Antioxidant flavone glycosides from the leaves of Fargesia robusta

The discovery of an anti-inflammatory monoterpenoid, neoroseoside from the Zea mays

A new monoterpenoid, neoroseoside (1), along with two previously reported compounds, 2″-O-α-l-rhamnosyl-6-C-fucosylluteolin (2) and farobin A (3) were isolated from the Zea mays. The structure of compound 1 was determined through the analysis spectroscopic data, including mass spectrometry (MS), infrared (IR) spectroscopy, and nuclear magnetic resonance (NMR) data. The absolute configurations of 1 were deduced from the comparing the values of optical rotations and from the interpretation of electronic circular dichroism (ECD) spectra. Compounds 2 and 3 displayed moderate antibacterial activity against Streptococcus mutans ATCC 25175 (inhibition rates 24 % and 28 %, respectively) and Streptococcus sobrinus ATCC 33478 (inhibition rate of 26 %), at a concentration of 100 μg/mL, whereas compound 1 did not have any significant antibacterial activities. The compounds 1-3 also showed anti-inflammatory activity on cytokine IL-6 and TNF-α.

Enhanced Two-Step Extraction from Biomass of Two Cymbopogon Species Cultivated in Santander, Colombia

The insertion of circular economy principles into the essential oil (EO) production chain aims to reduce waste generation and make integral use of harvested plant material. Higher profits from integral use with reduced waste generation contribute to the eventual use of the EO value chain as an alternative to illicit crops in Colombia (mostly coca). In this study, Java-type citronella (Cymbopogon winterianus) and palmarosa (C. martinii) plant materials were used in two consecutive processes to obtain EOs and extracts. The residual biomass after EO distillation was subjected to ultrasound-assisted hydroethanolic extraction to afford extracts that contained bioactive compounds. Citronella and palmarosa were distilled with typical EO yields (1.0 ± 0.1% for citronella; 0.41 ± 0.06% for palmarosa; n = 5) either through hydrodistillation assisted by microwave radiation or through steam distillation, and their composition (determined via GC/FID/MS analysis) and physicochemical parameters fell within their ISO standard specifications. The concentration of citronellal, the major compound of citronella oil, was 500 ± 152 mg/g. Geraniol, the main component of palmarosa oil, was found at 900 ± 55 mg/g. The citronella and palmarosa hydroalcoholic extracts (4-11% yield) were analyzed with UHPLC-ESI-Orbitrap-MS, which permitted the identification of 30 compounds, mainly C-glycosylated flavones and hydroxycinnamic acids. Both extracts had similar antioxidant activity values, evaluated using the ABTS+● and ORAC assays (110 ± 44 µmol Trolox®/g extract and 1300 ± 141 µmol Trolox®/g extract, respectively).

Interactions of isoorientin and its Semi-synthetic analogs with human serum albumin

Isoorientin is a C-glycosyl flavone with a wide range of health beneficial effects and inhibits glycogen synthase kinase 3β (GSK-3β) potentially against Alzheimer's disease. Its semi-synthetic derivatives have greater potency than isoorientin. The present study was aimed to determine the mechanism of interactions of isoorientin and its derivatives with human serum albumin (HSA) using multi-spectroscopic, microscale thermophoresis (MST) and computational studies. Spectra of steady-state fluorescence, UV-Vis, and time-resolved fluorescence indicated that isoorientin and its derivatives quenched the intrinsic fluorescence of HSA through a static quenching process. Isoorientin and its derivatives had a moderate affinity with HSA (K_a 7.7-14.9 × 10⁴ M^-1). The binding process was accompanied by an exothermic phenomenon, ΔG° of HSA-isoorientin and its derivatives systems were calculated as from -29.51 kJ mol^-1 to -27.87 kJ mol^-1. Displacement experiments with site-specific markers revealed that isoorientin and its derivatives bind to HSA at site II (subdomain IIIA) only. A reduction in the α-helical content of HSA-isoorientin and its derivatives complex was observed, because the conformational changes was structurally perturbed by the hydrophilic groups of the compounds. Further molecular modeling studies confirmed that the binding of isoorientin and its derivatives to the site II via hydrophobic interaction. The MST results confirmed the interactions between HSA and the compounds of interest. The esterase-like assay studies indicated that isoorientin and its derivatives shared the same binding site in HSA, and their induced structural changes of HSA may have been caused by partial unfolding of HSA. This work helps to understand transport, distribution, bioactivity, and design of flavonoid-based GSK-3β inhibitors.

