Shedding Light on the Volatile Composition of Broa, a Traditional Portuguese Maize Bread.

In Portugal, maize has been used for centuries to produce an ethnic bread called broa, employing traditional maize varieties, which are preferred by the consumers in detriment of commercial hybrids. In order to evaluate the maize volatiles that can influence consumers' acceptance of broas, twelve broas were prepared from twelve maize varieties (eleven traditional and one commercial hybrid), following a traditional recipe. All maize flours and broas were analyzed by HS-SPME-GC-MS (headspace solid-phase microextraction) and broas were appraised by a consumer sensory panel. In addition, the major soluble phenolics and total carotenoids contents were quantitated in order to evaluate their influence as precursors or inhibitors of volatile compounds. Results showed that the major volatiles detected in maize flours and broas were aldehydes and alcohols, derived from lipid oxidation, and some ketones derived from carotenoids' oxidation. Both lipid and carotenoids' oxidation reactions appeared to be inhibited by soluble phenolics. In contrast, phenolic compounds appeared to increase browning reactions during bread making and, consequently, the production of pyranones. Traditional samples, especially those with higher contents in pyranones and lower contents in aldehydes, were preferred by the consumer sensory panel. These findings suggest that, without awareness, consumers prefer broas prepared from traditional maize flours with higher contents in health-promoting phenolic compounds, reinforcing the importance of preserving these valuable genetic resources.

Polyketone metabolites isolated from Rhodiola tibetica endohytic fungus Alternaria sp. HJT-Y7 and their SARS-CoV-2 virus inhibitory activitives.

Six new polyketone metabolites, compounds (1-6) and seven known polyketone compounds (7-13) were isolated from Rhodiola tibetica endophytic fungus Alternaria sp. The structural elucidation of five new polyketone metabolites were elucidated on the basis of spectroscopic including 2D NMR and HRMS and spectrometric analysis. Inhibition rate evaluation revealed that compounds 1(EC50 = 0.02 mM), 3(EC50 = 0.3 mM), 6(EC50 = 0.07 mM), 8(EC50 = 0.1 mM) and 9(EC50 = 0.04 mM) had inhibitory effect on the SARS-CoV-2 virus.

Three New 2,2'-Difurylketone Derivatives and Two New Chromones from the Rehmanniae Radix Praeparata.

Rehmanniae Radix Praeparata is the processed products of the root of Rehmannia glutinosa. It has been used as a Traditional Chinese Medicine for thousands of years, and it has been found to possess widely pharmacological activities. In this study, three new 2,2'-difurylketone derivatives (rehmanniaeketone A-C) and two new chromones [3,8-dihydroxy-2-(2-hydroxyethyl)chromone and 3,8-dihydroxy-2-[(2-O-α-D-galactopyranosyloxy)ethyl]chromone] were isolated from the Rehmanniae Radix Praeparata. Furthermore all of the compounds were subjected to cytotoxic testing against the human lung carcinoma A549 cells. The cytotoxic results showed that rehmanniaeketone B and rehmanniaeketone C exhibited more stronger inhibition effects on the cell activity of A549 cells with the IC50 5.23 µM and 2.05 µM than other compounds. And 3,8-dihydroxy-2-(2-hydroxyethyl)chromone exhibited moderately inhibitory activity with the IC50 61 µM. Rehmanniaeketone A and 3,8-dihydroxy-2-[(2-O-α-D-galactopyranosyloxy]chromone showed no inhibitory effects.

Re-Analysis of Abdominal Gland Volatilome Secretions of the African Weaver Ant, Oecophylla longinoda (Hymenoptera: Formicidae).

The African weaver ant, Oecophylla longinoda, is used as a biological control agent for the management of pests. The ant has several exocrine glands in the abdomen, including Dufour's, poison, rectal, and sternal glands, which are associated with pheromone secretions for intra-specific communication. Previous studies have analyzed the gland secretions of Dufour's and poison glands. The chemistry of the rectal and sternal glands is unknown. We re-analyzed the secretions from Dufour's and poison glands plus the rectal and sternal glands to compare their chemistries and identify additional components. We used the solid-phase microextraction (SPME) technique to collect gland headspace volatiles and solvent extraction for the secretions. Coupled gas chromatography-mass spectrometry (GC-MS) analysis detected a total of 78 components, of which 62 were being reported for the first time. These additional components included 32 hydrocarbons, 12 carboxylic acids, 5 aldehydes, 3 alcohols, 2 ketones, 4 terpenes, 3 sterols, and 1 benzenoid. The chemistry of Dufour's and poison glands showed a strong overlap and was distinct from that of the rectal and sternal glands. The different gland mixtures may contribute to the different physiological and behavioral functions in this ant species.

