Developmental characteristics of aggregated lymphoid nodules area in the abomasum of fetal Bactrian camels (Camelus bactrianus).

BACKGROUND: Bactrian camel is one of the important economic animals in northwest China. They live in arid desert, and their gestation period is about 13 months, which is longer than other ruminants (such as cattle and sheep). The harsh living conditions have made its unique histological characteristics a research focus. Aggregated lymphoid nodules area (ALNA) in the abomasum of Bactrian camels, as one of the most important sites for the induction of the immune response, provide a comprehensive and effective protective role for the organism, and their lack of information will affect the feeding management, reproduction and epidemic prevention of Bactrian camels. In this study, the histological characteristics of the fetal ALNA in the abomasum of Bactrian camels at different developmental gestation have been described by using light microscopy and histology . RESULTS: The ALNA in the abomasum of the Chinese Alashan Bactrian camel is a special immune structure that was first discovered and reported by Wen-hui Wang. To further establish the developmental characteristics of this special structure in the embryonic stage, the abomasum ALNA of 8 fetuses of Alashan Bactrian camels with different gestational ages (5~13 months) were observed and studied by anatomy and histology. The results showed that the aggregation of reticular epithelial cells (RECs) surrounded by a very small number of lymphoid cells was detected for the first time in the abomasum of fetal camel at 5 months gestation, which was presumed to be primitive ALNA. At 7 months gestation, the reticular mucosal folds region (RMFR) appeared, but the longitudinal mucosal folds region (LMFR) was not significant, and histological observations showed that there were diffusely distributed lymphocytes around the RECs. At 10months gestation, RMFR and LMFR were clearly visible, lymphoid follicles appeared in histological observation, lymphocytes proliferated vigorously. By 13 months, the volume of lymphoid follicles increased, forming the subepithelial dome (SED), and there was a primitive interfollicular area between the lymphoid follicles, which contained high endothelial vein (HEV), but no germinal center (GC) was found. In summary, ALNA of Bactrian camels is not fully mature before birth. CONCLUSIONS: Generally, the small intestine PPs of ruminants (such as cattle and sheep) is already mature before birth, while the ALNA in the abomasum of Bactrian camels is not yet mature in the fetal period. During the development of ALNA in Bactrian camel, the development of lymphoid follicles extends from submucosa to Lamina propria. Interestingly, the deformation of FAE changes with age from simple columnar epithelium at the beginning of pregnancy to Simple cuboidal epithelium, which is opposite to the FAE deformation characteristics of PPs in the small intestine of fetal cattle and sheep. These results are the basis of further research on the specificity of ALNA in the abomasum of Bactrian camels.

Similar proteome expression profiles of the aggregated lymphoid nodules area and Peyer's patches in Bactrian camel.

BACKGROUND: The presence of Aggregated Lymphoid Nodules Area (ALNA) is a notable anatomical characteristic observed in the abomasum of Bactrian camels. This area is comprised of two separate regions, namely the Reticular Mucosal Folds Region (RMFR) and the Longitudinal Mucosal Folds Region (LMFR). The histological properties of ALNA exhibit significant similarities to those of Peyer's patches (PPs) found in the gastrointestinal system. The functional characteristics of ALNA were examined in relation to mucosal immunity in the gastrointestinal system. RESULTS: We used iTRAQ-based proteomic analysis on twelve Bactrian camels to measure the amount of proteins expressed in ALNA. In the experiment, we sampled the RMFR and LMFR separately from the ALNA and compared their proteomic quantification results with samples from the PPs. A total of 1253 proteins were identified, among which 39 differentially expressed proteins (DEPs) were found between RMFR and PPs, 33 DEPs were found between LMFR and PPs, and 22 DEPs were found between LMFR and RMFR. The proteins FLNA, MYH11, and HSPB1 were chosen for validation using the enzyme-linked immunosorbent assay (ELISA), and the observed expression profiles were found to be in agreement with the results obtained from the iTRAQ study. The InnateDB database was utilized to get data pertaining to immune-associated proteins in ALNA. It was observed that a significant proportion, specifically 76.6%, of these proteins were found to be associated with the same orthogroups as human immune-related genes. These proteins are acknowledged to be associated with a diverse range of functions, encompassing the uptake, processing and presentation of antigens, activation of lymphocytes, the signaling pathways of T-cell and B-cell receptors, and the control of actin polymerization. CONCLUSIONS: The experimental results suggest that there are parallels in the immune-related proteins found in ALNA and PPs. Although there are variations in the structures of LMFR and RMFR, the proteins produced in both structures exhibit a high degree of similarity and perform comparable functions in the context of mucosal immune responses.

