6-O-α-Sinuatosylaucubin from Verbascum sinuatum

From Verbascum sinuatum, besides aucubin, harpagide, 6-O-β-d-xylopyranosylaucubin and sinuatol (6-O- α-l-rhamnopyranosylaucubin), a new iridoid glycoside, sinuatoside, has been isolated and its structure elucidated as 6-O-(3-O-β-d-xylopyranosyl)α-d-galactopyranosyl aucubin on the basis of spectral data and chemical modifications. For the new disaccharide unit of the latter compound the name sinuatose is proposed.     

10-Deoxymelittoside,an iridoid diglucoside,and other iridoids from lamiastrum galeobdolon

From the aerial parts of Lamiastrum galeobdolon subsp. flavidum two known iridoid glucosides, harpagide and 8-O-acetylharpagide, were isolated, together with a new iridoid diglucoside, 10-deoxymelittoside.     

6-O-β-d-Xylopyranosylaucubin from Verbascum sinuatum

Verbascum sinuatum contains, in addition to aucubin and harpagide, four new highly polar iridoid glycosides one of which has been identified as 6-O-β-d-xylopyranosylaucubin on the basis of spectral data and chemical modifications.     

Leaf flavonoid glycosides as chemosystematic characters in Ocimum

Thirty-one accessions of nine species belonging to three subgenera of Ocimum (basil, family Lamiaceae) were surveyed for flavonoid glycosides. Substantial infraspecific differences in flavonoid profiles of the leaves were found only in O. americanum, where var. pilosum accumulated the flavone C-glycoside, vicenin-2, which only occurred in trace amounts in var. americanum and was not detected in cv. Sacred. The major flavonoids in var. americanum and cv. Sacred, and also in all other species investigated for subgenus Ocimum, were flavonol 3-O-glucosides and 3-O-rutinosides. Many species in subgenus Ocimum also produced the more unusual compound, quercetin 3-O-(6″-O-malonyl)glucoside, and small amounts of flavone O-glycosides. The level of flavonol glycosides produced was reduced significantly in glasshouse-grown plants, but levels of flavone glycosides were unaffected. A single species investigated from subgenus Nautochilus, O. lamiifolium, had a different flavonoid glycoside profile, although the major compound was also a flavonol O-glycoside. This was identified as quercetin 3-O-xylosyl(1‴→2″)galactoside, using NMR spectroscopy. The species investigated from subgenus Gymnocimum, O. tenuiflorum (=O. sanctum), was characterised by the accumulation of flavone O-glycosides. These were isolated, and identified as the 7-O-glucuronides of luteolin and apigenin. Luteolin 5-O-glucoside was found in all nine species of Ocimum studied, and is considered to be a key character for the genus.     

Anthocyanins and flavonols from the blue flowers of six Meconopsis species in Bhutan

Blue flowers of six Bhutani Meconopsis species, M. bhutanica, M. bella, M. horridula, M. simplicifolia, M. primulina and M. polygonoides, were surveyed for anthocyanins and other flavonoids. Four anthocyanins were isolated and identified as cyanidin 3-O-sambubioside-7-O-glucoside (1), cyanidin 3-O-[xylosyl-(1 → 2)-(6″-malonylglucoside)]-7-O-glucoside (2), cyanidin 3-O-sambubioside (4) and cyanidin 3-O-[xylosyl-(1 → 2)-(6″-malonylglucoside)] (5). On the other hand, 12 flavonols were isolated from their Meconopsis species with various combination and characterized as kaempferol 3-O-glycosides (8–12), kaempferol 3,7-O-glycosides (13–16), quercetin 3-O-glycosides (17 and 18) and isorhamnetin 3-O-glycoside (19). Of six Meconopsis species which were surveyed in this experiment, anthocyanin and flavonol composition of five species except for M. horridula was clarified for the first time. Their Meconopsis species showed the different flavonoid profiles, respectively, and flavonoid diversity within the glycosylation level of Meconopsis flowers were indicated.     

