Influence of Chewing Rate and Food Composition on in Vivo Aroma Release and Perception of Composite Foods.

This study investigated the effects of chewing rate and food composition on in vivo aroma release and perception of composite foods. Bread or sponge cake paired with varying sugar content and viscosity strawberry jams, spiked with citral and limonene, were examined. In-nose release was characterized using Proton-Transfer-Reaction-Time-of-Flight-Mass-Spectrometry (PTR-ToF-MS). Simultaneously, Time-Intensity (TI) profiling assessed citrus aroma perception (n = 8, triplicate) while fast and slow chewing protocols were applied (fast: 1.33 chews/s; slow 0.66 chews/s; each for 25 s). Chewing rate did not significantly impact the area under the curve and maximum intensity of in vivo citral and limonene release and citrus aroma perception. Faster chewing rates significantly decreased the time to reach maximum intensity of aroma release (p < 0.05) and citrus aroma perception (p < 0.001). Faster chewing rates probably accelerated structural breakdown, inducing an earlier aroma release and perception without affecting aroma intensity. Adding carriers to jams significantly (p < 0.05) increased aroma release, while perceived citrus aroma intensity significantly (p < 0.05) decreased regardless of chewing rate. In conclusion, chewing rate affects the temporality of in vivo aroma release and perception without affecting its intensity, and carrier addition increases in vivo aroma release while diminishing aroma perception.

Antimicrobial activity of geranium (Pelargonium graveolens) essential oil and its encapsulation in carioca bean starch ultrafine fibers by electrospinning.

Geranium (Pelargonium graveolens) is known for being an aromatic plant rich in bioactive compounds with antibacterial properties. In this study, geranium essential oil (GEO) was extracted and encapsulated in ultrafine bean starch fibers produced by electrospinning as an antibacterial agent. GEO revealed a composition rich in volatile compounds, including citronellol, cis-geraniol, ß-linalool, citronellyl formate, and linalool formate. In its free form, GEO exhibited high antibacterial activity against pathogenic bacteria strains (L. monocytogenes, S. aureus, and E. coli). The bean starch fibers, produced with and without the addition of GEO, were uniform and continuous, with an average diameter ranging from 249 to 373 nm. Confocal analysis indicated a uniform distribution of GEO in the fibers, with a loading capacity of 54.0 %, 42.9 %, and 36.5 % for 20 %, 30 %, and 40 % GEO concentrations, respectively. Remarkably, fibers containing 40 % GEO showed a significant reduction in tested bacteria (L. monocytogenes, S. aureus, and E. coli), suggesting promising applications in preventing losses and extending the shelf life of food through active packaging.

Revealing the mechanism of citral induced entry of Vibrio vulnificus into viable but not culturable (VBNC) state based on transcriptomics.

Citral has attracted much attention as a safe and effective plant-derived bacteriostatic agent. However, the ability of citral to induce the formation of VBNC state in Vibrio vulnificus has not been evaluated. In the present study, V. vulnificus was shown to be induced to form the VBNC state at 4.5 h and 3 h of citral treatment at 4MIC and 6MIC. Moreover, the citral-induced VBNC state of V. vulnificus maintained some respiratory chain activity and was able to recover well in both APW media, APW media supplemented with 5 % (v/v) Tween 80 and 2 mg/mL sodium pyruvate. Field emission and transmission electron microscopy showed that the external structure of the citral-induced VBNC V. vulnificus cells was shortened to short rods, with folded cell membrane, rough cell surface, and dense cytoplasm and loose nuclear material in the internal cell structure. In addition, the possible molecular mechanisms of citral-induced formation and recovery of V. vulnificus in the VBNC state were explored by transcriptomics. Transcriptome analyses revealed that 1118 genes were significantly altered upon entry into the VBNC state, and 1052 genes were changed after resuscitation. Most of the physiological activities related to energy production were inhibited in the citral-induced VBNC state of V. vulnificus; however, the bacteria retained its pathogenicity. The citral-induced resuscitation of V. vulnificus in the VBNC state selectively restored the activity of some genes related to bacterial growth and reproduction. Meanwhile, the expression levels of other genes may have been influenced by citral-induced resuscitation after the formation of the VBNC state. In conclusion, this study evaluated and analyzed the ability and possible mechanism of citral on the formation of VBNC state and the recovery of VBNC state of V. vulnificus, and made a comprehensive assessment for the safety of citral application in food production.

