Glycoside Profile Research Articles

Phenylethanoid Glycoside Profiles and Antioxidant Activities of Osmanthus fragrans Lour. Flowers by UPLC/PDA/MS and Simulated Digestion Model.

Variations of phenylethanoid glycoside profiles and antioxidant activities in Osmanthus fragrans flowers through the digestive tract were evaluated by a simulated digestion model and UPLC/PDA/MS. Major phenylethanoid glycosides and phenolic acids, namely, salidroside, acteoside, isoacteoside, chlorogenic acid, and caffeic acid, were identified in four cultivars of O. fragrans flowers, and the concentration of acteoside was the highest, being up to 71.79 mg/g dry weight. After simulated digestion, total phenylethanoid glycoside contents and antioxidant activities were significantly decreased. Acteoside was identified as decomposing into caffeic acid, whereas salidroside was found to be stable during simulated digestion. According to Pearson's correlation analysis, acteoside contents showed good correlations with antioxidant activities during simulated digestion (R(2) = 0.994, P < 0.01). In conclusion, acteoside was the major contributor to the antioxidant activity of O. fragrans flowers, and salidroside was considered as the major antioxidant compound of O. fragrans flowers in vivo.

Impact of cold atmospheric pressure plasma on physiology and flavonol glycoside profile of peas (Pisum sativum ‘Salamanca’)

Application of plasma is well-established in various industrial processes; its use has also been suggested as an innovative technology in the food sector. Besides the ability to inactivate undesirable microorganisms on heat-sensitive foods, cold atmospheric pressure plasma (CAPP) may also modify and intensify the secondary metabolism in agricultural plant produces along the whole value-added chain. This is because CAPP provides a source of reactive oxygen and nitrogen species and specific UV radiation.The objective of this study was to determine the effects of CAPP treatment on the flavonol glycoside profile of pea seedlings (Pisum sativum ‘Salamanca’), while considering the potential impact on their metabolic activity in different growth stages. Pea seeds, sprouts, and seedlings were exposed to semi-direct CAPP using a dielectric barrier discharge device with air as the process gas. Applying voltages between 6 and 12kVpp at a frequency of 3.0kHz resulted in optical emission spectra dominated by UV-B and UV-C radiation. The specific energy densities were monitored upon varying voltages and treatment times.Exposing swollen pea seeds to plasma (9kVpp) between 1 and 10min increased germination rate and dry matter content but decreased growth rate. Non-acylated and monoacylated triglycosides of quercetin and kaempferol dominated the flavonol glycoside profile, quercetin-3-O-p-coumaroyl-triglucoside being the main flavonoid glycoside. In 15d-old pea seedlings, the concentration of flavonoid glycosides was dose-dependently decreased after two CAPP treatments compared to none or three treatments. Furthermore, photosynthetic efficiency of treated pea sprouts and seedlings declined potentially indicating a negative effect of CAPP treatment on plant metabolism. The responses of pea tissues greatly depended on time point and duration of CAPP treatments. This study represents a first step towards the implementation of the CAPP technology for a targeted modification of valuable secondary plant metabolites during post-harvest chain of agricultural produces.

Identification of complex, naturally occurring flavonoid glycosides in Vicia faba and Pisum sativum leaves by HPLC-DAD-ESI-MSn and the genotypic effect on their flavonoid profile

Vicia faba and Pisum sativum are legumes belonging to the plant family Fabaceae. As their flavonoid profile is highly diverse with quite complex structures, the aim of this study was to identify the flavonol glycosides in the leaves of different cultivars of V. faba and P. sativum. In V. faba the main flavonol aglycon is kaempferol, whereas in P. sativum the main flavonol aglycon is quercetin. Furthermore, V. faba leaves contain mono-, di-, tri- and tetraglycosides of quercetin and kaempferol with primarily glucose, rhamnose, and galactose as sugar moieties. Two of these structures have been identified to be acylated with acetic acid. In contrast, in P. sativum leaves only triglycosides were identified being sophotriosides. Nine of the 11 quercetin and kaempferol glycosides were acylated with selected hydroxycinnamic acids. Depending on cultivar, V. faba and P. sativum provided different flavonol profiles. Here, shown for the first time in legume leaves. For example, the summer cultivars of V. faba showed a high concentration of kaempferol-3-O-rhamnoarabinoside-7-O-rhamnoside. However, P. sativum with especially the cv Salamanca, had the most desired flavonoid glycoside profile referring to high concentrations of quercetin glycosides and exemplarily the acylation with p-coumaric acid.

