Antioxidant Activity of Aqueous Extract of Leaves and Seeds of Datura metel (Solanaceae) in Frog's Heart Failure Model.

Objective: The aim of this work was to evaluate the antioxidant potential of Datura metel. Materials and Methods: Heart failure was induced in the frog's heart by continuous perfusion of hydrogen peroxide. Survival time and some heart tissue parameters of oxidative stress were recorded in the presence of aqueous extracts of the leaves and seeds of Datura metel. Ascorbic acid was used as a reference drug. Results: H2O2-enriched Ringer's solution inhibited the negative inotropic and chronotropic effects of acetylcholine, indicating the desensibilization of muscarinic receptors due to H2O2-induced oxidative stress. These hearts had a relatively short survival time (14 minutes). In the presence of the aqueous extract of the leaves and seeds of Datura metel (1.5 and 2.5 mg/mL), the time necessary to cause the cardiac arrest was extended to 35 and 37 minutes, respectively, versus 29 minutes for ascorbic acid and 14 minutes for H2O2. Furthermore, antioxidant parameters (MDA, SOD, and CAT) were significantly improved in plant extract-treated hearts, compared to peroxidized hearts. Conclusion: Aqueous extract of the leaves and seeds of D. metel can extend heart survival time through antioxidant mechanisms.

Anthocyanins as a potential therapy for diabetic retinopathy.

Diabetic retinopathy is one of the most common complications of diabetes. A plethora of literature indicates that oxidative stress may play a central role in the pathogenesis of diabetic retinopathy. One could thus hypothesise that antioxidant therapies may be protective for diabetic retinopathy. Anthocyanins are important natural bioactive pigments responsible for red-blue colour of fruits, leaves, seeds, stems and flowers in a variety of plant species. Apart from their colours, anthocyanins are known to be health-promoting phytochemicals with potential properties useful to protect against oxidative stress in some degenerative diseases. They also have a variety of biological properties including anti-inflammatory, antibacterial, anticancer, and cardio-protective properties. Some reports further suggest a therapeutic role of anthocyanins to prevent and/or protect against ocular diseases but more studies are needed to examine their potential as alternative therapy to diabetic retinopathy. The present article reviews the available literature concerning the beneficial role of anthocyanins in diabetic retinopathy.

Prooxidant action of knipholone anthrone: copper dependent reactive oxygen species generation and DNA damage.

Knipholone (KP) and knipholone anthrone (KA) are natural 4-phenylanthraquinone structural analogues with established differential biological activities including in vitro antioxidant and cytotoxic properties. By using DNA damage as an experimental model, the comparative Cu(II)-dependent prooxidant action of these two compounds were studied. In the presence of Cu(II) ions, the antioxidant KA (3.1-200 microM) but not KP (6-384 microM) caused a concentration-dependent pBR322 plasmid DNA strand scission. The DNA damage induced by KA could be abolished by reactive oxygen species scavengers, glutathione and catalase as well as EDTA and a specific Cu(I) chelator bathocuproine disulfonic acid. In addition to Cu(II) chelating activity, KA readily reduces Cu(II) to Cu(I). Copper-dependent generation of reactive oxygen species and the subsequent macromolecular damage may be involved in the antimicrobial and cytotoxic activity of KA.

Antioxidant and antiinflammatory effect of Epilobium parviflorum Schreb.

Epilobium parviflorum Schreb. (Onagraceae) is used for the treatment of benign prostatic hyperplasia (BPH), but its biological action is not entirely identified. This paper aims to report data on E. parviflorum with respect to its antioxidant and antiinflammatory effects. The aqueous acetone extract of E. parviflorum showed higher antioxidant effect in the DPPH assay than well known antioxidants and inhibited the lipid peroxidation determined by the TBA assay (IC(50) = 2.37 +/- 0.12 mg/mL). In concentrations of 0.2-15.0 microg/mL the extract possessed a protective effect, comparable to catalase (250 IU/mL), against oxidative damage, generated in fibroblast cells. In the COX inhibition assay E. parviflorum decreased the PGE(2) release, so showing inhibition of the COX-enzyme (IC(50) = 1.4 +/- 0.1 microg/mL).

Antiinflammatory activity of the antirheumatic herbal drug, gravel root (Eupatorium purpureum): further biological activities and constituents.

Previous reports from this laboratory revealed that cistifolin from the antirheumatic herbal drug, gravel root (rhizome of Eupatorium purpureum), showed activity both in in vitro and in vivo models of inflammation. Data are now presented to show that, in addition to the LFA-1 and other integrin-mediated leucocyte adhesions, cistifolin inhibits the Mac-1 (CD11b/CD18)-dependent monocyte adhesion to fibrinogen in a concentration-dependent manner. Further phytochemical analysis of the crude extract also led to the isolation of three known benzofurans, euparin, euparone, 6-hydroxy-3beta-methoxytrematone and a new benzofuran, 5-acetyl-6-hydroxy-2-(1-oxo-2-acetoxy-ethyl)-benzofuran. None of these compounds were active in suppressing integrin-mediated monocytic U937 cell adhesions in vitro.