Covalent modification of γ-cyclodextrin with geraniol: An antibacterial agent with good thermal stability, solubility and biocompatibility.

Geraniol (Ger) is an essential oil molecule with excellent biological activity. High hydrophobicity and volatility limit its practical application. Cyclodextrins (CDs) are water-soluble cyclic oligosaccharides with hydrophobic cavities. Physical encapsulation of CDs to improve the solubility and stability of essential oil molecules is not satisfactory. Therefore, this study synthesized the γ-CD derivative (γ-CD-Ger) by grafting Ger onto γ-CD using a bromide-mediated method. Compared to the inclusion complexes (γ-CD/Ger) formed by both, the derivatives exhibit better solubility and thermal stability. The derivative has better antibacterial activity when the ratio of γ-CD to Ger was 1:2. In addition, the derivatives did not exhibit cytotoxic and hemolytic properties. These results indicate that this research provides a water-soluble antibacterial agent with a wide range of promising applications and offers new ideas for the application of alcohol hydrophobic molecules in aqueous systems.

Enhancing acid stability of citral through internal structure modulation in nanostructured lipid carriers with solid lipids and phospholipids.

In this current study, the internal structure of nanostructured lipid carriers was modulated by phospholipids (lecithin PC, hydrogenated soybean phospholipid HPC) and solid lipids to achieve stable encapsulation of citral. The presence of high melting point HPC could construct α-crystalline type with more lattice defects and effectively inhibit ß-ization. The HPC group could maintain the particle size at 155.9-186.9 nm, the polydispersity index (PDI) at 0.182-0.321, the Zeta potential at -57.58 mV to -49.35 mV and the retention rate of citral at 91.33-98.49 % in the acidic environments of 2 mM and 20 mM hydrochloric acid solutions. The recrystallization index (RI) of NLC increased with the number of solid lipid ester bonds (from 3.57 % to 16.58 % in the PC group and from 0.82 % to 12.47 % in the HPC group). The results illustrated that the number of solid lipid ester bonds and the melting point of phospholipids affected crystallinity of the lipid matrix and thus the stability of encapsulated citral. Hydrogenated phospholipid with high melting points was more beneficial in stabilizing citral. The present study improved the acidic stability of citral and provided a new thought for the application of citral in acidic beverages.

Comparative analysis of chemical profiles, antioxidant, antibacterial, and anticancer effects of essential oils of two Thymus species from Montenegro.

The essential oils of Thymus vulgaris (TVEO) and Thymus serpyllum (TSEO) show different biological activities. The aim of the study was to evaluate the biological activities of TVEO and TSEO from Montenegro. The main components of TVEO were p-cymene (29.52%), thymol (22.8%) and linalool (4.73%) while the main components of TSEO were p-cymene (19.04%), geraniol (11,09%), linalool (9.16%), geranyl acetate (6.49%) and borneol (5.24%). Antioxidant activity determined via DPPH for TVEO was 4.49 and FRAP 1130.27, while for TSEO it was estimated that DPPH was 4.88 µL/mL and FRAP was 701.25 µmol FRAP/L. Both essential oils were active against all tested bacteria, with the highest level of sensitivity of E. coli with MIC of 1.5625 µL/mL. Essential oils showed strong cytotoxic effects on human cancer cell lines, with IC50 values ranging from 0.20 to 0.24 µL/mL for TVEO and from 0.32 to 0.49 µL/mL for TSEO. TVEO caused apoptosis in cervical adenocarcinoma HeLa cells through activation of caspase-3 and caspase-8, while TSEO caused apoptosis through caspase-3. EOs decreased levels of oxidative stress in normal MRC-5 cells. HeLa cells treated with TVEO had reduced MMP2 expression levels, while cells treated with TSEO had lowered MMP2 and MMP9 levels. The treatment of HeLa cells with TVEO increased the levels of miR-16 and miR-34a, indicating potential tumor-suppressive properties. Our findings suggest that Thymus essential oils may be considered as good candidates for further investigation as cancer-chemopreventive and cancer-therapeutic agents.