Metabolic fate of cardiac glycosides and flavonoids upon fermentation of aqueous sea squill (Drimia maritima L.) extracts

Sea squill (Drimia maritima L.) extracts have been used for centuries for the medical treatment of heart diseases. A procedure for the preparation of Drimia extracts applied for such purposes comprising a fermentation step is described in the German Homoeopathic Pharmacopoeia (GHP). However, little is known about the secondary metabolite profile of such extracts and the fate of these components upon processing and storage. Thus, in the present study sea squill extracts were monitored during fermentation and storage by HPLC-DAD–MSn and GC–MS to characterise and quantitate individual cardiac glycosides and phenolic compounds. For this purpose, a previously established HPLC method for the separation and quantitation of pharmacologically relevant cardiac glycosides (bufadienolides) was validated. Within 12 months of storage, total bufadienolide contents decreased by about 50%, which was attributed to microbial and plant enzyme activities. The metabolisation and degradation rates of individual bufadienolide glycosides significantly differed, which was attributed to differing structures of the aglycones. Further degradation of bufadienolide aglycones was also observed. Besides reactions well known from human metabolism studies, dehydration of individual compounds was monitored. Quantitatively predominating flavonoids were also metabolised throughout the fermentation process. The present study provides valuable information about the profile and stability of individual cardiac glycosides and phenolic compounds in fermented Drimia extracts prepared for medical applications, and expands the knowledge of cardiac glycoside conversion upon microbial fermentation.

A novel neolignan glycoside from Aquilaria sinensis

Phytochemical investigation of Aquilaria sinensis afforded one novel neolignan glycoside (1) and fourteen known compounds (2–15). Their structures were elucidated by spectroscopic methods. Among them, compounds 1–3, 5 and 7–9 were obtained from the genus Aquilaria for the first time. The profile of chromone glycosides and iriflophenone glycosides may have chemotaxonomic significance within this genus.

Agrobacterium tumefaciens-mediated transgenic plant and somaclone production through direct and indirect regeneration from leaves in Stevia rebaudiana with their glycoside profile

Agrobacterium tumefaciens (EHA-105 harboring pCAMBIA 1304)-mediated transgenic plant production via direct regeneration from leaf and elite somaclones generation through indirect regeneration in Stevia rebaudiana is reported. Optimum direct regeneration frequency along with highest transformation frequency was found on MS + 1mg/l BAP + 1mg/l NAA, while indirect regeneration from callus was obtained on MS + 1mg/l BAP + 2mg/l NAA. Successful transfer of GUS-positive (GUS assay and PCR-based confirmation) transgenic as well as four somaclones up to glasshouse acclimatization has been achieved. Inter-simple sequence repeat (ISSR) profiling of transgenic and somaclonal plants showed a total of 113 bands, out of which 49 were monomorphic (43.36%) and 64 were polymorphic (56.64%). Transgenic plant was found to be closer to mother plant, while on the basis of steviol, stevioside, and rebaudioside A profile, somaclone S2 was found to be the best and showed maximum variability in ISSR profiling.

