Quantitative HPLC-MS/MS analysis of toxins in soapberry seeds: Methylenecyclopropylglycine and hypoglycin A.

Methylenecyclcopropylglycine (MCPG) and hypoglycin A (HGA) are naturally occurring amino acids found in various soapberry (Sapindaceae) fruits. These toxins have been linked to illnesses worldwide and were recently implicated in Asian outbreaks of acute hypoglycemic encephalopathy. In a previous joint agricultural and public health investigation, we developed an analytical method capable of evaluating MCPG and HGA concentrations in soapberry fruit arils as well as a clinical method for the urinary metabolites of the toxins. Since the initial soapberry method only analyzed the aril portion of the fruit, we present here the extension of the method to include the fruit seed matrix. This work is the first method to quantitate both MCPG and HGA concentrations in the seeds of soapberry fruit, including those collected during a public health investigation. Further, this is the first quantitation of HGA in litchi seeds as well as both toxins in mamoncillo and longan seeds.

Biosynthesis and Conformational Properties of the Irregular Sesquiterpenoids Isothapsadiene and ß-Isothapsenol.

A carbocation cyclization/rearrangement mechanism for the biosynthesis of isothapsadiene and ß-isothapsenol is shown to be energetically viable on the basis of density functional theory (DFT) calculations. In addition, for both isothapsadiene and ß-isothapsenol, variable-temperature NMR experiments reveal two equilibrium conformers that undergo hindered exchange. The identities of these conformers, which are related by a chair-flip, are confirmed by DFT calculations on their structures, energies, 1H and 13C chemical shifts, and interconversion pathways.

Antimicrobial Carvacrol in Solution Blow-Spun Fish-Skin Gelatin Nanofibers.

Carvacrol is a volatile monoterpenic phenol and main component of oregano essential oil that shows nonspecific antimicrobial activity against foodborne pathogenic bacteria. Fish-skin gelatin (FSG) nanofibers encapsulating carvacrol (15%, 20%, 25%, and 30%, w/w FSG) were successfully prepared via solution blow-spinning (SBS) technique using lecithin (2.475% wb) as the surfactant. FSG emulsions with lower carvacrol ratios (5% and 10%) showed higher values in particle size and surface tension as well as lower values in viscosity and modulus, which led to failure of maintaining nanofibers shape. The formed carvacrol-FSG nanofibers showed round and smooth morphologies with average fiber diameters ranging from 103.2 to 138.1 nm as the carvacrol ratio increased from 15% to 30%. Carvacrol was evenly dispersed within the interior of nanofiber matrix. All carvacrol-FSG nanofibers showed inhibitive effects against the growth of Escherichia coli, Salmonella enterica, and Listeria monocytogenes. Moreover, nanofibers with lower carvacrol ratios showed bigger inhibition zones for E. coli and L. monocytogenes (20 mm compared with 12.5 mm for lowest to highest carvacrol ratios, respectively). Nanofibers stored at 20 °C (51% RH) showed better retention (40% to 60%) for carvacrol during the first 4 weeks of storage, while nanofibers stored at 2 °C (70% RH) showed better retention (10% to 30%) at the end of storage. PRACTICAL APPLICATION: Results obtained in the study may help with antimicrobial carvacrol addition levels for gelatin fiber preparation using solution blow spinning (SBS) method. SBS gelatin fibers with added antimicrobials have potential applications for food packaging and medical wound dressing.

Preparation of Fish Skin Gelatin-Based Nanofibers Incorporating Cinnamaldehyde by Solution Blow Spinning.

Cinnamaldehyde, a natural preservative that can non-specifically deactivate foodborne pathogens, was successfully incorporated into fish skin gelatin (FSG) solutions and blow spun into uniform nanofibers. The effects of cinnamaldehyde ratios (5-30%, w/w FSG) on physicochemical properties of fiber-forming emulsions (FFEs) and their nanofibers were investigated. Higher ratios resulted in higher values in particle size and viscosity of FFEs, as well as higher values in diameter of nanofibers. Loss of cinnamaldehyde was observed during solution blow spinning (SBS) process and cinnamaldehyde was mainly located on the surface of resultant nanofibers. Nanofibers all showed antibacterial activity by direct diffusion and vapor release against Escherichia coli O157:H7, Salmonella typhimurium, and Listeria monocytogenes. Inhibition zones increased as cinnamaldehyde ratio increased. Nanofibers showed larger inhibition effects than films prepared by casting method when S. typhimurium was exposed to the released cinnamaldehyde vapor, although films had higher remaining cinnamaldehyde than nanofibers after preparation. Lower temperature was favorable for cinnamaldehyde retention, and nanofibers added with 10% cinnamaldehyde ratio showed the highest retention over eight-weeks of storage. Results suggest that FSG nanofibers can be prepared by SBS as carriers for antimicrobials.

