Removal of C9-aldehydes and -alcohols from melon juice via cysteine addition.

BACKGROUND: The aroma of a melon fruit is among the most crucial qualities that influence consumer preferences. However, strong grassy and cucumber-like aromas can prevent consumer acceptance. These grassy and cucumber-like aromas are produced by aldehydes containing nine-carbon chains. Several studies have revealed that aldehydes exhibit a high affinity toward cysteine. Thus, the effect of adding cysteine to volatile compounds to melon juice was investigated. RESULTS: The volatile compounds released from the melon juice were analyzed via solid-phase microextraction coupled with gas chromatography-mass spectrometry (SPME-GC-MS) after 0.5, 5, and 24 h of adding cysteine. The results indicated that the concentrations of aldehydes, such as (E,Z)-2,6-nonadienal and (E)-2-nonenal, in the melon juice decreased after the addition of cysteine at all the analyzed times. Additionally, (E)-2-nonenol and (E,Z)-2,6-nonadien-1-ol, which were formed by the enzymatic reduction of the aldehydes, also decreased by cysteine addition. To confirm the binding of cysteine with the aldehydes, two cysteine adducts were analyzed via liquid chromatography-mass spectrometry (LC-MS) employing (E)-2-nonenal in the melon juice after the addition of cysteine. CONCLUSION: This study demonstrates that cysteine addition could be potentially used to reduce the grassy and cucumber-like aromas of melon juice. © 2022 Society of Chemical Industry.

Isopentylamine is a novel defence compound induced by insect feeding in rice.

Plants produce a broad variety of defensive metabolites to protect themselves against herbivorous insects. Although polyamines have been implicated in various responses to abiotic and biotic stress, there have been no studies focused on amines in response to insect herbivory. By screening for bioactive amines, we identified isopentylamine as a novel type of herbivory-induced compound in rice leaves, which was derived from the amino acid leucine in stable isotope labelling experiments. Accumulation of isopentylamine increased during herbivory by the brown planthopper (Nilaparvata lugens, BPH) and the rice-feeding armyworm (Mythimna loreyi), as well as in response to treatment with the plant hormone, jasmonic acid. Likewise, isopentylamine accumulation was compromised in rice jasmonate biosynthesis mutants, hebiba and Osjar1. In bio-assays, BPH insects feeding on rice seedlings submerged in 50 mg/L isopentylamine solution had a higher mortality compared with BPH feeding on seedlings submerged in water. Notably, the rice leaves submerged in 50 mg/L solution showed the endogenous concentrations of isopentylamine similar to that induced by BPHs. These results suggest that isopentylamine functions as a new type of plant defence metabolite that is rapidly induced by herbivore attack and deters insect herbivores in rice.

Omphaloprenol A: a new bioactive polyisoprenepolyol isolated from the mycelium of poisonous mushroom Omphalotus japonicus.

Mushrooms of the Omphalotus genus are known to be rich in secondary metabolites. In the quest for new bioactive compounds, we analyzed the compounds isolated from the mycelium of the poisonous mushroom Omphalotus japonicus. As a result, a new polyisoprenepolyol, which was named omphaloprenol A, was identified, along with known substances such as hypsiziprenol A10 and A11, illudin S, and ergosterol. The chemical structure of omphaloprenol A was elucidated by nuclear magnetic resonance and infrared spectroscopies and mass spectrometry, and its bioactivity was investigated. Omphaloprenol A showed growth promoting activity against the root of lettuce seeds and cytotoxicity against HL60 cells. To the best of our knowledge, this is the first report on the isolation of a polyisoprenepolyol compound from Omphalotaceae mushrooms.

Changes of volatile flavor compounds of watermelon juice by heat treatment.

Changes of volatile flavor compounds of watermelon juice by heat treatment were investigated by gas chromatography-olfactometry-mass spectrometry. Although the major volatile compounds in watermelon juice, three aldehydes, three alcohols, and one ketone, did not increase significantly by heat treatment, dimethylsulfide and methional increased in heated juice. These two sulfides were suggested to contribute to the off-flavors in heated watermelon juice.

Constituents of the Fruiting Body of Poisonous Mushroom Omphalotus japonicus.

Six new sesquiterpenes, tsukiyols A-C, neoilludin C, and 4-O-methylneoilludins A and B, were isolated from the fruiting body of Omphalotus japonicus (Kawam.) Kirchm. & O. K. Mill. Additionally, six known compounds, illudin S, neoilludins A-B, 5-hydroxydichomitol, ergosterolperoxide, and 3ß,5α,9α-trihydroxyergosta-7,22-diene-6-one, were also obtained. Their chemical structures were determined with MS, IR, and NMR spectra and the absolute configurations of neoilludins A-C, 4-O-methylneoilludins A, and B were determined with electronic circular dichroism (ECD). Illudin S and 3ß,5α,9α-trihydroxyergosta-7,22-diene-6-one showed cytotoxicity against human acute promyelocytic leukemia HL60 cells. Illudin S, 4-O-methylneoilludin A, B, and tsukiyol C showed growth-restoring activity against mutant yeast via Ca2+-signal transduction.

