MDA leakage along with increased expression of SOD level in SH-SY5Y cells. The JC-1 staining showed that 6-OHDA increased the number of green fluorescent dots with ruptured mitochondrial membrane potential, while citronellol increased the amount of red fluorescent, showing the rescue potential against the 6-OHDA-induced mitochondrial dysfunction. Furthermore, citronellol hampered the 6-OHDA-induced apoptosis via the suppression of Bcl-2/Bax pathway. The western blotting results hypothesized that citronellol rescued SH-SY5Y cells from 6-OHDA-induced neurotoxicity via modulating ROS-NO, MAPK/ERK, and PI3K/Akt signaling pathways. However, further clinical trials are required to verify the anti-Parkinson efficacy.

Engineering the Activity of Old Yellow Enzyme NemR-PS for Efficient Reduction of (E/Z)-Citral to (S)-Citronellol

The cascade catalysis of old yellow enzyme, alcohol dehydrogenase and glucose dehydrogenase has become a promising approach for one pot, two-step reduction of (E/Z)-citral to (S)-citronellol, serving as a chiral alcohol with rose fragrance. During the multi-enzymatic cascade catalysis, old yellow enzyme is responsible for the reduction of the conjugated C=C and the introduction of the chiral center, requiring high activity and (S)-enantioselectiviy. Herein, to improve the activity of the old yellow enzyme from Providencia stuartii (NemR-PS) with strict (S)-enantioselectivity, the semi-rational design on its substrate binding pocket was performed through a combination of homology modeling, molecular docking analysis, alanine scanning and iterative saturation mutagenesis. The NemR-PS variant D275G/F351A with improved activity was obtained and then purified for characterization, obeying the substrate inhibition kinetics. Compared with the wild type, the parameters Ki and Kcat/Km were increased from 39.79 mM and 2.09 s−1mM−1 to 128.50 mM and 5.01 s−1mM−1, respectively. Moreover, the variant D275G/F351A maintained strict (S)-enantioselectivity, avoiding the trade-off effect between activity and enantioselectivity. Either the enzyme NemR-PS or the variant D275G/F351A was co-expressed with alcohol dehydrogenase from Yokenella sp. WZY002 (YsADH) and glucose dehydrogenase from Bacillus megaterium (BmGDHM6). In contrast to the whole-cell biocatalyst co-expressing NemR-PS, that co-expressing the variant D275G/F351A shortened the reaction time from 36 h to 12 h in the reduction of 400 mM (E/Z)-citral. In the manner of substrate constant feeding, the accumulated product concentration reached up to 500 mM and completely eliminate the residual intermediate and by-product, suggesting the effectiveness of protein engineering and substrate engineering to improve catalytic efficiency.

Autoxidized citronellol: Free radicals as potential sparkles to ignite the fragrance induced skin sensitizing pathway

Citronellol, one of the most used fragrance compounds worldwide, is one ingredient of Fragrance Mix II used to assess skin allergy to fragrances in dermatitis patients. Pure citronellol is non-allergenic. Main issue is it autoxidizes when exposed to air becoming then allergenic. The increased skin sensitizing potency of air-exposed citronellol has been attributed to the hydroperoxides detected at high concentrations in the oxidation mixtures. It has been postulated that such hydroperoxides can give rise to specific antigens, although chemical mechanisms involved and the pathogenesis are far from being unraveled. Hydroperoxides are believed to react with skin proteins through mechanisms involving radical intermediates. Here, insights on the potential radicals involved in skin sensitization to citronellol hydroperoxides are given. The employed tool is a multispectroscopic approach based on (i) electron paramagnetic resonance and spin trapping, that confirmed the formation of oxygen- and carbon-radicals when exposing reconstructed human epidermis to concentrations of hydroperoxides close to those used for patch testing patients with air-oxidized citronellol; (ii) liquid chromatography-mass spectrometry, that proved the reaction with amino acids such as cysteine and histidine, known to be involved in radical processes and (iii) density functional theory calculations, that gave an overview on the preferential paths for radical degradation.