Pancreatic lipase inhibitory activity of Bambusa multiplex cv. Fernleaf leaf extract in vitro and in vivo

Bambusa multiplex cv Fernleaf (B. multiplex) is a species of bamboo. In the present study, B. multiplex leaf extract was prepared through the resin absorption/desorption procedure and analyzed by HPLC. C-Glycosyl flavonoids are the main constituents of B. multiplex extract, and the content of isoorientin and vitexin was 51.8 and 23.1 mg g^-1, respectively. Besides, the extract exhibited inhibitory activities on pancreatic lipase and α-glucosidase with IC50 values of 0.91 and 1.16 mg mL^-1, respectively. The extract could bind to pancreatic lipase and showed mixed-type inhibition. An in vivo study showed that pre-administration of B. multiplex extract significantly reduced the fat absorption in rats and increased fat excretion through feces. The change in the C-glycosyl flavonoid content in feces was the same as that in the triglyceride content. The inhibitory activity of B. multiplex leaf extract on pancreatic lipase was confirmed both in vitro and in vivo.

Anti-inflammatory constituents from Phyllostachys makinoi Hayata

A novel chromone analogue, phyllomakin A (1), and a new flavonolignan, (-)-quiquelignan C (2), along with 18 phenolic and 2 triterpenoids, were isolated from the leaves of Phyllostachys makinoi Hayata. The structures of 1-22 were elucidated by an application of various spectroscopic analyses (1D & 2D NMR and MS) and compared with reported data. A biological evaluation showed that compound 3 had very potent anti-NO production activity (IC₅₀ = 4.80 µM), while compounds 2, 6, 11, and 15 showed moderate inhibitory effects (IC₅₀ = 10.19, 13.26, 13.56, and 10.96 µM, respectively) without affecting cell viability at 20 μM.

A rapid thioacidolysis method for biomass lignin composition and tricin analysis

BACKGROUND

Biomass composition varies from plant to plant and greatly affects biomass utilization. Lignin is a heterogeneous phenolic polymer derived mainly from p-coumaryl, coniferyl, and sinapyl alcohols and makes up to 10-25% of lignocellulosic biomass. Recently, tricin, an O-methylated flavone, was identified as a lignin monomer in many grass species. Tricin may function as a nucleation site for lignification and is advocated as a novel target for lignin engineering to reduce lignin content and improve biomass digestibility in grasses. Thioacidolysis is an analytical method that can be adapted to analyze both lignin monomeric composition and tricin content in the lignin polymer. However, the original thioacidolysis procedure is complex, laborious, and time consuming, making it difficult to be adopted for large-scale screening in biomass research. In this study, a modified, rapid higher throughput thioacidolysis method was developed.

RESULTS

In combination with gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS), the modified thioacidolysis method can be used to simultaneously characterize the lignin composition and tricin content using 2-5 mg of dry samples. The modified method eliminates the solvent extraction and drastically improves the throughput; 80 samples can be processed in one day per person. Our results indicate that there is no significant difference in the determination of lignin S/G ratio and tricin content between the original and modified methods.

CONCLUSIONS

A modified thioacidolysis protocol was established. The results demonstrate that the modified method can be used for rapid, high-throughput, and reliable lignin composition and tricin content analyses for screening transgenic plants for cell wall modifications or in large-scale genome-wide association studies (GWAS).

Two new phenolic glucosides from marine-derived fungus Aspergillus sp

Two new phenolic glucosides, including a new O-glycoside (1) and a new C-glycoside (2), were isolated from a marine-derived fungus Aspergillus sp. The structures of new compounds were elucidated through interpretations of spectroscopic evidence and high-resolution electrospray ionization mass spectrometry. The hexose unit of 1 was identified as β-D-glucose by comparison with an authentic sample via HPLC after acid hydrolysis and derivatization. All compounds were evaluated for their ability to inhibit LPS-induced NO production in RAW264.7 macrophages, but none of them displayed significant activity.