Promoter characterization of a citrus linalool synthase gene mediating interspecific variation in resistance to a bacterial pathogen.

BACKGROUND: Terpenoids play essential roles in plant defense against biotic stresses. In Citrus species, the monoterpene linalool mediates resistance against citrus canker disease caused by the gram-negative bacteria Xanthomonas citri subsp. citri (Xcc). Previous work had associated linalool contents with resistance; here we characterize transcriptional responses of linalool synthase genes. RESULTS: Leaf linalool contents are highly variable among different Citrus species. "Dongfang" tangerine (Citrus reticulata), a species with high linalool levels was more resistant to Xcc than "Shatian" pummelo (C. grandis) which accumulates only small amounts of linalool. The coding sequences of the major leaf-expressed linalool synthase gene (STS4) are highly conserved, while transcript levels differ between the two Citrus species. To understand this apparent differential transcription, we isolated the promoters of STS4 from the two species, fused them to a GUS reporter and expressed them in Arabidopsis. This reporter system revealed that the two promoters have different constitutive activities, mainly in trichomes. Interestingly, both linalool contents and STS4 transcript levels are insensitive to Xcc infestation in citrus plants, but in these transgenic Arabidopsis plants, the promoters are activated by challenge of a bacterial pathogen Pseudomonas syringae, as well as wounding and external jasmonic acid treatment. CONCLUSIONS: Our study reveals variation in linalool and resistance to Xcc in citrus plants, which may be mediated by different promoter activities of a terpene synthase gene in different Citrus species.

Characterization of volatile compounds from healthy and citrus black spot-infected Valencia orange juice and essential oil by using gas chromatography-mass spectrometry.

Citrus black spot (Phyllosticta citricarpa, CBS) is an important fungal disease that causes rind blemishes and affects quality of citrus fruits. The response of citrus to CBS in terms of volatiles was evaluated using molecular sensory science approaches. Fifty and twenty-one volatiles were identified in the orange juice and essential oil samples, respectively, via gas chromatography-mass spectrometry (GC-MS). The total volatile content in the samples increased after CBS infection, especially in the severe-infection group (SEG) juice and moderate-infection group (MOG) essential oil, which reached the highest levels. CBS enhanced floral, fruity, and off-flavor aromas and decreased the green aroma in citrus juice. Citrusy, floral, and green aromas increased in the CBS-infected essential oil. Six/five potential markers were screened in citrus juice/essential oil, respectively using the orthogonal partial least-square discriminant analysis (OPLS-DA) model. The changes in aroma profile and the difference in infection levels in citrus were attributed to these odorants.

Comparative investigation on the aroma profiles of edible citrus flowers in the main organs and different developmental stages.

Pomelo flowers emit a strong fragrance and give aromatic odors. Volatile compounds from pomelo flowers were analyzed at three developmental stages and in the main organs by molecular sensory science. A total of 134 volatiles including 25 odorants, were analyzed by gas chromatography-mass spectrometry/pulsed flame photometric detector (GC-MS/PFPD) and multidimensional GC-MS/olfactory (MDGC-MS/O). The total volatile content varied among pomelo flowers at different developmental stages (stage-III > stage-II > stage-I) and among different organs of pomelo flowers (petal > pistil > stamen). Linalool was an important odorant with a high OAV, and floral/fruity comprised the predominant aroma profile. Four odorants, ethyl 2-methylbutanoate, linalool, ß-myrcene, and 2-butenal, were selected based on variable importance in projection (VIP) values and contributed mainly to the discrimination of pomelo flowers at three different developmental stages. Linalool, ß-myrcene, d-limonene, and ethyl hexanoate were potential markers for evaluating flavor differences in pomelo floral organs.