Synthesis and Enzymatic Degradation of Sustainable Levoglucosenone-Derived Copolyesters with Renewable Citronellol Side Chains

Recently, a renewable five-membered lactone containing citronellol (HBO-citro) was synthesized from levoglucosenone (LGO). A one-pot two-step pathway was then developed to produce a mixture of 5- and 6-membered Lactol-citro molecules (5ML and 6ML, respectively) from HBO-citro. Proton nuclear magnetic resonance (¹H NMR) of a mixture of 5ML and 6ML at varying temperatures showed that the chemical shifts of the hydroxyls, as well as the 5ML:6ML ratio, are temperature-dependent. Indeed, a high temperature, such as 65 °C, led to an up-field shielding of the hydroxyl protons as well as a drop in the 5ML:6ML ratio. The monomers 5ML and 6ML were then engaged in polycondensation reactions involving diacyl chlorides. Renewable copolyesters with low glass transition temperatures (as low as −67 °C) and cross-linked citronellol chains were prepared. The polymers were then hydrolyzed using a commercial lipase from Thermomyces lanuginosus (Lipopan^® 50 BG). A higher degradation rate was found for the polymers prepared using Lactol-citro molecules, compared to those obtained by the polycondensation reactions of diacyl chlorides with Triol-citro—a monomer recently obtained by the selective reduction of HBO-citro.

Anxiolytic and antidepressant-like effects of monoterpene tetrahydrolinalool and in silico approach of new potential targets

INTRODUCTION- The drugs currently available for treatment of anxiety and depression act through modulation of the neurotransmission systems involved in the neurobiology of the disorder, yet they of-ten present side effects, which can impair patient adherence to treatment. METHOD- This, has driven the search for new molecules with anxiolytic and antidepressant potential. Aromatic plants are rich in essential oils, and their chemical constituents, such as monoterpenes, are be-ing studied for these disorders. This study aims to evaluate the anxiolytic and antidepressant-like poten-tial of the monoterpene tetrahydrolinalool in in vivo animal models, and review pharmacological targets with validation through molecular docking. Male Swiss mice (Mus musculus) were treated with THL (37.5-600 mg kg-1 p.o.) and submitted to the elevated plus maze, open field, rota rod, and forced swim tests. In the elevated plus-maze, THL at doses of 37.5 and 75 mg kg-1 induced a significant increase in the percentage of entries (72.7 and 64.3% respectively), and lengths of stay (80.3 and 76.8% respective-ly) in the open arms tests. RESULT- These doses did not compromise locomotor activity or motor coordination in the animals. In the open field, rota rod tests, and the forced swimming model, treatment with THL significantly reduced immobility times at doses of 150, 300, and 600 mg kg-1, and by respective percentages of 69.3, 60.9 and 68.7%. CONCLUSION- In molecular docking assay, which investigated potential targets, THL presented sat-isfactory energy values for: nNOs, SGC, IL-6, 5-HT1A, NMDAr, and D1. These demonstrate the po-tential of THL (a derivative of natural origin) in in vivo and in silico models, making it a drug candidate.

Chemical Diversity and Potential Target Network of Woody Peony Flower Essential Oil from Eleven Representative Cultivars (Paeonia × suffruticosa Andr.)

Woody peony (Paeonia × suffruticosa Andr.) has many cultivars with genetic variances. The flower essential oil is valued in cosmetics and fragrances. This study was to investigate the chemical diversity of essential oils of eleven representative cultivars and their potential target network. Hydro-distillation afforded yields of 0.11–0.25%. Essential oils were analyzed by GC-MS and GC-FID which identified 105 compounds. Three clusters emerged from multivariate analysis, representative of phloroglucinol trimethyl ether (‘Caihui’), citronellol (‘Jingyu’, ‘Zhaofen’ and ‘Baiyuan Zhenghui’) and mixed (the rest of the cultivars) chemotypes. ‘Zhaofen’ and ‘Jingyu’ also exhibited low levels of other rose-related compounds. The main components were subjected to a target network approach. Drug-likeness screening gave 20 compounds with predictive blood–brain barrier permeation. Compound target network identified six key compounds, namely nerol, citronellol, geraniol, geranic acid, cis-3-hexen-1-ol and 1-hexanol. Top enriched terms in GO, KEGG and DisGeNET were mostly related to the central nervous system (CNS). Protein—protein interactions revealed a core network of 14 targets, 11 of which were CNS-related (targets for antidepressants, analgesics, antipsychotics, anti-Alzheimer’s and anti-Parkinson’s agents). This work provides useful information on the production of woody peony essential oils with specific chemotypes and reveals their potential importance in aromatherapy for alternative treatment of CNS disorders.