OPUNTIA FICUS-INDICA AND OPUNTIA MACRORHIZA: PROMISING SOURCES OF FLAVONOLS - COMPARISON BETWEEN CULTIVARS FROM DIFFERENT ORIGINS

Identification and quantification of flavonol glycosides in pulps and peels of Opuntia ficus-indica from different origins (Egypt, Sicily and South Africa) and Opuntia macrorhiza fruits were done using HPLC-DAD and HPLC-MS. In addition a gentle enzymatic hydrolysis of flavonol glycosides using commercial pectolytic enzymes was applied. Finally a comparison of antioxidant activities between all investigated matrices was carried out using electron paramagnetic resonance (EPR) spectroscopy. Results indicated that both, O. ficus-indica and O. macrorhiza, are characterized by high amounts of isorhamnetin glycosides (mainly isorhamnetin 3-O-rutinoside). O. ficus-indica showed the same profile of isorhamnetin glycosides in the peels of all origins. However, the isorhamnetins have not been detected in the pulps. In contrast, O. macrorhiza peels illustrated a different profile of isorhamnetin glycosides. The enzymatic hydrolysis of flavonol glycosides, produced only isorhamnetin as the only aglycon. Obtained results indicate that isorhamnetins could be considered as markers for the cactus pear fruits, or for adulteration of their processed products. Antioxidant activities of all investigated O. ficus-indica peels were higher than those of all pulps.

Human Psychometric and Taste Receptor Responses to Steviol Glycosides

Steviol glycosides, the sweet principle of Stevia Rebaudiana (Bertoni) Bertoni, have recently been approved as a food additive in the EU. The herbal non-nutritive high-potency sweeteners perfectly meet the rising consumer demand for natural food ingredients in Europe. We have characterized the organoleptic properties of the most common steviol glycosides by an experimental approach combining human sensory studies and cell-based functional taste receptor expression assays. On the basis of their potency to elicit sweet and bitter taste sensations, we identified glycone chain length, pyranose substitution, and the C16 double bond as the structural features giving distinction to the gustatory profile of steviol glycosides. A comprehensive screening of 25 human bitter taste receptors revealed that two receptors, hTAS2R4 and hTAS2R14, mediate the bitter off-taste of steviol glycosides. For some test substances, e.g., stevioside, we observed a decline in sweet intensity at supra-maximum concentrations. This effect did not arise from allosteric modulation of the hTAS1R2/R3 sweet taste receptor but might be explained by intramolecular cross-modal suppression between the sweet and bitter taste component of steviol glycosides. These results might contribute to the production of preferentially sweet and least bitter tasting Stevia extracts by an optimization of breeding and postharvest downstream processing.

Distinct chemotypes of Tephrosia vogelii and implications for their use in pest control and soil enrichment