Association of acute toxic encephalopathy with litchi consumption in an outbreak in Muzaffarpur, India, 2014: a case-control study.

BACKGROUND: Outbreaks of unexplained illness frequently remain under-investigated. In India, outbreaks of an acute neurological illness with high mortality among children occur annually in Muzaffarpur, the country's largest litchi cultivation region. In 2014, we aimed to investigate the cause and risk factors for this illness. METHODS: In this hospital-based surveillance and nested age-matched case-control study, we did laboratory investigations to assess potential infectious and non-infectious causes of this acute neurological illness. Cases were children aged 15 years or younger who were admitted to two hospitals in Muzaffarpur with new-onset seizures or altered sensorium. Age-matched controls were residents of Muzaffarpur who were admitted to the same two hospitals for a non-neurologic illness within seven days of the date of admission of the case. Clinical specimens (blood, cerebrospinal fluid, and urine) and environmental specimens (litchis) were tested for evidence of infectious pathogens, pesticides, toxic metals, and other non-infectious causes, including presence of hypoglycin A or methylenecyclopropylglycine (MCPG), naturally-occurring fruit-based toxins that cause hypoglycaemia and metabolic derangement. Matched and unmatched (controlling for age) bivariate analyses were done and risk factors for illness were expressed as matched odds ratios and odds ratios (unmatched analyses). FINDINGS: Between May 26, and July 17, 2014, 390 patients meeting the case definition were admitted to the two referral hospitals in Muzaffarpur, of whom 122 (31%) died. On admission, 204 (62%) of 327 had blood glucose concentration of 70 mg/dL or less. 104 cases were compared with 104 age-matched hospital controls. Litchi consumption (matched odds ratio [mOR] 9·6 [95% CI 3·6 - 24]) and absence of an evening meal (2·2 [1·2-4·3]) in the 24 h preceding illness onset were associated with illness. The absence of an evening meal significantly modified the effect of eating litchis on illness (odds ratio [OR] 7·8 [95% CI 3·3-18·8], without evening meal; OR 3·6 [1·1-11·1] with an evening meal). Tests for infectious agents and pesticides were negative. Metabolites of hypoglycin A, MCPG, or both were detected in 48 [66%] of 73 urine specimens from case-patients and none from 15 controls; 72 (90%) of 80 case-patient specimens had abnormal plasma acylcarnitine profiles, consistent with severe disruption of fatty acid metabolism. In 36 litchi arils tested from Muzaffarpur, hypoglycin A concentrations ranged from 12·4 µg/g to 152·0 µg/g and MCPG ranged from 44·9 µg/g to 220·0 µg/g. INTERPRETATION: Our investigation suggests an outbreak of acute encephalopathy in Muzaffarpur associated with both hypoglycin A and MCPG toxicity. To prevent illness and reduce mortality in the region, we recommended minimising litchi consumption, ensuring receipt of an evening meal and implementing rapid glucose correction for suspected illness. A comprehensive investigative approach in Muzaffarpur led to timely public health recommendations, underscoring the importance of using systematic methods in other unexplained illness outbreaks. FUNDING: US Centers for Disease Control and Prevention.

Quantification of Toxins in Soapberry (Sapindaceae) Arils: Hypoglycin A and Methylenecyclopropylglycine.

Methylenecyclopropylglycine (MCPG) and hypoglycin A (HGA) are naturally occurring amino acids found in some soapberry fruits. Fatalities have been reported worldwide as a result of HGA ingestion, and exposure to MCPG has been implicated recently in the Asian outbreaks of hypoglycemic encephalopathy. In response to an outbreak linked to soapberry ingestion, the authors developed the first method to simultaneously quantify MCPG and HGA in soapberry fruits from 1 to 10 000 ppm of both toxins in dried fruit aril. Further, this is the first report of HGA in litchi, longan, and mamoncillo arils. This method is presented to specifically address the laboratory needs of public-health investigators in the hypoglycemic encephalitis outbreaks linked to soapberry fruit ingestion.