Isoorientin: A dietary flavone with the potential to ameliorate diverse metabolic complications

Isoorientin is a natural C-glucosyl flavone that is generating a lot of interest due to its multiple pharmacological activities. Increasing experimental data have shown that the robust antioxidant and anti-inflammatory properties of isoorientin remain important in ameliorating a number of metabolic complications. In fact, plants rich in isoorientin have demonstrated strong ameliorative properties against complications such as hyperglycemia, hyperlipidemia, and insulin resistance. However, while such evidence is accumulating, it has not been reviewed to better inform on the therapeutic potential of this flavone in improving human health. This review examines and extrapolates available literature on the potential beneficial or detrimental effects associated with the use of isoorientin in mitigating metabolic diseases, with a specific focus on diabetes, obesity, and insulin resistance, including associated complications. The discussion includes effective doses in various experimental settings and proposed molecular mechanisms by which isoorientin may exert its therapeutic effects. In addition, the protective effects of extracts of a number of isoorientin-rich plants against metabolic complications will be highlighted.

Chemical profile and pancreatic lipase inhibitory activity of Sinobambusa tootsik (Sieb.) Makino leaves

Background

Sinobambusa tootsik (Sieb.) Makino (S. tootsik) is one species of bamboo distributed in China, Japan and Vietnam. The chemical profile of its leaves and its potential application was unknown yet.

Methods

The chemical profile of S. tootsik was studied by HPLC and UPLC-DAD-QTOF-MS. The S. tootsik extract was prepared by extraction with 50% aqueous ethanol, followed by H103 macroporous resins adsorption and desorption processes. Pancreatic lipase inhibitory activity was determined using p-nitrophenyl palmitate as the substance, which was hydrolyzed by lipase to form coloured p-nitrophenol.

Results

Eighteen compounds were identified in S. tootsik. Most of them were the C-glycosylated derivatives of luteolin and apigenin, such as isoorientin, isoorientin-2″-O-rhamnoside and isovitexin. Isoorientin-2″-O-rhamnoside was the most dominant flavonoid in the sample. S. tootsik extract was prepared through resin adsorption/desorption with yield of 1.12 ± 015% and total flavonoids content of 82 ± 2 mg/g (in term of isoorientin). The extract exhibited pancreatic lipase inhibitory activity with IC50 value of 0.93 mg/mL.

Conclusion

The chemical profile of S. tootsik leaves was uncovered for the first time. C-glycosyl flavonoids were the main constituents in the plant. The extract exhibited pancreatic lipase inhibitory activity and may have potential for use as a food supplement for controlling obesity.

Identification and quantification of main flavonoids in the leaves of Bambusa multiplex cv. Fernleaf

The chemical profile of Bambusa multiplex cv. Fernleaf (B. multiplex) leaves was analysed by UPLC-DAD-Q-TOF-MS. Twelve compounds were identified and C-glycosyl flavonoids, including vitexin, isovitexin, isoorientin and its derivatives, are the main constitutes of the plant. Besides, a HPLC method for isoorientin quantification was developed. The RSD of retention time and peak area were 0.05% and 2.04% for six times analysis of isoorientin with concentration of 20 μg/mL. The recovery of isoorientin in real sample was 99.2%. The general trend of isoorientin content in B. multiplex leaves was that it steady increased from Jan. to May, and then quickly decreased. The maximum was found on May with value of 4.7 mg/g. The lowest level of isoorientin was found during Aug. to Nov. with value of about 1.66 mg/g. In different seasons, isoorientin is always the most dominant flavonoid which was accounted for about 50% of total flavonoids in the sample.

Dietary flavonoid aglycones and their glycosides: Which show better biological significance?