Tephrosia vogelii Hook. f. (Leguminosae) is being promoted as a pest control and soil enrichment agent for poorly-resourced small-scale farmers in southern and eastern Africa. This study examined plants being cultivated by farmers and found two chemotypes. Chemotype 1 (C1) contained rotenoids, including deguelin, rotenone, sarcolobine, tephrosin and α-toxicarol, required for pest control efficacy. Rotenoids were absent from chemotype 2 (C2), which was characterised by prenylated flavanones, including the previously unrecorded examples (2S)-5,7-dimethoxy-8-(3-hydroxy-3-methylbut-1Z-enyl)flavanone, (2S)-5,7-dimethoxy-8-(3-methylbut-1,3-dienyl)flavanone, (2S)-4′-hydroxy-5-methoxy-6″,6″-dimethylpyrano[2″,3″:7,8]flavanone, (2S)-5-methoxy-6″,6″-dimethyl-4″,5″-dihydrocyclopropa[4″,5″]furano[2″,3″:7,8]flavanone, (2S)-7-hydroxy-5-methoxy-8-prenylflavanone, and (2R,3R)-3-hydroxy-5-methoxy-6″,6″-dimethylpyrano[2″,3″:7,8]flavanone. The known compounds (2S)-5-methoxy-6″,6″-dimethylpyrano[2″,3″:7,8]flavanone (obovatin 5-methyl ether) and 5,7-dimethoxy-8-(3-hydroxy-3-methylbut-1Z-enyl)flavone (Z-tephrostachin) were also found in C2. This chemotype, although designated Tephrosia candida DC. in collections originating from the World Agroforestry Centre (ICRAF), was confirmed to be T. vogelii on the basis of morphological comparison with verified herbarium specimens and DNA sequence analysis. Sampling from 13 locations in Malawi where farmers cultivate Tephrosia species for insecticidal use indicated that almost 1 in 4 plants were T. vogelii C2, and so were unsuitable for this application. Leaf material sourced from a herbarium specimen of T. candida contained most of the flavanones found in T. vogelii C2, but no rotenoids. However, the profile of flavonol glycosides was different to that of T. vogelii C1 and C2, with 6-hydroxy-kaempferol 6-methyl ether as the predominant aglycone rather than kaempferol and quercetin. The structures of four unrecorded flavonol glycosides present in T. candida were determined using cryoprobe NMR spectroscopy and MS as the 3-O-α-rhamnopyranosyl(1→6)-β-galactopyranoside-7-O-α-rhamnopyranoside, 3-O-α-rhamnopyranosyl(1→2)[α-rhamnopyranosyl(1→6)]-β-galactopyranoside, 3-O-α-rhamnopyranosyl(1→2)[α-rhamnopyranosyl(1→6)]-β-galactopyranoside-7-O-α-rhamnopyranoside, and 3-O-α-rhamnopyranosyl(1→2)[(3-O-E-feruloyl)-α-rhamnopyranosyl(1→6)]-β-galactopyranosides of 6-hydroxykaempferol 6-methyl ether. Tentative structures for a further 37 flavonol glycosides of T. candida were assigned by LC–MS/MS. The correct chemotype of T. vogelii (i.e. C1) needs to be promoted for use by farmers in pest control applications.

Endogenous Enzymes, Heat, and pH Affect Flavone Profiles in Parsley (Petroselinum crispum var. neapolitanum) and Celery (Apium graveolens) during Juice Processing

Flavones are abundant in parsley and celery and possess unique anti-inflammatory properties in vitro and in animal models. However, their bioavailability and bioactivity depend in part on the conjugation of sugars and other functional groups to the flavone core. The effects of juice extraction, acidification, thermal processing, and endogenous enzymes on flavone glycoside profile and concentration in both parsley and celery were investigated. Parsley yielded 72% juice with 64% of the total flavones extracted, whereas celery yielded 79% juice with 56% of flavones extracted. Fresh parsley juice averaged 281 mg flavones/100 g and fresh celery juice, 28.5 mg/100 g. Flavones in steamed parsley and celery were predominantly malonyl apiosylglucoside conjugates, whereas those in fresh samples were primarily apiosylglucoside conjugates; this was apparently the result of endogenous malonyl esterases. Acidification and thermal processing of celery converted flavone apiosylglucosides to flavone glucosides, which may affect the intestinal absorption and metabolism of these compounds.

Comparative Analyses of Total Phenols, Antioxidant Activity, and Flavonol Glycoside Profile of Cladode Flours from Different Varieties of Opuntia spp.

The phenolic, flavonoid, and antioxidant contents of methanol extracts of nine samples of Mexican cactus ( Opuntia spp.) cladodes processed into flours were studied. Opuntia undulata contained the highest amount of phenols [905.08 ± 64.51 μg of gallic acid equivalents (GAE)/g]. The oxygen radical absorbance capacity (ORAC) of the cladode flour extracts indicated that Opuntia robusta var. Gavia [738.8 ± 89.9 μmol of Trolox equivalents (TE)/g] contained the highest antioxidant capacity. ORAC values significantly correlated to total phenols but not to flavonoid contents and were comparable to cranberries and blackberries. Glycosidic forms of isorhamnetin and kaempferol were identified via high-performance liquid chromatography-photodiode array (HPLC-PDA) and HPLC-mass spectrometry (MS), with isorhamnetin being the most abundant flavonol in all samples, except for Opuntia lindheimeri . The effectiveness of acid hydrolysis varied among species because of the different flavonol profiles. For some varieties, the triglycosidic forms were partially acid-hydrolyzed, giving an increase in the content of diglycosides. Optimization of hydrolysis for each species is required to estimate the total amount of each flavonol.