Unprecedented Biodegradable Cellulose-Derived Polyesters with Pendant Citronellol Moieties: From Monomer Synthesis to Enzymatic Degradation

Levoglucosenone (LGO) is a cellulose-derived molecule that is present commercially on a multi-ton/year scale. Taking advantage of the α,β-conjugated ketone of LGO, a new citronellol-containing 5-membered lactone (HBO-citro) was synthesized through a one-pot two-step pathway involving oxa-Michael addition and Baeyer-Villiger oxidation. The solvent-free treatment of HBO-citro with NaBH4 at room temperature led to the full reduction of the lactone moiety which gave a novel fully renewable triol monomer having a citronellol side chain (Triol-citro). Noticeably, by simply changing the reducing agent, temperature and reaction duration, the partial reduction of HBO-citro can be achieved to yield a mixture of 5- and 6-membered Lactol-citro molecules. Triol-citro was chosen to prepare functional renewable polyesters having citronellol pendant chains via polycondensation reactions with diacyl chlorides having different chain lengths. Good thermal stability (Td5% up to 170 °C) and low glass transition temperatures (as low as -42 °C) were registered for the polyesters obtained. The polymers were then hydrolyzed using a commercial lipase from Thermomyces lanuginosus (Lipopan® 50 BG) to assess their biodegradability. A higher degradation profile was found for the polyesters prepared using co-monomers (acyl chlorides) having longer chain lengths. This is likely due to the decreased steric hindrance around the ester bonds which allowed enhanced accessibility of the enzyme.

A comparative study on chemical compositions and biological activities of four essential oils: Cymbopogon citratus (DC.) Stapf, Cinnamomum cassia (L.) Presl, Salvia japonica Thunb. and Rosa rugosa Thunb

ETHNOPHARMACOLOGICAL RELEVANCE

Essential oils (EOs) are important active ingredients in Chinese herbal medicine. Cymbopogon citratus (DC.) Stapf, Cinnamomum cassia (L.) Presl, Salvia japonica Thunb., and Rosa rugosa Thunb. are used in local and traditional medicine to treat inflammation-related diseases. While the constituents and bioactivities of EOs of the above four Chinese herbals have been reported previously, but their anti-inflammatory and antioxidant activities have not been systematically evaluated.

AIM OF THE STUDY

The purpose of this study was to research the chemical constituents, anti-inflammatory activities, and antioxidant activities of EOs of four Chinese herbal medicines.

MATERIALS AND METHODS

Fresh plant materials were collected both in August 2018. The compositions of EOs were determined by the gas chromatography-mass spectrometry (GC-MS) method. TPA (12-O-tetradecylphophenol-13-acetate)-induced mouse ear model was evaluated the anti-inflammatory activities of EOs. The reduction of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), cyclooxygenase-2 (COX-2) and RelA protein of the nuclear factor kappa-B (NF-κB) in the signal pathway (P65) were measured. The antioxidant activities of EOs from four plants were determined by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging method.

RESULTS

A total of 217 compounds were separated and identified from four EOs, mainly including trans-cinnamylaldehyde (68.75%), citronellal (38.16%), linalool (1.02-33.73%), geraniol (19.39%) and citronellol (17.18%). All four EOs reduced the damage of the ear tissue and had certain anti-inflammatory effects, and the EOs of C. citratus (CyCEOs) and S. japonica (SJEOs) had the best anti-inflammatory activities among others, even better than ibuprofen. The four EOs exhibited different DPPH radical-scavenging activities (IC₅₀, 0.101-1.017%), where most of them were much lower than that of EOs of C. citratus (CiCEOs) (IC₅₀, 0.101%) and EOs of R. rugosa (RREOs) (IC₅₀, 0.142%).

CONCLUSIONS

The main components determine diverse propertise of these four EOs, our results suggested that four EOs presented anti-inflammatory and antioxidant effect via reducing the expression of TNF-a, IL-6, COX-2, and NF-κB p65, which may provide a new approach for development of new anti-inflammatory drugs.