The dietary flavonoids, especially their glycosides, are the most vital phytochemicals in diets and are of great general interest due to their diverse bioactivity. The natural flavonoids almost all exist as their O-glycoside or C-glycoside forms in plants. In this review, we summarized the existing knowledge on the different biological benefits and pharmacokinetic behaviors between flavonoid aglycones and their glycosides. Due to various conclusions from different flavonoid types and health/disease conditions, it is very difficult to draw general or universally applicable comments regarding the impact of glycosylation on the biological benefits of flavonoids. It seems as though O-glycosylation generally reduces the bioactivity of these compounds - this has been observed for diverse properties including antioxidant activity, antidiabetes activity, anti-inflammation activity, antibacterial, antifungal activity, antitumor activity, anticoagulant activity, antiplatelet activity, antidegranulating activity, antitrypanosomal activity, influenza virus neuraminidase inhibition, aldehyde oxidase inhibition, immunomodulatory, and antitubercular activity. However, O-glycosylation can enhance certain types of biological benefits including anti-HIV activity, tyrosinase inhibition, antirotavirus activity, antistress activity, antiobesity activity, anticholinesterase potential, antiadipogenic activity, and antiallergic activity. However, there is a lack of data for most flavonoids, and their structures vary widely. There is also a profound lack of data on the impact of C-glycosylation on flavonoid biological benefits, although it has been demonstrated that in at least some cases C-glycosylation has positive effects on properties that may be useful in human healthcare such as antioxidant and antidiabetes activity. Furthermore, there is a lack of in vivo data that would make it possible to make broad generalizations concerning the influence of glycosylation on the benefits of flavonoids for human health. It is possible that the effects of glycosylation on flavonoid bioactivity in vitro may differ from that seen in vivo. With in vivo (oral) treatment, flavonoid glycosides showed similar or even higher antidiabetes, anti-inflammatory, antidegranulating, antistress, and antiallergic activity than their flavonoid aglycones. Flavonoid glycosides keep higher plasma levels and have a longer mean residence time than those of aglycones. We should pay more attention to in vivo benefits of flavonoid glycosides, especially C-glycosides.

Flavonoid Glycosides from Siparuna gigantotepala Leaves and Their Antioxidant Activity

Two new flavonol glycosides were isolated from the leaves of Siparuna gigantotepala. Their structures were determined to be kaempferol 3-O-β-xylopyranosyl-(1→2)-α-arabinofuranoside (1) and kaempferol 3,7-di-O-methyl-4'-O-α-rhamnopyranosyl-(1→2)-β-glucopyranoside (2). In addition, three known flavonol glycosides, rutin (3), kaempferol 3-O-rutinoside (4), and kaempferol 3,7-di-O-methyl-4'-O-rutinoside (5), and three flavonol aglycones, quercetin (6), kaempferol 3,7-dimethyl ether (7), and kaempferol 3,7,4'-trimethyl ether (8), were also isolated and are reported here for the first time in this species. The structures of compounds 1 and 2 were established on the basis of their LC-MS and one- and two-dimensional (1D)- and (2D)-NMR spectroscopic analyses, combined with acid methanolysis and silylation of sugar moieties for GC-MS. Evaluation of the antioxidant activity, conducted in the 96-well plate format, showed that the flavonoids isolated possess strong 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity and moderate oxygen radical absorption capacity.

Tricin-lignins: occurrence and quantitation of tricin in relation to phylogeny

Tricin [5,7-dihydroxy-2-(4-hydroxy-3,5-dimethoxyphenyl)-4H-chromen-4-one], a flavone, was recently established as an authentic monomer in grass lignification that likely functions as a nucleation site. It is linked onto lignin as an aryl alkyl ether by radical coupling with monolignols or their acylated analogs. However, the level of tricin that incorporates into lignin remains unclear. Herein, three lignin characterization methods: acidolysis; thioacidolysis; and derivatization followed by reductive cleavage; were applied to quantitatively assess the amount of lignin-integrated tricin. Their efficiencies at cleaving the tricin-(4'-O-β)-ether bonds and the degradation of tricin under the corresponding reaction conditions were evaluated. A hexadeuterated tricin analog was synthesized as an internal standard for accurate quantitation purposes. Thioacidolysis proved to be the most efficient method, liberating more than 91% of the tricin with little degradation. A survey of different seed-plant species for the occurrence and content of tricin showed that it is widely distributed in the lignin from species in the family Poaceae (order Poales). Tricin occurs at low levels in some commelinid monocotyledon families outside the Poaceae, such as the Arecaceae (the palms, order Arecales) and Bromeliaceae (Poales), and the non-commelinid monocotyledon family Orchidaceae (Orchidales). One eudicotyledon was found to have tricin (Medicago sativa, Fabaceae). The content of lignin-integrated tricin is much higher than the extractable tricin level in all cases. Lignins, including waste lignin streams from biomass processing, could therefore provide a large and alternative source of this valuable flavone, reducing the costs, and encouraging studies into its application beyond its current roles.