Isolation and characterization of a novel antimicrobial oxatetracyclo ketone from Bacillus stercoris MBTDCMFRI Ba37 isolated from the tropical estuarine habitats of Cochin.

Antimicrobial compounds from the safest source have gained greater relevance because of their wide spectrum of possible applications, especially in aquaculture industry, where pathogenic threat and antibacterial resistance are serious concerns. Bacillus stercoris MBTDCMFRI Ba37 isolated from mangrove environment of tropical estuarine habitats of Cochin exhibited a wide spectrum of antibacterial activity against major aquaculture pathogens belonging to genus Vibrio and Aeromonas. The structural characterization of the antibacterial compound from this strain may help in identifying their role as a biocontrol agent in aquaculture and allied sectors. The highest antibacterial activity was detected in 3rd day culture, grown in a modified Bacillus medium containing 1% of glycerol and 0.5% of glutamic acid at 30 °C, pH 8.0 and 15 ppt saline conditions. The inhibitory activity of the cell free supernatant was evident even at 20% v/v dilution. Preliminary studies on the nature of antibacterial action indicated that the bioactive principle is stable at temperatures up to 70 °C, between pH 6-9 and instable to lyzozyme and proteolytic enzymes. Bioassay guided purification followed by spectroscopic characterization of active fractions of B. stercoris MBTDCMFRI Ba37 revealed that the compound 1-(1-Hydroxyethyl)-1,7,10,12,13,15,17 heptamethyl-16-oxatetracyclo[8.7.0.02,3.012,13]heptadecan-5-one, is responsible for its major antibacterial activity. This is the first report on isolation and characterization of an antibacterial compound from the species B. stercoris. The results of this study indicated that B. stercoris MBTDCMFRI Ba37 has beneficial antibacterial properties which could be useful in developing novel antimicrobial therapeutics against a variety of aquaculture and other pathogens.

Chemical detection triggers honey bee defense against a destructive parasitic threat.

Invasive species events related to globalization are increasing, resulting in parasitic outbreaks. Understanding of host defense mechanisms is needed to predict and mitigate against the consequences of parasite invasion. Using the honey bee Apis mellifera and the mite Varroa destructor, as a host-parasite model, we provide a comprehensive study of a mechanism of parasite detection that triggers a behavioral defense associated with social immunity. Six Varroa-parasitization-specific (VPS) compounds are identified that (1) trigger Varroa-sensitive hygiene (VSH, bees' key defense against Varroa sp.), (2) enable the selective recognition of a parasitized brood and (3) induce responses that mimic intrinsic VSH activity in bee colonies. We also show that individuals engaged in VSH exhibit a unique ability to discriminate VPS compounds from healthy brood signals. These findings enhance our understanding of a critical mechanism of host defense against parasites, and have the potential to apply the integration of pest management in the beekeeping sector.

Antibacterial assay guided isolation of a novel hydroxy-substituted pentacyclo ketonic compound from Pseudomonas aeruginosa MBTDCMFRI Ps04.

