P-OGC39 The smell of oesophageal adenocarcinoma: opportunities for tests and treatments

Background Exhaled breath analysis is a promising approach for oesophageal adenocarcinoma (OAC) early detection. The biomarkers of interest are low molecular weight metabolites including volatile aldehydes. In this translational study we investigated whether these metabolites originated from a tumoral source, and how this might impact the diagnosis and treatment of OAC patients. Methods The investigative strategy was directed by an unbiased informatics screen of metabolic reprogramming in OAC, and validated using complimentary gene expression assays (n = 638, including controls). Mass spectrometric methods were used to quantify corresponding metabolites and putative source compounds at a tissue level (n = 158), and also in exhaled breath for correlative purposes. Targeted in vitro experiments were performed to demonstrate the cause and effect of the proposed model of metabolic reprogramming in OAC. Results The unbiased screen and subsequent validation found that reduced aldehyde detoxification is an OAC hallmark. In vitro and in vivo this was associated with endogenous aldehyde accumulation. OAC tissue was generally enriched for volatile aldehydes, including the genotoxins formaldehyde, acetaldehyde, 4-hydroxy-2-nonenal and 2-butenal, and the exhaled biomarker decanal (all P < 0.0001). Decanal concentrations correlated with exhaled concentrations. Considering potential aldehyde sources, the OAC phospholipidome was characterised by desaturated and longer lipid acyls, and these spontaneously generated biomarker aldehyde species at ambient conditions. Enriched genotoxic aldehydes were detectable in base-pairing positions in DNA; this genotoxicity was therapeutically targetable with aldehyde scavengers in vitro. Conclusions These data support a model for enriched exhaled aldehydes based on increased production from an altered lipid phenotype, and reduced detoxification. Some aldehydes are non-reactive and thus support non-invasive detection. Others react with DNA and increase local genotoxicity; this process is druggable. These findings have implications for OAC early diagnosis and chemoprevention.

Typical Defects of Natural Phospholipid Fatliquors in Leather Industry and Their Solutions

Leather made with soybean phospholipid fatliquors is prone to problems such as yellowing, elevated hexavalent chromium content, and undesirable odor. In this study, the aforementioned typical defects of soybean phospholipid fatliquors were investigated in respect to the main components, the antioxidants and the unsaturation degree of the natural soybean phospholipid. The results showed that the oxidation of soybean phospholipid is the primary source for its yellowing, elevated hexavalent chromium content, and undesirable odor. The volatile aldehydes produced by lipid oxidative rancidity are the main components of the undesirable odor. The purification of natural soybean phospholipid through removing the non-phospholipid components cannot solve the problems caused by oxidation of phospholipid. Furthermore, as a typical natural antioxidant existing in natural soybean phospholipid, tocopherols can restrain the oxidation of phospholipid to a certain degree, however, the dissolving out and destruction of tocopherols at high temperature in the phospholipid purification process can lead to more obviously oxidation of phospholipids. Additionally, the oxidation defects of phospholipid cannot be completely resolved by adding extra tocopherols, even at high dosages. The research finds that the defects of soybean phospholipid fatliquors can be thoroughly solved by increasing the saturation degree of lipid through addition reaction, the suggested iodine value of phospholipid products is lower than 20 g I2/100 g.

Dry-Aged Beef Steaks: Effect of Dietary Supplementation with Pinus taeda Hydrolyzed Lignin on Sensory Profile, Colorimetric and Oxidative Stability

Flavor is one of the main factors involved in consumer meat-purchasing decision and use of natural antioxidants in animal feeding had a great appeal for consumers. The aim of this trial is to evaluate the effect of Pinus taeda hydrolyzed lignin (PTHL) feed addition on oxidative stability, volatile compounds characteristics, and sensory attributes of 35 days dry-aged beef steaks. Forty steer six months old were randomly divided into a control group (CON; n = 20) and an experimental group (PTHL; n = 20). Both groups were fed ad libitum for 120 days with the same TMR and only the PTHL group received PTHL supplement. Samples of LT muscle were removed from carcasses and dry aged for 35 days at 2 °C, 82% of humidity, and 0.4 m/s of ventilation and then analyzed. Meat of CON group showed lower yellowness (p < 0.01) and higher TBARS (p < 0.01) values. Moreover, CON meat showed higher volatile aldehydes and lower sulfur compounds (p < 0.01), with higher unpleasant odor (p < 0.05) and meaty odor (p < 0.01) score revealed by sensory assessors. PTHL inclusion in beef diet delayed the oxidative mechanisms in 35 days dry-aged steaks, resulting in an improved colorimetric, volatolomic, and sensory profile.

