Erdal Bedir

Inhibition of human cytochromes P450 by components of Ginkgo biloba.

The extraction, isolation and characterization of 29 natural products contained in Ginkgo biloba have been described, which we have now tested for their in‐vitro capacity to inhibit the five major human cytochrome P450 (CYP) isoforms in human liver microsomes. Weak or negligible inhibitory activity was found for the terpene trilactones (ginkgolides A, B, C and J, and bilobalide), and the flavonol glycosides. However 50% inhibitory activity (IC50) was found at concentrations less than 10 μg mL−1 for the flavonol aglycones (kaempferol, quercetin, apigenin, myricetin, tamarixetin) with CYP1A2 and CYP3A. Quercetin, the biflavone amentoflavone, sesamin, as well as (Z,Z)‐4,4′‐(1,4‐pentadiene‐1,5‐diyl)diphenol and 3‐nonadec‐8‐enyl‐benzene‐1,2‐diol, were also inhibitors of CYP2C9. The IC50 of amentoflavone for CYP2C9 was 0.019 μg mL−1 (0.035 μm). Thus, the principal components of Ginkgo biloba preparations in clinical use (terpene trilactones and flavonol glycosides) do not significantly inhibit these human CYPs in‐vitro. However, flavonol aglycones, the biflavonol amentoflavone and several other non‐glycosidic constituents are significant in‐vitro inhibitors of CYP. The clinical importance of these potential inhibitors will depend on their amounts in ginkgo preparations sold to the public, and the extent to which their bioavailability allows them to reach the CYP enzymes in‐situ.

The role of chemical fingerprinting: application to Ephedra

Ephedra sinica, known as Ma Huang, is one of the oldest medicinal herbs in Traditional Chinese Medicine (TCM). Preparations, namely teas, of E. sinica have been used for over 5000 years as a stimulant and as an antiasthmatic. In the West, extracts of E. sinica, E. intermedia or E. equisetina are most commonly used in dietary supplements as a stimulant and to promote weight loss. More than 50 species of Ephedra are native to both hemispheres, but the detection of ephedrine alkaloids has been limited to species in Eurasia. Currently, methods exist to quantitate the ephedrine alkaloids in extracts of plant material or dietary supplements, but the methods are not able to verify the extract is of an Ephedra species. Reverse phase high performance liquid chromatography with photodiode array detection was applied for the chemical fingerprinting of the Ephedra species. Two regions of comparison were determined in the chromatograms at 320 nm. The series of peaks between 52 and 64 min confirms an Ephedra species is being analyzed. The aforementioned peaks also could distinguish between Ephedra species from Eurasia, North America and South America. Peaks at ca. 57 and 59 min were isolated and determined to be two new compounds, 4-(2-eicosyloxycarbonyl-vinyl)-benzoic acid and 4-(2-docosyloxycarbonyl-vinyl)-benzoic acid respectively. Authentication of ground plant material as Ephedra can be achieved by this chemical fingerprinting method.

Analysis of saponins and phenolic compounds as inhibitors of α-carbonic anhydrase isoenzymes

A series of phenolic and saponin type natural products such as quercetin, rutin, catechin, epicatechin, silymarin, trojanoside H, astragaloside IV, astragaloside VIII and astrasieversianin X, were investigated for their inhibitory effects against the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1). We here report inhibitory effects of these compounds against five α-CA isozymes (hCA I, hCA II, bCA III, hCA IV and hCA VI). Most of the phenolic and saponin type compounds inhibited the isoenzymes quite effectively at low micromolar KI-s ranging between 0.1 and 4 µM, whereas a few derivatives were ineffective (KI-s > 100 µM). The results were remarkable which might lead to design of novel CAIs with a diverse inhibition mechanism compared to sulfonamide/sulfamate inhibitors.

Evaluation of the immunomodulatory properties in mice and in vitro anti-inflammatory activity of cycloartane type saponins from Astragalus species.

ETHNOPHARMACOLOGICAL RELEVANCE Astragalus roots are used to treat leukemia and for their wound healing properties in Southeast Anatolia-Turkey. MATERIALS AND METHODS In vivo studies to investigate the effects of two Astragalus saponins were carried out on the immune response cytokines by using six to eight weeks old male Swiss albino mice. The production of IL-1β, TGF-1β, TNF-α, IL-2, IL-4 and IFN-γ cytokines was determined by ELISA. The spleen and lymph nodes, isolated from the mice subjects, were analyzed to realize induction of the surface antigen productions for IL-2Rα (CD25) and CD69. In addition, their effects on the targets of inflammation such as NF κB, iNOS and NAG-1 were investigated in cell-based assays. RESULTS The results suggested that AST VII and Mac B had positive effect on Th1 cytokine release (IL-2 and IFN-γ), and suppression on Th2 cytokine production (IL-4). The immunohistochemical results exhibited induction of both IL-Rα (CD25) and CD69 surface receptors justifying the Th1 cytokine release. The compounds did not affect NF-κB or NAG-1 activity but iNOS activity was inhibited by Mac B with an IC(50) of 156 μg/ml. CONCLUSIONS The results show that Ast VII and Mac B create powerful immunoregulatory effects without the stimulation of inflammatory cytokines in mice, and have no significant effect on the inflammatory cellular targets in vitro.