Coumarins rather than alkylamides evoke the numbing orosensation of pomelo peel.

Liangpingyou, a well-known Chinese pomelo (Citrus grandis L.) variety, elicits a unique and uncharacterized numbing aftertaste. To understand the molecular bases and characteristics of the pomelo-induced numbing sensation, we first determined that hydroxyl sanshools, the major Sichuan pepper chemosensates, were not responsible via silylation-GC-MS analysis. Pomelo peel juice was then subjected to solid-phase extraction to form 4 fractions, and key sensory-active substances were screened via taste dilution analysis. Three simple coumarins, meranzin hydrate, isomeranzin, and marmin, were identified to induce numbing, which has not been previously reported. Sensory studies via extensively modified half-tongue tests and verification steps revealed recognition thresholds within 0.49-1.78, 0.32-1.56, and 0.43-1.46 µmol/L for numbness, pungency, and astringency, respectively. The temporal dominance trends showed the following taste notes: Meranzin hydrate-numbing dominated, isomeranzin-numbing and pungent, and marmin-astringent and numbing. Molecular docking analysis suggested that coumarins target the receptors TRPV1, TPRA1, and KCNK3.

Age-dependent distribution of IgA and IgG antibody-secreting cells in the pharyngeal tonsil of the Bactrian camel.

The pharyngeal tonsil, located in the nasopharynx, can effectively defend against pathogens invading the body from the upper respiratory tract and play a crucial role in mucosal immunity of the respiratory tract. Immunoglobulin A (IgA) and Immunoglobulin G (IgG) serve as key effector molecules in mucosal immunity, exhibiting multiple immune functions. This study aimed to investigate the distribution patterns and age-related alterations of IgA and IgG antibody-secreting cells (ASCs) in the pharyngeal tonsils of Bactrian camels. Twelve Alashan Bactrian camels were categorized into four age groups: young (1-2 years, n=3), pubertal (3-5 years, n=3), middle-aged (6-16 years, n=3) and old (17-20 years, n=3). The distribution patterns of IgA and IgG ASCs in the pharyngeal tonsils of Bactrian camels of different ages were meticulously observed, analyzed and compared using immunohistochemical and statistical methods. The results revealed that IgA ASCs in the pharyngeal tonsils of all age groups were primarily clustered or diffusely distributed in the reticular epithelium and its subepithelial regions (region A) and around the glands (region C), scattered in the subepithelial regions of non-reticular epithelium (region B), and sporadically distributed in the interfollicular regions (region D). Interestingly, the distribution pattern of IgG ASCs in the pharyngeal tonsils closely mirrored that of IgA ASCs. The distribution densities of IgA and IgG ASCs in these four regions were significantly decreased in turn (P<0.05). However, IgA ASCs exhibited significantly higher densities than IgG ASCs in the same region (P<0.05). Age-related alterations indicated that the distribution densities of IgA and IgG ASCs in each region of the pharyngeal tonsils exhibited a trend of initially increasing and subsequently decreasing from young to old camels, reaching a peak in the pubertal group. As camels age, there was a significant decrease in the densities of IgA and IgG ASCs in all regions of the pharyngeal tonsils (P<0.05). The results demonstrate that the reticular epithelium and its subepithelial regions in the pharyngeal tonsils of Bactrian camels are the primary regions where IgA and IgG ASCs colonize and exert their immune functions. These regions play a pivotal role in inducing immune responses and defending against pathogen invasions in the pharyngeal tonsils. IgA ASCs may be the principal effector cells of the mucosal immune response in the pharyngeal tonsils of Bactrian camels. Aging significantly reduces the densities of IgA and IgG ASCs, while leaving their distribution patterns unaffected. These findings will provide valuable insights for further investigations into the immunomorphology, immunosenescence, and response mechanisms of the pharyngeal tonsils in Bactrian camels.