A review on the improvement of stevia [Stevia rebaudiana(Bertoni)

Yadav, A. K., Singh, S., Dhyani, D. and Ahuja, P. S. 2011. A review on the improvement of Stevia [Stevia rebaudiana (Bertoni)]. Can. J. Plant Sci. 91: 1–27. Stevia rebaudiana (Bertoni) is a herbaceous perennial plant (2n=22) of genus Stevia Cav., which consists of approximately 230 species of herbaceous, shrub and sub-shrub plants. Leaves of stevia produce diterpene glycosides (stevioside and rebaudiosides), non-nutritive, non-toxic, high-potency sweeteners and may substitute sucrose as well as other synthetic sweetners, being 300 times sweeter than sucrose. In addition to its sweetening property, it has medicinal values and uses. Stevia is self-incompatible plant and the pollination behaviour is entomophilous. Rebaudioside-A is of particular interest among the glycosides produced in the leaves of stevia because of the most desirable flavour profile, while, stevioside is responsible for aftertaste bitterness. Development of new varieties of S. rebaudiana with a higher content of rebaudioside-A and a reduced content of stevioside is the primary aim of plant breeders concerned with the improvement and utilization of this source of natural sweeteners. The proportions of rebaudioside-A and -C are controlled by a single additive gene known to be co-segregating suggesting synthesis by the same enzyme. Stevioside and rebaudioside-A are negatively correlated, while rebaudioside-A and -C are positively correlated. Conventional plant breeding approaches such as selection and intercrossing among various desirable genotypes is the best method for improving quality traits in a highly cross-pollinated crop like stevia. Various plant types with larger amounts of specific glycoside have already been patented, such as RSIT 94-1306, RSIT 94-75, RSIT 95-166-1 through selection and intercrossing. Composites and synthetics can be used to capture part of the available heterosis because of the high degree of natural out-crossing and the absence of an efficient system of pollination control. Synthetics and composites like “AC Black Bird” and “PTA-444” have already been developed. Polyploidy results in better adaptability of individuals and increased organ and cell sizes. Tetraploids have larger leaf size, thickness and have potential use in increasing biomass and yield in comparison with diploid strains. Characters of interest with low variability in the population may be improved through mutation breeding. Use of biotechnological approaches, such as tissue culture for the mass propagation of elite genotypes, anther culture for development of pure homozygous doubled haploid and molecular marker technology for identification of marker loci linked to rebaudioside-A trait, can create new opportunities for plant breeders. Understanding the mechanism and pathway of biosynthesis of steviol glycosides can help to improve the glycoside profile by up-regulation and down-regulation of genes.

Identification of complex, naturally occurring flavonoid glycosides in kale (Brassica oleracea var. sabellica) by high‐performance liquid chromatography diode‐array detection/electrospray ionization multi‐stage mass spectrometry

Kale is a member of the Brassicaceae family and has a complex profile of flavonoid glycosides. Therefore, kale is a suitable matrix to discuss in a comprehensive study the different fragmentation patterns of flavonoid glycosides. The wide variety of glycosylation and acylation patterns determines the health-promoting effects of these glycosides. The aim of this study is to investigate the naturally occurring flavonoids in kale. A total of 71 flavonoid glycosides of quercetin, kaempferol and isorhamnetin were identified using a high-performance liquid chromatography diode-array detection/electrospray ionization multi-stage mass spectrometry (HPLC-DAD/ESI-MS(n)) method. Of these 71 flavonol glycosides, 27 were non-acylated, 30 were monoacylated and 14 were diacylated. Non-acylated flavonol glycosides were present as mono-, di-, tri- and tetraglycosides. This is the first time that the occurrence of four different fragmentation patterns of non-acylated flavonol triglycosides has been reported in one matrix simultaneously. In addition, 44 flavonol glycosides were acylated with p-coumaric, caffeic, ferulic, hydroxyferulic or sinapic acid. While monoacylated glycosides existed as di-, tri- and tetraglycosides, diacylated glycosides occurred as tetra- and pentaglycosides. To the best of our knowledge, 28 compounds in kale are reported here for the first time. These include three acylated isorhamnetin glycosides (isorhamnetin-3-O-sinapoyl-sophoroside-7-O-D-glucoside, isorhamnetin-3-O-feruloyl-sophoroside-7-O-diglucoside and isorhamnetin-3-O-disinapoyl-triglucoside-7-O-diglucoside) and seven non-acylated isorhamnetin glycosides.

