Phenolic constituents from the rhizomes of Dryopteris crassirhizoma

A new phenolic glycoside, dryopteroside (1), was isolated from the rhizomes of Dryopteris crassirhizoma (Dryopteridaceae), together with five known compounds, 4beta-carboxymethyl-(-)-epicatechin (2), isobiflorin (3), biflorin (4), 1-beta-D-glucopyranosyloxy-3-methoxy-5-hydroxybenzene (5) and (+)-catechin-6-C-beta-D-glucopyranoside (6). The new compound was elucidated to be 1-butanoyl-3-C-beta-D-glucopyranosyl-5-methyl-phloroglucinyl-6-O-beta-D-glucopyranoside (1) by chemical and various spectroscopic analyses. The known compounds 2-6 were first reported from the genus Dryopteris.     

Two new glycosides from the whole plants of Glechoma hederacea L

Two new glycosides, 7S,7'S,8R,8'R-icariol A(2)-9-O-beta-D-glucopyranoside (1) and 4-allyl-2-hydroxyphenyl 1-O-beta-D-apiosyl-(1-->6)-beta-D-glucopyranoside (2), were isolated from the dried whole plants of Glechoma hederacea L. (Labiatae) together with four known compounds, cistanoside E (3), dihydrodehydrodiconiferyl alcohol 4-O-beta-D-glucopyranoside (4), apigenin 7-O-beta-D-glucuronopyranoside (5) and luteolin 7-O-beta-D-glucopyranoside (6). The structures of the new compounds were elucidated on the basis of chemical and spectral analysis.     

Two new alkaloids from Capparis himalayensis

Two new alkaloids, Capparin A (1) and B (2), along with seven known compounds 6-methoxyindoline-2,3-dione (3), wogonin (4), oroxylin A (5), kaempferol (6), apigenin (7), quercetin (8) and luteolin (9), were isolated from the whole plant of Capparis himalayensis. Their structures have been established on the basis of spectral methods and the structure of 1 was confirmed by X-ray crystallographic analysis.     

Benzolignanoid and Polyphenols from Origanum Vulgare

A new dihydrobenzodioxane derivative, origalignanol ( 10 ), together with nine polyphenolic compounds, salvianolic acid A ( 1 ), salvianolic acid C ( 2 ), lithospermic acid ( 3 ), apigenin 7‐O‐β‐D‐glucuronide ( 4 ), apigenin 7‐O‐β‐D‐(6″‐methyl)glucuronide ( 5 ), luteolin, ( 6 ), luteolin 7‐O‐β‐D‐glucopyranoside ( 7 ), luteolin 7‐O‐β‐D‐glucuronide ( 8 ), and luteolin 7‐O‐β‐D‐xylopyranoside ( 9 ), were isolated from the aqueous ethanolic extract of the aerial parts of Origanum vulgare for the first time. The structure of new compound 10 was determined on the basis of spectroscopic methods. Compound 5 is probably an artifact formed during the isolation. Compounds 1, 2 and 3 showed strong DPPH radical scavenging activity with an EC₅₀ of 7.2 ± 0.4, 9.6 ± 0.9, and 9.5 ± 0.7 μM, respectively, and protected rat hepatocytes from CCl₄‐damage at 100 μM.     

Identification and partial characterization of C-glycosylflavone markers in Asian plant dyes using liquid chromatography-tandem mass spectrometry

Flavonoids in the grasses (Poaceae family), Arthraxon hispidus (Thunb.) Makino and Miscanthus tinctorius (Steudel) Hackel have long histories of use for producing yellow dyes in Japan and China, but up to now there have been no analytical procedures for characterizing the dye components in textiles dyed with these materials. LC-MS analysis of plant material and of silk dyed with extracts of these plants shows the presence, primarily, of flavonoid C-glycosides, three of which have been tentatively identified as luteolin 8-C-rhamnoside, apigenin 8-C-rhamnoside and luteolin 8-C-(4-ketorhamnoside). Two of these compounds, luteolin 8-C-rhamnoside (M=432), apigenin 8-C-rhamnoside (M=416), along with the previously known tricin (M=330) and several other flavonoids that appear in varying amounts, serve as unique markers for identifying A. hispidus and M. tinctorius as the source of yellow dyes in textiles. Using this information, we have been able to identify grass-derived dyes in Japanese textiles dated to the Nara and Heian periods. However, due to the high variability in the amounts of various flavonoid components, our goal of distinguishing between the two plant sources remains elusive.     