New Anti-HBV C-Boivinopyranosyl Flavones from Alternanthera philoxeroides

C-boivinopyranosyl flavones have rarely been isolated from nature. In the search for anti-HBV (hepatitis b virus) constituents of Alternanthera philoxeroides, two new compounds, luteolin-6-C-β-d-boivinopyranosyl-3′-O-β-d-glucopyranoside (1) and chrysoeriol-6-C-β-d-boivinopyranosyl-4′-O-β-d-glucopyranoside (2), along with three known C-boivinopyranosyl flavones (compounds 3–5) were isolated. Their structures were determined by spectroscopic analyses including 1D and 2D NMR, HR-ESI-MS, IR spectra. Compounds 1, 2 and 3 showed significant anti-HBV activities through specifically inhibiting the secretion of HBsAg in HepG2.2.15.

Tricin, a flavonoid monomer in monocot lignification

Tricin was recently discovered in lignin preparations from wheat (Triticum aestivum) straw and subsequently in all monocot samples examined. To provide proof that tricin is involved in lignification and establish the mechanism by which it incorporates into the lignin polymer, the 4'-O-β-coupling products of tricin with the monolignols (p-coumaryl, coniferyl, and sinapyl alcohols) were synthesized along with the trimer that would result from its 4'-O-β-coupling with sinapyl alcohol and then coniferyl alcohol. Tricin was also found to cross couple with monolignols to form tricin-(4'-O-β)-linked dimers in biomimetic oxidations using peroxidase/hydrogen peroxide or silver (I) oxide. Nuclear magnetic resonance characterization of gel permeation chromatography-fractionated acetylated maize (Zea mays) lignin revealed that the tricin moieties are found in even the highest molecular weight fractions, ether linked to lignin units, demonstrating that tricin is indeed incorporated into the lignin polymer. These findings suggest that tricin is fully compatible with lignification reactions, is an authentic lignin monomer, and, because it can only start a lignin chain, functions as a nucleation site for lignification in monocots. This initiation role helps resolve a long-standing dilemma that monocot lignin chains do not appear to be initiated by monolignol homodehydrodimerization as they are in dicots that have similar syringyl-guaiacyl compositions. The term flavonolignin is recommended for the racemic oligomers and polymers of monolignols that start from tricin (or incorporate other flavonoids) in the cell wall, in analogy with the existing term flavonolignan that is used for the low-molecular mass compounds composed of flavonoid and lignan moieties.

Antioxidant compounds from ethanol extracts of bamboo (Neosinocalamus affinis) leaves

Activity-guided fractionation of Neosinocalamus affinis leaves led to obtain two new flavonoids, 4'-O-((7″R,8″S)-8″-guaiacylglyceryl)-pleioside B (9) and apigenin 6-C-β-d-fucopyranosyl-7-O-β-d-glucopyranoside (10) along with eight known compounds. Their structures were elucidated on the basis of spectroscopic data (UV, IR, NMR, and MS). Among these 10 compounds, farobin A (4) and isoorientin (7) showed significant antioxidant activity evaluated by 1,1-diphenyl-2-picrylhydrazyl, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid), superoxide anion and nitric oxide (NO) radical-scavenging assays.