Flavonoids and xanthones from the leaves of Amorphophallus titanum (Araceae)

The flavonoids and xanthones in the leaves of Amorphophallus titanum, which has the largest inflorescence among all Araceous species, were surveyed. Eight C-glycosylflavones, five flavonols, one flavone O-glycoside and two xanthones were isolated and characterized as vitexin, isovitexin, orientin, isoorientin, schaftoside, isoschaftoside, vicenin-2 and lucenin-2 (C-glycosylflavones), kaempferol 3-O-robinobioside, 3-O-rutinoside and 3-O-rhamnosylarabinoside, and quercetin 3-O-robinobioside and 3-O-rutinoside (flavonols), luteolin 7-O-glucoside (flavone), and mangiferin and isomangiferin (xanthones). Although the inflorescence of this species has been surveyed for flavonoids, those of the leaves were reported for the first time.     

7-O-methyl-(2R:3R)-dihydroquercetin 5-O-β-D-glucoside and other flavonoids from Podocarpus nivalis

In the course of a chemotaxonomic survey of New Zealand Podocarpus species, a number of new flavonoid glycosides have been isolated from P. nivalis. These are: luteolin 3′-O-β-D-xyloside, luteolin 7-O-β-D-glucoside-3′-O-β-D-xyloside, dihydroquercetin 7-O-β-D-glucoside, 7-O-methyl-(2R:3R)-dihydrokaempferol 5-O-β-D-glucopyranoside, 7-O-methyl-(2R:3R)-dihydroquercetin 5-O-β-D-glucopyranoside, 7-O-methylkaempferol 5-O-β-D-glucopyranoside and 7-O-methylquercetin 5-O-β-D-glucopyranoside. Diagnostically useful physical techniques for distinguishing substitution patterns in dihydroflavonols are discussed and summarized. Glucosylation of the 5-hydroxyl group in (+)-dihydroflavonols is shown to reverse the sign of rotation at 589 nm.     

Flower pigment composition of Crocus species and cultivars used for a chemotaxonomic investigation

A survey of floral anthocyanins and other flavonoids by analytical high-performance liquid chromatography (HPLC) was performed among 70 species and subspecies, 43 cultivars and six artificial hybrids of Crocus and the results were compared with taxonomical delimitations established by Mathew (The Crocus. B.T. Batsford Ltd, London, 1982).Nine anthocyanins were detected. The Crocus species and cultivars were placed into seven chemotypes according to their contents of 3,7-di-O-, 3,5-di-O-glucosides or 3-O-rutinosides of delphinidin and petunidin and to the presence of 3,7-di-O-malonyl-glucosides of petunidin and malvidin and delphinidin 3-O-glucoside-5-O-malonylglucoside. These malonated anthocyanins have only been found in Crocus and may be characteristic for this genus.The same 18 flavonoids were detected in every taxon. However, quantitative differences were noted and four chemotypes of Crocus were defined by their major contents of flavonoids. Six of the flavonoids appear to be unique for Crocus.The anthocyanin/flavonoid patterns of some of the taxa provide a valuable supplement to the taxonomy based on morphological and cytological patterns. Most chemotypes were represented in several series but the chemical data were useful in distinguishing different species. For all series except Series h the chemical data were very similar for all subspecies or accessions within a species, and chemotypes within a series were more similar than between series. However for six species, the analyses suggest that they should be further investigated using other methods, to evaluate their relations to other series.     

The flavonoids of tetragonotheca (compositae)

Fifteen flavonols, five aglycones and ten glucosides were isolated from the four species of Tetragonotheca, T. repanda, T. helianthoides, T. texana and T. ludoviciana. Included among the isolated flavonols are four previously unreported 7-O-glucosides, 6-hydroxykaempferol 7-O-glucoside, 6-hydroxykaempferol 6-methyl ether 7-O-glucoside, quercetagetin 6,3′-dimethyl ether 7-O-glucoside and quercetagetin 3,6-dimethyl ether 7-O-glucoside.     