Association between flavor composition and sensory profile in thermally processed mandarin juices by multidimensional gas chromatography and multivariate statistical analysis.

Thermal pasteurization decreases the sensory quality of mandarin juice. Flavor composition was determined in four fresh-squeezed and heat-processed mandarin juice varieties using molecular sensory science approaches. The relationships between odorants and sensory profiles were analyzed, and markers for flavor deterioration were screened by multivariate statistical analysis. Seventy-four volatiles were identified, among which 36 odorants with flavor dilution factors ranging from 2 to 128 were detected by multidimensional gas chromatography-mass spectrometry/olfactometry (MDGC-MS/O) coupled with aroma extract dilution analysis (AEDA). Higher intensities of cooked and off-flavor notes were observed in the heated mandarin juice, which was related to the concentration changes of the methional, methanethiol, dimethyl sulfide, and carbon disulfide by partial least squares (PLS) analysis. Ten potential markers (methional, methanethiol, dimethyl sulfide, hydrogen sulfide, ß-damascenone, camphene, trans-ß-ionone, decanal, d-limonene, and α-pinene) were responsible for the sensory discrimination of fresh-squeezed and heated mandarin juices.

Content analysis and drug safety evaluation of four furanocoumarins in six pomelos produced in China.

The content of 4 6',7'-dihydroxybergamottin (DHB), bergamottin, isoimperatorin and epoxybergamottin of six pomelos produced in China were detected by High-performance liquid chromatography-diode array detection and their safety of related medicines was evaluated by inhibition of medium concentration (IC50) of cytochrome oxidases CYP450-like. The results showed that the total content of the four furanocoumarins in these pomelo juices from high to low in order was Guanximi pomelo > Liangping pomelo > Pinghemi pomelo > grapefruit > Huyou > Shatian pomelo. The concentration of isoimperatorin in grapefruit, DHB, bergamottinand and isoimperatorin in Liangping, bergamottin and epoxybergamottin in Pinghemi and all the four furanocoumarins in Guanximi were exceeded the corresponding IC50; although Huyou and Shatian contained some furanocoumarins, they did not exceed IC50. Therefore, when taking drugs metabolised by CYP450-like enzymes, Guanximi, Liangping, Pinghemi, and grapefruit should be avoided to consume, but it is relatively safe to eat Huyou and Shatian.

Age-dependent changes in the anatomical and histological characteristics of the aggregated lymphoid nodules in the stomach of Dromedary camels (Camelus Dromedarius).

Gastrointestinal associated lymphoid tissue (GALT) is an important component of the mucosal immune system. It is the largest mass of lymphoid tissues in the body and makes up more than 70% immune cells of entire body. GALT is considered to be the origin of systemic mucosal immunity and consists of solitary lymphoid nodules, aggregated lymphoid nodules (Peyer's patches, PPs), scattered lymphoid tissues, and follicular associated epithelia. PPs play important roles as antigen inductive sites of the mucosal immune system, which are mainly distributed in the intestine of animals and humans (especially ileum and appendix). However, a special area of well-developed aggregated lymphoid nodules in the abomasum of Dromedary camel was found in our laboratory. Its existence was rarely described in the stomach before. In the present study, we investigated this special structure with the dromedary camels of different ages (young, 0.5-2 years; pubertal, 3-5 years; middle-aged, 6-16 years; old, 17-20 years), by the anatomical, histological and immunohistochemical approaches. The results showed that the special structure was mainly distributed in the cardiac glandular area of the abomasum, forming a triangular area. The mucosal folds in this area were significantly thicker than those in the surrounding region. These mucosal folds had two different forms, namely reticular mucosal folds (RMF) and longitudinal mucosal folds (LMF). There were abundant lymphoid nodules in the submucosa of RMF and LMF, which were arranged in one or multiple rows. The statistical analysis of the height and thickness of RMF and LMF showed that the structure was most developed in pubertal dromedary camels. The histological characteristics of the structure were the same as PPs in the intestine of the Dromedary camel, while anatomical appearance showed some difference. The immunohistochemical examination revealed that both immunoglobulin A (IgA) and G (IgG) antibodies-producing cells (APCs) were extensively distributed in the gastric lamina propria (LP) in all age group. Our finding suggest that camel stomach not only performs digestive functions, but also involves parts of body immunity.