Phenolic constituents of Knautia arvensis aerial parts

A new C-6 flavone glycoside (6), together with seven known compounds, cryptochlorogenic acid (1), chlorogenic acid (2), 2-O-trans-caffeoylhydrocitric acid (3), isovitexin 7-beta-D-glucopyranoside (4), 7,4'-dihydroxy-5-methoxyflavone-6-C-beta-D-glucopyranoside (5), 3,5-O-dicaffeoylquinic acid (7) and 4,5-O-dicaffeoylquinic acid (8), were isolated from the aerial parts of Knautia arvensis. Their structures were elucidated by extensive spectroscopic methods including 1D- (1H, 13C and TOCSY) and 2D-NMR (DQF-COSY, HSQC, HMBC) experiments, as well as ESIMS analysis. Compounds 1, 3-5 and 8 are reported for the first time in Knautia arvensis.     

Synthesis of carpachromene and related isopentenylated derivatives of apigenin

Acacetin (4) on reaction with prenyl bromide in the presence of methanolic sodium methoxide yielded 6,8-di-C-prenyl-(5) and 6-C-prenyl-(10) derivatives. The former (5) formed the corresponding bisdihydropyrano derivative (8). Monomethyl derivative of 10 (12) gave monodihydropyrano derivative (13). DDQ reaction of 10 followed by methylation afforded di-O-methyl carpachromene (2); whereas that of 5 gave a mixture of 21 and 22.

Nuclear prenylation of apigenin (3) in a similar way gave 6,8-di-C-C-prenyl-(16), its 7-0-prenyl-(15) and 6-C-prenyl-(18) derivatives. DDQ reaction of 18 provided natural carpachromene.¹ The structure of the isopentylated apigenin isolated by Dreyer et al.² needs further consideration.     

Analysis and quantification of flavonoidic compounds from Portuguese olive (Olea europaea L.) leaf cultivars

Twenty three samples of 18 Portuguese olive leaf cultivars were analysed by a reversed-phase HPLC/DAD procedure and eight flavonoidic compounds were identified and quantified (luteolin 7,4'-O-diglucoside, luteolin 7-O-glucoside, rutin, apigenin 7-O-rutinoside, luteolin 4'-O-glucoside, luteolin, apigenin and diosmetin). Luteolin 7,4'-O-diglucoside and luteolin 4'-O-glucoside were identified by HPLC/DAD/MS/MS - ESI. The studied olive leaf samples showed a common phenolic pattern, in which luteolin 4'-O-glucoside was almost always the major compound.     

Specific Deuteration in Patuletin and Related Flavonoids via Keto–Enol Tautomerism: Solvent‐ and Temperature‐Dependent 1H‐NMR Studies

An H/D exchange process in patuletin ( 1 ) and its derivatives in D‐donor solvents (e.g., CF₃COOD), which occurs regioselectively at C(8) was observed for the first time during NMR studies. The effect of substituents and temperature on the deuteration of various flavonoids (see Fig. 1) which include apigenin, chrysin, galangin, kaempferol, luteolin, morin, myricetin, patuletin, patulitrin, and quercetin, as well as derivatives of patuletin was examined extensively under NMR conditions. The rate constant of deuteration at C(8) of patuletin ( 1 ) and two flavones, luteolin ( 3 ) and apigenin ( 12 ), was also determined in CF₃COOD. The D‐atom was introduced into the flavonoids via a keto–enol tautomerism (Scheme 1). During these studies, monodeuterated patuletin was also obtained as a new compound. The examined flavonoids have been reported to possess significant pharmacological activities, and their deuterated derivatives would be of importance for the identification and quantification of these compounds in biological matrices.     

24-Epimarkhacanasin C,An Epimeric Cycloartane-Type Triterpenoid from the Leaves of Markhamia stipulata var. canaense

Chemistry of Natural Compounds - One new cycloartane-type triterpenoid, named 24-epimarkhacanasin C (1), together with four known flavonoids, apigenin (2), luteolin (3), apigenin...     