Host plant species affects the quality of the generalistTrichoplusia nias a host for the polyembryonic parasitoidCopidosoma floridanum

Diet of herbivorous insects can influence both the herbivores and their natural enemies. We examined the direct and indirect effects of diet on the interactions between the polyphagous herbivore Trichoplusia ni Hübner (Lepidoptera: Noctuidae) and its polyembryonic parasitoid Copidosoma floridanum Ashmead (Hymenoptera: Encyrtidae). To determine how host plant species and host plant iridoid glycoside content affect host caterpillars and their parasitoids, parasitized and unparasitized T. ni were given leaves of either Plantago lanceolata L., which contains the iridoid glycosides aucubin and catalpol, Plantago major L. (Plantaginaceae), which contains only aucubin, or Taraxacum officinale F.H. Wigg (Asteraceae), which contains neither. Survival of unparasitized T. ni was much lower when fed P. major compared with the other two host plants, whereas pupae were smallest when fed T. officinale and developed most slowly when fed P. lanceolata as larvae. Neither aucubin nor catalpol were detected in intact Plantago-fed T. ni larvae or their hemolymph, and only trace amounts of aucubin were detected in frass, suggesting that these compounds are mostly metabolized in the midgut and are not encountered by the parasitoid. Copidosoma floridanum clutch size was almost doubled when reared from P. lanceolata-fed T. ni compared with T. officinale-fed larvae and tripled compared with P. major-fed larvae, although the percent of parasitoids surviving to adulthood was uniformly high regardless of host diet. The observed variation in C. floridanum fitness among host diets is likely mediated by the effect of the diets on host quality, which in turn may be influenced more by other factors in the host plants than their iridoid glycoside profiles. Interactions between plant metabolites, generalist herbivores like T. ni, and their parasitoids may be predominantly indirect.

Liquid chromatography–tandem mass spectrometry reveals the widespread occurrence of flavonoid glycosides in honey, and their potential as floral origin markers

HPLC-MS–MS analysis of unifloral honey extracts has shown the occurrence of flavonoid glycosides in most of the analyzed samples. These compounds are not present in large amounts, but can reach up to 600 μg/100 g honey in canola and rapeseed honeys. Rhamnosyl-hexosides (tentatively rutinosides and neohesperidosides) and dihexosides (hexosyl(1→2)hexosides and hexosyl(1→6)hexosides) of flavonols such as quercetin, kaempferol, isorhamnetin and 8-methoxykaempferol, are the main flavonoid glycosides found in honey. However, flavonoid triglycosides and monoglycosides are also detected in some floral origins. Eucalyptus and orange blossom nectars were collected and analyzed showing that nectar flavonoid glucosides, as is the case of eucalyptus flavonoids, can be readily hydrolyzed by the bee saliva enzymes, while flavonoid rhamnosyl-glucosides, as is the case of citrus nectar flavonoids, are not hydrolyzed, and because of these reasons the flavonoid glycoside content of citrus honey is higher than that of eucalyptus honey that contains mainly aglycones. The flavonoid glycoside profiles detected in honeys suggest that this could be related to their floral origin and the results show that the HPLC-MSn ion trap analysis of flavonoid glycosides in honey is a promising analytical method to help in the objective determination of the floral origin of unifloral honeys.