Cascading Old Yellow Enzyme, Alcohol Dehydrogenase and Glucose Dehydrogenase for Selective Reduction of (E/Z)-Citral to (S)-Citronellol

Citronellol is a kind of unsaturated alcohol with rose-like smell and its (S)-enantiomer serves as an important intermediate for organic synthesis of (-)-cis-rose oxide. Chemical methods are commonly used for the synthesis of citronellol and its (S)-enantiomer, which suffers from severe reaction conditions and poor selectivity. Here, the first one-pot double reduction of (E/Z)-citral to (S)-citronellol was achieved in a multi-enzymatic cascade system: N-ethylmaleimide reductase from Providencia stuartii (NemR-PS) was selected to catalyze the selective reduction of (E/Z)-citral to (S)-citronellal, alcohol dehydrogenase from Yokenella sp. WZY002 (YsADH) performed the further reduction of (S)-citronellal to (S)-citronellol, meanwhile a variant of glucose dehydrogenase from Bacillus megaterium (BmGDHM6), together with glucose, drove efficient NADPH regeneration. The Escherichia coli strain co-expressing NemR-PS, YsADH, and BmGDHM6 was successfully constructed and used as the whole-cell catalyst. Various factors were investigated for achieving high conversion and reducing the accumulation of the intermediate (S)-citronellal and by-products. 0.4 mM NADP+ was essential for maintaining high catalytic activity, while the feeding of the cells expressing BmGDHM6 effectively eliminated the intermediate and by-products and shortened the reaction time. Under optimized conditions, the bio-transformation of 400 mM citral caused nearly complete conversion (>99.5%) to enantio-pure (S)-citronellol within 36 h, demonstrating promise for industrial application.

Effects of citronellol grafted chitosan oligosaccharide derivatives on regulating anti-inflammatory activity

In order to improve the anti-inflammatory activity of chitosan oligosaccharide (COS), chitosan oligosaccharide graft citronellol derivatives (COS-g-Cit1-3) were successfully synthesized via grafting citronellol (Cit) onto COS backbone. The degrees of substitution (DS) of COS-g-Cit1-3 were 0.165, 0.199 and 0.182, respectively. The structure of COS-g-Cit1-3 was confirmed by UV-vis, FT-IR, ¹H NMR and elemental analysis. The in vivo anti-inflammatory activity evaluation results displayed that COS-g-Cit1-3 drastically reduced the paw swelling, and the oedema inhibitions were 22.58 %, 29.03 % and 25.81 %, respectively. The results indicated that the anti-inflammatory effects of COS-g-Cit1-3 were significantly higher than COS and COS-g-Cit2 exhibited the highest anti-inflammatory ability. The results also presented that COS-g-Cit1-3 reduced the expression levels of TNF-α by promoting the secretion of IL-4 and IL-10. Moreover, western blot analysis data proved that COS-g-Cit1-3 inactivated the NF-κB signaling pathway via inhibiting the phosphorylation of p65, IKBα and IKKβ.

Impact of citronellol on river and soil environments using non-target model organisms and natural populations

Citronellol is an acyclic monoterpenoid with a wide range of pharmacological activities (antibacterial, antifungal, anti-lice, repellent, lipolytic, anti-allergic, anti-inflammatory, antispasmodic, antidiabetic, anti-cholesterol, among other) and potential to replace synthetic products. However, the impact of citronellol on the environment remains unknown. We analysed, for the first time, the environmental impact of citronellol on river and soil environments using non-target model organisms and natural populations. The acute toxicity of citronellol on the aquatic invertebrate Daphnia magna, the plant Allium cepa L and the earthworm Eisenia fetida was quantified. The effect of citronellol in a river ecosystem was analysed using river periphyton communities taxonomically characterised and a river microbial community characterised through 16 S rRNA gene sequencing. Finally, a microbial community from natural soil was used to monitor the effect of citronellol on the soil ecosystem. The results showed that E. fetida was most sensitive to citronellol (LC₅₀ = 12.34 mg/L), followed by D. magna (LC₅₀ = 14.11 mg/L). Citronellol affected the photosynthesis of the fluvial periphyton (LC₅₀ = 94.10 mg/L) and was phytotoxic for A. cepa. Furthermore, citronellol modified the growth and metabolism of both fluvial (LC₅₀ = 0.19% v/v) and edaphic (LC₅₀ = 5.07% v/v) bacterial populations. The metabolism of the microorganisms in the soil and water exposed to citronellol decreased with respect to the control, especially their ability to metabolise carbohydrates. Our results show that citronellol has a negative impact on the environment. Although acute effects cannot be expected, it is necessary to quantify the environmental levels as well as the long-term and persistent effects of this monoterpene.