Protein glycation inhibitory activity and antioxidant capacity of clove extract

Syzygium aromaticum (L.) (clove) is one of the most widely cultivated spices in many tropical countries. The aim of this study was to determine the phytochemical content, the antioxidant properties and the antiglycation properties of aqueous extract of clove against fructose-mediated protein glycation and oxidation. The result showed that the content of total phenolics and flavonoids in clove extract was 239.58 ± 0.70 mg gallic acid equivalents/g dried extract and 65.67 ± 0.01 mg catechin equivalents/g dried extract, respectively. In addition, clove exhibited antioxidant properties including DPPH radical scavenging activity (IC50 = 0.29 ± 0.01 mg/ml), Trolox equivalent antioxidant capacity (4.69 ± 0.03 μmol Trolox equivalents/mg dried extract), ferric reducing antioxidant power (20.55 ± 0.11 μmol ascorbic acid equivalents/mg dried extract), Oxygen radical absorbance capacity (31.12 ± 0.21 μmol Trolox equivalents/mg dried extract), hydroxyl radical scavenging activity (0.15 ± 0.04 mg Trolox equivalents/mg dried extract), and superoxide radical scavenging activity (18.82 ± 0.50 mg Trolox equivalents/mg dried extract). The aqueous extract of clove (0.25-1.00 mg/ml) significantly inhibited the formation of fluorescent advanced glycation end products (AGEs) and non-fluorescent AGEs (N(ɛ)-(carboxymethyl) lysine (CML)) in glycated BSA during 4 weeks of incubation. The extract also markedly prevented oxidation-induced protein damage by decreasing protein carbonyl formation and protecting against the loss of protein thiol group. These results clearly demonstrated that a polyphenol enriched clove extract, owing to its antioxidant, was capable to inhibit the formation of AGEs and protein glycation. The findings might lead to the possibility of using the clove extract for targeting diabetic complications.

Seasonal, diurnal and vertical variation in photosynthetic parameters in Phyllostachys humilis bamboo plants

In recent years, temperate bamboo species have been introduced in Europe for multiple uses such as renewable bio-based materials (wood, composites, fibres, biochemicals…) and numerous ecological functions (soil and water conservation, erosion control, phytoremediation…). Despite their interesting potential, little is known on the ecophysiology of these plants in their new habitat. Therefore, we studied gas exchange parameters on a full soil bamboo plantation of Phyllostachys humilis on a test field in Ireland (Europe). We evaluated the seasonal, diurnal and vertical variation of the parameters of two commonly used photosynthetic models, i.e. the light response curve (LRC) model and the model of Farquhar, von Caemmerer and Berry (FvCB). Furthermore, we tested if there were environmental effects on the photosynthetic parameters of these models and if a correlation between photosynthetic parameters and fluorescence parameters was present, fluorescence parameters can be easily and fast determined. Our results show that the gas exchange parameters do not vary diurnally or vertically. Only seasonal variations were found and should, therefore, be taken into account when using the LRC or FvCB model when modelling canopy growth. Therefore, a big-leaf model or a sunlit-shade model can be used for modelling bamboo growth in Western Europe. There is no straightforward relation between environmental variables and the photosynthetic parameters. Although fluorescence parameters showed a correlation with the photosynthetic parameters, application of such correlation may be limited.

WITHDRAWN: Flavonoid glycosylation and biological benefits

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Seasonal, diurnal and vertical variation of chlorophyll fluorescence on Phyllostachys humilis in Ireland

In recent years, temperate bamboo species have been introduced in Europe not only as an ornamental plant, but also as a new biomass crop. To measure adaptation stress of bamboo to the climate of Western Europe, chlorophyll fluorescence was measured on a diurnal and seasonal basis in Ballyboughal, Co. Dublin, Ireland. Measurements were attained on the leaves of each node of Phyllostachys humilis. The most frequently used parameter in chlorophyll fluorescence is the photosynthetic efficiency (Fv/Fm). A seasonal dip - as well as a larger variation - of Fv/Fm in spring compared to the rest of the year was observed. Over the year, the upper leaves of the plant perform better than the bottom leaves. These findings were linked to environmental factors such as light intensity, air temperature and precipitation, as increased light intensities, decreasing air temperatures and their interactions, also with precipitation levels have an effect on the photosynthetic efficiency (Fv/Fm) in these plants.