Cytotoxicity and antibacterial activity of ethanol extract from leaves of a herbal drug, boneset (Eupatorium perfoliatum).

The cytotoxic and antibacterial activity of an ethanol extract of leaves of a herbal drug, boneset (Eupatorium perfoliatum), was investigated. The extract showed potent cytotoxicity with EC(50) values (12-14 microg/mL) comparable to a standard cytotoxic agent, chlorambucil. The extract showed a weak antibacterial activity against gram-positive test organisms (Staphylococcus aureus and Bacillus megaterium).

Natural inhibitors of tumour necrosis factor-alpha production, secretion and function.

Tumour necrosis factor-alpha (TNF), originally discovered by its antitumor activity, is one of the most pleotropic cytokines acting as a host defence factor in immunologic and inflammatory responses. Although the antitumour activity and mediation of inflammation by TNF could be beneficial to the host, unregulated TNF is now known to be the basis for development of various diseases including septic shock, the wasting disease, cachexia, and various inflammatory and/or autoimmune diseases. With an attempt to find potential therapeutic agents for TNF-mediated diseases, research during the last decade has led in the identification of well over one hundred natural inhibitors of either TNF production/secretion or function. This review summarises the structures, mechanism of action and therapeutic potential of these natural products.

17-Epiacnistin-A, a further withanolide from the leaves of Discopodium penninervium.

A novel withanolide (1) has been isolated from the leaves of Discopodium penninervium and identified as 17-epiacnistin-A on the basis of spectroscopic and X-ray diffraction data.

Extract of corn silk (stigma of Zea mays) inhibits the tumour necrosis factor-alpha- and bacterial lipopolysaccharide-induced cell adhesion and ICAM-1 expression.

Treatment of human endothelial cells with cytokines such as tumour necrosis factor-alpha (TNF) or E. coli lipopolysaccharide (LPS) induces the expression of several adhesion molecules and enhances leukocyte adhesion to endothelial cell surface. Interfering with this leukocyte adhesion or adhesion molecules upregulation is an important therapeutic target for the treatment of bacterial sepsis and various inflammatory diseases. In the course of screening marketed European anti-inflammatory herbal drugs for TNF antagonistic activity, a crude ethanolic extract of corn silk (stigma of Zea mays) exhibited significant activity. The extract at concentrations of 9-250 micrograms/ml effectively inhibited the TNF- and LPS-induced adhesiveness of EAhy 926 endothelial cells to monocytic U937 cells. Similar concentration ranges of corn silk extract did also block the TNF and LPS but not the phorbol 12-myristate 13-acetate-induced ICAM-1 expression on EAhy 926 endothelial cell surface. The extract did not alter the production of TNF by LPS-activated macrophages and failed to inhibit the cytotoxic activity of TNF. It is concluded that corn silk possesses important therapeutic potential for TNF- and LPS-mediated leukocyte adhesion and trafficking.

Cistifolin, an integrin-dependent cell adhesion blocker from the anti-rheumatic herbal drug, gravel root (rhizome of Eupatorium purpureum).

During routine screening of medicinal plants for small molecular weight inhibitors of cell adhesion, the crude ethanolic extract of the anti-rheumatic herbal drug gravel root (rhizome of Eupatorium purpureum), was identified as a potent inhibitor of some beta 1 and beta 2 integrin-mediated cell adhesions. The active principle of gravel root has now been isolated and identified as 5-acetyl-6-hydroxy-2,3-dihydro-cis-2-isopropenyl-3- tiglinoyloxybenzofuran (1). Compound 1 inhibited integrin-dependent cell-cell and cell-protein interactions in vitro with EC50 values between 7-20 micrograms/ml. As with indomethacin, 1 administered orally two hours before induction of inflammation (in rat paw) by carrageenan inhibited oedema formation in a dose (10 and 50 mg/kg)-dependent manner. It appears that 1 has therapeutic potential for diseases where integrin adhesion molecules play a significant role.

Withanolides from the roots of Discopodium penninervium.

A new withanolide, 6alpha,7alpha-epoxy-5alpha,17beta-dihydroxy-1-oxowitha-2,24-dienolide, together with the known compounds withanolide A and withanone have been isolated from the roots of Discopodium penninervium. The identity of the new compound was established from spectroscopic data.

Flavonoids as inhibitors or enhancers of the cytotoxicity of tumor necrosis factor-alpha in L-929 tumor cells.

