Linalyl and bornyl disaccharide glycosides from Gardenia jasminoides flowers

Molluscicidal Activity of Compounds From the Roots of Aralia armata Against the Golden Apple Snail (Pomacea canaliculata)

Background: Aralia armata (Araliaceae) is considered to exhibit effective molluscicidal activity, however, the relationship between the chemical components and molluscicidal activity has not been clearly elucidated. This research attempts to decipher these correlations among the 15 compounds isolated from Vietnam-grown A. armata roots against the freshwater snail, Pomacea canaliculata, a gastropod causing severe damage in agricultural production. Methods: Fifteen saponins were isolated from the methanol root extract of A. armata using chromatographic methods and were identified using spectroscopic techniques. The compounds were screened for molluscicidal activity against P. canaliculata, as well as toxicity against brine shrimp ( Artemia sp.) and phytotoxicity against rice germination and growth. Results: The saponin compounds exhibited extraordinary inhibition of P. canaliculata with LC50 values ranging from 7.90 to 17.50 µg/mL. Notably, the active compounds from A. armata exhibit safety for both nontarget aquatic animals, specifically Artemia sp. with LC50 values between 148.55 and 193.22 µg/mL, and the growth and development of Oryza sativa L. plants showed very little difference compared with the negative control . A molecular docking analysis indicated P. canaliculata acetylcholinesterase (PcAChE) and the actin-binding protein villin (PcVillin) to be potential biomolecular targets of the A. armata saponins. Conclusion: The present experimental and in silico data illustrate the potential of A. armata in agricultural applications.

Glycosidically bound aroma precursors in fruits: A comprehensive review

Fruit aroma is mainly contributed by free and glycosidically bound aroma compounds, in which glycosidically bound form can be converted into free form during storage and processing, thereby enhancing the overall aroma property. In recent years, the bound aroma precursors have been widely used as flavor additives in the food industry to enhance, balance and recover the flavor of products. This review summarizes the fruit-derived aroma glycosides in different aspects including chemical structures, enzymatic hydrolysis, biosynthesis and occurrence. Aroma glycosides structurally involve an aroma compound (aglycone) and a sugar moiety (glycone). They can be hydrolyzed to release free volatiles by endo- and/or exo-glucosidase, while their biosynthesis refers to glycosylation process using glycosyltransferases (GTs). So far, aroma glycosides have been found and studied in multiple fruits such as grapes, mangoes, lychees and so on. Additionally, their importance in flavor perception, their utilization in food flavor enhancement and other industrial applications are also discussed. Aroma glycosides can enhance flavor perception via hydrolyzation by β-glucosidase in human saliva. Moreover, they are able to impart product flavor by controlling the liberation of active volatiles in industrial applications. This review provides fundamental information for the future investigation on the fruit-derived aroma glycosides.

Aliphatic Glucoside, Zanthoionic Acid and Megastigmane Glucosides: Zanthoionosides A-E from the Leaves of Zanthoxylum ailanthoides

From the leaves of Zanthoxylum ailanthoides, 4'-O-p-E-coumaric acid esters of 2-propanol β-D-glucopyranoside, megastigmane and megastigmane glucosides were isolated. Their structures were elucidated by spectroscopic evidence. The absolute configurations of the megastigmane and aglycone of megastigmane glucosides were determined by the octant rule and modified Mosher's method after protection of carboxylic acids by p-bromophenacyl esters and primary alcohols by pivaloyl esters.

Characteristic Fluctuations in Glycosidically Bound Volatiles during Tea Processing and Identification of Their Unstable Derivatives

A recently developed method enabled us to simultaneously characterize and quantitate glycosidically bound volatiles (GBVs) at picomole levels using liquid chromatography-mass spectrometry (LC-MS). On the basis of the analytical data it is possible to screen tea varieties most suitable for black tea processing, in which higher concentrations of primeverosides accumulate. The primeverosides decreased at the rolling step in black tea processing, whereas the glucopyranosides did not change much. The total contents of GBVs gradually increased at the withering steps and then remarkably increased after the fixing step at 230 °C, during oolong tea processing. The presence of 6'-O-malonyl ester type β-D-glucopyranosides in the tea samples suggested a contribution to the increment in glucopyranosides during oolong tea processing. The method was also used to analyze GBVs and their derivatives to understand their possible role in the metabolic pathway of tea.

