Chemical constituents from the stem bark of Acer tegmentosum

A new phenolic glycoside, 4-hydroxyphenylethyl-1-O-β-D-[6′-O-(4-hydroxybenzoyl)]-glucopyranoside (1) was isolated from the stem bark of Acer tegmentosum, along with seven known phenolic compounds (2–8). The structure of compound 1 was determined by spectral analyses, including HR-ESI-MS, 1D and 2D NMR (COSY, HMQC and HMBC) experiments. Compounds 3 and 4 were found in the family Aceraceae for the first time.     

Chemical constituents of the Piper crocatum leaves and their chemotaxonomic significance

Chemical study of Piper crocatum leaves has led to isolation of a new megastigmane glucoside isomer (18), along with 23 known compounds including fifteen phenolic compounds (1–15), two monoterpenes (16 and 17), three sesquiterpenes (19–21), a phenolic amide glycoside (22), a neolignan (23), and a flavonoid C-glycoside (24). Structures of these compounds were identified via spectroscopic methods and compared with those reported in the literature. Seven compounds (7, 11, 13, 14, 17, 20, and 24) from the P. crocatum species and 17 others (1–6, 8–10, 12, 15–16, 18–19, and 21–23) from the Piper genus and Piperaceae family were isolated and reported for the first time. Furthermore, this study discusses chemotaxonomic relations between P. crocatum and other Piper species.     

The susceptibility of plants to Agrobacterium: A discussion of the role of phenolic compounds

Abstract An extensive literature survey of the host-range of Agrobacterium -induced neoplasms has revealed that highly susceptible plant families are accumulators of polyphenolics, whereas families assumed to be non-sensitive to the pathogen seem to lack this property. These and other results might indicate that polyphenolics play a role in the host-pathogen relationship of Agrobacterium -induced neoplasms. This hypothesis will be discussed in the light of the present knowledge of crown gall/hairy root induction and progress in plants.     

The hidden face of food phenolic composition

Plant polyphenols are extremely diverse, due to the occurrence of several basic structures, numerous substitutions and, for some groups, of polymers (tannins). Plant polyphenol composition depends on the plant species and organ, with some molecules specific of particular plant families while others are ubiquitous. The polyphenol content is classically assessed by global analysis methods, which lack specificity and accuracy. These methods have been replaced with high performance liquid chromatography (HPLC), that enables accurate determination of individual molecules, provided they can be unambiguously identified and calibration curves can be established. However, HPLC analysis is restricted to simple compounds and difficult to apply in the case of complex extracts. Further difficulties encountered in the case of polymers include irreversible adsorption on the stationary phases. Proanthocyanidin analysis by HPLC after acid-catalysed depolymerisation in the presence of a nucleophile permits to overcome these problems and shows that proanthocyanidins predominate in the polyphenol composition of most plants. Large varietal differences in tannin quantitative and qualitative composition were observed for all plant species studied. Moreover, analysis is usually performed after extraction, which may lead to significant underestimation of the polyphenol content, since a large proportion is not extracted by usual solvents. This may be due to covalent binding to other plant constituents and to non-covalent adsorption on plant solids. Such matrix effect also influences the taste perception of polyphenols and their fate in the digestive tract, from in-mouth interactions with salivary proteins to their metabolism by colon microflora, with potential influence on bioavailability.     

A chemosystematic study of the genus Gomphostemma and related genera (Lamiaceae)

Species in the genera Gomphostemma, Chelonopsis and Bostrychanthera were systematically studied with reference to their flavonoid and phenolic acid compounds in order to investigate whether the profiles of these compounds would support a classification of the genus and related genera based on morphological characters. Thirty-five flavonoid glycosides, eight phenolic acids and derivatives were identified by LC-UV-MS/MS analysis of aqueous 80% MeOH extracts on the basis of their UV and mass spectra, retention times and comparison with in-house library. The occurrence of individual compounds was not particularly informative in Gomphostemma, although the overall chemical profile supported G. subgen. Pogosiphon and vicenin-2 was a characteristic component of Gomphostemma leptodon and Gomphostemma curtisii. In contrast, the flavonoids and phenolic acids of Chelonopsis were informative at infrageneric level. Glycosides of 6-substituted flavones were well represented in Ch. subgen. Aequidens, including Ch. forrestii, Ch. rosea, Ch. odontochila, Ch. lichiangensis and C. giraldii. A dicaffeoylquinic acid was produced in Ch. subgen. Chelonopsis, (for example, in Ch. longipes and Ch. Moschata), but absent from Ch. subgen. Aequidens. The same dicaffeoylquinic acid was also found in the genus Bostrychanthera and suggests a close relationship with Ch. subgen. Chelonopsis, in agreement with a recent DNA based phylogeny. There is correlation between trichome type and phenolic acid compound distribution in Chelonopsis, but this is not observed in Gomphostemma.     

Chemical constituents from Artemisia argyi and their chemotaxonomic significance

Twelve compounds, including one monoterpene (1), two sesquiterpene lactones (2–3), six flavonoids (4–9), one phenolic glycoside (10), one chromone (11) and one phenolic acid (12), were isolated and identified from the leaves of Artemisia argyi. Compounds 1–2, 4 and 6–7 have not been recorded before in this plant. Compounds 3, 9 and 11 were isolated from the genus Artemisia for the first time. This paper is the first report on the presence of compound 10 in species of Asteraceae. In addition, the chemotaxonomic significance of these compounds was summarized.     

Chemical constituents from Celastrus aculeatus Merr.

Phytochemical investigation of Celastrus aculeatus Merr. led to the isolation of nine compounds. Their structures were identified to be dulcitol (1), β-sitosterol (2), n-tritriacontane (3), nimbidiol (4), pristimerin (5), p-hydroxybenzoic acid (7), vanillic acid (8), 3, 5-dimethoxy-4-hydroxybenzoic acid (9) and a new compound named pristimerol (6) on the basis of mass and NMR spectra. This is the first report of phenolic acids (compounds 7–9) from C. aculeatus Merr. We present the HR-MS, 1D NMR (¹H, ¹³C NMR, DEPT) and 2D NMR (HMBC) data of the new compound (6).     

Acremonoside,a phenolic glucoside from the sea fan-derived fungus Acremonium polychromum PSU-F125

A new phenolic glucoside, acremonoside (1), along with two known compounds, F-11334 A₂ and 2,2-dimethyl-2H-chromen-6-ol, were isolated from the sea fan-derived fungus Acremonium polychromum PSU-F125. The structure of 1 was elucidated by spectroscopic techniques, acid hydrolysis and X-ray crystallographic analysis. The isolated compounds were tested for antibacterial, antimalarial, antimycobacterial and cytotoxic activities.