Targeted Metabolomics With a Chemometric Study of Oxygenated Heterocyclic Aglycones as a Tool for Preliminary Authenticity Assessment of Orange and Grapefruit Juices.

Profiles of citrus juice oxygenated heterocyclic aglycones (OHAs), which are notable marker secondary metabolites, were used to assess the authenticity of sweet orange and grapefruit juices in situations where mandarin and pomelo juices might be adulterants. Thirty-nine known OHAs, including 10 methoxyflavones, 13 coumarins, and 16 furanocoumarins, as well as 13 tentatively screened OHAs, were analyzed in orange, mandarin, grapefruit and pomelo juices using our newly developed high-resolution HPLC-UV and fluorescence detection method. Quantitative OHA profiles from 158 pure juice samples were obtained to establish a purity discriminant model using an omics strategy. Reduction of OHA variables showed that three important methoxyflavones, i.e. isosinensetin, tangeretin and sinensetin provided the best discrimination ability between sweet orange and mandarin juices. There are two subtypes of pomelos, Shatianyou Group and Wendan Group, of which juices should be separately compared to grapefruit juice. Five OHAs, namely meranzin, 3,5,6,7,8,3',4'-heptamethoxyflavone, osthole, 6',7'-epoxybergamottin, and bergamottin were found to discriminate Shatianyou Group of pomelo juice from grapefruit juice; whereas three OHAs, namely bergaptol, isomeranzin, and 6',7'-dihydroxybergamottin were able to discriminate Wendan Group of pomelo juice from grapefruit juice. The established partial least squares discriminant analysis (PLS-DA) models were capable of detecting as little as 10% mandarin juice in sweet orange juice and 10% pomelo juice in grapefruit juice, allowing for fast prescreening of excess addition with good reliability (root mean square error of prediction, RMSEP < 5%).

Identification of Light-Induced Key Off-Flavors in Ponkan Mandarin Juice Using MDGC-MS/O and GC-MS/PFPD.

Light-induced off-flavor compounds in Ponkan mandarin juice were investigated during its shelf-life by headspace solid-phase microextraction multidimensional gas chromatography-mass spectrometry/olfactometry (MDGC-MS/O) and a GC-MS/pulsed flame photometric detector (GC-MS/PFPD). A total of 34 aroma-active compounds with flavor dilution (FD) factors from 2 to 128 were tentatively identified by aroma extract dilution analysis-MDGC-MS/O. Among them, a light-induced off-flavor compound with a high FD factor, methional (cooked potato), was positively identified in the Ponkan mandarin juice at the end of the shelf-life. In addition, 11 volatile sulfur compounds (VSCs), including 6 screened shelf-markers (variable identification, VID > 0.80), were identified in Ponkan mandarin juice by a sulfur detector (PFPD). Four VSCs exhibited odor activity values exceeding 1. Three VSCs (methanethiol, dimethyl trisulfide, and methional) were confirmed as key light-induced off-flavor compounds in Ponkan mandarin juice based on addition/omission experiments. Furthermore, light irradiation accelerated the degradation of sulfur precursors (methionine and MMS) and the formation of these VSCs leading to an increase in off-flavor intensity.

Characterization of Oxygenated Heterocyclic Compounds and in vitro Antioxidant Activity of Pomelo Essential Oil.