Approach to the study of C-glycosyl flavones acylated with aliphatic and aromatic acids from Spergularia rubra by high-performance liquid chromatography-photodiode array detection/electrospray ionization multi-stage mass spectrometry

The use of mass spectrometry (MS) coupled to liquid chromatography (LC) as working tool for the study of the C-glycosyl flavones acylated with aliphatic and aromatic acids has allowed the tentative characterization of these compounds in Spergularia rubra and the establishment of the position of the acylation on the sugar moiety of the C-glycosylation by use of MS data. The combination of retention time (Rt), ultraviolet (UV) and MS(n) data of the compounds revealed their C-glycosyl flavone nature, being luteolin, apigenin and chrysoeriol derivatives. Ten non-acylated flavones were identified, from which six are described for the first time (one 7-O-glycosyl-6,8-diC-glycosyl flavone, four 6,8-diC-glycosyl flavones and one 2"-O-glycosyl-6-C-glycosyl flavone). Twenty-six acylated derivatives were also found for the first time. These compounds are grouped in three classes, namely, C-glycosyl flavones acylated with aliphatic acids, with aromatic acids or with a mixed acylation. The first group is characterized by the presence of one 6,8-diC-(acetyl)glycosyl flavone, four 6,8-diC-(malonyl)glycosyl flavones and two 7-O-glycosyl-6,8-diC-(malonyl)glycosyl flavones, while in the second one twelve 6,8-diC-(acyl)glycosyl flavones and two 7-O-glycosyl-6,8-diC-(acyl)glycosyl flavones are described. The last class contained five 6,8-diC-(malonyl,acyl)glycosyl flavones. No previous work has described the presence of C-glycosyl flavones acylated with aliphatic acids in this genus.     

Constituents of the Whole Herb of Clinoponium laxiflorum

The isolation and identification of twenty‐two components (including one new compound) from the whole herb of Clinoponium laxiflorum (Hay) Matsum (Labiatae) are described. Their structures were determined on the basis of spectral and chemical transformation. One new compound is methyl rosmarinate. The other twenty‐one compounds include three steroids (α‐spinasterol, α‐spinasteryl‐3‐O‐β‐D‐glucopyranoside, and β‐sitosteryl‐3‐O‐β‐glucopyranoside), three triterpenes (oleanolic acid, ursolic acid, and betulinic acid), nine flavonoids (didymin, apigenin‐7‐O‐β‐glucopyranoside, luteolin‐7‐O‐β‐glucopyranoside, isosakuranetin, narigenin, apigenin, luteolin, narirutin, and hesperidin), three lignolic acids (rosmarinic acid, 3‐(3,4‐dihydroxyphenyl)lactic acid, and caffeic acid), and three phenols (4‐hydroxybenzaldehyde, 3,4‐dihydroxybenzaldehyde, and 3,4‐dihydroxybenzoic acid).     

Chemical constituents of two sages with free radical scavenging activity

From the aerial parts of Salvia trichoclada Bentham and S. verticillata L. one new and two known phenolic acids, 3-(3',4'-dihydroxyphenyl)-2-hydroxymethyl propionic acid (1), 3-(3',4'-dihydroxyphenyl) lactic acid (2), and rosmarinic acid (3); two flavonoids, apigenin 4'-methyl ether 7-O-glucuronide (4), and luteolin 7-O-beta glucuronide (5); two lupan type triterpene aglycones, lupeol (6), and 30-hydroxylup-20 (29)-en-3-on (7); an oleanane-type triterpene acid, oleanolic acid (8); and an ursan-type triterpene acid, ursolic acid (9) were isolated. The structures of the compounds were elucidated by spectroscopic analysis. Different extracts of the plants were examined for their free radical scavenging activities by DPPH (2,2-Diphenyl-1-picrylhydrazyl) assay. Some of the polar extracts showed high free radical scavenging activity.     