Anthocyanins in Caprifoliaceae

The qualitative and relative quantitative anthocyanin content of 19 species belonging to the genera Sambucus, Lonicera and Viburnum in the family Caprifoliaceae has been determined. Altogether 12 anthocyanins were identified; the 3-O-glucoside (2), 3-O-galactoside (5), 3-O-(6″-O-arabinosylglucoside) (7), 3-O-(6″-O-rhamnosylglucoside) (9), 3-O-(2″-O-xylosyl-6″-O-rhamnosylglucoside) (10), 3-O-(2″-O-xylosylgalactoside) (11), 3-O-(2″-O-xylosylglucoside) (12), 3-O-(2″-O-xylosylglucoside)-5-O-glucoside (14), 3-O-(2″-O-xylosyl-6″-O-Z-p-coumaroylglucoside)-5-O-glucoside (15) and 3-O-(2″-O-xylosyl-6″-O-E-p-coumaroylglucoside)-5-O-glucoside (16) of cyanidin, in addition to the 3-O-glucosides of pelargonidin and delphinidin (1 and 3). Pigment 7 is the first complete identification of the disaccharide vicianose, 6″-O-α-arabinopyranosyl-β-glucopyranose, linked to an anthocyanidin.     

Flavonoid profiles in the Heliohebe group of New Zealand Veronica (Plantaginaceae)

The Heliohebe group of Veronica (sect. Hebe) consists of five species occurring in the South Island of New Zealand. These species and a hybrid were analysed for their flavonoids. Five flavone glycosides were isolated and identified by NMR spectroscopy and three additional glycosides were detected by LC–UV–MS. Luteolin 7-O-, 3′-O- and 4′-O-glucosides and apigenin 7-O-glucoside were present in all six taxa investigated, 6-hydroxyluteolin glycosides were found in five and a luteolin caffeoylglycoside in four taxa, while a hypolaetin 7-O-glycoside was detected only in Veronica pentasepala. The 3′-O- and 4′-O-glucosides of luteolin are also common in other species of Veronica sect. Hebe (restricted to the Southern Hemisphere), but are rare in Northern Hemisphere species of Veronica and thus act as good chemotaxonomic markers for the section. The relatively simple flavonoid profiles found in the Heliohebe group are plesiomorphic and consistent with the group's status as sister to the Hebe clade. Based on the detected flavonoids, two groups could be distinguished within the Heliohebe clade: (1) Veronica hulkeana, Veronica lavaudiana and Veronica raoulii, characterised by luteolin caffeoylglycoside, and (2) V. pentasepala and Veronica scrupea, where this compound is replaced by a 6-hydroxyluteolin dihexoside.     

Polyphenols isolated from antiradical extracts of Mallotus metcalfianus

Six flavonoids including two new flavones, luteolin 7-O-(4″-O-(E)-coumaroyl)-β-glucopyranoside), chrysoeriol-7-O-(4″-O-(E)-coumaroyl)-β-glucopyranoside) and a mixture of two pairs of diastereoisomeric flavonolignans, (±)-hydnocarpin 7-O-(4″-O-(E)-coumaroyl)-β-glucopyranoside)/(±)-hydnocarpin-D 7-O-(4″-O-(E)-coumaroyl)-β-glucopyranoside) with a 2:1 ratio were isolated from the whole plant of Mallotus metcalfianus Croizat, in addition to 10 known compounds. Their structures were evaluated on the basis of different spectroscopic methods, including extensive 1D and 2D NMR spectroscopy. Some extracts have moderate antimicrobial properties and interesting antiradical (DPPH) activity, as well as some compounds isolated from this species. Tannins were also identified in some active extracts.     

Flavonoids in the leaves of Hillebrandia and Begonia species (Begoniaceae)

The fresh leaves of Hillebrandia sandwicensis and 126 Begonia taxa were chemotaxonomically surveyed for flavonoids. Of their taxa, H. sandwicensis and 119 species, one variety and three hybrids were analyzed for flavonoids for the first time. Ten flavonols and eleven C-glycosylflavones were isolated and characterized as quercetin 3-O-rutinoside (1), kaempferol 3-O-rutinoside (2), isorhamnetin 3-O-rutinoside (3), quercetin 3-O-glucoside (4), quercetin 3-methyl ether 7-O-rhamnosylglucoside (5), quercetin 3,3'-dimethyl ether 7-O-rhamnosylglucoside (6), quercetin glycoside (13), quercetin glycoside (acylated) (14), kaempferol glycoside (17) and quercetin 3-O-rhamnoside (18) as flavonols, and isovitexin (7), vitexin (8), isoorientin (9), orientin (10), luteolin 6-C-pentoside (11), luteolin 8-C-pentoside (12), schaftoside (15), isoschaftoside (16), chrysoeriol 6,8-di-C-pentoside (19), apigenin 6,8-di-C-arabinoside (20) and isovitexin 2''-O-glucoside (21) as C-glycosylflavones. Quercetin 3-O-rutinoside (1) alone was isolated from H. sandwicensis endemic to Hawaii. Major flavonoids of almost Begonia species was also 1. Begonia species were divided into two chemotypes, i.e. flavonol containing type and C-glycosylflavone containing type. Of 14 section of the Begonia, almost species of many section, i.e. sect. Augustia, Coelocentrum, Doratometra, Leprosae, Loasibegonia, Monopteron and Ruizoperonia, were flavonol types. On the other hand, C-glycosyflavone type was comparatively most in sect. Platycentrum.     