Volatile constituents of commercial imported and domestic black-ripe table olives (Olea europaea).

Volatile constituents of commercial black-ripe table olives (Olea europaea) from the United States, Spain, Egypt and Morocco were analysed by gas chromatography and gas chromatography-mass spectrometry (GC-MS). Dynamic headspace sampling was used to isolate a variety of aldehydes, alcohols, esters, ketones, phenols, terpenes, norisoprenoids, and pyridines. Odour unit values, calculated from concentration and odour threshold data, indicate that the following compounds are major contributors to black-ripe table olive aroma: ß-damascenone, nonanal, (E)-dec-2-enal, 3-methylbutanal, ethyl benzoate, octanal, 2-methoxyphenol, 2-methylbutanal and 2-methoxy-4-methylphenol. Imported olives contained a variety of fermentation derived volatiles that were not detected in domestic olives. Constituents such as ethyl 2-methylbutanoate, ethyl 3-methylbutanoate, 3-methylbutyl acetate, oct-1-en-3-one, ethyl hexanoate, (Z)-hex-3-enyl acetate, hexyl acetate, ethyl cyclohexanecarboxylate, benzyl acetate and 4-ethylphenol contributed to the odour of imported olives but were not detected in domestic olives.

Cooked carrot volatiles. AEDA and odor activity comparisons. Identification of linden ether as an important aroma component.

MS with GC-RI evidence was found for the presence of linden ether in cooked carrot (Daucus carota). Evaluation of the GC effluent from cooked carrot volatiles using aroma extract dilution analysis (AEDA) found linden ether with the highest flavor dilution (FD) factor. Others with 10-fold lower FD factors were ß-ionone, eugenol, the previously unidentified ß-damascenone, (E)-2-nonenal, octanal (+ myrcene), and heptanal. All other previously identified volatiles showed lower FD factors. Odor thresholds, concentrations, and odor activity values of previously identified compounds are reviewed. This indicated that at least 20 compounds occur in cooked carrots above their odor thresholds (in water). Compounds showing the highest odor activity values included ß-damascenone, (E)-2-nonenal, (E,E)-2,4-decadienal, ß-ionone, octanal, (E)-2-decenal, eugenol, and p-vinylguaiacol.

Irregular sesquiterpenoids from Ligusticum grayi roots.

Root oil of Ligusticum grayi (Apiaceae) contains numerous irregular sesquiterpenoids. In addition to the known acyclic sesquilavandulol and a sesquilavandulyl aldehyde, two thapsanes, one epithapsane, and 14 sesquiterpenoids representing eight hitherto unknown carbon skeletons were found. These skeletons are: prethapsane, i.e. 1,1,2,3a,7,7-hexamethyloctahydro-1H-indene; isothapsane, i.e. 1,2,3a,6,7,7a-hexamethyloctahydro-1H-indene; ligustigrane, i.e. 1,1,2,7,7,7a-hexamethyloctahydro-1H-indene; isoligustigrane, i.e. 1,1,2,6,7,7a-hexamethyloctahydro-1H-indene; preisothapsane, i.e. 1,1,2,3a,6,7-hexamethyloctahydro-1H-indene; isoprethapsane, i.e. 1,1,2,4,7,7-hexamethyloctahydro-1H-indene; allothapsane, i.e. 1,1,2,3a,7,7a-hexamethyloctahydro-1H-indene; and oshalagrane, i.e. 1,1,2,4,6,6-hexamethylspiro[4.4]nonane. The bicyclic sesquiterpenoids are presumably biosynthesized by head-to-head coupling of geranyl diphosphate and dimethylallyl diphosphate, followed by a cyclization sequence leading to a hydroindane skeleton with six one-carbon substituents. Subsequent rearrangements--primarily methyl migrations--account for the remarkable variety of structures represented in L. grayi root oil.

Antiplatelet activities of newly synthesized derivatives of piperlongumine.