Endogenous aldehyde accumulation generates genotoxicity and exhaled biomarkers in esophageal adenocarcinoma

Volatile aldehydes are enriched in esophageal adenocarcinoma (EAC) patients’ breath and could improve early diagnosis, however the mechanisms of their production are unknown. Here, we show that weak aldehyde detoxification characterizes EAC, which is sufficient to cause endogenous aldehyde accumulation in vitro. Two aldehyde groups are significantly enriched in EAC biopsies and adjacent tissue: (i) short-chain alkanals, and (ii) medium-chain alkanals, including decanal. The short-chain alkanals form DNA-adducts, which demonstrates genotoxicity and confirms inadequate detoxification. Metformin, a putative aldehyde scavenger, reduces this toxicity. Tissue and breath concentrations of the medium-chain alkanal decanal are correlated, and increased decanal is linked to reduced ALDH3A2 expression, TP53 deletion, and adverse clinical features. Thus, we present a model for increased exhaled aldehydes based on endogenous accumulation from reduced detoxification, which also causes therapeutically actionable genotoxicity. These results support EAC early diagnosis trials using exhaled aldehyde analysis.

Quantitative and Predictive Modelling of Lipid Oxidation in Mayonnaise

Food emulsions with high amounts of unsaturated fats, such as mayonnaise, are prone to lipid oxidation. In the food industry, typically accelerated shelf life tests are applied to assess the oxidative stability of different formulations. Here, the appearance of aldehydes at the so-called onset time, typically weeks, is considered a measure for oxidative stability of food emulsions, such as mayonnaise. To enable earlier assessment of compromised shelf-life, a predictive model for volatile off-flavor generation is developed. The model is based on the formation kinetics of hydroperoxides, which are early oxidation products and precursors of volatile aldehydes, responsible for off-flavor. Under accelerated shelf-life conditions (50 °C), hydroperoxide (LOOH) concentration over time shows a sigmoidal curvature followed by an acceleration phase that occurs at a LOOH-concentration between 38–50 mmol/kg, here interpreted as a critical LOOH concentration (CCLOOH). We hypothesize that the time at which CCLOOH was reached is related to the onset of aldehyde generation and that the characterization of the LOOH-generation curvature could be based on reaction kinetics in the first days. These hypotheses are tested using semi-empirical models to describe the autocatalytic character of hydroperoxide formation in combination with the CCLOOH. The Foubert function is selected as best describing the LOOH-curvature and is hence used to accurately predict onset of aldehyde generation, in most cases within several days of shelf-life. Furthermore, we find that the defining parameters of this model could be used to recognize antioxidant mechanisms at play.

Fluorescence sensors for aldehydes based on luminescent metal-organic frameworks

Volatile aldehydes have a great harm to human health and living environment and the detection of aldehydes attracts much attention from chemists and material scientists. In recent years, as one...

Ontogenesis of Aldehyde Pheromones in Two Synanthropic Bed Bug Species (Heteroptera: Cimicidae)

Bed bugs produce volatile aldehydes that have alarm and aggregation functions. Using two synanthropic bed bug species, Cimex lectularius L. and C. hemipterus (Fabricius), developmental changes were examined for (E)-2-hexenal, 4-oxo-(E)-2-hexenal, (E)-2-octenal, and 4-oxo-(E)-2-octenal, the four most abundant aldehydes shared between the two species. Quantitative analyses of the aldehydes in the nymphal exuviae indicated that the aldehydes’ ratio remained similar throughout nymphal development. In general, (E)-2-octenal was most abundant, and (E)-2-hexenal and 4-oxo-(E)-2-octenal were least abundant. The fourth aldehyde, 4-oxo-(E)-2-hexenal, was present in intermediate quantities. The quantities and percent abundances of the aldehydes in nymphal exuviae and the adults were significantly different between C. lectularius and C. hemipterus. The ratio between (E)-2-hexenal and (E)-2-octenal was determined in adult male and female bed bugs of each species. Adult C. hemipterus had a higher proportion of (E)-2-hexenal than C. lectularius, while no sex differences were found. This work provides the first systematic quantification of four aldehydes [(E)-2-hexenal, 4-oxo-(E)-2-hexenal, (E)-2-octenal and 4-oxo-(E)-2-octenal] for all five of the nymphal stages for both C. lectularius and C. hemipterus.