Chemotaxonomic consideration of flavonoids from the leaves of Chrysanthemum arcticum subsp. arcticum and yezoense,and related species

We examined the foliar flavonoids of Chrysanthemum arcticum subsp. arcticum and yezoense, and related Chrysanthemum species. Five flavonoid glycosides (luteolin 7-O-glucoside and 7-O-glucuronides of luteolin, apigenin, eriodictyol and naringenin) were isolated from these taxa. Luteolin 7-O-xylosylglucoside, luteolin, apigenin and quercetin 3-methyl ether were found in subsp. yezoense as very minor compounds that were not recognised by high-performance liquid chromatography/photodiode array (HPLC/PDA). The related species C. yezoense contained acacetin 7-O-rutinoside and some methoxylated flavone aglycones as major compounds. Thus, C. arcticum was distinguished from C. yezoense according to their flavonoid profiles.     

Species Specific Flavone Glucuronides in Elodea Species

The flavonoid patterns of plants of Elodea canadensis, E. ernstae and E. nuttallii apigenin were investigated. The main flavonoids of E. canadensis are apeginin, luteolin and chrysoeriol 7-O-diglucuronides, of E. nuttalli apigenin and luteolin 7-O- diglucuronides, and of E. ernstae apigenin and luteonin 7-O-monoglucoronides. The qualitative stability of these flavonoid patterns is checked by chromatographic comparison of various populations from a wide area of the three species, it is shown that the flavonoid patterns are valuable criteria for the separation of these species.     

Flavonoids of Helichrysum chasmolycicum and its antioxidant and antimicrobial activities

From the aerial parts of Helichrysum chasmolycicum P.H Davis, which is an endemic species in Turkey, the flavonoids apigenin, luteolin, kaempferol, 3,5-dihydroxy-6,7,8-trimethoxyflavone, 3,5-dihydroxy-6,7,8,4′-tetramethoxyflavone, apigenin 7-O-glucoside, apigenin 4′-O-glucoside, luteolin 4′-O-glucoside, luteolin 4′,7-O-diglucoside, kaempferol 3-O-glucoside, kaempferol 7-O-glucoside and quercetin 3-O-glucoside were isolated. The methanol extract of the aerial parts of H. chasmolycicum showed antioxidant activity by DPPH method (IC₅₀ 0.92 mg/mL). Antimicrobial activity test was performed on the B, D, E extracts and also 3,5-dihydroxy-6,7,8-trimethoxyflavone and kaempferol 3-O-glucoside which were the major flavonoid compounds obtained from aerial parts of H. chasmolycicum by microbroth dilutions technique. The E (ethanol-ethyl acetate) extract showed moderate antimicrobial activity against Pseudomonas aeruginosa, B (petroleum ether-60% ethanol-chloroform) extract and 3,5-dihydroxy-6,7,8-trimethoxyflavone showed moderate antifungal activity against Candida albicans.     