Antimicrobial compounds from the natural source have gained greater relevance because of their wide spectrum of possible applications, especially in the aquaculture industry where pathogenic threat and antibacterial resistance are serious concerns. In this regard, Pseudomonas aeruginosa MBTDCMFRI Ps04 (P. aeruginosa Ps04) strain isolated from the tropical estuarine habitats of Cochin was evaluated for its antibacterial potential against major aquaculture pathogens. The physiological conditions for the maximum production of the active metabolite were also optimized. An activity-guided approach was employed further to isolate and characterize the secondary metabolite responsible for the inhibitory potential. It was found that the cell free supernatant (CFS) of P. aeruginosa Ps04 exhibited strong antibacterial activity against major aquaculture pathogens belonging to the genus Vibrio and Aeromonas and retained its potential even at 30% (v/v) dilution. The highest antibacterial activity was detected from 3rd day culture, grown in glycerol alanine media (1% each) as carbon and nitrogen source, respectively, at 30 °C, pH 7.0 and at a salinity of 20 parts per thousand (ppt). The activity of the antagonistic principle was found to be stable against variations in pH (pH 2-pH 12), temperature (up to 120 °C) and enzymatic treatments. Bioassay-guided purification followed by spectroscopic characterization of active fractions of P. aeruginosa Ps04 revealed that the compound 4-Hydroxy-11-methylpentacyclo [11.8.0.02,3.011, 12.016,17]henicosa-1,3,5,8(9),17-penten-14-one is responsible for its major antibacterial activity. The results of this study indicated that P. aeruginosa Ps04 has beneficial antibacterial properties which could be used in developing novel antimicrobial therapeutics against a variety of aquaculture pathogens.

Chemical Composition and Bioactivity of Essential Oil of Ten Labiatae Species.

Using antibiotics as feed additives have been successively banned worldwide from 1986; therefore, it is an urgent task to finding safe and effective alternatives. As natural products of plant origin, essential oils (EOs) are an outstanding option due to their reported bioactivity. In this research, ten EOs of Labiatae species were extracted by steam distillation and its chemical constituents were identified by gas chromatography-mass spectrometry (GC-MS). A total of 123 chemical compounds, including alkenes, phenols, aldehydes and ketones, were identified. The results of antioxidant activity carried out through DPPH free radical scavenging (DPPH) and ferric reducing antioxidant power (FRAP), showing that EOs of Ocimum basilicum Linn. (ObEO), Thymus mongolicus Ronn. (TmEO), Origanum vulgare Linn. (OvEO) and Mosla chinensis Maxim. (McEO) have strong antioxidant activities. Their 50%-inhibitory concentration (IC50) value was <1.00, 1.42, 1.47 and 1.92 µg/mL, respectively; and their FRAP value was 1536.67 ± 24.22, 271.84 ± 4.93, 633.71 ± 13.14 and 480.66 ± 29.90, respectively. The results of filter paper diffusion showing that McEO, OvEO and TmEO inhibition zone diameter (IZD) are all over 30 mm. The results of two-fold dilution method showed that McEO, OvEO and TmEO have strong antibacterial activities against Staphylococcus aureus (S. aureus) and their minimal inhibitory concentrations (MIC) value was 1 µL/mL, 2 µL/mL, and 2 µL/mL, respectively. In conclusion, the results in this work demonstrate the possibility for development and application of EOs as potential feed additives.

Chemical Components and Antibacterial Activity of the Essential Oil of Six Pyrrosia Species.

The present study was aimed at analyzing the chemical components of the essential oil from six Pyrrosia species by GC/MS and evaluating their in vitro antibacterial activities. Seventy volatile compounds were identified in the essential oil of six Pyrrosia samples. The identified volatile components were divided into following nine categories: aldehydes, terpenoids, fatty acids, ketones, furans, hydrocarbons, alcohols, esters, and phenols. The major components of the essential oil were 2,4-pentadienal, phytol and nonanal. The antimicrobial assays showed that the essential oils from Pyrrosia samples exhibited a broad-spectrum antimicrobial activity. However, P. lingua had the highest antibacterial activity against Staphylococcus aureus (ATCC 25923) with a minimum inhibitory concentration (MIC) of 2.5 µL/mL. This article is the first report of the chemical components and antimicrobial activity of the essential oil from six Pyrrosia species, which will lay the foundation for developing medicinal resources from Pyrrosia fronds.

Volatile Profile in Yogurt Obtained from Saanen Goats Fed with Olive Leaves.

