Objective: Persistence of postprandial hyperglycemia causes elevation of glycative stress. The purpose of this study was to examine the suppressing effect of lemon juice on postprandial hyperglycemia when ingesting cooked rice, thereby, the changes in blood glucose (BG) levels were compared and verified, based on an intake of cooked rice alone as a standard, when lemon juice was ingested before cooked rice. Methods: Subjects were 12 healthy males and females aged 20 to 30 years old who participated in a briefing session held in advance and provided written consent. The changes in BG level were verified between three test foods as follows: when the cooked rice was ingested alone (A), 15 g of lemon juice was ingested before the rice (B), and 30 g of lemon juice was ingested before the rice (C). Lemon juice was ingested after diluting it with 150 mL of water. FreeStyle Libre Pro was used for the test, and the measured glucose concentration in the interstitial fluid was taken as the BG level. The BG levels evaluated were collected before ingesting the test food (0 min), 15, 30, 45, 60, 90, and 120 min after the start of the test. The results were evaluated by the BG level, the maximum BG change (ΔCmax) and the incremental area under the curve of BG (iAUC). Bonferroni multiple test was performed for statistical analysis. Results: There were no adverse events and no subject met the exclusion criteria for analysis, therefore, all 12 subjects were included in the efficacy analysis. The blood glucose change (ΔBG) increased until 45 min after the start of the A to C intake test, and decreased until 120 min thereafter. After 30 min, ΔBG of test food C tended to be lower than that of A and B (p < 0.1). The highest value was shown 45 min after ingestion of the test foods A to C, when ΔBG was significantly lower in C than in A (p < 0.05). ΔCmax was 20.3% lower in C than in A (p < 0.05). iAUC in C tended to be 24.8% lower than that of A (p < 0.1). Conclusion: This study showed that a diet that ingest lemon juice prior to rice suppressed postprandial hyperglycemia that was observed when 30 g of lemon juice was taken. A dietary habit of ingesting a beverage containing lemon juice before meals may reduce glycative stress by suppressing postprandial hyperglycemia, and may contribute to the prevention of aging and disease progression.

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Current study determined effects of lemon grass (LG) essential oil on allergic rhinitis (AR) induced by Japanese cedar pollen (JCP). Male ICR mice were sensitized by i.p. injections with JCP+alum on days 0, 7 and 14. From day 21, the sensitized mice were challenged by intranasal (i.n.) administrations of JCP for 4 consecutive days. Animals were also treated with LG (i.n.) 30 min before each JCP challenge. Frequency of sneezing was counted for 20 min after each nasal challenge. Sneezing induced by histamine (Hist, i.n.) was also counted on days 18 and 25. In the JCP sensitized and repeatedly challenged mice, both serum levels of IgG and IgE specific for Cry J1, a major allergen of JCP, were significantly increased. The i.n. JCP challenge to sensitized mice caused a significant increase in sneezing, indicating an induction of nasal allergic response. An increase in sneezing was also induced by the i.n. application of Hist. The Hist-induced sneezing was further increased significantly on day 25, indicating an induction of nasal hyperresponsiveness (NHR) after the repeated JCP challenges. Both the JCP-induced nasal allergic response and NHR were inhibited by the pretreatments with LG. It is thus possible that aromatherapy using LG is effective for the treatment of Japanese cedar pollinosis.

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Perception of particular sensory stimuli from the surroundings can influence emotion in individuals. In an uncomfortable situation, humans protect themselves from some aversive stimulus by acutely evoking a stress response. Animal model studies have contributed to an understanding of neuronal mechanisms underlying the stress response in humans. To study a possible anti-stressful effect of lemon odor, an excitation of neurons secreting corticotropin-releasing hormone (CRH) as a primary factor of the hypothalamic-pituitary-adrenal axis (HPA) was analyzed in animal model experiments, in which rats are restrained in the presence or absence of the odor. The effect was evaluated by measuring expression of c-Fos (an excited neuron marker) in the hypothalamic paraventricular nucleus (PVN), a key structure of the HPA in the brain. We prepared 3 animal groups: Groups S, L and I. Groups S and L were restrained for 30 minutes while being blown by air and being exposed to the lemon odor, respectively. Group I was intact without any treatment. Two hours later of the onset of experiments, brains of all groups were sampled and processed for microscopic examination. Brain sections were processed for c-Fos immunostaining and/or in situ hybridization for CRH. In Group S but not in Group I, c-Fos expression was found in the PVN. A combined in situ hybridization-immunohistochemical dual labeling revealed that CRH mRNA-expressing neurons express c-Fos. In computer-assisted automatic counting, the incidence of c-Fos-expressing neurons in the entire PVN was statistically lower in Group L than in Group S. Detailed analysis of PVN subregions demonstrated that c-Fos-expressing neurons are fewer in Group L than in Group S in the dorsal part of the medial parvocellular subregion. These results may suggest that lemon odor attenuates the restraint stress-induced neuronal activation including CRH neurons, presumably mimicking an aspect of stress responses in humans.