Chemical Components of Seriphidium Santolium Poljak

A new biflavonoid glucoside, apigenin‐7‐O‐β‐D‐glucopyranoside‐(3′‐O‐7″)‐quercetin‐3″‐methyl ether ( 1 ) together with twenty known compounds, apigenin ( 2 ), luteolin ( 3 ), chrysoeriol ( 4 ), tricin ( 5 ), hispidulin ( 6 ), pectolinarigenin ( 7 ), eupatilin ( 8 ), 5,7‐dihydroxy‐6,3′,4′,5′‐tetramethoxyflavone ( 9 ), 5,7,4′‐trihydroxy‐6,3′,5′‐trimethoxyflavone ( 10 ), 3,6‐O‐dimethylquercetagetin‐7‐O‐β‐D‐glucoside ( 11 ), 6‐hydroxy‐5,7‐dimethoxy‐coumarin ( 12 ), taraxerol ( 13 ), taraxeryl acetate ( 14 ), a mixture of β‐sitosterol ( 15 ) and stigmasterol ( 16 ), a mixture of the n‐alkyl trans‐p‐coumarates ( 17 ), a mixture of the n‐alkyl trans‐ferulates ( 18 ), 2‐hydroxy‐4,6‐dimethoxyacetophenone ( 19 ), 4‐hydroxy‐2,6‐dimethoxyphenol‐1‐O‐β‐D‐glucopyranoside ( 20 ), and 2‐hydroxycinnamoyl‐β‐D‐glucopyranoside ( 21 ), were isolated from the whole plant of Seriphidium santolium Poljak. The structures of these compounds were determined by means of spectral and chemical studies.     

UHPLC-UV/PDA Method Validation for Simultaneous Quantification of Luteolin and Apigenin Derivatives from Elaeis guineensis Leaf Extracts: An Application for Antioxidant Herbal Preparation

Luteolin and apigenin derivatives present in oil palm (Elaeis guineensis) leaves (OPL) are reported to possess excellent antioxidant properties relating to numerous health benefits. To meet the global demand for flavonoids, OPL, which is plentifully generated as an agricultural by-product from oil palm plantations, can be further exploited as a new source of natural antioxidant compounds. However, to produce a standardized herbal preparation, validation of the quantification method for these compounds is required. Therefore, in this investigation, we developed and validated an improved and rapid analytical method, ultra-high-performance liquid chromatography equipped with ultraviolet/photodiode array (UHPLC-UV/PDA) for the quantification of 12 luteolin and apigenin derivatives, particularly focusing on flavonoid isomeric pairs: orientin/isoorientin and vitexin/isovitexin, present in various OPL extracts. Several validation parameters were assessed, resulting in the UHPLC-UV/PDA technique offering good specificity, linearity, accuracy, precision, and robustness, where the values were within acceptable limits. Subsequently, the validated method was employed to quantify luteolin and apigenin derivatives from OPL subjected to different drying treatments and extraction with various solvent systems, giving total luteolin (TLC) and apigenin content (TAC) in the range of 2.04–56.30 and 1.84–160.38 µg/mg extract, respectively. Additionally, partial least square (PLS) analysis disclosed the combination of freeze dry-aqueous methanol yielded OPL extracts with high TLC and TAC, which are strongly correlated with antioxidant activity. Therefore, we provide the first validation report of the UHPLC-UV/PDA method for quantification of luteolin and apigenin derivatives present in various OPL extracts, suggesting that this approach could be employed in standardized herbal preparations by adopting orientin, isoorientin, vitexin, and isovitexin as chemical markers.     

Diisophorone and related compounds. Part 19 Synthesis and reactions of 6,8-dibromodiisophorones

Novel 6,8-dibromo-derivatives of diisophor-2(7)-en-1-ol-3-one and the corresponding 1-carboxylic acid methyl ester are readily accessible by the action of 2 mol of N-bromosuccinimide on the respective parent compounds. Treatment with alkali converts the 6,8-dibromo-ketol, by a simultaneous 8-substitution and ring A-aromatisation, into 6-methyl-5-nordiisophora-2(7),3,5-triene-1,3,8-triol; acetolysis and methanolysis produce the corresponding 8-acetoxy- and 8-methoxy-compounds. The 6,8-dibromo-1-carboxylic acid reacts analogously, with the added option of 1,3-lactone formation. The assigned¹³C-nmr spectra and fragmentation patterns of the new compounds are in accord with their proposed formulation.

---

Diisophoron und verwandte Verbindungen, 19. Mitt.: Synthese und Reaktionen von 6,8-Dibromdiisophoronen

Zusammenfassung Neuartige 6,8-Dibrom-Abkömmlinge des Diisophor-2(7)-en-1-ol-3-ons und der entsprechenden 1-Carbonsäure (als Methylester) sind durch Einwirkung von 2 mol N-Bromsuccinimid auf die betreffende Grundverbindung leicht zugänglich. Bei der Umsetzung des 6,8-Dibromketols mit Alkalien entsteht 6-Methyl-5-nordiisophora-2(7),3,5-trien-1,3,8-triol, unter gleichzeitiger 8-Substituierung und Ring-A-Aromatisierung. Acetolyse und Methanolyse ergeben die entsprechenden 8-Acetoxy- und 8-Methoxy-Verbindungen. Die 6,8-Dibrom-1-carbonsäure reagiert analog, mit weiterer Möglichkeit zur 1,3-Lacton-Bildung. Die¹³C-Kernresonanz-und Massenspektren der neuen Verbindungen stehen mit den Strukturzuordnungen im Einklang.