Geraniol attenuates oxidative stress and neuroinflammation-mediated cognitive impairment in D galactose-induced mouse aging model.

D-galactose (D-gal) administration was proven to induce cognitive impairment and aging in rodents' models. Geraniol (GNL) belongs to the acyclic isoprenoid monoterpenes. GNL reduces inflammation by changing important signaling pathways and cytokines, and thus it is plausible to be used as a medicine for treating disorders linked to inflammation. Herein, we examined the therapeutic effects of GNL on D-gal-induced oxidative stress and neuroinflammation-mediated memory loss in mice. The study was conducted using six groups of mice (6 mice per group). The first group received normal saline, then D-gal (150 mg/wt) dissolved in normal saline solution (0.9%, w/v) was given orally for 9 weeks to the second group. In the III group, from the second week until the 10th week, mice were treated orally (without anesthesia) with D-gal (150 mg/kg body wt) and GNL weekly twice (40 mg/kg body wt) four hours later. Mice in Group IV were treated with GNL from the second week up until the end of the experiment. For comparison of young versus elderly mice, 4 month old (Group V) and 16-month-old (Group VI) control mice were used. We evaluated the changes in antioxidant levels, PI3K/Akt levels, and Nrf2 levels. We also examined how D-gal and GNL treated pathological aging changes. Administration of GNL induced a significant increase in spatial learning and memory with spontaneously altered behavior. Enhancing anti-oxidant and anti-inflammatory effects and activating PI3K/Akt were the mechanisms that mediated this effect. Further, GNL treatment upregulated Nrf2 and HO-1 to reduce oxidative stress and apoptosis. This was confirmed using 99mTc-HMPAO brain flow gamma bioassays. Thus, our data suggested GNL as a promising agent for treating neuroinflammation-induced cognitive impairment.

Protective role of citronellol on antioxidant enzymes and oxidative damage induced by gentamicin in experimental nephrotoxic rats.

BACKGROUND: Gentamicin leads to nephrotoxicity with increasing oxidative stress. In the present research the role of citronellol on oxidative damage induced by gentamicin in nephrotoxic rats was evaluated. METHODS AND RESULTS: Forty-twomale Wistar rats were randomly divided into seven equal groups; healthy control, gentamicin, DMSO, citronellol 50, citronellol 100, citronellol 200 and vitamin E. The animals were anesthetized after 12 days of treatment. Kidney and serum samples were received for biochemical, histological changes, and gene expression assessments. The levels of serum glutathione (GSH), serum and kidney glutathione peroxidase (GPX) and the expression of GPX gene against gentamicin group were increased in citronellol treatment groups. The levels of serum and kidney malondialdehyde (MDA), urine protein, serum creatinine and the gene expression of inflammatory factors including tumor necrosis factor-alpha (TNF-α) and Interleukin 6 (IL-6) against gentamicin group were decreased in these groups. Moreover, recuperation in histological alterations was shown in three groups receiving citronellol compared to the gentamicin group. CONCLUSIONS: Citronellol with its antioxidant and anti-inflammatory properties can decrease kidney damage caused by nephrotoxicity induced by gentamicin.

Linalool, a Fragrance Compound in Plants, Protects Dopaminergic Neurons and Improves Motor Function and Skeletal Muscle Strength in Experimental Models of Parkinson's Disease.