Estimation of aroma precursors in radiation processed fenugreek

abstract Bound volatile compounds of fenugreek were isolated and identified. The glycoside profile was domi-nated by phenyl glucopyranoside accounting for 90% of the total glycosides. The content of this glycosideas estimated both by high performance liquid chromatography (HPLC) and thin layer chromatography(TLC)-densitometry was found to be approximately 0.7 mg gm 1 of fenugreek. Gamma-radiation process-ing resulted in dose dependent break down of phenyl glucopyranoside with a reduction by almost 30% ata dose of 10 kGy. A corresponding increase in phenol content with dose was also observed in the steamvolatile oil of the irradiated spice. Based on pulse radiolytic studies the mechanism of radiolytic cleavagewas shown to occur via a carbon centred radical. Estimation of absorbed dose based on phenol releasedduring radiation processing is proposed herein. The method is simple and rapid and could estimateabsorbed dose in the range of 2.5–10 kGy within an error of 15%. 2009 Elsevier Ltd. All rights reserved.

Direct analysis of Stevia leaves for diterpene glycosides by desorption electrospray ionization mass spectrometry

The analysis of Stevia leaves has been demonstrated without any sample preparation using desorption electrospray ionization (DESI) mass spectrometry. Direct rapid analysis was achieved using minimal amounts of sample ( approximately 0.15 cm x 0.15 cm leaf fragment). Characteristic constituents of the Stevia plant are observed in both the positive and negative ion modes including a series of diterpene 'sweet' glycosides. The presence of the glycosides was confirmed via tandem mass spectrometry analysis using collision-induced dissociation and further supported by exact mass measurements using an LTQ-Orbitrap. The analysis of both untreated and hexane-extracted dry leaves proved that DESI can be successfully used to analyze untreated leaf fragments as identical profiles were obtained from both types of samples. Characterization and semi-quantitative determination of the glycosides was achieved based on the glycoside profile within the full mass spectrum. In addition, the presence of characteristic glycosides in an all-natural commercial Stevia dietary supplement was confirmed. This study provides an example of the application of DESI to direct screening of plant materials, in this case diterpene glycosides.

Flavonol glycosides in wild and cultivated berries of three major subspecies of Hippophaë rhamnoides and changes during harvesting period

Abstract Flavonol glycosides are an important group of bioactive components of sea buckthorn ( Hippophae rhamnoides ). The content and profile of flavonol glycosides of some major subspecies and most cultivars as well as the variation amongst the harvesting years and dates are largely unknown. This study investigated flavonol glycosides in wild berries of two major subspecies H. rhamnoides ssp. rhamnoides and ssp. sinensis and berries of eight cultivars of ssp. rhamnoides and mongolica by reverse phase high performance liquid chromatography combined with diode array detection. The major flavonol glycosides were isorhamnetin-3-O-glucoside-7-O-rhamnoside, isorhamnetin-3-O-rutinoside, isorhamnetin-3-O-glucoside, isorhamnetin-3-O-sophoroside-7-O-rhamnoside, quercetin-3-O-rutinoside, quercetin-3-O-glucoside and quecertin-3-O-sophoroside-7-O-rhamnoside. The total content of flavonol glycosides fell in the range of 27–130 mg per 100 g fresh berries with considerable variation amongst the origins and the harvesting years. Compared with the berries of ssp. sinensis and ssp. mongolica , the berries of ssp. rhamnoides contained high levels of isorhamnetin-3-O-glucoside-7-O-rhamnoside and isorhamnetin-3-O-glucoside and lower levels of quercetin-3-O-rutinoside and quercetin-3-O-glucoside. In the wild berries of ssp. sinensis , the contents of flavonol glycosides reached maxima around late September to early October and decreased thereafter, whereas a general decreasing trend was seen in the cultivated berries of ssp. rhamnoides from the end of August to the end of October.

