New glycosylsphingolipids from Psychotria serpens L.

In clinical, Psychotria serpens L. was often substitute for Caulis trachelospermi to treat cancer in China. Meanwhile, EtOAc and n-BuOH fractions of MeOH extract of P. serpens L. show power activity against H460, HepG2, Hela, and PC9/GR cell lines, and no toxic effects against normal 16HBE cell lines. In our ongoing search for bioactive novel compounds from Chinese material medica, one new type of glycosylsphingolipids Psychotramide (1a-1c) were isolated from P. serpens L., and their structures were identified through spectroscopic techniques including NMR (1D and 2D) and MS (LC-MS, and GC-MS).

[Interaction of phenylethanoid glycosides and calf thymus DNA].

In physiological condition, the interaction of acteoside and forsythoside B with calf thymus DNA using neutral red (NR) as a fluorescence probe were investigated by fluorescence, UV-visible spectrophotometry, viscosity, DNA melting techniques, and molecular docking. It is observed that acteoside and forsythoside B can react with DNA. The major mode of recognition between drug and DNA is groove binding by hydrogen bonds, and the interaction of acteoside with DNA is stronger than that of forsythoside B.

Structure-activity relationships of antioxidant activity in vitro about flavonoids isolated from Pyrethrum tatsienense.

AIM: Antioxidant activity is one of the important indexes for estimating medicinal value for the traditional Chinese medicine. The aim of this study is to investigate the antioxidant activity of 11 flavonoids mainly revealing luteolin as mother nucleus isolated from Pyrethrum tatsienense. MATERIALS AND METHODS: The antioxidant activity of 11 flavonoids was measured in vitro using the classical 1,1-diphenyl-2-picrylhydrazyl removal method. The percentages of scavenging activity of 11 flavonoids were analyzed by taking the choice of a-tocopherol as positive drugs, and the scavenging activity was plotted against the sample concentration to obtain the IC50 values. RESULTS: Ten flavonoids containing phenolic hydroxyl groups have different levels of antioxidant activity. Antioxidant activity mainly depends on the numbers and the substitutional positions of phenolic hydroxyls in B ring. When C-3', 4' positions in B ring of flavonoids are replaced by hydroxyl groups, the antioxidant activity improved remarkably. Phenolic hydroxyl groups in A ring contribute some to antioxidant activity because of the electrophilic effect of C ring, and the numbers and substitutional positions of methoxyl and glycosyl have a little effect on the antioxidant activity. CONCLUSION: Structure-activity relationships of antioxidant activity about flavonoids isolated from P. tatsienense are concluded, which will be beneficial to deep understanding the pharmacological functions of this Tibetan medicine in vivo from the point of antioxidation.

Investigation on the differences of four flavonoids with similar structure binding to human serum albumin.

Flavonoids are structurally diverse and the most ubiquitous groups of polyphenols distributed in the various plants, which possess intensive biological activities. In this study, the interaction mechanisms between four flavonoids containing one glucose unit with similar molecular weight isolated from the Tibetan medicinal herb Pyrethrum tatsienense, namely, apigenin-7-O-ß-D-glucoside(1), luteolin-7-O-ß-D-glucoside(2), quercetin-7-O-ß-D-glucoside(3), quercetin-3-O-ß-D-glycoside(4), and human serum albumin(HSA), were investigated by fluorescence, UV-vis absorbance, circular dichroism, and molecular modeling. The effects of biological metal ions Mg2+, Zn2+, and Cu2+ on the binding affinity between flavonoids and HSA were further examined. Structure-activity relationships of four flavonoids binding to HSA were discussed in depth and some meaningful conclusions have been drawn by the experiment data and theoretical simulation. In addition, an interesting phenomenon was observed that the microenvironment of the binding site I in HSA has hardly changed in the presence of 4 differentiating from the other three flavonoids on the basis of conformation investigations.

Phenylethanoid glycosides from the stems of Callicarpa peii (hemostatic drug).

Two new trisaccharide intermediates of phenylethanoid glycosides, peiioside A(1)/A(2) (1a/1b) and peiioside B (2), were isolated from the n-BuOH fraction of MeOH extract of the stems of Callicarpa peii H.T. Chang, together with five biogenetic relevant known compounds 3-7. The structures of compounds 1 and 2 were elucidated by extensive spectroscopic methods (especially 2D-NMR techniques) and acid-catalyzed hydrolysis as O-α-l-rhamnopyranosyl-(1″→3')-O-[ß-d-apiofuranosyl-(1‴→6')] -4'-O-[(E)-caffeoyl]-d-glucopyranoside] (1a/1b), 3,4-dihydroxy-ß-phenylethoxy-O-[ß-d-apiofuranosyl-(1‴→6')-α-l-rhamnopyranosyl-(1″→3')-O-ß-d-glucopyranoside] (2), respectively. On the basis of the isolated compounds, a presumable biogenetic pathway of the biologically interesting phenylethanoid glycosides about forsythoside B (3) and acteoside (4) isolated from this species was proposed. Isolation of five related intermediates (1-2, 5-7) provided further support for the biogenetic path. This is the first report about phytochemical research on C. peii and the biogenetic hypothesis of forsythoside B and acteoside.