Parkinson's disease (PD) is a common neurodegenerative disorder characterized by the gradual loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc), resulting in reduced dopamine levels in the striatum and eventual onset of motor symptoms. Linalool (3,7-dimethyl-1,6-octadien-3-ol) is a monoterpene in aromatic plants exhibiting antioxidant, antidepressant, and anti-anxiety properties. The objective of this study is to evaluate the neuroprotective impacts of linalool on dopaminergic SH-SY5Y cells, primary mesencephalic and cortical neurons treated with 1-methyl-4-phenylpyridinium ion (MPP+), as well as in PD-like mice induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Cell viability, α-tubulin staining, western blotting, immunohistochemistry and behavioral experiments were performed. In MPP+-treated SH-SY5Y cells, linalool increased cell viability, reduced neurite retraction, enhanced antioxidant defense by downregulation of apoptosis signaling (B-cell lymphoma 2 (Bcl-2), cleaved caspase-3 and poly ADP-ribose polymerase (PARP)) and phagocyte NADPH oxidase (gp91phox), as well as upregulation of neurotrophic signaling (brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF)) and nuclear factor-erythroid 2 related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway. In MPP+-treated primary mesencephalic neurons, linalool enhanced the expressions of tyrosine hydroxylase (TH), Sirtuin 1 (SirT1), and parkin. In MPP+-treated primary cortical neurons, linalool upregulated protein expression of SirT1, γ-Aminobutyric acid type A-α1 (GABAA-α1), and γ-Aminobutyric acid type B (GABAB). In PD-like mice, linalool attenuated the loss of dopamine neurons in SNpc. Linalool improved the motor and nonmotor behavioral deficits and muscle strength of PD-like mice. These findings suggest that linalool potentially protects dopaminergic neurons and improves the impairment symptoms of PD.

Evaluation of the Antimicrobial Activity of Geraniol and Selected Geraniol Transformation Products against Gram-Positive Bacteria.

Both geraniol and the products of its transformation, thanks to their beneficial properties, find a variety of applications in cosmetics. Due to their antioxidant and moisturizing properties, these compounds can be added to skin care products such as face creams, lotions, oils, and masks. In addition, these compounds show some antibacterial and antifungal properties, making them suitable for application in skin care products to help fight against bacteria or fungi. This study determined the antimicrobial activity of geraniol and the compounds which were formed during its transformation in relation to selected Gram-positive bacteria, and the preliminary assessment was made whether these compounds can act as ingredients of preparations with potential antimicrobial activity in the treatment of various human diseases (for example diseases of the skin, digestive system, or urinary tract). In addition, this work presents studies on the microbiological purity of cream samples obtained with different contents of geraniol and its transformation products (contents of the tested compounds: 0.5%, 1.5%, 2.5%, 4%, 8%, and 12%). Antibacterial activity tests were performed using the disc diffusion method against Gram-positive cocci, including the reference strains Staphylococcus aureus ATCC 29213 and Enterococcus faecalis ATCC 29212, and against the clinical strains Staphylococcus aureus MRSA, Staphylococcus epidermidis, Enterococcus faecalis VRE VanB, Enterococcus faecium VRE VanA, and Enterococcus faecium VRE VanB. The most active ingredient against bacteria of the Staphylococcus genus was citral, followed by linalool and then geraniol. During our tests, in the case of bacteria of the Enterococcus genus, citral also showed the highest activity, but linalool, ocimenes, and geraniol showed a slightly lower activity. Moreover, this study examined the microbiological purity of cream samples obtained with various contents of geraniol and its transformation products. In the tests of the microbiological purity of cream samples, no growth of aerobic bacteria and fungi was found, which proves the lack of microbiological contamination of the obtained cosmetic preparations. On this basis, it was assessed that these compounds have preservative properties in the prepared creams. The addition of the analyzed compounds also had influence on the durability of the creams and had no effect on the change in their consistency, did not negatively affect the separation of phases during storage, and even had a positive effect on organoleptic sensations by enriching the smell of the tested samples.

