Evaluation of cytotoxic activity of Schisandra chinensis lignans.

Using exhaustive chromatographic separation we have isolated (-)-tigloyl-deangeloyl-gomisin F as a novel dibenzocyclooctadiene lignan from schisandra chinensis. With the help of HPLC, we further isolated (+)-schisandrin, (+)-deoxyschisandrin, (+)-γ-schisandrin, (-)-gomisin J, (+)-gomisin A, (-)-gomisin N, (-)-tigloyl-gomisin P, (-)-wuweizisu C, (-)-gomisin D, rubrisandrin A, (-)-gomisin G, (+)-gomisin K (3) and (-)-schisantherin C. A full NMR description of (-)-schisantherin C was carried out with the aim to confirm previous reports of its structure. Compounds isolated were identified on the basis of UV, IR, (1)H- and (13)C-NMR and MS. The cytotoxicity of lignans was tested for the BY-2 cell line alone and as a synergistic effect with the cytotoxic agent camptothecin. Lignans showed various toxicity and synergistic and antagonistic effects on camptothecin-induced cytotoxicity. Cytotoxicity against colon cancer cell line LoVo was also tested.

Evaluation of the antiradical activity of Schisandra chinensis lignans using different experimental models.

The in vitro antiradical activity of Schisandra chinensis lignans was investigated using DPPH, ABTS+, Fenton reaction inhibition and tyrosine-nitration inhibition assays, as were the in vivo antidiabetic activities of selected lignans in an animal model of alloxan-induced diabetes. Different degrees of antiradical activity were found, depending upon the structural parameters of the tested compounds. Unfortunately, the compounds showed no antidiabetic activity in concentration range tested.

Electrochemical and spectrometric study of antioxidant activity of pomiferin, isopomiferin, osajin and catalposide.

The antioxidant properties of pomiferin, isopomiferin, osajin and catalposide are evaluated. The electrochemical behaviour of these compounds at a carbon paste electrode was studied using square wave voltammetry. Oxidative signals, optimized frequencies and appropriate pH acetate buffer conditions were determined. The detection limits (3S/N) for pomiferin, isopomiferin, osajin and catalposide were estimated to be 50 pg/ml, 800 pg/ml, 40 pg/ml and 10 ng/ml, respectively. Furthermore, spectrometric test was employed with 2,2-diphenyl-1-picrylhydrazyle (DPPH) to evaluate the antioxidant activities of these compounds. Based on the obtained results, the highest antioxidant activity measured by DPPH tests was found at pomiferin followed by isopomiferin. The activities of osajin and catalposide were undetectable. The protective effects of pomiferin, isopomiferin, osajin and catalposide on DNA exposed to oxygen radicals in vitro were also studied. Changes in height of oxidative signals for the four bases (guanine, thymine, adenine and cytosine) were measured for DNA exposed to oxygen radicals, generated by Fenton's reaction, non-oxidized ssDNA (50 microg/ml) displayed well developed signals; however, after oxidative damage the observed oxidative signals decreased. Significant protective effects were observed for pomiferin and osajin. Decreased effect was observed for isopomiferin while a further reduced protective effect was seen for DNA exposed to catalposide. Based on the obtained results, pomiferin had the highest antioxidant activity followed by isopomiferin, osajin and catalposide.

Antibacterial C-geranylflavonoids from Paulownia tomentosa Fruits.

Eight C-6-geranylflavonoids ( 1- 8) were isolated from an ethanol extract of Paulownia tomentosa fruits. Tomentodiplacone ( 1), 3'- O-methyl-5'-hydroxydiplacone ( 2), 3'- O-methyl-5'- O-methyldiplacone ( 3), and tomentodiplacone B ( 4) were obtained as new compounds, and 3'- O-methyldiplacol ( 5) was isolated for the first time from a natural source. The structures of these new compounds were determined by using mass spectrometry (including HRMS) and 1D and 2D NMR spectroscopy, and the absolute configurations of the compounds were determined by circular dichroism. The antibacterial activities of 1- 8 against seven bacteria and yeast were evaluated.

Antiradical activity of Paulownia tomentosa (Scrophulariaceae) extracts.

Paulownia tomentosa is a large indecidous tree planted mostly for its fast growing wood and decorative purposes. The tree is also used in traditional Chinese medicine. As a part of our study of natural polyphenols, the fruits of Paulownia tomentosa were extracted by EtOH and than subjected to liquid/liquid extraction. Fractions were analysed by TLC and HPLC to determine presence of phenolic substances. We identified and quantified acteoside (1) and isoacteoside (2) in the EtOAc and n-BuOH extracts; mimulone (3) and diplacone (4) in the MeOH extract. To determine the antiradical activity of extracts we used the anti DPPH and peroxynitrite assays. The activity was expressed as Trolox C equivalents, IC50 for DPPH scavenging and a time dependency course was established. The polyphenols content was determined; results were expressed as gallic acid equivalents. Using these methods we found the fractions of the n-BuOH, EtOAc and MeOH extracts that display antiradical activity, which could be exploited as potential pharmaceuticals.

Antioxidant activity of Catalpa bignonioides.

Antioxidant activity of methanolic extracts from inflorescence rachises, corollas, calyxes, leaves, valves of capsules and hypertrophied placenta of Catalpa bignonioides by 1,1-diphenyl-2-picrylhydrazyl reduction (DPPH) and tyrosine nitration inhibition induced by peroxynitrite was tested.