The aim of this study was to evaluate the development of volatile compounds in yogurt samples obtained from goats fed a dietary supplementation with olive leaves (OL). For this purpose, thirty Saanen goats were divided into two homogeneous groups of 15 goats each: a control group that received a standard diet (CG) and an experimental group whose diet was supplemented with olive leaves (OLG). The trial lasted 28 days, at the end of which the milk of each group was collected and used for yogurt production. Immediately after production, and after 7 days of storage at 4 °C in the absence of light, the yogurt samples were characterized in terms of fatty acid profile, oxidative stability and volatile compounds by the solid-phase microextraction (SPME)-GC/MS technique. Dietary OL supplementation positively affected the fatty acid composition, inducing a significant increase in the relative proportion of unsaturated fatty acids, mainly oleic acid (C18:1 cis9) and linolenic acid (C18:3). With regard to the volatile profile, both in fresh and yogurt samples stored for 7 days, the OL supplementation induced an increase in free fatty acids, probably due to an increase in lipolysis carried out by microbial and endogenous milk enzymes. Specifically, the largest variations were found for C6, C7, C8 and C10 free fatty acids. In the same samples, a significant decrease in aldehydes, mainly heptanal and nonanal, was also detected, supporting-at least in part-an improvement in the oxidative stability. Moreover, alcohols, esters and ketones appeared lower in OLG samples, while no significant variations were observed for lactones. These findings suggest the positive role of dietary OL supplementation in the production of goats' milk yogurt, with characteristics potentially indicative of an improvement in nutritional properties and flavor.

Triketone-terpene meroterpenoids from the leaves of Rhodomyrtus tomentosa.

Eight new meroterpenoids (1-8) featuring ß-triketone-conjugated terpenoids, rtomentones A-H, were isolated from the leaves of Rhodomyrtus tomentosa. Structures of the isolates were unambiguously established by a combination of NMR and ECD spectroscopy and X-ray diffraction analysis. Rtomentone C (3) was the first example of aromadendrane-based meroterpenoid containing an oxa-spiro[5.6] ring. Rtomentone D (4) was obtained as a racemic mixture confirmed by chiral HPLC analysis. The cytotoxicity against MDA-MB-231, A549, and DLD-1 cells of all isolates was evaluated.

Volatile composition of prickly pear fruit pulp from six Spanish cultivars.

This research analyzed the volatile composition of the fruits pulp of six prickly pear cultivars (NT, NE, NO, NA, FR, and ORI) growing in Spain, by headspace solid-phase microextraction and gas chromatography (GC-MS and GC-FID). A total of 35 compounds were isolated, identified, and quantified, with aldehydes, alcohols, and terpenes being the predominant chemical families, and esters, ketones, linear hydrocarbons, and terpenoids being also found. Nonanol, 2,6-nonadienal, 1-hexanol, 2-hexenal, and D-limonene were the predominant compounds. NT and FR cultivars showed the highest concentration of total volatile compounds. On the other hand, NE and NO cultivars presented the lowest concentration. Future studies on sensory evaluation are required to determine the sensory quality of the fruits of these Spanish cultivars.

Identification and analysis of new α- and ß-hydroxy ketones related to the formation of 3-methyl-2,4-nonanedione in musts and red wines.

The formation of 3-methyl-2,4-nonanedione (MND) during red wine aging can contribute to the premature evolution of aroma, characterized by the loss of fresh fruit and development of dried fruit flavors. The identification of two new hydroxy ketones, 2-hydroxy-3-methylnonan-4-one (syn- and anti-ketol diastereoisomers) and 3-hydroxy-3-methyl-2,4-nonanedione (HMND), prompted the investigation of the precursors and pathways through which MND is produced and evolves. An HS-SPME-GC-MS method was optimized for their quantitation in numerous must and wine samples, providing insight into the evolution of MND, HMND, and ketols through alcoholic fermentation and wine aging. Alcoholic fermentation resulted in a significant decrease in MND and HMND and the simultaneous appearance of ketol diastereoisomers. The analysis of 167 dry red wines revealed significant increases in MND and anti-ketol contents through aging and a significant positive correlation between MND and anti-ketols. Additional experiments demonstrated that ketols are precursors to MND during red wine oxidation.

Effect of bound water on the quality of dried Lentinus edodes during storage.