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In the present study, we examined the cognitive function during mastication of lemon-flavored gum, which is said to enhance cerebral blood flow. Nine healthy subjects (8 female and 1 male) participated in this study. Subjects chewed the gum for 3 min after fasting for 2 h and conducted a Stroop test while continuing to chew. At the end of all answers, gum chewing ended. The response time in the Stroop test was used as an indicator of cognitive function. We set the three conditions (lemon-flavored gum, mint-flavored gum, no gum chewing). There was no significant difference in reaction time between chewing mint-flavored gum and not chewing (p>0.05). However, the response time during chewing gum with a lemon flavor was significant slower than the conditions with mint-flavored gum and without gum chewing (p<0.05, in both). From the results of the present study, it was suggested that the response time delay of the Stroop test observed during the chewing of lemon-flavored gum revealed temporary decay of cognitive function during lemon-flavored gum chewing. It is suggested that lemon-flavored chewing gum forces a brain overload, resulting in a temporary decrease in cognitive function.

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The concentrations of metabolites in human plasma after ingestion of flavanone glycosides (FG) and their aglycones (FA) in lemon were examined. FG consisting abundantly of eriocitrin were prepared from lemon peel and FA consisting abundantly of eriodictyol were prepared from FG by treatment with β-glucosidase. Eriodictyol, homoeriodictyol, and hesperetin in plasma up to 4 h after ingestion of FG with water or FA with water by subjects were not detected in plasma of non-enzyme treatment but in plasma after treatment with β-glucronidase and sulfatase. Metabolites in plasma after ingestion of FG and FA in humans were shown to exist as the glucuro- and/or sulfo-conjugates of eriodictyol, homoeriodictyol, and hesperetin. After ingestion of FA, the concentration of metabolites in plasma exhibited a high maximum peak at 1 h. The AUC (area under the blood concentration time curve) level of metabolites of FA was higher than that of FG. FA were suggested to be absorbed faster and in higher amounts than FG. The AUC of metabolites in subject plasma after ingestion of FG with flavonoid-depleted lemon juice was shown to change to a low level in comparison with that of FG with water. The maximum concentration peak of metabolites in plasma was faster at 0.5 h than FA with water but the AUC level was similar to FA with water, when subjects ingested FA with vodka (40% ethanol). The absorption hour of FG and FA was shown to be affected by the co-existing solution.

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The aim of this study was to investigate the effect of dietary lemon polyphenols on high-fat diet-induced obesity in mice, and on the regulation of the expression of the genes involved in lipid metabolism to elucidate the mechanisms. Mice were divided into three groups and fed either a low fat diet (LF) or a high fat diet (HF) or a high fat diet supplemented with 0.5% w/w lemon polyphenols (LP) extracted from lemon peel for 12 weeks. Body weight gain, fat pad accumulation, the development of hyperlipidemia, hyperglycemia, and insulin resistance were significantly suppressed by lemon polyphenols. Supplementation with lemon polyphenols also significantly up-regulated the mRNA level of the peroxisome proliferator activated receptor-α (PPARα) compared to the LF and HF groups in the liver. Furthermore, the mRNA level of acyl-CoA oxidase (ACO) was up-regulated in the LP group compared to the LF group, but not HF group in the liver, and was also significantly increased in the epididymal white adipose tissue. Thus, feeding with lemon polyphenols suppressed body weight gain and body fat accumulation by increasing peroxisomal β-oxidation through up-regulation of the mRNA level of ACO in the liver and white adipose tissue, which was likely mediated via up-regulation of the mRNA levels of PPARα.