     

Structure elucidation of two new unusual monoterpene glycosides from Euphorbia decipiens, by 1D and 2D NMR experiments

Two new unusual monoterpene glycosides, (Z)-3,6-dimethyl-3-(β-D-O-glucosylmethylene)cyclohept-4-ene-1-one (1) and 3,6-dimethyl-3-(β-D-O-glucosylmethylene)cycloheptanone (2) have been isolated along with five known compounds, 3-hydroxy-4-methoxybenzoic acid, 6,7-dihydroxycoumarin, luteolin, apigenin 5-O-αl-L-rhamnoside, and pinocembrin-7-O-rutinoside from ethyl acetate extract of Euphorbia decipiens. The structures of the isolated compounds were elucidated by extensive 1D- and 2D-NMR, and mass spectroscopic analyses.     

Phenolic compounds and antimicrobial activity of olive (Olea europaea L. Cv. Cobrançosa) leaves

We report the determination of phenolic compounds in olive leaves by reversed-phase HPLC/DAD, and the evaluation of their in vitro activity against several microorganisms that may be causal agents of human intestinal and respiratory tract infections, namely gram positive (Bacillus cereus, B. subtilis and Staphylococcus aureus), gram negative bacteria (Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae) and fungi (Candida albicans and Cryptococcus neoformans). Seven phenolic compounds were identified and quantified: caffeic acid, verbascoside, oleuropein, luteolin 7-O-glucoside, rutin, apigenin 7-O-glucoside and luteolin 4'-O-glucoside. At low concentrations olive leaves extracts showed an unusual combined antibacterial and antifungal action, which suggest their great potential as nutraceuticals, particularly as a source of phenolic compounds.     

RP-HPLC analysis of Jirakadyarishta and chemical changes during fermentation

Jirakadyarishta, an Ayurvedic formulation prepared by the fermentation of a decoction of Cuminum cyminum (seeds) is traditionally used for intestinal disorders. RP-HPLC analysis of the decoction and the final processed formulation revealed that apigenin-7-O-[galacturonide (1 --> 4)-O-glucoside] and luteolin-4'-O-glucoside-7-O-galacturonide) were the two major constituents of the decoction of C. cyminum. Selective hydrolysis of 7-O-glucosides of luteolin and apigenin during fermentation resulted in an increase in the amount of luteolin and apigenin. The 4'-O-glucoside-7-O-galacturonide of luteolin and galacturonide derivative of apigenin were not hydrolyzed during fermentation. Monomeric phenolics, together with 5-hydroxymethyl furfural (5-HMF), were also introduced into the formulation through the jaggery and other plant materials during fermentation. This communication highlights the importance of the ancient processing methods used in Ayurveda.     

Phenolic constituents in Erythrina x bidwilli and their activity against oral microbial organisms.

Five flavonoid compounds, including two new isoflavanones, were isolated from the root bark of Erythrina x bidwilli. Their structures were determined to be 2,10-di(gamma,gamma-dimethylallyl)-3,9-dihydroxypterocarpan (erythrabyssin II), 6,8-di(gamma,gamma-dimethylallyl)-7,2',4'-trihydroxyisoflavanone (bidwillon A), 8-gamma,gamma-dimethylallyl-2',4'-dihydroxy-[6",6"-di-methylpyrano - (2",3":7,6)]isoflavanone (bidwillon B), 8-gamma,gamma-dimethylallyl-7,4'-dihydroxyisoflavone (8-gamma,gamma-dimethyl-allyldaidzein), and 8-gamma,gamma-dimethylallyl-5,2',4'-trihydroxy-[6",6"-dimethylpyrano+ ++- (2",3":7,6)]isoflavone (auriculatin), by means of spectroscopic analysis. Some potent activities against oral microbial organisms (Fusobacterium nucleatum and Prevotella intermedia) were shown in these flavonoid compounds.