A herbivore-induced homoterpene volatile is emitted from Basella alba leaves.

An irregular C11 homoterpene, (E)-4,8-dimethylnona-1,3,7-triene (DMNT) was identified as a major component of the volatile compounds emitted from Basella alba leaves induced by herbivore. The terpenes including DMNT were not detected from the leaves infected by Botrytis cinerea. These results suggested that volatile emission from B. alba leaves was induced by herbivory but not by a fungal infection.

Flavonoid glycosides in Malabar spinach Basella alba inhibit the growth of Spodoptera litura larvae.

Basella alba is a perennial plant of the Basellaceae and is known by various common names including Malabar spinach. There are few insects that cause damage to B. alba. In this study, we examined the effect of B. alba leaves on the growth of Spodoptera litura larvae. B. alba leaves and a methanolic extract of the leaves inhibited the growth of S. litura larvae. Half of the larvae reared on the leaves died within 1 week. We found that two flavonoids, vitexin, and vitexin-2″-O-arabinofuranoside, were abundant in the methanol extract of leaves. When larvae were reared on purified vitexin or vitexin-2″-O-arabinofuranoside, their growth was significantly impaired compared with larvae reared on control spinach leaves. These results suggested that the flavonoid glycosides in B. alba leaves act as deterrents to S. litura larvae.

New Metabolites Produced by Cylindrocarpon sp. SY-39 from a Driftwood.

Four novel compounds, cylindropyrone A (1), 10'-hydroxyilicicolinic acid D (3), cylindrolactones A (4) and B (5), together with known dihydroinfectopyrone (2) were isolated from the culture of Cylindrocarpon sp. SY-39 from a driftwood. Their structures were elucidated using 1D- and 2D-NMR spectroscopy. Compound 3 showed antimicrobial activity against Staphylococcus aureus with MIC value of 5.0 µg/mL.

Antifungal abietane-type diterpenes from the cones of Taxodium distichum Rich.

The chemical composition of Taxodium distichum cones and the antifungal activities of twelve diterpenoids against two wood decay fungi, Trametes versicolor (white-rot) and Fomitopsis palustris (brown-rot) were examined. The chemical composition of the major extractive fraction, the n-C(6)H(14) extract, was evaluated and its antifungal properties were identified. Twelve diterpenoids including ten abietane-type components were isolated from the n-C(6)H(14) extract: 6,7-dehydroferruginol (1), ferruginol (2), 6,7-dehydroroyleanone (3), sandaracopimaric acid (4), taxodione (5), taxodal (6), taxodone (7), sugiol (8), xanthoperol (9), salvinolone (10), 5,6-dehydrosugiol (11), and 14-deoxycoleon U (12). Compounds 5 and 12 were highly active against both wood-decay fungi. In particular, the activities of these compounds against F. palustris were potent. The results suggest that the position and the number of hydroxyl groups on abietane-type structures may be related to antifungal activities against T. versicolor and F. palustris.

Characterization of a chimeric enzyme comprising feruloyl esterase and family 42 carbohydrate-binding module.

We engineered a chimeric enzyme (AwFaeA-CBM42) comprising of type-A feruloyl esterase from Aspergillus awamori (AwFaeA) and family 42 carbohydrate-binding module (AkCBM42) from glycoside hydrolase family 54 alpha-L-arabinofuranosidase of Aspergillus kawachii. The chimeric enzyme was successfully produced in Pichia pastoris and accumulated in the culture broth. The purified chimeric enzyme had an apparent relative molecular mass (M(r)) of 53,000. The chimeric enzyme binds to arabinoxylan; this indicates that the AkCBM42 in AwFaeA-CBM42 binds to arabinofuranose side chain moiety of arabinoxylan. The thermostability of the chimeric enzyme was greater than that of AwFaeA. No significant difference of the specific activity toward methyl ferulate was observed between the AwFaeA and chimeric enzyme, but the release of ferulic acid from insoluble arabinoxylan by the chimeric enzyme was approximately 4-fold higher than that achieved by AwFaeA alone. In addition, the chimeric enzyme and xylanase acted synergistically for the degradation of arabinoxylan. In conclusion, the findings of our study demonstrated that the components of the AwFaeA-CBM42 chimeric enzyme act synergistically to bring about the degradation of complex substrates and that the family 42 carbohydrate-binding module has potential for application in the degradation of polysaccharides.