Neo-clerodane diterpenoids from Teucrium polium

Two new neo-clerodane type diterpenoids, teulolin A (15,16-epoxy-6,7,18,19-tetrahydroxy-neo-cleroda-3(4),13(16),14-trien-20, 12(S)-olide, 1) and teulolin B (15,16-epoxy-3α, 6,7,18,19-tetrahydroxy-neo-cleroda-4(18),13(16),14- trien-20,12(S)-olide, 2) were isolated from the aerial parts of Teucrium polium. The structures of 1-2 were proposed on the basis of extensive NMR experiments and molecular modeling studies

In vitro growth stimulatory and in vivo wound healing studies on cycloartane-type saponins of Astragalus genus

AIM OF THE STUDY The present study was undertaken to evaluate the wound healing effects of the four chief saponins of Astragalus species [cycloastragenol (CA), astragaloside IV (AG), cyclocephaloside I (CCI) and cyclocanthoside E (CCE)]. MATERIAL AND METHODS Effects of cell viability and proliferation of the isolated compounds were evaluated by the MTT assay on human keratinocyte. The wound healing activity was studied by using in vitro wound healing, proliferation and migration scratch assay. In order to see in vivo effectiveness of the compounds, an animal study with Sprague-Dawley male rats at the age of 12 weeks was carried out, and then the main histological outcomes were investigated to observe reepithelization, neovascularization, and presence of inflammatory cells, granulation tissue amount and maturation. RESULTS All the compounds increased both fibroblast proliferation and migration, but the effects were much superior for CA at 1 ng/ml concentration. Among the compounds, based on the histological findings, 5% CA preparation was found to be the most remarkable in vivo wound healing agent showing greater cell density, more regularly organized dermis and more newly formed blood vessels. CONCLUSION Results of this study indicate that the cycloartane-type saponins are the principal constituents responsible for wound healing activities of the roots of Astragalus species substantiating its use in traditional medicine.

Adjuvant effects of Astragalus saponins macrophyllosaponin B and astragaloside VII.

AIM OF THE STUDY The present study was undertaken to evaluate the hemolytic activities of two immunomodulator Astragalus saponins [Macrophyllosaponin B (MacB) from Astragalus oleifolius DC. and Astragaloside VII (Ast VII) from Astragalus trojanus Stev.], and their adjuvant potentials on the cellular and humoral immune responses of Swiss albino mice against BSA. MATERIALS AND METHODS The hemolytic activity of Mac B and Ast VII was determined using 0.5% rabbit red blood cell. For adjuvant activity, Swiss albino mice were immunized subcutaneously with BSA 100 μg alone or with BSA 100 μg dissolved in saline containing Ast VII (30, 60, 120 and 240 μg), Mac B (30, 60, 90 and 120 μg) or Freunds adjuvant on Days 1 and 15. Sera and splenocytes were collected 2 weeks after the last immunization for concanavalin A (Con A)-, lipopolysaccharide (LPS)- and BSA-stimulated splenocyte proliferation assay and measurement of BSA-specific antibodies in serum. RESULTS Mac B and Ast VII showed a slight hemolytic effect, with 0.42% and 0.54% values, respectively, at the highest concentration of 500 μg/ml. Mac B and Ast VII significantly enhanced the Con A-, LPS-, and BSA-induced splenocyte proliferation in the BSA-immunized mice especially at 120 and 240 μg (P<0.001), and 60, 90 and 120 μg (P<0.05, P<0.01 or P<0.001) doses, respectively. BSA-specific IgG, IgG1 and IgG2b antibody titers in serum were also significantly enhanced by Ast VII (120 μg), Mac B (90 μg) and Freunds as compared to the control group (P<0.01 or P<0.001). Moreover, the IFN-γ and IL-4 levels in the sera were detected using ELISA two weeks after the last immunization. Ast VII and Mac B were also found to stimulate IFN-γ production such as Freunds, two weeks after the last immunization at doses of 120 μg and 90 μg, respectively, as compared to the control. CONCLUSION Results show that Ast VII and Mac B generate important specific antibody and cellular response against BSA in mice, proving their potentials as a new class saponin adjuvant.

Neo-clerodane diterpenoids and phenylethanoid glycosides from Teucrium chamaedrys L.

A neo-clerodane type diterpenoid, 12(S)-15,16-epoxy-19-hydroxy-neo-cleroda-13(16),14-dien-18,6alpha:20,12-diolide, and two phenylethanoid glycosides, teucrioside-3(IIII)-O-methylether and teucrioside-3(IIII),4(IIII)-O-dimethylether were isolated from the aerial parts of Teucrium chamaedrys. Their structures were identified on the basis of extensive NMR spectra, LC-ESIMS analysis, and molecular modeling studies.

Trojanoside H: a cycloartane-type glycoside from the aerial parts of Astragalus trojanus

Abstract A novel cycloartane-type glycoside was isolated from the aerial parts of Astragalus trojanus along with the known glycosides astragaloside II, astragaloside IV, astragaloside VII, brachyoside B, brachyoside C and the pterocarpan derivative maackiain. The structure of 1 was determined by spectral methods (1-D and 2-D NMR, and FABMS) and established as 3- O -β-[α- l -arabinopyranosyl(1→2)β- d -xylopyranosyl]-6- O -β- d -glucopyranosyl-20( R ),24( S )-epoxy-3β,6α,16β,25-tetrahydroxycycloartane.

Triterpene saponins from the fruits of Hedera helix.

Six triterpene saponins, including two new compounds, were isolated from the fruits of Hedera helix L. (Araliaceae). The structures of the new compounds, named helixosides A and B, were established as 3-O-beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl hederagenin 28-O-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl ester, and 3-O-beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl oleanolic acid 28-O-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl ester, respectively, on the basis of chemical and spectral data.