LiNAC100 contributes to linalool biosynthesis by directly regulating LiLiS in Lilium 'Siberia'.

MAIN CONCLUSION: The transcription factor LiNAC100 has a novel function of regulating floral fragrance by directly regulating linalool synthase gene LiLiS. Lilium 'Siberia', an Oriental hybrid, is renowned as both a cut flower and garden plant, prized for its color and fragrance. The fragrance comprises volatile organic compounds (VOCs), primarily monoterpenes found in the plant. While the primary terpene synthases in Lilium 'Siberia' were identified, the transcriptional regulation of these terpene synthase (TPS) genes remains unclear. Thus, understanding the regulatory mechanisms of monoterpene biosynthesis is crucial for breeding flower fragrance, thereby improving ornamental and commercial values. In this study, we isolated a nuclear-localized LiNAC100 transcription factor from Lilium 'Siberia'. The virus-induced gene silencing (VIGS) of LiNAC100 was found to down-regulate the expression of linalool synthase gene (LiLiS) and significantly inhibit linalool synthesis. Conversely, transient overexpression of LiNAC100 produced opposite effects. Additionally, yeast one-hybrid and dual-luciferase assays confirmed that LiNAC100 directly activates LiLiS expression. Our findings reveal that LiNAC100 plays a key role in monoterpene biosynthesis in Lilium 'Siberia', promoting linalool synthesis through the activation of LiLiS expression. These results offer insights into the molecular mechanisms of terpene biosynthesis in Lilium 'Siberia' and open avenues for biotechnological enhancement of floral scent.

N-terminal truncation (N-) and directional proton transfer in an old yellow enzyme enables tunable efficient producing (R)- or (S)-citronellal.

(R)-Citronellal is a valuable molecule as the precursor for the industrial synthesis of (-)-menthol, one of the worldwide best-selling compounds in the flavors and fragrances field. However, its biocatalytic production, even from the optically pure substrate (E)-citral, is inherently limited by the activity of Old Yellow Enzyme (OYE). Herein, we rationally designed a different approach to increase the activity of OYE in biocatalytic production. The activity of OYE from Corynebacterium glutamicum (CgOYE) is increased, as well as superior thermal stability and pH tolerance via truncating the different lengths of regions at N-terminal of CgOYE. Next, we converted the truncation mutant N31-CgOYE, a protein involved in proton transfer for the asymmetric hydrogenation of CC bonds, into highly (R)- and (S)-stereoselective enzymes using only three mutations. The mixture of racemic (E/Z)-citral is reduced into the (R)-citronellal with ee and conversion up to 99 % by the mutant of CgOYE, overcoming the problem of the reduction for the mixtures of (E/Z)-citral in biocatalytic reaction. The present work provides a general and effective strategy for improving the activity of OYE, in which the partially conserved histidine residues provide "tunable gating" for the enantioselectivity for both the (R)- and (S)-isomerases.

The behavioral sensitivity of mice to acyclic, monocyclic, and bicyclic monoterpenes.