Relative abundance of Delta(5)-sterols in plasma membrane lipids of root-tip cells correlates with aluminum tolerance of rice.

We investigated variations in aluminum (Al) tolerance among rice plants, using ancestor cultivars from the family line of the Al-tolerant and widely cultivated Japonica cultivar, Sasanishiki. The cultivar Rikuu-20 was Al sensitive, whereas a closely related cultivar that is a descendant of Rikuu-20, Rikuu-132, was Al tolerant. These two cultivars were compared to determine mechanisms underlying variations in Al tolerance. The sensitive cultivar Rikuu-20 showed increased permeability of the plasma membrane (PM) and greater Al uptake within 1 h of Al treatment. This could not be explained by organic acid release. Lipid composition of the PM differed between these cultivars, and may account for the difference in Al tolerance. The tolerant cultivar Rikuu-132 had a lower ratio of phospholipids to Delta(5)-sterols than the sensitive cultivar Rikuu-20, suggesting that the PM of Rikuu-132 is less negatively charged and less permeabilized than that of Rikuu-20. We used inhibitors of Delta(5)-sterol synthesis to alter the ratio of phospholipids to Delta(5)-sterols in both cultivars. These inhibitors reduced Al tolerance in Rikuu-132 and its Al-tolerant ancestor cultivars Kamenoo and Kyoku. In addition, Rikuu-132 showed a similar level of Al sensitivity when the ratio of phospholipids to Delta(5)-sterols was increased to match that of Rikuu-20 after treatment with uniconazole-P, an inhibitor of obtusifoliol-14alpha-demethylase. These results indicate that PM lipid composition is a factor underlying variations in Al tolerance among rice cultivars.

Antitermitic activities of abietane-type diterpenes from Taxodium distichum cones.

Eight known abietane-type diterpenes were isolated from the weak acidic fraction of the n-hexane extract from cones of Taxodium distichum, one of the extant, living fossil conifers. They were identified as 6,7-dehydroroyleanone (1), taxodal (2), taxodione (3), salvinolone (4), 14-deoxycoleon U (5), 5,6-dehydrosugiol (6), sandaracopimaric acid (7), and xanthoperol (8). The structures of these compounds were determined by comparison of NMR spectral data with published data. The antitermitic (termicidal and antifeedant) activities of the compounds 1-8 against the subterranean termite, Reticulitermes speratus Kolbe, were evaluated. Compounds 1 and 3 showed potent termicidal activity, and 5 and 8 showed potent antifeedant activity. Compound 1 was found to be one of the representative bioactive compounds in the n-hexane extract of T. distichum cones. Compounds 1-8, with the exception of 7, were oxides of ferruginol (9). Therefore, the presence of various oxidation forms of the abietane-type structure reflects their various bioactivities.

Characterization of two distinct feruloyl esterases, AoFaeB and AoFaeC, from Aspergillus oryzae.

Two hypothetical proteins XP_001818628 and XP_001819091 (designated AoFaeB and AoFaeC, respectively), showing sequence identity with known type-C feruloyl esterases, have been found in the genomic sequence of Aspergillus oryzae. We cloned the putative A. oryzae feruloyl esterase-encoding genes and expressed them in Pichia pastoris. Both purified recombinant AoFaeB (rAoFaeB) and AoFaeC (rAoFaeC) had apparent relative molecular masses of 61,000 and 75,000, respectively, on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. After N-deglycosylation, both proteins had a relative molecular mass of 55,000. The optimum pH for rAoFaeB was 6.0, although it was stable at pH values ranging from 3.0 to 9.0; rAoFaeC had an optimum pH of 6.0 and was stable in the pH range of 7.0-10.0. Thermostability of rAoFaeC was greater than that of rAoFaeB. Whereas rAoFaeC displayed hydrolytic activity toward methyl caffeate, methyl p-coumarate, methyl ferulate, and methyl sinapate, rAoFaeB displayed hydrolytic activity toward methyl caffeate, methyl p-coumarate, and methyl ferulate but not toward methyl sinapate. Substrate specificity profiling of rAoFaeB and rAoFaeC revealed type-B and type-C feruloyl esterases, respectively. Ferulic acid was efficiently released from wheat arabinoxylan when both esterases were applied with xylanase from Thermomyces lanuginosus. Both recombinant proteins also exhibited hydrolytic activity toward chlorogenic acid.

New cytotoxic phenolic derivatives from matured fruits of Magnolia denudata.

Magnolia species are widely cultivated in Japan as garden plants, and have been found to contain various compounds, including alkaloids, terpenoids, lignans, and neolignans. The constituents of the mature fruits of M. denudata were investigated, and two new phenolic derivatives, named denudalide and denudaquinol, were isolated and characterized, together with a known neolignan compound (denudatin A). Denudalide and denudaquinol showed cytotoxicity against the SFME and r/mHM-SFME-1 cell lines.

