Unusual sesquiterpene glucosides from Amaranthus retroflexus

Implementing the phytochemical study of the weed Amaranthus retroflexus, four new sesquiterpene glucosides were isolated from the methanolic extract of the plant. The structures of these metabolites are determined on the basis of the mass spectrometry, and 1D and 2D NMR spectroscopies (DQ-COSY, TOCSY, HSQC, HSQC-TOCSY, HMBC, and NOESY). Two compounds are characterized by a new aglycone and differed from the site of glucosylation. The other two compounds are dimeric diastereoisomers.All the glucoside sesquiterpenes were tested on the wild species Taraxacum officinale to evaluate the role of this weed in the habitat and on the seed of A. retroflexus to verify the potential autotoxic effect of the plant.     

Secologanin,a Biogenetic Key Compound—Synthesis and Biogenesis of the Iridoid and Secoiridoid Glycosides

The monoterpene glycoside secologanin is a key intermediate in the biosynthesis of most indole, cinchona, ipecacuanha, and pyrroloquinoline alkaloids, as well as of simple monoterpene alkaloids. More than a thousand alkaloids are formed from secologanin in vivo; this represents almost a quarter of this large group of natural products. It is also the parent compound of the secoiridoids. Many of the compounds derived from secologanin display a high degree of biological activity and are employed as pharmaceuticals, e.g., the dimeric indole alkaloid leurocristine (vincristine) which is used very successfully in the treatment of acute leukemia. A knowledge of the biosynthesis and biological reactions of secologanin provides a sound basis for the biosynthesis-orientated classification of numerous natural products and the taxonomy of many plants. Secologanin and structurally related substances can be synthesized in a few steps by stereocontrolled photochemical and thermal cycloadditions. Its biomimetic reaction with amines and amino acids yields other natural products and compounds of pharmacological interest.     

反相高效液相色谱法制备纯化大豆异黄酮糖苷

利用制备高效液相色谱法从大豆总异黄酮提取物中制备出了3种大豆异黄酮糖苷。在Nova-Pak HR C18色谱柱(100 mm×25 mm i.d.,6 μm)上,以甲醇-体积分数为0.1%的乙酸水溶液(体积比为23∶77)为流动相,流速为20 mL/min,采用 等度洗脱方式,制备了3种大豆异黄酮糖苷,经质谱分析,确认它们分别为大豆苷、黄豆苷和染料木苷。高效液相色谱分析 表明,所制备的3种化合物的纯度均达到了99%以上。     

Sterol surfactants: from synthesis to applications

An overview is given of sterol surfactants, including raw material aspects, classification and synthesis routes, physico-chemical behaviour and applications in pharmaceuticals and cosmetics.     

Dye sensitized luminescent europium nanoparticles and its time-resolved fluorometric assay for DNA

High performance liquid chromatography (HPLC) method has been developed for simultaneous quantification of limonoid aglycones and glucosides on a reversed phase C₁₈ column using a binary solvent system, coupled with diode array detector. Seven limonoids such as limonin, nomilin, isolimonic acid, ichangin, isoobacunoic acid, limonin 17-β-d glucopyranoside and deacetyl nomilinic acid 17-β-d glucopyranoside were separated and detected at 210 nm. Furthermore, limonoids were separated, identified and quantified in four varieties of citrus fruits and seeds using developed method. Limonin and limonin glucoside were found to be the predominant limonoid aglycone and glucoside, respectively, in all tested samples. The sensitivity of the method was found to be 0.25–0.50 μg for tested limonoids.     

Flavone 8‐C‐Glycosides from Haberlea rhodopensis Friv. (Gesneriaceae)

Phytochemical profiling of a MeOH extract from Haberlea rhodopensis by a combination of liquid/liquid extraction, and preparative and semi‐preparative HPLC afforded three new flavone C‐glycosides, hispidulin‐8‐C‐(2″‐O‐syringoyl)‐β‐glucopyranoside ( 3 ), hispidulin 8‐C‐(6‐O‐acetyl‐β‐glucopyranoside) ( 4 ), and hispidulin 8‐C‐(6‐O‐acetyl‐2‐O‐syringoyl‐β‐glucopyranoside) ( 5 ), along with two known phenolic glycosides, myconoside ( 1 ) and paucifloside ( 2 ). The structures were established by extensive spectroscopic analyses including 1D‐ and 2D‐NMR (COSY, HSQC, and HMBC), and HR‐ESI‐TOF‐MS, and by comparison with published data.     