Monoterpenes are a large class of naturally occurring fragrant molecules. These chemicals are commonly used in olfactory studies to survey neural activity and probe the behavioral limits of odor discrimination. Monoterpenes (typically in the form of essential oils) have been used for centuries for therapeutic purposes and have pivotal roles in various biological and medical applications. Despite their importance for multiple lines of research using rodent models and the role of the olfactory system in detecting these volatile chemicals, the murine sensitivity to monoterpenes remains mostly unexplored. We assayed the ability of C57BL/6J mice to detect nine different monoterpenes (the acyclic monoterpenes: geraniol, citral, and linalool; the monocyclic monoterpenes: r-limonene, s-limonene, and γ-terpinene; and the bicyclic monoterpenes: eucalyptol, α-pinene, and ß-pinene) using a head-fixed Go / No-Go operant conditioning assay. We found that mice can reliably detect monoterpene concentrations in the low parts per billion (ppb) range. Specifically, mice were most sensitive to geraniol (threshold: 0.7 ppb) and least sensitive to γ-terpinene (threshold: 18.1 ppb). These estimations of sensitivity serve to set the lower limit of relevant monoterpene concentrations for functional experiments in mice. To define an upper limit, we estimated the maximum concentrations that a mouse may experience in nature by collating published headspace analyses of monoterpene concentrations emitted from natural sources. We found that natural monoterpenes concentrations typically ranged from ~1 to 1000 ppb. It is our hope that this dataset will help researchers use appropriate monoterpene concentrations for functional studies and provide context for the vapor-phase delivery of these chemicals in studies investigating their biological activity in mice.

Transcriptome Analysis Provides Insights into Catalpol Biosynthesis in the Medicinal Plant Rehmannia glutinosa and the Functional Characterization of RgGES Genes.

Rehmannia glutinosa, a member of the Scrophulariaceae family, has been widely used in traditional Chinese medicine since ancient times. The main bioactive component of R. glutinosa is catalpol. However, the biogenesis of catalpol, especially its downstream pathway, remains unclear. To identify candidate genes involved in the biosynthesis of catalpol, transcriptomes were constructed from R. glutinosa using the young leaves of three cultivars, Beijing No. 3, Huaifeng, and Jin No. 9, as well as the tuberous roots and adventitious roots of the Jin No. 9 cultivar. As a result, 71,142 unigenes with functional annotations were generated. A comparative analysis of the R. glutinosa transcriptomes identified over 200 unigenes of 13 enzymes potentially involved in the downstream steps of catalpol formation, including 9 genes encoding UGTs, 13 for aldehyde dehydrogenases, 70 for oxidoreductases, 44 for CYP450s, 22 for dehydratases, 30 for decarboxylases, 19 for hydroxylases, and 10 for epoxidases. Moreover, two novel genes encoding geraniol synthase (RgGES), which is the first committed enzyme in catalpol production, were cloned from R. glutinosa. The purified recombinant proteins of RgGESs effectively converted GPP to geraniol. This study is the first to discover putative genes coding the tailoring enzymes mentioned above in catalpol biosynthesis, and functionally characterize the enzyme-coding gene in this pathway in R. glutinosa. The results enrich genetic resources for engineering the biosynthetic pathway of catalpol and iridoids.

Identification of Volatile Compounds and Terpene Synthase (TPS) Genes Reveals ZcTPS02 Involved in ß-Ocimene Biosynthesis in Zephyranthes candida.

Zephyranthes candida is a frequently cultivated ornamental plant containing several secondary metabolites, including alkaloids, flavonoids, and volatile organic compounds (VOCs). However, extensive research has been conducted only on non-VOCs found in the plant, whereas the production of VOCs and the molecular mechanisms underlying the biosynthesis of terpenes remain poorly understood. In this study, 17 volatile compounds were identified from Z. candida flowers using gas chromatography-mass spectrometry (GC-MS), with 16 of them being terpenoids. Transcriptome sequencing resulted in the identification of 17 terpene synthase (TPS) genes; two TPS genes, ZcTPS01 and ZcTPS02, had high expression levels. Biochemical characterization of two enzymes encoded by both genes revealed that ZcTPS02 can catalyze geranyl diphosphate (GPP) into diverse products, among which is ß-ocimene, which is the second most abundant compound found in Z. candida flowers. These results suggest that ZcTPS02 plays a vital role in ß-ocimene biosynthesis, providing valuable insights into terpene biosynthesis pathways in Z. candida. Furthermore, the expression of ZcTPS02 was upregulated after 2 h of methyl jasmonate (MeJA) treatment and downregulated after 4 h of the same treatment.