Chemical markers in Veronica sect. Hebe. II

In a continued chemosystematic investigation of the water-soluble compounds in Veronica sect. Hebe, four additional species were investigated. In comparison to other, Northern Hemisphere (NH) species of Veronica, those belonging to the New Zealand species in sect. Hebe are apparently more variable in chemical content. In addition to the compounds characteristic for NH Veronica, namely mannitol, aucubin, catalpol and 6-O-esters of catalpol as well as some caffeoyl phenylethanoid glucosides (CGPs), Veronica topiaria (syn. Hebe topiaria) also gave an unusual 6-O-ester of aucubin named topiarioside. The former Hebe species Veronica cupressoides and Veronica stenophylla each provided one of the two previously undescribed disaccharide esters named hebitol I and II, respectively, and the former plant also provided a CPG named cuproside, a 6-O-β-glucopyranosyl derivative of the known hebeoside. The last species, namely Veronica hulkeana (syn. Heliohebe hulkeana) only contained compounds common to other species of Veronica. The taxonomic results are discussed and it is concluded that carbohydrate esters are common in sect. Hebe. The data so far obtained indicate that the occurrences of esters of 6-O-rhamnopyranosylcatalpol are confined to the most derived species in the section.     

Two new phenolic glucosides and an ellagitannin from the leaves of Castanopsis sclerophylla

In the course of a chemotaxonomical study of Castanopsis species (Fagaceae), detailed investigation of the leaves of C. sclerophylla led to isolation of three new phenolic compounds together with 62 known compounds. The structures of the new compounds were elucidated as 2-O-galloyl-O-4,6-(S)-valoneoyl-d-glucose (1), 6-O-galloyl-1-O-vanilloyl-β-d-glucose (2), and 4″-O-galloylchestanin (3) by means of spectroscopic analyses and enzymatic hydrolysis with tannase. Comparison with other Castanopsis species indicated that C. sclerophylla characteristically accumulates chlorogenic acid and a dimeric ellagitannin, rugosin E. Triterpene hexahydroxydiphenoyl esters, which are major constituents of C. cuspidata var. sieboldii, C. hystrix, and C. fissa were not detected.     

Flavonoids and phenolic acids from the aerial parts of Alyssum alyssoides L. (Brassicaceae)

Two phenolic acids (1 and 2) and seven flavonoids (3–9) were isolated from the aerial parts of Alyssum alyssoides (Brassicaceae). All these compounds (1–9) were isolated from this particular species for the first time. Their structures were identified, on the basis of MS and NMR spectra as: p-hydroxy-benzoic acid (1), 3-methoxy-4-hydroxybenzoic acid (vanillic acid) (2), kaempferol 3-O-β-D-glucopyranoside (astragalin) (3), kaempferol 3-O-(6″-α-L-rhamnopyranosyl)-β-D-glucopyranoside (nicotiflorin) (4), quercetin 3-O-β-D-glucopyranoside (isoquercetin) (5), quercetin 3-O-β-D-galactopyranoside (hyperoside) (6), isorhamnetin 3-O-β-D-glucopyranoside (7), isorhamnetin 3-O-β-D-galactopyranoside (8) and isorhamnetin 3-O-(6″-α-L-rhamnopyranosyl)-β-D-glucopyranoside (narcissin) (9). The chemotaxonomic significance of these compounds was summarized.     

Differences in the floral anthocyanin content of violet–blue flowers of Vinca minor L. and V. major L. (Apocynaceae)

Two novel delphinidin 3-(tri or di)-glycoside-7-glycosides were isolated from the violet–blue flowers of Vinca minor L. and V. major L. (Family: Apocynaceae), and determined to be delphinidin 3-O-[2-O-(β-xylopyranosyl)-6-O-(α-rhamnopyranosyl)-β-galactopyranoside]-7-O-(α-rhamnopyranoside) [= delpphinidin 3-(2^G-xylosylrobinobioside)-7-rhamnoside] as major floral anthocyanin of V. minor and delphinidin 3-O-[6-O-(α-rhamnopyranosyl)-β-galactopyranoside]-7-O-(α-rhamnopyranoside) [= delpphinidin 3-robinobioside-7-rhamnoside] as major floral anthocyanin of V. major by chemical and spectroscopic methods. In addition, chlorogenic acid and kaempferol 3-O-[6-O-(α-rhamnopyranosyl)-β-galactopyranoside]-7-O-(α-rhamnopyranoside) [= kaempferol 3-robinobioside-7-rhamnoside (robinin)] were identified in these flowers. In this paper, the relation between the structure of floral anthocyanins and classification of Vinca species was discussed.