Gene coexpression analysis reveals complex metabolism of the monoterpene alcohol linalool in Arabidopsis flowers

The cytochrome P450 family encompasses the largest family of enzymes in plant metabolism, and the functions of many of its members in Arabidopsis thaliana are still unknown. Gene coexpression analysis pointed to two P450s that were coexpressed with two monoterpene synthases in flowers and were thus predicted to be involved in monoterpenoid metabolism. We show that all four selected genes, the two terpene synthases (TPS10 and TPS14) and the two cytochrome P450s (CYP71B31 and CYP76C3), are simultaneously expressed at anthesis, mainly in upper anther filaments and in petals. Upon transient expression in Nicotiana benthamiana, the TPS enzymes colocalize in vesicular structures associated with the plastid surface, whereas the P450 proteins were detected in the endoplasmic reticulum. Whether they were expressed in Saccharomyces cerevisiae or in N. benthamiana, the TPS enzymes formed two different enantiomers of linalool: (-)-(R)-linalool for TPS10 and (+)-(S)-linalool for TPS14. Both P450 enzymes metabolize the two linalool enantiomers to form different but overlapping sets of hydroxylated or epoxidized products. These oxygenated products are not emitted into the floral headspace, but accumulate in floral tissues as further converted or conjugated metabolites. This work reveals complex linalool metabolism in Arabidopsis flowers, the ecological role of which remains to be determined.

A new abietic acid-type diterpene glucoside from the needles of Pinus densiflora

From the ethyl acetate fraction of the methanol extract of the needles of Pinus densiflora (Pinaceae), a new diterpenoid glucoside [9alpha,13alpha-epoxy-8beta,14beta-dihydroxy-abietic acid-18-O-beta-D: -glucopyranoside] (1), two flavonoid glucosides [kaempferol 3-O-beta-D: -glucoside (2) and 6-C-methyl kaempferol 3-O-beta-D: -glucoside (3)], and two monoterpenoid glucosides [bornyl 6-O-alpha-Larabinofuranosyl (1-->6)-beta-D: -glucopyranoside (4) and bornyl 6-O-beta-D: -apiofuranosyl (1-->6)-beta-D: -glucopyranoside (5)] were isolated and characterized on the basis of spectral analysis. Of all the compounds, 2 and 3 showed peroxynitrite scavenging activity.

Astonishing diversity of natural surfactants: 7. Biologically active hemi- and monoterpenoid glycosides

This review article presents 90 hemi- and 188 monoterpenoid glycosides, isolated and identified from plants and microorganisms, that demonstrate different biological activities. These natural bioactive glycosides are good prospects for future chemical preparations from these compounds as antioxidants and as anticancer, antimicrobial, and antibacterial agents. These glycosidic compounds have been subdivided into several groups, including hemiterpenoids; acyclic, monocyclic, and bicyclic monoterpenoids; and iridoid monoterpenoids.

Crocetin esters, picrocrocin and its related compounds present in Crocus sativus stigmas and Gardenia jasminoides fruits. Tentative identification of seven new compounds by LC-ESI-MS

Crocetin esters present in saffron (Crocus sativus L.) stigmas and in Gardenia jasminoides Ellis fruit are the compounds responsible for their color. Of the fifteen crocetin esters identified in this study, five new compounds were tentatively identified: trans and cis isomers of crocetin (beta-D-triglucoside)-(beta-D-gentibiosyl) ester, trans and cis isomers of crocetin (beta-D-neapolitanose)-(beta-D-glucosyl) ester, and cis crocetin (beta-D-neapolitanose)-(beta-D-gentibiosyl) ester. The most relevant differences between both species were a low content of the trans crocetin (beta-D-glucosyl)-(beta-D-gentibiosyl) ester, the absence of trans crocetin di-(beta-D-glucosyl) ester in gardenia, and its higher content of trans crocetin (beta-D-gentibiosyl) ester and cis crocetin di-(beta-D-gentibiosyl) ester. With the same chromatographic method it was possible to identify, in a single run, ten glycosidic compounds in saffron extracts with a UV/vis pattern similar to that of picrocrocin; among them, 5-hydroxy-7,7-dimethyl-4,5,6,7-tetrahydro-3H-isobenzofuranone 5-O-beta-D-gentibioside and 4-hydroxymethyl-3,5,5-trimethyl-cyclohexen-2-one 4-O-beta-D-gentibioside were tentatively identified for the first time in saffron. Of these ten glycosides, only the O-beta-D-gentibiosyl ester of 2-methyl-6-oxo-2,4-hepta-2,4-dienoic acid was found in gardenia samples, but it was possible to identify the iridoid glycoside, geniposide.