Chromenone Glucosides Acylated with Monoterpene Acids from the Leaves of Eucalyptus camaldulensis var. obtusa

Three new chromenone glucosides acylated with monoterpene acids, eucamaldusides A ( 1 ), B ( 2 ), and C ( 3 ), were isolated from the leaves of Eucalyptus camaldulensis var. obtusa, together with the five known compounds ursolic acid lactone, obtusilin, β‐sitosterol glucoside, 4‐hydroxybenzoic acid, and cypellocarpin C. The structures of the new compounds were established by exhaustive 1D‐ and 2D‐NMR spectroscopic studies. Their configuration was determined by measuring the [α]_D of the known methyl esters of the monoterpene acids obtained by methanolysis of 1 – 3 .     

New Secoiridoid Glucosides from Swertia japonica

Four new secoiridoid glucosides, swertiajaposides C–F ( 1 – 4 , resp.), were isolated from the whole plant of Swertia japonica Makino together with two known compounds, 8‐hydroxy‐10‐hydrosweroside ( 5 ) and senburiside IV ( 6 ). The structures of 1 – 4 were elucidated on the basis of spectroscopic, chemical, and physicochemical evidence.     

Characterization of multiple absorbed constituents in rats after oral administration of Paederia scandens decoction

Paederia scandens (Lour.) Merri. (Jishiteng in Chinese) is a Chinese traditional medicine widely used in treating various diseases. However, its active components have remained unknown. In the present study, a rapid and sensitive method by high-performance liquid chromatography coupled with electrospray ionization mass spectrometry (HPLC-MSn) techniques was employed to investigate the absorbed constituents in rats after oral administration of Paederia scandens decoction. By comparing their MS data with those of authentic compounds and published data, a total of six compounds (paederosid, 1; paederosidic acid, 2; paederosidic acid methyl ester, 3; 6-hydroxy geniposide, 4; asperuloside, 5; and deacetyl asperuloside, 6) were identified in the P. scandens decoction samples. In addition, a total of seven compounds, including three iridoid glucosides and four of their metabolites, were identified in rat urine samples after administration. In addition, six compounds, including four iridoid glucosides and two of their metabolites, were identified in rat serum samples after administration. Our results significantly narrow the range of potentially active compounds in P. scandens decoction, and build a solid foundation for future research on its mechanism.     

3‐O‐Methylquercetin Glucosides from Ophioglossum pedunculosum and Inhibition of Lipopolysaccharide‐Induced Nitric Oxide Production in RAW 264.7 Macrophages

The three new 3‐O‐methylquercetin glucosides 1 – 3 , together with three known congeners and 3‐O‐methylquercetin, were isolated from the fern Ophioglossum pedunculosum (quercetin=2‐(3,4‐dihydroxyphenyl)‐3,5,7‐trihydroxy‐4H‐1‐benzopyran‐4‐one). The new compounds were identified on the basis of spectroscopic analysis as 5′‐isoprenyl‐3‐O‐methylquercetin 4′,7‐di‐β‐D ‐glucopyranoside ( 1 ), 3‐O‐methylquercetin 4′‐β‐D ‐glucopyranoside 7‐[O‐β‐D ‐glucopyranosyl‐(1→2)‐β‐D ‐glucopyranoside] ( 2 ), and 3‐O‐methylquercetin 7‐[O‐β‐D ‐glucopyranosyl‐(1→2)‐β‐D ‐glucopyranoside] ( 3 ). The effect of the isolated compounds on lipopolysaccharide (LPS)‐induced NO production was evaluated. The inhibitory activity of 3‐O‐methylquercetin derivatives decreased markedly with the increasing number of glucosyl groups in the structures.