PURPOSE: Citrus essential oils are widely used for aromatherapy and the alternative treatment of chronic diseases. Beyond the aroma substances, they are known to contain bioactive nonvolatile components; however, little knowledge has been gained about nonvolatiles in the essential oil of pomelo (Citrus grandis Osbeck), the largest citrus fruit. The purpose of this study was to analyze the nonvolatile oxygenated heterocyclic compounds (OHCs) of pomelo essential oils and evaluate their in vitro antioxidant activities for further development. METHODS: Cold-pressed essential oil (CPEO) and distilled essential oil (DEO) were obtained from the peel of the Liangping pomelo cultivar. High-performance liquid chromatography (HPLC) coupled with a photodiode array and fluorescence detection method was developed to identify and quantify the OHCs of the two essential oils. Ferric reducing antioxidant power and 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl 3-oxide (PTIO) radical scavenging assays were used to determine the antioxidative capabilities. RESULTS: Thirteen OHCs were identified in CPEO. Coumarins such as meranzin (2.0 mmol L-1) and furanocoumarins such as isoimperatorin (1.3 mmol L-1) composed the majority of nonvolatiles in CPEO. These OHCs were characterized by high proportion (58%) of side chain epoxides. Five OHCs, namely, auraptenol, 6',7'-dihydroxybergamottin (6',7'-DHB), imperatorin, isoimperatorin and 8-geranyloxypsoralen were first identified in pomelo CPEO. Eight OHCs were detected at trace amounts in pomelo DEO. Antioxidant assays showed that CPEO was multiple times more potent than DEO regarding the total reducing power and radical scavenging capacity. Clearance of PTIO, a stable reactive oxygen species, followed slow kinetics. CONCLUSION: Coumarins and furanocoumarins, two families of OHCs, constituted most of the nonvolatile components in CPEO. The nonvolatiles contributed significantly to the in vitro antioxidant activity of CPEO. Pomelo CPEO showed good prospects as a potential long-lasting natural antioxidant.

Effects of Cold-Pressing and Hydrodistillation on the Active Non-volatile Components in Lemon Essential Oil and the Effects of the Resulting Oils on Aging-Related Oxidative Stress in Mice.

The aim of this study was to analyze the non-volatile composition and antioxidant differences of lemon essential oils (LEOs) obtained by cold-pressing vs. hydrodistillation. Pathological observations showed that LEO effectively inhibited liver injury caused by oxidative stress, and CPLEO was more effective than HDLEO. CPLEO increased serum T-AOC, SOD, GSH, and GSH-Px levels while decreasing NO, COX-2, IL-6, IL-1ß, IFN-γ, and TNF-α levels in mice with oxidative damage. The effects of CPLEO were stronger than those of HDLEO and similar to those of vitamin C. CPLEO upregulated mRNA and protein expressions of Cu/Zn-SOD, Mn-SOD, CAT, HO-1, Nrf2, and NQO1 while downregulating nNOS, iNOS, IL-1ß, COX-2, TNF-α, and NF-κB mRNA expression and nNOS, eNOS, iNOS, and COX-2 protein expression in mice with oxidative damage. The results demonstrate that LEO has good antioxidant effects and that CPLEO has a better antioxidant effect than HDLEO as it retains more active non-volatile substances.

Protective Effect of Lemon Peel Extract on Oxidative Stress in H9c2 Rat Heart Cell Injury.