BACKGROUND: Water absorption is the dominant factor affecting the quality deterioration of dried Lentinus edodes. We therefore analyzed the effect of moisture content and dynamic water status on physical properties of the mushroom stored at water activity (aw ), 0.33, 0.43, 0.67, 0.76, and 0.84 for 50 days. Moisture mobility and water status were analyzed using low-field nuclear magnetic resonance, while hardness and microstructure were determined as texture characteristics. Meanwhile, an electronic nose and headspace solid-phase micro-extraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS) were used to analyze the flavor properties of dried L. edodes. RESULTS: The results showed that bound water was the dominant water status in dried L. edodes. The content and molecular mobility of bound water increased at aw = 0.67, 0.76, and 0.84. This contributed to discoloration, hardness loss, and microstructure sparsity of dried L. edodes. The increasing content and molecular mobility of bound water aggravated the deterioration of characteristic flavor by reducing acid, aldehyde, and ketone content. CONCLUSION: Unlike immobilized or free water, bound water had a critical influence on the quality deterioration of dried L. edodes during storage. © 2019 Society of Chemical Industry.

Enriching cancer pharmacology with drugs of marine origin.

Marine natural products have proven, over the last half-century, to be effective biological modulators. These molecules have revealed new targets for cancer therapy as well as dissimilar modes of action within typical classes of drugs. In this scenario, innovation from marine-based pharmaceuticals has helped advance cancer chemotherapy in many aspects, as most of these are designated as first-in-class drugs. Here, by examining the path from discovery to development of clinically approved drugs of marine origin for cancer treatment-cytarabine (Cytosar-U®), trabectedin (Yondelis®), eribulin (Halaven®), brentuximab vedotin (Adcetris®), and plitidepsin (Aplidin®)- together with those in late clinical trial phases-lurbinectedin, plinabulin, marizomib, and plocabulin-the present review offers a critical analysis of the contributions given by these new compounds to cancer pharmacotherapy.

Determination of Key Volatile Compounds Related to Long-Term Fermentation of Soy Sauce.

The changes of volatile compounds in soy sauce during long-term fermentation (12 months) were investigated using solid-phase microextraction (SPME) and stir bar sorptive extraction (SBSE). A total of 144 and 129 compounds were identified in soy sauce with long-term fermentation by SPME and SBSE, respectively. The contents of most compounds, such as acids, aldehydes, benzene and benzene derivatives, esters, lactones, pyrazines, pyrones, and pyrroles, showed a tendency to increase, whereas those of alcohols and ketones decreased according to long-term fermentation. In addition, principal component analysis and partial least squares discriminant analysis were applied to discriminate soy sauce samples according to fermentation periods and determine key volatile compounds related to long-term fermentation. The initial fermentation stages were mainly associated with some alcohols, ketones, and lactones, whereas the later stages were strongly associated with most esters, some phenols, benzene and benzene derivatives, and pyrroles. Moreover, the key volatile compounds associated with long-term fermentation in soy sauce samples were ethyl 3-methylbutanoate (ethyl isovalerate), ethyl pentanoate (ethyl valerate), 1-octen-3-yl acetate, 3-(methylthio)-1-propanol (methionol), ethyl benzoate, ethyl 2-phenylacetate, 1-(1H-pyrrol-2-yl)ethanone (2-acetylpyrrole), and 5-pentyl-2-oxolanone (γ-nonalactone). PRACTICAL APPLICATION: This study investigated changes of volatile compounds in soy sauce during long-term fermentation (12 months) using solid-phase microextraction and stir bar sorptive extraction. In addition, the key volatile compounds associated with long-term fermentation in soy sauce samples were determined. These results may help to predict the effective contributors related to long-term fermentation of soy sauce and improve the quality of soy sauce during long-term fermentation.

Determination of Volatile Compounds in Nut-Based Milk Alternative Beverages by HS-SPME Prior to GC-MS Analysis.