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Glycation, a non-enzymatic glycosylation of proteins, induces tissue damage in association with various diseases and aging phenomena. Pentosidine, an advanced glycation end product, is involved in aging phenomena such as tissue stiffness. In this study, we aimed to find a potent anti-glycation food material and to verify its health benefits by clinical trial. From among 681 hot water plant extracts, lemon balm (Melissa officinalis; LB) leaf extract was selected and revealed to have more potent inhibitory activity for pentosidine formation than a representative anti-glycation agent, aminoguanidine. Rosmarinic acid (RA), a typical polyphenol in Lamiaceae plants, was identified as a major active component in LB extract (LBE). Furthermore, LBE or RA dose-dependently suppressed glycation-associated reactions such as increased fluorescence, yellowing of collagen fiber sheets, and degeneration of the fibrous structure of elastin fiber sheets. An open-label, parallel-group comparative trial was conducted in 28 healthy Japanese subjects aged 31-65 y who consumed LB tea (LB group) or barley tea (Control group) for 6 wk. The LB group showed significant reductions in brachial-ankle pulse wave velocity, reflecting arterial stiffness, and b* (yellow) color values in forearm skin compared with the Control group. A gender-stratified analysis revealed that cheek skin elasticity was significantly improved in the LB group compared with the Control group only in female subjects. It is concluded that the hot water extract of LB leaf has the potential to provide health benefits with regard to glycation-associated tissue damage in blood vessels and skin of healthy adults.

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The purpose of this study is to effectively utilize fragrance in order to form a comfortable working environment, for which we obtained necessary data. The subjects were 14 female students. We made them do addition work in laboratories with and without lemon fragrance, and investigated their task performances, physiological changes and mood conditions. Our results showed that, although the existence or nonexistence of fragrance did not affect their work efficiency, it was revealed that fragrance mitigated exhaustion and maintained vigor.

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Food products can be possible vectors of the agent responsible for cholera epidemics, because some of these products allow Vibrio cholerae O1 to develop to concentrations above the dangerous level. This study deals with the behaviour of essential oils, natural and concentrated lemon juice and fresh and dehydrated lemon peel against V. cholerae O1 biotype Eltor serotype Inaba tox⁺. Our aim was to evaluate whether these products, used at different dilutions, exhibit bactericidal or bacteriostatic activity against the microorganism, when present at concentrations of 10², 10⁴, 10⁶ and 10⁸ colony forming units (CFU) ml^-1, and after different exposure times. 10⁸ CFU ml^-1 was considered an infectious dose. Concentrated lemon juice and essential oils inhibited V. cholerae completely at all stuidied dilutions and exposure times. Fresh lemon peel and dehydrated lemon peel partially inhibited growth of V. cholerae. Freshly squeezed lemon juice, diluted to 10^-2, showed complete inhibition of V. cholerae at a concentration of 10⁸ CFU ml^-1 after 5 min of exposure time; a dilution of 2×10^-3 produced inhibition after 15 min and a dilution of 10^-3 after 30 min. It can be concluded that lemon, a natural product which is easily obtained, acts as a biocide against V. cholerae, and is, therefore, an efficient decontaminant, harmless to humans.

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In this study, strawberry and lemon flavored fish oil organogels (FOO) were prepared with beeswax as the organogelator. The physical, thermal and textural characteristics as well as the consumer preferences of the flavored organogels were determined in comparison with fish oil and FOO containing no flavor. Furthermore, the stability of the organogels was evaluated during 90 day storage at 4°C. The results revealed that, structurally stable fish oil organogels as spreadable products might be formed and that flavoring of the gels enhances consumer preference. Thus, flavoring of fish oil organogels could be a challenge in increasing the consumption of fish oil.

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This study sought to investigate the effects of essential oil from lemon (Citrus limoni) peels on acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities in vitro. The essential oil was extracted by hydrodistillation, dried with anhydrous Na₂SO₄ and characterized using gas chromatography. Antioxidant properties of the oil and inhibition of pro-oxidant-induced lipid peroxidation in rats brain homogenate were also assessed. The essential oil inhibited AChE and BChE activities in a concentration-dependent manner. GC analysis revealed the presence of sabinene, limonene, α-pinene, β-pinene, neral, geranial, 1,8-cineole, linalool, borneol, α-terpineol, terpinen-4-ol, linalyl acetate and β-caryophyllene. Furthermore, the essential oil exhibited antioxidant activities as typified by ferric reducing property, Fe²⁺-chelation and radicals [DPPH, ABTS, OH, NO] scavenging abilities. The inhibition of AChE and BChE activities, inhibition of pro-oxidant induced lipid peroxidation and antioxidant activities could be possible mechanisms for the use of the essential oil in the management and prevention of oxidative stress-induced neurodegeneration.