The effects of some selected flavonoids on tumor necrosis factor-alpha (TNF)-induced cytotoxicity in murine fibroblast L-929 cells were studied. All of the flavanones tested as well as a flavan, epicatechin, protected L-929 cells from TNF-induced cell death of the flavanones tested, hesperetin, isosakuranetin, and pinocembrin failed to modify TNF cytotoxicity, but the 3',4'-dihydroxyflavanones, eriodictyol and taxifolin, showed a protective effect. Eriodictyol was the most potent protective agent of all the flavonoids tested, while a 4'-hydroxyflavanone, naringenin, rather showed enhancement of TNF cytotoxicity. Of the flavones tested, chrysin and apigenin markedly augmented the cytotoxicity of TNF, while luteolin showed a weak protective effect. The magnitude of protection and potentiation by these flavonoids were concentration-dependent and these effects were not altered when the flavonoids were added as much as 2 h after TNF treatment.

Cytotoxicity and immunosuppressive activity of withanolides from Discopodium penninervium.

The cytotoxicity and immunosuppressive activities of jaborosalactone-L and three 16 alpha-oxygenated withanolides from the leaves of Discopodium penninervium were studied. Jaborosalactone-L showed cytotoxicity only to the murine macrophage cell line, RAW 264.7, but the 16 alpha-oxygenated withanolides exhibited cytotoxicity to both human (COR-L23 and ECV 304) and murine (L929 and RAW 264.7) carcinoma cell lines with IC50 values ranging from 1.2-150 microM. The non-toxic concentrations of these withanolides were also found to reduce the proliferative response of both inactive and E. coli lipopolysaccharide and concanavalin A activated rat spleen cells in vitro.

Cytotoxicity of extracts from the mushroom Paxillus involutus.

The cytotoxicity of extracts of freshly collected Paxillus involutus against murine (L929 and RAW 264.7) and human (HeLa and EAhy926) derived cell lines was investigated. The water extract (15.6-1000 micrograms/ml) did not affect the viability of cells, while the butanol extract reduced cell viability by 30-45% at the highest concentration tested (1 mg/ml). The ethyl acetate extract was cytotoxic in a concentration-dependent manner, with IC50 values between 125 and 250 micrograms/ml. The cytotoxic principle appears to be heat and acid stable, as neither incubation at 37 degrees C for 4 hr nor overnight treatment at pH 0.5 altered the cytotoxicity of the ethyl acetate extract. This non-polar, acid- and thermo-stable cytotoxic principle may play a role in the haemolysis and other clinical manifestations that occur during poisoning by P. involutus.

Cytotoxicity of diterpenes from Premna schimperi and Premna oligotricha.

The cytotoxicity of two diterpenes from Premna schimperi and Premna oligotricha (Verbenaceae) was studied using the MTT assay. Their cytotoxic activity against three human (HeLa, SK.N.SH, and ECV 304) and two murine (L929 and RAW 264.7) carcinoma cell lines varied between 1.5 to 35 micrograms/ml and was comparable with azauridine and chlorambucil.

The muscle relaxant properties of Portulaca oleracea are associated with high concentrations of potassium ions.

The juice and aqueous extracts from the plant Portulaca oleracea have been used in West Africa for a variety of medical purposes, and extracts were previously shown to have muscle relaxant properties on isolated nerve-muscle preparations. We have attempted to characterise the components responsible for this activity. Ethanolic extracts caused an initial augmentation of twitch height in chick biventer cervicis preparations and then blockade which appeared to be mediated by an action directly on muscle fibres rather than on neuromuscular transmission. Solvent fractionation of the crude ethanolic extract followed by bioassay on the chick biventer cervicis preparation showed that muscle paralysis increased with increasing polarity: i.e. water fraction > butanol > ethyl acetate approximately equal to crude extracts. These fractions contained 28%, 18%, 12.2% and 9%, respectively, of potassium by weight of dried extract. Similar concentrations of KCl reproduced the same effect as the extracts on muscle activity, and when the most active fraction (water fraction) was desalted, it had no neuromuscular activity even at 10 times higher concentration than used previously. We conclude that the neuromuscular activity of extracts of Portulaca oleracea is caused by high concentrations of potassium ions.

A new antibacterial sesquiterpene from Premna oligotricha.

A novel sesquiterpene, 7 alpha-hydroxy-6, 11-cyclofarnes-3(15)-en-2-one [1], has been isolated from the aerial parts of Premna oligotricha (Verbenaceae) using an antimicrobial bioassay-guided isolation procedure. The sesquiterpene was identified on the basis of spectroscopic data and showed weak activity against Gram-positive bacteria Bacillus pumilus, Bacillus subtilis, Staphylococcus aureus, and Streptococcus faecalis.

A novel antibacterial diterpene from Premna schimperi.

A novel diterpene, (5R, 8R, 9S, 10R)-12-oxo-ent-3,13(16)-clerodien-15-oic acid, has been obtained from the leaves of Premna schimperi (Verbenaceae) using an anti-microbial bioassay-guided isolation procedure. The diterpene was identified on the basis of spectroscopic data and is active against the Gram-positive bacteria Staphylococcus aureus and Bacillus subtilis in the concentration range 20-25 micrograms ml-1.