Characterization of an alpha-L-rhamnosidase from Aspergillus kawachii and its gene.

An alpha-L-rhamnosidase was purified by fractionating a culture filtrate of Aspergillus kawachii grown on L-rhamnose as the sole carbon source. The alpha-L-rhamnosidase had a molecular mass of 90 kDa and a high degree of N-glycosylation of approximately 22%. The enzyme exhibited optimal activity at pH 4.0 and temperature of 50 degrees C. Further, it was observed to be thermostable, and it retained more than 80% of its original activity following incubation at 60 degrees C for 1 h. Its T (50) value was determined to be 72 degrees C. The enzyme was able to hydrolyze alpha-1,2- and alpha-1,6-glycosidic bonds. The specific activity of the enzyme was higher toward naringin than toward hesperidin. The A. kawachii alpha-L-rhamnosidase-encoding gene (Ak-rhaA) codes for a 655-amino-acid protein. Based on the amino acid sequence deduced from the cDNA, the protein possessed 13 potential N-glycosylation recognition sites and exhibited a high degree of sequence identity (up to 75%) with the alpha-L-rhamnosidases belonging to the glycoside hydrolase family 78 from Aspergillus aculeatus and with hypothetical Aspergillus oryzae and Aspergillus fumigatus proteins.

Two cyathane-type diterpenoids from the liquid culture of Strobilurus tenacellus.

The structures of two new cyathane-type diterpenoids isolated from a liquid culture of Strobilurus tenacellus have been elucidated. The chemical structures of the new compounds 1 and 2 were identified as (12S)-11alpha,14alpha-epoxy-13alpha,14beta,15-trihydroxycyath-3-ene and (12R)-11alpha,14alpha-epoxy-13alpha,14beta,15-trihydroxycyath-3-ene, respectively, by spectral methods, including HR-EI-MS, and 1D- and 2D-NMR techniques. Compounds 1 and 2 show antimicrobial activity against Pseudomonas aeruginosa. In addition, both compounds were also tested for activity against human cancer cells, and 2 showed growth inhibitory activity against YMB and COLO 201 cells.

Spectroscopic characterisation of two polyketide metabolites from Cylindrocarpon sp. from driftwood.

Two new polyketides, (5R,7R,9R)-7,9-dihydroxy-5-decanolide and (4E,6R,9R)- 6,9-dihydroxydec-4-enoic acid (2), were isolated from rice cultures of Cylindrocarpon sp. SY-39 discovered during screening of driftwood at a Shonai coast area in Yamagata, Japan. The structures of 1 and 2 were determined using a variety of spectroscopic methods. Compound 2 exhibited moderate antimicrobial activity against Staphylococcus aureus NBRC 13276 and Aspergillus clavatus F 318a at a concentration of 50 µg per disk.

New isocoumarins, naphthoquinones, and a cleistanthane-type diterpene from Nectria pseudotrichia 120-1NP.

Four new compounds, namely, nectriapyrones A (2) and B (3), nectriaquinone B (5), and zythiostromic acid C (8), were isolated from the brown rice culture of Nectria pseudotrichia 120-1NP together with four known compounds (1, 4, 6, and 7). To the best of our knowledge, this is the first report of 4 from a natural source. Their structures were determined on the basis of 1D/2D-NMR spectroscopy and HRESITOFMS data. In addition, the absolute configuration of secondary alcohols in 8 were determined using modified Mosher's ester method. All isolated compounds were evaluated for their antimicrobials activity, phytotoxicity, and cytotoxicity.

Strobilols A-D: four cadinane-type sesquiterpenes from the edible mushroom Strobilurus ohshimae.

Four sesquiterpenoids--strobilols A (1), B (2), C (3), and D (4)--were isolated from the organic extracts of fruiting bodies of the edible mushroom Strobilurus ohshimae. Their structures were determined by spectroscopic methods. Compound 1 exhibited moderate activity against the brine shrimp Artemia salina. This paper is the first report on isolation of cadinane-type sesquiterpenoids from S. ohshimae.

Fusaristatins A and B, two new cyclic lipopeptides from an endophytic Fusarium sp.

Two new cyclic lipopeptides, fusaristatins A (1) and B (2) were isolated from rice cultures of a Fusarium sp. YG-45 in the course of a screening of endophytic fungi. Their structures of 1 and 2 were determined by spectroscopic methods. 2 showed a moderate inhibitory effect on topoisomerases I (IC50: 73 microM) and II (IC50: 98 microM) without cleavable complexes. Furthermore, 1 and 2 showed the growth-inhibitory activity toward lung cancer cells LU 65 with IC50 values of 23 and 7 microM, respectively.