A reliable Headspace-Solid Phase Microextraction (HS-SPME) method was developed for the determination of polar volatile components of commercial nut-based milk alternative drinks prior to Gas Chromatography-Mass Spectrometry (GC-MS) analysis. Under the optimum extraction conditions, a divinylbenzene (DVB)/Carboxen™ CAR)/polydimethylsiloxane (PDMS) fiber was used and 2 mL of sample was heated at 60 °C for 40 min under stirring, without salt addition. Ten compounds from different chemical classes (heptane, a-pinene, toluene, 2-methylpyrazine, 3-heptanone, heptanal, 2-octanone, 1-heptanol, benzaldehyde and 1-octanol) were chosen as model analytes for quantification. Limits of detection and limits of quantification were found to be 0.33-1.67 ng g-1 and 1-5 ng g-1, accordingly. Good linearity, precision and accuracy were obtained as well as a wide linear range. The proposed method was successfully applied to various beverages including almond milk, walnut milk, peanut milk and almond chocolate milk. More than 70 volatile compounds were detected in the different samples. Most of the detected volatiles were aldehydes, ketones and alcohols. This technique can be used for the determination of volatile compounds in nut-based beverages, to detect compositional changes during storage and technological treatment used for their production.

An efficient approach to eliminate steryl ethers and miscellaneous esters/ketones for gas chromatographic analysis of alkenones and alkenoates.

Long-chain alkenones (LCAs) and alkenoates (LCEs) are highly valuable biomarkers for paleotemperature reconstructions. A major problem, however, for accurate quantification of these compounds using gas chromatography (GC) is co-elution with steryl ethers, wax esters, saturated ketones and other numerous mid-polarity compounds frequently encountered in marginal marine and lake sediments. Co-elution during GC separation is prevalent, particularly if the full homologous series of alkenones and alkenoates are to be analyzed. Taking advantage of the presence of two or more double bonds in LCAs and LCEs, the conventional silica gel impregnated with silver nitrate has previously been used to remove co-eluting compounds for LCAs. However, this conventional argentation chromatography is hampered by the extreme instability of silver nitrate, poor reproducibility, low recovery and short lifetime. Here we demonstrate a highly efficient flash chromatographic approach based on silver thiolate chromatographic material (AgTCM) that overcomes the shortcomings of the traditional argentation chromatography and allows repeated sample preparation (up to 62 samples in one test) with little loss in separation efficiency. AgTCM selectively extracts LCAs and LCEs and effectively eliminates co-eluting compounds including steryl ethers and wax esters for the subsequent gas chromatography (GC) analysis. This new method, therefore, allows low-cost and high-throughput sample preparation for comprehensive quantification of the full homologous series of LCAs and LCEs in marine and lake sediments.

Identification of key odorant compounds in starch-based polymers intended for food contact materials.

Biopolymers used for food contact materials must be evaluated in order to ensure food safety and quality. In this work, the aroma profile of starch-based packaging materials, presented as pellets and films has been characterized. Headspace solid phase microextraction (HS-SPME) technique and gas chromatography coupled to both mass spectrometry and a sniffing port (GC-MS-O) were used for identification. In total, 35 odorant compounds were detected. The results showed that aldehydes were the odorants with the highest aromatic impact in starch-based films. Eight odorant compounds, such as trimethylamine, 1-octen-3-one, sotolon, (Z) and (E)-2-nonenal, p-vinylguaiacol, eugenol and 1-undecanol, defined as aroma-impact compounds, obtained modified frequency values (MF%) above 60% in at least 3 out of 4 films. A sensory panel evaluated the toasted, sweet/fruity, green, flower, distasteful, fat and spices notes in the films and it was observed that the quality of all samples decreased when the toasted and spices notes increased.

Click regulation of cyclodextrin primary face for the preparation of novel chiral stationary phases.

In this study, a series of novel CD chiral stationary phases were fabricated by immobilization of mono-6A -deoxy-N3 -cyclodextrin onto silica surfaces followed by click regulation of CD primary face with 4-pentynoic acid (acidic moiety), 2-propynylamine (alkaline moiety) and L-propargylglycine (chiral amino acid moiety), respectively. Enantioseparations of various kinds of racemates including dansyl-amino acids, chiral lactides and diketones were conducted in reversed phase modes on these chiral stationary phases, where nearly forty diketones and chiral lactides were firstly separated on cyclodextrin stationary phases. 4-Pentynoic acid moiety can make the retention ability decline while amine moiety significantly enhanced the retention ability of the stationary phases. For most of the studied analytes, the chiral amino acid moiety had the most positive effects on both the retention time and the resolution. The inclusion complexation between chiral analytes and cyclodextrins were also investigated by fluorescence method.