Piperlongumine, a pyridone alkaloid isolated from Piper longum L., exhibited a potential inhibitory effect on washed rabbit platelet aggregation induced by collagen, arachidonic acid (AA) and platelet activating factor (PAF), without any inhibitory effect on that induced by thrombin. Piperlongumine was used as a lead compound for the synthesis of new antiplatelet agents. Seven synthetic compounds were newly synthesized from 3,4,5-trimethoxycinnamic acid (TMCA). They were 1-piperidin-1-yl-3-(3,4,5-trimethoxy-phenyl)prop-2-en-1-one (1'), 1-morpholin-4-yl-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (2'), 1-(3,5-dimethylpiperidin-1-yl)-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (3'), 1-(2-methylpiperidin-1-yl)-3-(3,4,5-tri-methoxyphenyl)prop-2-en-1-one (4'), 1-(3-hydroxypiperidin-1-yl)-3-(3,4,5-trimethoxyphenyl)- prop-2-en-1-one (5'), 1-[3-(3,4,5-tri-methoxyphenyl) acryloyl]-piperidin-2-one (6') and ethyl 1-[3-(3,4,5-trimethoxyphenyl)-acryloyl]piperidine-4-carboxylate (7'). Among those seven synthetic derivatives, 1-(3,5-dimethylpiperidin-1-yl)-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (3') had the most inhibitory effect on platelet aggregation induced by collagen, AA and PAF.

Studies on the aroma of five fresh tomato cultivars and the precursors of cis- and trans-4,5-epoxy-(E)-2-decenals and methional.

Three tasty (BR-139, FA-624, and FA-612) and two less tasty (R-144 and R-175) fresh greenhouse tomato cultivars, which significantly differ in their flavor profiles, were screened for potent odorants using aroma extract dilution analysis (AEDA). On the basis of AEDA results, 19 volatiles were selected for quantification in those 5 cultivars using gas chromatography-mass spectrometry (GC-MS). Compounds such as 1-penten-3-one, ( E, E)- and ( E, Z)-2,4-decadienal, and 4-hydroxy-2,5-dimethyl-3(2 H)-furanone (Furaneol) had higher odor units in the more preferred cultivars, whereas methional, phenylacetaldehyde, 2-phenylethanol, or 2-isobutylthiazole had higher odor units in the less preferred cultivars. Simulation of the odor of the selected tomato cultivars by preparation of aroma models and comparison with the corresponding real samples confirmed that all important fresh tomato odorants were identified, that their concentrations were determined correctly in all five cultivars, and that differences in concentration, especially of the compounds mentioned above, make it possible to distinguish between them and are responsible for the differential preference. To help elucidate formation pathways of key odorants, labeled precursors were added to tomatoes. Biogenesis of cis- and trans-4,5-epoxy-( E)-2-decenals from linoleic acid and methional from methionine was confirmed.

Antimalarial activity of anthothecol derived from Khaya anthotheca (Meliaceae).

Antimalarial activity of anthothecol, a limonoid of Khaya anthotheca (Meliaceae) against Plasmodium falciparum was tested using a [(3)H]-hypoxanthine and 48h culture assay in vitro. Anthotechol showed potent antimalarial activity against malaria parasites with IC(50) values of 1.4 and 0.17microM using two different assays. Also, gedunin had antimalarial activity with IC(50) values of 3.1 and 0.14microM. However, the citrus limonoids, limonin and obacunone did not show any antimalarial activity. The antimalarial activities were compared with the three currently used antimalarial medicines quinine, chloroquinine and artemisinin.

Inhibitory effects of Tabebuia impetiginosa inner bark extract on platelet aggregation and vascular smooth muscle cell proliferation through suppressions of arachidonic acid liberation and ERK1/2 MAPK activation.

The antiplatelet and antiproliferative activities of extract of Tabebuia impetiginosa inner bark (taheebo) were investigated using washed rabbit platelets and cultured rat aortic vascular smooth muscle cells (VSMCs) in vitro. n-Hexane, chloroform and ethyl acetate fractions showed marked and selective inhibition of platelet aggregation induced by collagen and arachidonic acid (AA) in a dose-dependent manner. These fractions, especially the chloroform fraction, also significantly suppressed AA liberation induced by collagen in [(3)H]AA-labeled rabbit platelets. The fractions, especially the chloroform fraction, potently inhibited cell proliferation and DNA synthesis induced by platelet derived growth factor (PDGF)-BB, and inhibited the levels of phosphorylated extracellular signal regulated kinase (ERK1/2) mitogen activated protein kinase (MAPK) stimulated by PDGF-BB, in the same concentration range that inhibits VSMC proliferation and DNA synthesis.

Antibacterial activity of Tabebuia impetiginosa Martius ex DC (Taheebo) against Helicobacter pylori.