Anticonvulsant effect of (±) citronellal possibly through the GABAergic and voltage-gated sodium channel receptor interaction pathways: In vivo and in silico studies.

This study aimed to investigate the anticonvulsant effects of citronellal (CIT) and possible underlying mechanisms through an isoniazid (INH)-induced seizure (convulsion) via in vivo and in silico studies. For this, convulsions were induced by the oral administration of INH (300 mg/kg) to the mice. The animals were treated orally with different doses of CIT (50, 100, and 200 mg/kg). Vehicle served as a negative control (NC), while diazepam (DZP) (2 mg/kg) and carbamazepine (CAR) (80 mg/kg) were provided (p.o.) as positive controls (PC). A combination therapy of CIT (middle dose) with DZP and CAR was also given to two separate groups of animals to estimate the synergistic or antagonistic effects. Molecular docking and visualization of ligand-receptor interactions are also estimated through different computational tools. The results of the in vivo study showed that CIT dose-dependently significantly (p < 0.05) exhibited a higher onset of seizures while reducing the frequency and duration of seizures in mice compared to the NC group. Besides these, in combination therapy, CIT significantly antagonized the activity of CAR and DZP, leading to a reduction in the onset of seizures and an increase in their frequency and duration compared to treatment with CAR and DZP alone. Additionally, molecular docking revealed that the CIT exhibited a moderate binding affinity (-5.8 kcal/mol) towards the GABAA receptor and a relative binding affinity (-5.3 kcal/mol) towards the voltage-gated sodium channel receptor by forming several bonds. In conclusion, CIT showed moderate anticonvulsant activity in INH-induced convulsion animals, possibly by enhancing GABAA receptor activity and inhibiting the voltage-gated sodium channel receptor.

Anti-breast cancer activity of the essential oil from grapefruit mint (Mentha suaveolens × piperita).

Grapefruit mint (Mentha suaveolens × piperita) is a hybrid, perennial, and aromatic plant widely cultivated all over the world and used in the food, cosmetics, and pharmaceutical industries mostly for its valuable essential oil. Herein, we evaluated the anticancer activity of the grapefruit mint essential oil, cultivated in Iran. For the chemical composition analysis of essential oil, GC-MS was used. MTT assay was utilized for assessing the cytotoxic activity of the essential oil. The type of cell death was determined by annexin V/PI staining. Essential oil effect on the expression of maternally expressed gene 3 (MEG3), a regulatory lncRNA involved in cell growth, proliferation, and metastasis, was studied using qRT-PCR. Linalool (43.9%) and linalool acetate (40.1%) were identified as the dominant compounds of essential oil. Compared with MCF-7, the MDA-MB-231 cells were more sensitive to essential oil (IC50 = 7.6 µg/ml in MCF-7 and 5.9 µg/ml in MDA-MB-231 after 48 h). Essential oil induced cell death by apoptosis. Wound healing scratch assay confirmed the anti-invasive effect of essential oil. In addition, essential oil upregulated the tumor suppressor MEG3 in breast cancer cells. These results provide new insights into grapefruit mint essential oil potential application as an anticancer adjuvant in combination treatments for breast cancer patients.

Schiff base linkage of citral to zinc-casein hydrolysate chelates for preparing starch-based active films against L. monocytogenes on ready-to-eat foods.