Soil Quality Effects on Chenopodium album Flavonoid Content and Antioxidant Potential

Antioxidant capacity, total phenolic content and flavonoid glycosides profile were compared in C.album samples grown in intensively cultivated (IC) and nondisturbed (ND) soils to evaluate differences in their nutraceutical potential. Petroleum ether, methanol, and aqueous extracts were sequentially obtained from C. album dried samples. Methanol crude extract exhibited the highest antioxidant potential and phenolic content, which were significantly enhanced by soil deterioration. This feature was enhanced in its ethyl acetate/n-buthanol subextract that also yielded higher amounts of the fraction containing flavonoid glycosides in samples grown in IC soils. Compounds were isolated by activity guided fractionation, and chemical structure-antioxidant activity relationships were established. Chemical structures were elucidated by chemical and spectroscopic methods. Six known flavonoid glycosides were isolated, and their antioxidant activity was determined by DPPH assay. 1, quercetin-3-O-(2",6"-di-O-R-L-rhamnopyranosyl)-beta-D-glucopyranoside; 2, kaempferol-3-O-(2",6"-di-O-R-L-rhamnopyranosyl)-beta-D-glucopyranoside; 3, quercetin-3-O-beta-D-glucopyranosyl-(1'''-->6")-beta-D-glucopyranoside; 4, rutin; 5, quercetin-3-O-beta-D-glucopyranoside; and 6, kaempferol-3-O-beta-D-glucopyranoside. Triosides 1 and 2 were identified for the first time in C. album. Our results suggest that this edible weed, ubiquitously present in cultivated fields, should be considered as a nutraceutical food and an alternative source for nutrients and free radical scavenging compounds, particularly when collected from cultivated fields that seem to increase some of its advantages.

Flavonol tetraglycosides and other constituents from leaves of Styphnolobium japonicum (Leguminosae) and related taxa

Two flavonol tetraglycosides comprising a trisaccharide at C-3 and a monosaccharide at C-7 were isolated from the leaves of Styphnolobium japonicum (L.) Schott and characterised as the 3- O-α-rhamnopyranosyl(1 → 2)[α-rhamnopyranosyl(1 → 6)]-β-glucopyranoside-7- O-α-rhamnopyranosides of quercetin and kaempferol. The 3- O-α-rhamnopyranosyl(1 → 2)[α-rhamnopyranosyl(1 → 6)]-β-galactopyranoside-7- O-α-rhamnopyranoside of kaempferol, the 3- O-α-rhamnopyranosyl(1 → 2)[α-rhamnopyranosyl(1 → 6)]-β-glucopyranosides of kaempferol and quercetin and the 3- O-α-rhamnopyranosyl(1 → 2)[α-rhamnopyranosyl(1 → 6)]-β-galactopyranoside of kaempferol were also obtained from this species for the first time. Some or all of these flavonol tetra- and triglycosides were detected in 17 of 18 specimens of S. japonicum examined from living and herbarium material, although the most abundant flavonoid in the leaves was generally quercetin 3- O-α-rhamnopyranosyl(1 → 6)-β-glucopyranoside (rutin). The triglycosides, but not the tetraglycosides, were detected in herbarium specimens of Styphnolobium burseroides M. Sousa, Rudd & Medrano and Styphnolobium monteviridis M. Sousa & Rudd, but specimens of Styphnolobium affine (Torrey & A. Gray) Walp. contained a different profile of flavonol glycosides. The flavonol tetra- and triglycosides of S. japonicum were also present in leaves of Cladrastis kentukea (Dum. Cours.) Rudd, a representative of a genus placed close to Styphnolobium in current molecular phylogenies. An additional constituent obtained from leaves of Styphnolobium japonicum was identified as the maltol derivative, 3-hydroxy-2-methyl-4 H-pyran-4-one 3- O-(4′- O- p-coumaroyl-6′- O-(3-hydroxy-3-methylglutaroyl))-β-glucopyranoside.