AIM: Lemon peel, a traditional Chinese medicine, was tested in this study for its novel application in inhibiting cellular oxidative stress, and the effect of lemon peel extract (LPE) on protecting H9c2 rat heart cells from oxidative stress was investigated. METHODS: The scavenging effects of LPE on 1,1-diphenyl-2-picryhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) free radicals were measured in extracellular experiments. The 3-(4,5-dimethyl-2-thiazolinyl)-2,5-diphenyl-2-h-tetrazolylammonium bromide (MTT) assay was used to detect the cell survival rate. The cell supernatant and intracellular oxidation-related indicators were detected by a kit, and the mRNA expression in H9c2 cells was detected by quantitative polymerase chain reaction (qPCR). The chemical substances of LPE were analyzed by high-performance liquid chromatography (HPLC). RESULTS: The results showed that LPE exhibited better DPPH and ABTS free radical scavenging abilities than vitamin C. Compared with the cells in the normal state (control group), the cell survival rate in the model group decreased, and the level of lactate dehydrogenase (LDH) increased, the levels of superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) decreased, and the content of malondialdehyde (MDA) increased. Compared with the control group, the expression of Bcl-2-related X protein (Bax), caspase-3, nuclear factor erythroid 2-related factor 2 (Nrf2), and heme oxygenase-1 (HO-1) in the model group was increased, and the expression of B-cell lymphoma-2 (Bcl-2) was reduced. Compared with the model group, LPE treatment improved the cell survival rate, reduced the levels of LDH and MDA, increased the levels of SOD, CAT, and GSH, downregulated the expression of Bax, caspase-3, Nrf2 and HO-1, and upregulated the expression of Bcl-2. The composition analysis showed that LPE contained catechin, rutin, naringin, quercetin, and hesperidin. CONCLUSION: The results indicated that LPE could protect H9c2 cells from oxidative stress through five active components. LPE has the potential to be developed into natural medicine or health food for the inhibition of cell oxidative damage.

Methanethiol, an Off-Flavor Produced from the Thermal Treatment of Mandarin Juices: A Study of Citrus Sulfur Volatiles.

The off-flavor produced after thermal stabilization of mandarin (Citrus reticulata, Blanco) juices has limited the production of commercial juices. Methanethiol, a putrid-smelling sulfur volatile, has been identified for the first time in heated mandarin juices. Identification was achieved using a combination of capillary gas chromatography with two dissimilar columns and a dual sulfur-specific pulsed flame photometric detector and selected ion mass spectrometry detection. Static headspace solid-phase microextraction quantitation found that average odor activity values (OAVs) in heated juices were 25.5 for methanethiol compared to 10.8 for dimethyl sulfide. OAVs for methanethiol and dimethyl sulfide in fresh juices were ND (not detected) and 5.5, respectively. Hydrogen sulfide, carbonyl sulfide, carbon disulfide, and dimethyl disulfide were also identified and quantitated. Thermal decomposition studies of nonvolatile sulfur-containing potential precursors indicated that methionine was the major source of methanethiol. Additional heating studies with model juices demonstrated that ascorbic acid greatly accelerated the formation of methanethiol and methional, as well as dimethyl di and tri sulfides.

Effect of lemon peel flavonoids on UVB-induced skin damage in mice.

By establishing an effective ultraviolet B (UVB) radiation model of skin damage in mice, the effect of lemon peel flavonoids (LPF) on skin damage was explored. UVB skin damage in UV-irradiated mice was simulated, and animal models were established. Serum parameters were measured using kits, skin sections were stained with hematoxylin-eosin (H&E) and Masson, and quantitative polymerase chain reaction (qPCR) was used to detect the expression of skin tissue-related mRNA. The experimental results showed that LPF increased the activity of catalase (CAT) and superoxide dismutase (SOD) oxidases in serum of mice with UVB-induced skin damage and decreased MDA, interleukin-1ß (IL-1ß), IL-6, IL-10, and tumor necrosis factor-alpha (TNF-α) levels. Pathological observation indicated that LPF alleviated the skin tissue lesions caused by UVB. LPF upregulated the mRNA expression of SOD1, SOD2, CAT, nuclear factor erythroid-2 related factor 2 (Nrf2), heme oxygenase-1 (HO-1), and inhibitor of NF-κB alpha (IκB-α) and downregulated the expression of nuclear factor kappa B (NF-κB), p38 MAPK, and cyclooxygenase-2 (COX-2) in the skin tissue of skin-damaged mice. There was a greater protective effect of LPF on the skin as compared to vitamin C (VC) at the same application concentration, and the effect of LPF was positively correlated with the concentration. High performance liquid chromatography (HPLC) analysis showed that LPF contained five flavonoid compounds, namely isomangiferin, rutin, astragalin, naringin, and quercetin. We demonstrated that flavonoids from LPF exhibit an excellent skin protection effect with satisfactory application value.