Listeria monocytogenes (L. monocytogenes) is a foodborne pathogen often found in ready-to-eat (RTE) foods, posing significant threats to human health. In this study, an active film based on cross-linking via Schiff base and electrostatic interaction to inactivate L. monocytogenes on RTE foods was constructed. Zinc-casein hydrolysate chelates (Zn-HCas) was prepared and blended with cationic starch (CSt) to form the substrates of the film. Then, Citral (CI) with excellent antibacterial properties was added to enhance the biological and packaging properties of the film through covalent cross-linking (Schiff base). Based on the zinc ion-activated metalloproteinases produced by L. monocytogenes, the cross-linked film could be disrupted and the release of CI was accelerated. The variation in color, FTIR, and amino group content proved that Schiff base reaction had taken place. Enhanced mechanical properties, barrier properties, thermal stability and antimicrobial activity against L. monocytogenes (exceed 99.99 %) were obtained from the CI/Zn-HCas/CSt film. The application on RTE cheese results demonstrated that the cross-linked film could be employed in active packaging field with the ability in maintaining the original chroma and texture properties of RTE cheese. In summary, the prepared cross-linked film could be used as an active packaging against L. monocytogenes contamination with great potential.

Biological effects of Lippia alba essential oil against Anopheles gambiae and Aedes aegypti.

The management of mosquito resistance to chemical insecticides and the biting behaviour of some species are motivating the search for complementary and/or alternative control methods. The use of plants is increasingly considered as a sustainable biological solution for vector control. The aim of this study was to evaluate the biological effects of the essential oil (EO) of Lippia alba harvested in Abidjan (Côte d'Ivoire) against Anopheles gambiae and Aedes aegypti mosquitoes. Phytochemical compounds were identified by GC-MS. Knockdown and mortality were determined according to the WHO test tube protocol. Contact irritancy was assessed by observing the movement of mosquitoes from a treated WHO tube to a second untreated tube. Non-contact repellency was assessed using a standardised high-throughput screening system (HITSS). Blood meal inhibition was assessed using a membrane feeding assay treated with EO. The EO was identified as the citral chemotype. The EO gave 100% KD60 in both species at a concentration of 1%. Mortalities of 100% were recorded with An. gambiae and Ae. aegypti at concentrations of 1% and 5% respectively. The highest proportions of females escaping during the contact irritancy test were 100% for An. gambiae at 1% concentration and 94% for Ae. aegypti at 2.5% concentration. The 1% concentration produced the highest proportions of repelled mosquitoes in the non-contact repellency tests: 76.8% (An. gambiae) and 68.5% (Ae. aegypti). The blood meal inhibition rate at a dose of 10% was 98.4% in Ae. aegypti but only 15.5% in An. gambiae. The citral chemotype of L. alba EO has promising biological effects in both species that make it a potentially good candidate for its use in mosquito control. The results obtained in this study encourage the further evaluation of L. alba EOs from other localities and of different chemotypes, under laboratory and field conditions.

Bioactive chitosan-citral Schiff base zinc complex: A pH-responsive platform for potential therapeutic applications.

The application of CO2 supercritical fluid (SCF) technology has developed rapidly because of its non-toxic, environmentally friendly, mild reaction conditions and safety. The SCF technology can effectively speed up the reaction process of nano-material synthesis, and maintains a high degree of controllability and repeatability. This study mainly included carboxymethyl chitosan sodium salt (CCS), citral (CT), p-coumaric acid (CA), and ZnSO4 as raw materials to prepare CCS-CT-CA-Zn complex as a pH-responsive agent and was investigated using supercritical fluid technique. The coordination structure of Bridge-CCS-CT-CH3COO-CA-Zn-Schiff base/OH and the morphology of the complex agents were verified. The prepared CCS-CT-CA-Zn complex showed good dispersion and uniformity (mean size: 852 ± 202 nm, PdI: 0.301, and mean zeta potential: -31 ± 6 mV). Also, it has a good pH responsive release in an acid environment. Besides, both of CCS-CT-CA-Zn complex (DS-B) and its decomposed mixture in acid (DS-A) demonstrated significant antioxidant and anti-vibrio activity. Moreover, both DS-B complex and DS-A mixture inhibited biofilm formation, swimming, and swarming motilities of V. parahaemolyticus in a dose-dependent manner. This work will provide a scientific basis for the further design and development of natural products derived antibacterial-antioxidant complex agents, food additives and feed additives.