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This paper investigates effects of temperature and density of lemon aroma on a subjective evaluation. We used the semantic differential (SD) method in the evaluation test with the following 5 words; clean, thick, refreshing, relaxing, and favorite-and their antonyms. We made a total of 12 aromatic gases (4 amounts of lemon essential oil (0.5, 1, 5, and 10 mg in a glass bottle of 1.35 L volume) × 3 temperatures (5, 25, and 60 degrees in Celsius)), and performed a quantitative analysis of limonene, β-pinene, γ-terpinene, and citral in the gases by a gas chromatography-mass spectrometry (GC-MS) measurement. As results, we found that the effect of the temperature of aromatic gas was dominant for the evaluation items; cleanliness, refresh feeling, relaxing, and preference, and that the lemon aroma less or equal 25 degrees in Celsius was effective for the impressions of cleanliness, refresh feeling, relaxing, and preference.

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The oxidative effects of sorbitan esters on lemon oil and γ-terpinene in emulsion and solubilization were investigated. The oxidation was followed by gas chromatography (GC) and peroxide value (POV). The determination of the site of γ-terpinene within micelles was made by ultraviolet spectro scopy (UV) and solubility measurement. The summary of the results is shown below.
1) The formation of p-cymene from γ-terpinene during deterioration of lemon oil was shown.
2) Sorbitan esters strongly inhibitted oxidative activities.
3) The monomolecular film of sorbitan esters appeared to inhibit the oxidation.
4) Lemon oil in the emulsion of O/W type did not oxidize, while in that of W/O type it did,
5) The site of γ-terpinene within the Tween 20 micelles was deep penetration of the palisade layer.
6) Suspended or emulsified γ-terpinene was oxidised at greater rate than solubilised γ-terpinene. Then, Tween 20 micelles were considered to inhibit the oxidation of γ-terpinene.

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Using a homology-based PCR strategy, we identified a cDNA with sequence similarity to linalool synthase from lemon myrtle. Functional expression of the cDNA (designated BcLS) gene in Escherichia coli yielded an active enzyme capable of catalyzing the conversion of geranyl diphosphate to (−)-linalool, i.e., an acyclic monoterpene alcohol, and to lesser amounts of cyclic monoterpenes. The kinetic parameters of BcLS were similar to those of synthases producing cyclic monoterpenes. PCR analysis revealed that the BcLS gene transcript was ubiquitously expressed in lemon myrtle and was upregulated in response to jasmonic acid treatment. Although the physiological role of neryl diphosphate (NPP) dependency of BcLS remains unclear, the cyclization activity of BcLS was enhanced when NPP was used as substrate, resulting in predominant production of cyclic monoterpenes. These findings indicate that BcLS has novel specificity and kinetic parameters, but its physiological responses to stresses such as insect damage appear to be similar to known linalool synthases.

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The characteristics of flavonoids and coumarins in ten types of lemon (Lemon, Pink-lemonade, Meyer lemon, Ogasawarashima lemon, Hachijyo fruit lemon, Alen-eureka lemon, Lisbon, Vilafranca, Sweet lemon, Ponderosa) were examined. Twelve flavonoids and seven coumarins from the peel and juice of the different lemon types were analyzed using HPLC, and the quantitative values were subjected to a multivariate statistics principal component analysis. The ten lemon types were separated into four (I ～ IV) categories, corresponding to genus-species in plant classification (Citrus limon, Citrus meyeri, Citrus limetta, Citrus pyriformis), based on the scatter diagram of the score plot from the principal component analysis. Lemon, Pink-lemonade, Alen-eureka lemon, Lisbon, and Vilafranca were in category I: C. limon. Meyer lemon, Ogasawara-shima lemon, and Hachijyo fruit lemon were in category II: C. meyeri. Sweet lemon (C. limetta) was in category III, and Ponderosa (C. pyriformis) was in category IV. The characteristic flavonoids in the lemon types of category I were eriocitrin, diosmin, 6,8-C-diglucosylapigenin, and 6,8-C-diglucosyldiosmetin. Those of category III were narirutin, nobiletin, and tangeretin, and those of category IV were neoeriocitrin, neohesperidin, and naringin. Coumarins were not found in the juices but were found in the peels. The characteristic coumarins in the category I lemon types were 8-geranyloxypsolaren, 5-geranyloxypsolaren (bergamottin), and 5-geranyloxy-7- methoxycoumarin. That of the category II lemon types was 7-methoxy-5-prenyloxycoumarin, and that of the category IV types was 7-geranyloxycoumarin (auraptene). The antioxidative activity for the peel extract of the category I lemon types was the highest activity of all categories (p < 0.05) suggesting a relationship to the eriocitrin and neoeriocitrin content.