Involvement of nuclear factor κB and descending pain pathways in the anti-hyperalgesic effect of β-citronellol, a food ingredient, complexed in β-cyclodextrin in a model of complex regional pain syndrome - Type 1

Complex regional pain syndrome type 1 (CRPS-1) is a painful syndrome without effective treatment. In order to explore possible new treatments, we used an animal model of CRPS-1 to examine the effects of β-Citronellol (βCT), a monoterpene found in a variety of plants that has been shown to have analgesic effects. We aimed to assess its effects alone, and complexed with β-cyclodextrin (βCD), which has been previously used to enhance the effects of a number of medicines. The βCT-βCD was characterized physiochemically using high performance liquid chromatography (HPLC) and differential scanning calorimetry (DSC) and shown to have 80% efficiency. In the animal model, Swiss mice were treated with βCT, βCT-βCD, vehicle, pregabalin or sham and evaluated for hyperalgesia and motor coordination. Inflammatory mediators were measured by Western blot or ELISA and the descending pain pathway by immunofluorescence. βCT was shown to have an anti-hyperalgesic effect (without affecting motor coordination) that reduced inflammatory mediators and activated the descending pain pathway, and these effects were increased with complexation in βCD. Our results showed βCT-βCD to be a promising treatment for CRPS-1.

Cymbopogon winterianus Essential Oil Attenuates Bleomycin-Induced Pulmonary Fibrosis in a Murine Model

The essential oil of Cymbopogon winterianus (EOCW) is a natural product with antioxidant, anti-inflammatory, and antifibrotic properties. We studied the effect of EOCW in the progression of histological changes of pulmonary fibrosis (PF) in a rodent model. The oil was obtained by hydrodistillation and characterized using gas chromatography–mass spectrometry. Intratracheal instillation of bleomycin was performed in 30 rats to induce PF, while Sham animals were subjected to instillation of saline solution. The treatment was performed using daily oral administration of distilled water, EOCW at 50, 100, and 200 mg/kg, and deflazacort (DFC). After 28 days, hemogram and bronchoalveolar lavage fluid (BALF), tissue levels of malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT) were assayed. Histological grading of PF, immunohistochemical expression of α-smooth muscle actin (α-SMA), and transforming growth factor-β (TGF-β) were also analyzed. The EOCW major compounds were found to be citronellal, geraniol, and citronellol. EOCW significantly reduced inflammation in BALF, reduced MDA levels, and increased SOD activity. EOCW attenuated histological grading of PF and reduced immunohistochemical expression of α-SMA and TGF-β in a dose-dependent way, likely due to the reduction of oxidative stress, inflammation, and TGF-β-induced myofibroblast differentiation.

A "push-pull-restrain" strategy to improve citronellol production in Saccharomyces cerevisiae

Microbial production of monoterpenes has attracted increasing attention in recent years. Up to date, there are only few reports on the biosynthesis of the monoterpene alcohol citronellol that is widely used as fragrant and pharmaceutical intermediates. Here, we engineered Saccharomyces cerevisiae by employing a "push-pull-restrain" strategy to improve citronellol production based on the reduction of geraniol. Starting from a engineered geraniol-producing strain, different reductases were investigated and the best performing iridoid synthase from Catharanthus roseus (CrIS) resulted in 285.89 mg/L enantiomerically pure S-citronellol in shake flasks. Geranyl diphosphate (GPP), the most important precursor for monoterpenes, was enhanced by replacing the wild farnesyl diphosphate synthase (Erg20) with the mutant Erg20^F96W, increasing the citronellol titer to 406.01 mg/L without negative influence on cell growth. Moreover, we employed synthetic protein scaffolds and protein fusion to colocalize four sequential enzymes to achieve better substrate channeling along with the deletion of an intermediate degradation pathway gene ATF1, which elevated the citronellol titer to 972.02 mg/L with the proportion of 97.8% of total monoterpenes in YPD medium. Finally, the engineered strain with complemented auxotrophic markers produced 8.30 g/L of citronellol by fed-batch fermentation, which was the highest citronellol titer reported to date. The multi-level engineering strategies developed here demonstrate the potential of monoterpenes overproduction in yeast, which can serve as a generally applicable platform for overproduction of other monoterpenes.