Chiral high-performance liquid chromatographic separation of the enantiomers of tetrahydropalmatine and tetrahydroberberine, isolated from Corydalis yanhusuo

HPLC methods have been developed for chiral resolution of the enantiomers of dl-tetrahydropalmatine (THP) and dl-tetrahydroberberine (THB), two active constituents of Corydalis yanhusuo W.T. Wang. On the analytical scale, good baseline separation of the enantiomers was achieved using cellulose tris(3,5-dimethylphenylcarbamate) chiral stationary phases in both normal-phase and polar organic modes. Validation of the analytical methods, including linearity, limits of detection, recovery, and precision, and semipreparative resolution of dl-THP and dl-THB, were achieved with methanol as mobile phase, without any basic additives, in polar organic mode using cellulose tris(3,5-dimethylphenylcarbamate) chiral stationary phases. On the semipreparative scale, small quantities of the individual enantiomers of THP and THB were isolated for study of the chiroptical properties of the individual enantiomers.

Biogenetic studies in Syringa vulgaris L.: synthesis and bioconversion of deuterium-labeled precursors into lilac aldehydes and lilac alcohols

Syringa vulgaris L. inflorescences were fed with aqueous solutions of regioselectively deuterated compounds assumed to be precursors of lilac aldehyde and lilac alcohol, respectively. Volatiles were extracted by stir bar sorptive extraction (SBSE) and analyzed using enantioselective multidimensional gas chromatography/mass spectrometry (enantio-MDGC/MS); deuterium-labeled lilac aldehydes and lilac alcohols were separated from unlabeled stereoisomers on a fused silica capillary column, coated with heptakis(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)-beta-cyclodextrin (DIME-beta-CD) (30%) in SE 52 (70%), as the chiral stationary phase. Feeding experiments with [5,5-(2)H(2)]mevalonic acid lactone 22 and [5,5-(2)H(2)]deoxy-d-xylose 23 indicate that the novel mevalonate independent 1-deoxy-d-xylose 5-phosphate/2C-methyl-d-erythritol 4-phosphate pathway is the dominant metabolic route for biosynthesis in lilac flowers. Additionally, bioconversion of deuterium-labeled d(5)-(R/S)-linalool 3, d(6)-(R)-linalool 21, d(5)-(R/S)-8-hydroxylinalool 6, d(5)-(R/S)-8-oxolinalool 7, d(5)-lilac aldehydes 8-11 and d(5)-lilac alcohols 12-15 into lilac during in vivo feeding experiments was investigated and the metabolic pathway is discussed. Incubation of petals with an aqueous solution of deuterated d(5)-(R/S)-linalool 3 indicates an autonomic terpene biosynthesis of lilac flavor compounds in the flower petals of lilac.

First isolation of geranyl disaccharides from ginger and their relations to aroma formation

Three geraniol glycosides were isolated from immature fresh ginger rhizomes (Zingiber officinale Roscoe). Their structures were identified as geranyl 6-O-alpha-L-arabinopyranosyl-beta-D-glucopyranoside (1) geranyl 6-O-beta-D-apiofuranosyl-beta-D-glucopyranoside (2) and geranyl 6-O-beta-D-xylopyranosyl-beta-D-glucopyranoside (3) by spectrometric analyses. After incubating each glycoside with a crude enzyme solution prepared from ginger, geraniol was liberated in all of those fractions. This result indicates that the glycosides are related to the formation of geraniol-related compounds in ginger aroma.

Glycoconjugated aroma compounds: occurrence, role and biotechnological transformation

The present paper reviews the occurrence of glycosidically bound aroma compounds in the plant kingdom and discusses different hypotheses concerning their role in plants. Emphasis is on biotechnological methods for flavor release and flavor enhancement through enzymatic hydrolysis of glycoconjugated aroma substances.

6-O-alpha-L-Arabinopyranosyl-beta-D-glucopyranosides as aroma precursors from passion fruit

The 6-O-alpha-L-Arabinopyranosyl-beta-D-glucopyranosides of linalool, benzyl alcohol and 3-methyl-but-2-en-1-ol were isolated from passion fruit (Passiflora edulis) by adsorption chromatography on XAD-2 resin, then further extracted on the same resin after partial enzymic hydrolysis and semi-preparative chromatography on RP-18 phase by HPLC. Their structures were identified by 1H NMR spectroscopy and mass spectral analysis and by methylation analysis of the carbohydrate moieties.