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The present research was set up to verify whether the chemical products used in lemon production (from cultivation until packaging) have a bactericidal or a bacteriostatic ability against Vibrio cholerae O1. The studied products were : copper oxychloride, benomil (a carbamate), active chlorine, sodium-o-phenylphenoate, guazatine (a polyamine mixture), imazalil (an imidazole) and lemon peel. The latter was studied with and without treatment using the above mentioned chemicals. Different dilutions of these products were tried out with varying exposure times against the bacterium V. cholerae Serogroup O1, Biotype El Tor, Serotype Inaba. The concentrations of the microorganism ranged from 10² to 10⁸ CFU ml^-1, the latter one being considered an infectious dose. The following results were obtained : 1) active chlorine (chlorinated water) showed bactericidal activity at concentrations of 50, 100 and 200 ppm after 10 min of exposure time, 2) copper oxychloride, sodium-o-phenylphenoate, guazatine and imazalil showed bactericidal activity against V. cholerae at concentrations of 10² and 10⁴ CFU ml^-1, 3) due to the fact that during its cultivation the fruit is successively sprayed with several chemical products, it could be that the result of the successive treatments is superior to the result of a repeated treatment with each of the individual products. This consideration should be taken into account when evaluating the eventual protection of the lemon.

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Phenolic glucosides having radical scavenging activity were examined from the fraction eluted with 20% methanol on Amberlite XAD-2 resin applied to lemon (Citrus limon) juice by using reversed phase chromatography. Four phenolic glucosides were identified as 1-feruloyl-β-D-glucopyranoside, 1-sinapoyl-β-D-glucopyranoside, 6,8-di-C-glucosylapigenin and 6,8-di-C-glucosyldiosmetin by ¹H-NMR, ¹³C-NMR, and MS analyses. They exhibited radical scavenging activity for 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide, although the activity was low in comparison with eriocitrin, a potent antioxidant in lemon fruit, and the eriodictyol of its aglycone. The phenolic compounds in lemon juice were examined for their suppressive effect on the expression of blood adhesion molecules by measuring the expression of intercellular adhesion molecule-1 (ICAM-1) in human umbilical vein endothelial cells (HUVECs) induced by necrosis factor-α (TNF-α). 6,8-Di-C-glucosylapigenin, apigenin, and diosmentin of the flavones were found to significantly suppress the expression of ICAM-1 at 10 μM (P<0.05). The phenolic glucosides isolated in this study were contained in comparative abundance in daidai (Citrus aurantium) and niihime (Citrus unshiu × Citrus tachibana) among the sour citrus juices.

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In this study, the in vivo potential of lemon balm water extract on Fusarium wilt control in strawberry and the antifungal properties of secondary metabolites in the extract were investigated. Runner plants of strawberry (Fragaria × ananassa Duch., ‘Sachinoka’) were treated with water extracts (20%, w/v) of lemon balm (Melissa officinalis L.) and inoculated with Fusarium oxysporum f. sp. fragariae (Fof). Four weeks after Fof inoculation, lower disease incidence and indices in both shoots and roots were observed in lemon balm-treated plants. These effects could be attributed to reduced Fusarium populations due to the fungistasis and fungicidal effects induced by the extract in the rhizospheric soil. Consequently, dry weights of shoots and roots in the plants treated with lemon balm extracts were higher than those of the control. Based on the results of ultra performance liquid chromatography-tandem mass spectrometer (UPLC-MS/MS) analyses, rosmarinic acid was the metabolite with the highest concentration and was also the most stable metabolite in the water extract. In addition, the antifungal effect of rosmarinic acid against Fof was confirmed by in vitro tests. Therefore, water extracts of lemon balm could suppress Fusarium wilt in strawberry plants and rosmarinic acid was one of the key metabolites with antifungal properties present in the water extract.

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