Citrus hystrix Extracts Protect Human Neuronal Cells against High Glucose-Induced Senescence

Citrus hystrix (CH) is a beneficial plant utilized in traditional folk medicine to relieve various health ailments. The antisenescent mechanisms of CH extracts were investigated using human neuroblastoma cells (SH-SY5Y). Phytochemical contents and antioxidant activities of CH extracts were analyzed using a gas chromatograph–mass spectrometer (GC-MS), 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) assay and 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) assay. Effects of CH extracts on high glucose-induced cytotoxicity, reactive oxygen species (ROS) generation, cell cycle arrest and cell cycle-associated proteins were assessed using a 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide tetrazolium (MTT) assay, non-fluorescent 2′, 7′-dichloro-dihydrofluorescein diacetate (H₂DCFDA) assay, flow cytometer and Western blot. The extracts protected neuronal senescence by inhibiting ROS generation. CH extracts induced cell cycle progression by releasing senescent cells from the G1 phase arrest. As the Western blot confirmed, the mechanism involved in cell cycle progression was associated with the downregulation of cyclin D1, phospho-cell division cycle 2 (pcdc2) and phospho-Retinoblastoma (pRb) proteins. Furthermore, the Western blot showed that extracts increased Surtuin 1 (SIRT1) expression by increasing the phosphorylation of Glyceraldehyde 3-phosphate dehydrogenase (GAPDH). Collectively, CH extracts could protect high glucose-induced human neuronal senescence by inducing cell cycle progression and up-regulation of SIRT1, thus leading to the improvement of the neuronal cell functions.

Eplingiella fruticosa (Lamiaceae) essential oil complexed with β-cyclodextrin improves its anti-hyperalgesic effect in a chronic widespread non-inflammatory muscle pain animal model

Eplingiella fruticosa (Lamiaceae), formally known as Hyptis fruticosa, is an important aromatic medicinal herb used in folk medicine in northeastern Brazil. We aimed to evaluate the anti-hyperalgesic effect of essential oil obtained from E. fruticosa (HypEO) complexed with βCD (HypEO-βCD) in a chronic widespread non-inflammatory muscle pain animal model (a mice fibromyalgia-like model, FM). The HypEO was extracted by hydro distillation and its chemical composition was determined by GC-MS/FID. Moreover, Fos protein expression in the spinal cord was assessed by immunofluorescence. (E)-caryophyllene, bicyclogermacrene, 1,8-cineole, α-pinene, β-pinene and 21 other compounds were identified in the HypEO. The treatment with HypEO-βCD produced a longer-lasting anti-hyperalgesic effect compared to HypEO, without alterations in motor coordination or myorelaxant effects. Moreover, HypEO and HypEO-βCD produced a significant anti-hyperalgesic effect over 7 consecutive treatment days. Immunofluorescence assay demonstrated a decrease in Fos protein expression in the spinal cord (p < 0.001). We demonstrated that the anti-hyperalgesic effect produced by HypEO was improved after complexation with β-CD and this seems to be related to the central pain-inhibitory pathway, suggesting the possible use of E. fruticosa for chronic pain management.

Antimicrobial and antioxidant activities of hydrocarbon and oxygenated monoterpenes against some foodborne pathogens through in vitro and in silico studies

The present work describes the antimicrobial action of 25 monoterpenes (six hydrocarbons, five ketones, two aldehydes, six alcohols and six acetate analogues) against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus and antifungal activity against Aspergillus flavus. The antibacterial activity was evaluated by broth microdilution technique as a minimum inhibitory concentration (MIC) and the antifungal activity was performed by mycelia radial growth technique as the effective concentration causing 50% inhibition of the mycelial growth (EC₅₀). The results showed that thymol and α-terpineol were the most potent against E. coli (MIC = 45 and 55 mg/L, respectively) and S. aureus (MIC = 135 and 225 mg/L, respectively). The results also showed that thymol displayed the maximum antifungal action against A. flavus with EC₅₀ 20 mg/L. Furthermore, the antioxidant activity was determined using N,N-dimethyl-1,4-phenylenediamine (DMPD) and the results showed that geraniol were the most potent compound (IC₅₀ = 19 mg/L). Molecular docking studies indicated that the compounds displayed different binding interactions with the amino acid residues at the catalytic sites of N5-carboxyaminoimidazole synthetase and oxysterol binding protein Osh4 enzymes. Non-covalent interactions including van der Waals, hydrogen bonding as well as hydrophobic were observed between the compounds and the enzymes. A significant relationship was found between the docking score and the biological activity of the tested monoterpenes compared to the ceftriaxone and carbendazim as standard bactericide and fungicide, respectively. In silico ADMET properties were also performed and displayed potential for the development of promising antimicrobial agents. For these reasons, these compounds may be considered as potential ecofriendly alternatives in food preservation to delay or prevent the microbial infection and prolong the shelf life of food products.