The growth-inhibiting activity of Tabebuia impetiginosa Martius ex DC dried inner bark-derived constituents against Helicobacter pylori ATCC 43504 was examined using paper disc diffusion and minimum inhibitory concentration (MIC) bioassays. The activity of the isolated compounds was compared to that of the commercially available anti-Helicobacter pylori agents, amoxicillin, metronidazole, and tetracycline. The biologically active components of Tabebuia impetiginosa dried inner bark (taheebo) were characterized by spectroscopic analysis as 2-(hydroxymethyl)anthraquinone, anthraquinone-2-carboxylic acid, and 2-hydroxy-3-(3-methyl-2-butenyl)-1,4-naphthoquinone (lapachol). With the paper disc diffusion assay 2-(hydroxymethyl)anthraquinone exhibited strong activity against Helicobacter pylori ATCC 43504 at 0.01 mg/disc. Anthraquinone-2-carboxylic acid, lapachol and metronidazole were less effective, exhibiting moderate anti-Helicobacter pylori activity at 0.1 mg/disc. Amoxicillin and tetracycline were the most potent compounds tested, displaying very strong activity at 0.005 mg/disc. 2-(Hydroxymethyl)anthraquinone exhibited moderate activity at this dose. Tetracycline still had strong activity at 0.001 mg/disc while amoxicillin had little activity at this dose. In the MIC bioassay, 2-(hydroxymethyl)anthraquinone (2 microg/mL), anthraquinone-2-carboxylic acid (8 microg/mL), and lapachol (4 microg/mL) were more active than metronidazole (32 microg/mL) but less effective than amoxicillin (0.063 microg/mL) and tetracycline (0.5 microg/mL). The anti-Helicobacter pylori activity of seven 1,4-naphthoquinone derivatives (structurally related to lapachol), 1,4-naphthoquinone, 5,8-dihydroxy-1,4-naphthoquinone (naphthazarin), 2-methyl-1,4-naphthoquinone (menadione), 2-hydroxy-1,4-naphthoquinone (lawsone), 5-hydroxy-2-methyl-1,4-naphthoquinone (plumbagin), 5-hydroxy-1,4-naphthoquinone (juglone), and 2,3-dichloro-1,4-naphthoquinone (dichlone) was also evaluated using the paper disc assay. Menadione and plumbagin were the most potent compounds tested with the later still exhibiting very strong activity at 0.001 mg/disc. Menadione, juglone and tetracycline had strong activity at this low dose while the latter two compounds and amoxicillin had very strong activity at 0.005 mg/disc. Lawsone was unusual in that it had very strong activity at 0.1 and 0.05 mg/disc but weak activity at doses of 0.01 mg/disc and lower. Naphthazalin, lapachol and dichlone had similar activities while metronidazole had the lowest activity of all compounds tested. These results may be an indication of at least one of the pharmacological actions of taheebo. The Tabebuia impetiginosa dried inner bark-derived materials, particularly 2-(hydroxymethyl)anthraquinone, merit further study as potential Helicobacter pylori eradicating agents or lead compounds.

Curcuma longa L. constituents inhibit sortase A and Staphylococcus aureus cell adhesion to fibronectin.

The inhibitory activity of Curcuma longa L. (turmeric) rhizome constituents against sortase A, a bacterial surface protein anchoring transpeptidase, from Staphylococcus aureus ATCC 6538p was evaluated. The activity of the isolated compounds (1-4) was compared to that of the positive control,p-hydroxymecuribenzoic acid (pHMB). The biologically active components of C. longa rhizome were characterized by spectroscopic analysis as the curcuminoids curcumin (1), demethoxycurcumin (2), and bisdemethoxycurcumin (3). Curcumin was a potent inhibitor of sortase A, with an IC50 value of 13.8 +/- 0.7 microg/mL. Bisdemethoxycurcumin (IC50 = 31.9 +/- 1.2 microg/mL) and demethoxycurcumin (IC50 = 23.8 +/- 0.6 microg/mL) were more effective than pHMB (IC50 = 40.6 +/- 1.2 microg/mL). The three isolated compounds (1-3) showed no growth inhibitory activity against S. aureus strain Newman, with minimum inhibitory concentrations (MICs) greater than 200 microg/mL. Curcumin also exhibited potent inhibitory activity against S. aureus cell adhesion to fibronectin. The suppression of fibronectin-binding activity by curcumin highlights its potential for the treatment of S. aureus infections via inhibition of sortase activity. These results indicate that curcumin is a possible candidate in the development of a bacterial sortase A inhibitor.