TLC screening for antioxidant activity of extracts from fifteen bamboo species and identification of antioxidant flavone glycosides from leaves of Bambusa. textilis McClure

Interest in the antioxidant activity of bamboo leaves is growing. To discover new sources of natural antioxidants, a TLC bioautography method combined with a new image processing method was developed to evaluate the antioxidant activity of leaf extracts from 15 different species of bamboo. The results showed that the methanolic extract of Bambusa. textilis McClure possessed the highest antioxidant activity among the selected bamboo species. To rapidly identify the antioxidant compounds, the crude extract of B. textilis McClure was analysed by HPLC-UV, and HPLC-micro-fractionation of the extract was carried out. Based on TLC bioautography-guided fractionation, three antioxidant fractions were isolated from B. textilis McClure by preparative chromatography. These three antioxidant compounds were identified as isoorientin 4''-O-β-D-xylopyranoside (1), isoorientin 2''-O-α-L-rhamnoside (2) and isoorientin (3) according to their UV, MS, and NMR data. The proposed TLC screening method could therefore be an easy way to evaluate the antioxidant activity of bamboo leaves, and the results achieved should prove very helpful for promoting their utilization, as B. textilis McClure can be considered a promising plant source of natural antioxidants.

Phenolic compounds and anti-oxidant capacity of twelve morphologically heterogeneous bamboo species

INTRODUCTION

Despite the growing interest in the use of bamboo for both food and health-related applications because it provides a rich source of anti-oxidants, there is still a lack of information on the responsible secondary metabolites of the great variety of bamboo species.

OBJECTIVE

To extend the knowledge on secondary metabolites of different bamboo species and to link anti-oxidant capacity with the different classes of phenolic compounds that are present in the leaves.

METHODOLOGY

Chromatographic profiles of 12 morphological heterogeneous bamboo species from different genera were recorded using HPLC-DAD (diode array detector) and LC-MS/MS. In addition, the in vitro anti-oxidant capacity was evaluated using a variety of anti-oxidant assays (1,1-diphenyl-2-picrylhydrazyl, Trolox-equivalent anti-oxidant capacity and oxygen radical absorbance capacity). Using partial least square (PLS) analysis as a chemometric method, the anti-oxidant capacity could be linked to specific groups of polyphenols.

RESULTS

Flavones and phenolic acids are the two main polyphenolic classes present in the leaf extracts of the 12 selected bamboo species. Luteolin derivatives and phenolic acids were identified as the most potent anti-oxidants.

CONCLUSION

The most abundant classes of phenolic compounds present in a selection of bamboo species were flavone glycosides and phenolic acids. Luteolin flavones and phenolic acids are the main anti-oxidant phenolic compounds in bamboo leaf extract. The information obtained in this study provides further support for the development of bamboo-based anti-oxidant food applications and food supplements.

C-dideoxyhexosyl flavones from the stems and leaves of Passiflora edulis Sims

The stems and leaves of Passiflora edulis Sims, are used as a folk medicine for treating both anxiety and nervousness in American countries. Phytochemical investigation of the n-butanol (n-BuOH) fraction of this plant led to the isolation of four new 2,6-dideoxyhexose-C-glycosyl flavones, including luteolin-8-C-β-digitoxopyranosyl-4'-O-β-d-glucopyranoside (1), apigenin-8-C-β-digitoxopyranoside (2), apigenin-8-C-β-boivinopyranoside (3) and luteolin-8-C-β-boivinopyranoside (4), together with five known compounds (5-9). The structures of these compounds were elucidated by extensive spectroscopic methods. All compounds were evaluated for their neurite outgrowth enhancing activities and the results indicated that luteolin (7) enhanced NGF-induced neurite outgrowth in PC12 cells at 50.0μM.

Novel indole C-glycosides from Isatis indigotica and their potential cytotoxic activity

Two novel indole C-glycosides, which were the first reported alkaloids C-glycosides from Isatis indigotica, together with five known alkaloids were isolated. The novel alkaloids were elucidated to be indole-3-acetonitrile-4-methoxy-2-C-β-D-glucopyranoside (1) and N-methoxy-indole-3-acetonitrile-2-C-β-D-glucopyranoside (2) on the basis of spectroscopic analysis. 1 exhibited significant cytotoxic activities against human myeloid leukemia HL-60 and human liver cancer HepG2 cells with the IC(50) of 1.3 ± 0.1 and 2.1 ± 0.3 μM, respectively. 2 showed potential cytotoxic activities against HL-60 and human myeloid leukemia Mata cells with the IC(50) of 5.1 ± 0.4 and 12.1 ± 0.8 μM, respectively.