Identification of benzalkonium chloride in commercial grapefruit seed extracts.

Commercial grapefruit seed extracts (GSE) were extracted with chloroform. The solvent was evaporated, and the resulting solid was subsequently analyzed by high-performance liquid chromatography (HPLC), electrospray ionization mass spectrometry (ESI/MS), tandem mass spectrometry (ESI/MS/MS), and elemental analysis (by proton-induced X-ray emission analysis). Three major constituents were observed by HPLC and were identified as benzyldimethyldodecylammonium chloride, benzyldimethyltetradecylammonium chloride, and benzyldimethylhexadecylammonium chloride. This mixture of homologues is commonly known as benzalkonium chloride, a widely used synthetic antimicrobial ingredient used in cleaning and disinfection agents.

Delphinidin 3-O-(2-O-beta-D-Glucopyranosyl-alpha-l-arabinopyranoside): a novel anthocyanin identified in Beluga black lentils.

A major anthocyanin was isolated from the acidified methanolic extract of Beluga black lentils by XAD7 column chromatography and preparative high-performance liquid chromatography. By means of electrospray ionization mass spectrometry and one- and two-dimensional nuclear magnetic resonance spectroscopy, its structure was determined to be delphinidin 3-O-(2-O-beta-D-glucopyranosyl-alpha-l-arabinopyranoside).

Inhibitory effect on proliferation of vascular smooth muscle cells and protective effect on CCl(4)-induced hepatic damage of HEAI extract.

The effects of methanol extract from Hericium erinaceus cultivated with Artemisia iwayomogi (HEAI) on proliferation of vascular smooth muscle cells and CCl(4)-induced hepatic damage were evaluated. HEAI was shown to have a potent inhibitory effect on the proliferation of vascular smooth muscle cells (VSMCs). Interestingly, a methanol extract of Hericium erinaceus showed no inhibitory effect on the proliferation of VSMCs, while a methanol extract of Artemisia iwayomogi possessed strong inhibitory effects on the proliferation of VSMCs. Therefore, the inhibitory effects of HEAI may be caused by the changes of chemical components in the culture broth after the addition of Artemisia iwayomogi in the HEAI growth media. HEAI also had a strong protective effect on CCl(4)-induced hepatic damage in rats. The activity was evaluated using biochemical parameters such as glutamic oxalacetic transaminase (GOT), glutamic pyruvic transaminase (GPT) and alkaline phosphatase (ALP). HEAI treatment caused a significant reduction in the activity of GOT but not of GPT and ALP in comparison with CCl(4) treatment alone. Histopathological studies showed that liver samples treated with HEAI were significantly different when compared to non-treated animals after CCl(4) exposure.

Selective growth-inhibiting effects of compounds identified in Tabebuia impetiginosa inner bark on human intestinal bacteria.

The growth-inhibiting activity of anthraquinone-2-carboxylic acid and lapachol identified in the inner bark of taheebo, Tabebuia impetiginosa, toward 10 human intestinal bacteria was evaluated by using a paper disk diffusion bioassay and compared to those of seven lapachol congeners (1,4-naphthoquinone, naphthazarin, menadione, lawsone, plumbagin, juglone, and dichlone) as well as two commercially available antibiotics, chloramphenicol and tetracycline. Anthraquinone-2-carboxylic acid exhibited very strong growth inhibition of Clostridium paraputrificum at 1 microg/disk while 100 microg/disk of lapachol was needed for moderate growth inhibition of the same organism. These two isolates exhibited weak inhibition of Clostridium perfringens and Escherichia coli at 100 microg/disk while no adverse effects were observed on the growth of Bifidobacterium adolescentis, Bifidobacterium bifidum, Bifidobacterium infantis, Lactobacillus acidophilus, and Lactobacillus casei at 1000 microg/disk. Structure-activity relationships indicate that a methyl group in the C-2 position of 1,4-naphthoquinone derivatives might play an important role in antibacterial activity.

Some unusual minor volatile components of tomato.

The identities and possible origins of three minor unusual volatile components of tomato are discussed. These are pentyl nitrate, the first identification of a volatile alkyl nitrate in a fresh vegetable or fruit; 5-ethyl-2(5H)-furanone, which, besides its presence in tomato, was found to be a major autoxidation product of pure (Z)-3-hexenal; and 5-ethylcyclopentene-1-carbaldehyde, a likely unusual linolenic acid oxidation product.