C. Desmarchelier

Antioxidant and free radical scavenging effects in extracts of the medicinal herb Achyrocline satureioides (Lam.) DC. ("marcela")

Achyrocline satureioides (Lam.) DC. (Compositae) is a medicinal herb used in Argentina, Uruguay, Brazil and Paraguay for its choleretic, antispasmodic and hepatoprotective properties. The presence of the flavonoid quercetin and its derivatives, and of different phenolic acids such as caffeic, chlorogenic and isochlorogenic acids in the aerial parts of this plant has led us to study the antioxidant activity of its extracts using different bioassays. The inhibition of luminol-enhanced chemiluminescence by the aqueous and methanolic extracts was used to show that their total reactive antioxidant potential index (TRAP; in microM Trolox equivalents) was 91.0 +/- 15.4 and 128.1 +/- 20.1 microM, respectively, while the total antioxidant reactivity index (TAR) was calculated to be 1537 +/- 148 and 1910 +/- 171 microM. Only the methanolic extract was capable of reducing iron (II)-dependent DNA damage. Lipid peroxidation was assessed by two different methods. The aqueous extract reduced hydroperoxide-initiated chemiluminescence in rat liver homogenates at all concentrations in a dose-dependent manner, with a calculated IC50 = 225 micrograms/ml, while the methanolic extract was only effective at higher concentrations (100 and 1000 micrograms/ml). Both aqueous and methanolic extracts were capable of reducing the production of thiobarbituric acid reactive substances (TBARS) in rat liver homogenates, with an IC50 > 1000 micrograms/ml. The results obtained suggest that the extracts of A. satureioides possess significant free radical scavenging and antioxidant activity in vitro, a fact that should encourage future in vivo studies.

Evaluation of the in vitro antioxidant activity in extracts of Uncaria tomentosa (Willd.) DC.

Different extracts of U. tomentosa were tested in vitro for their antioxidant activity utilizing tert ‐butyl‐hydroperoxide‐initiated chemiluminescence in rat liver homogenates. Methanol fractions of both stem‐bark and roots were capable of exerting antioxidant activity by this technique. The presence of different concentrations of bark and root methanol extracts also prevented TBARS production and free radical‐mediated DNA‐sugar damage.

In vitro antioxidant and cytotoxic activity of extracts of Baccharis coridifolia DC

The in vitro antioxidant and cytotoxic activities in different extracts of Baccharis coridifolia DC. (Compositae) were studied using different bioassays. Antioxidant activity was tested using hydroperoxide-initiated chemiluminescence (CL) in rat liver homogenates. The aqueous extract showed antioxidant activity (IC50 = 141 microg/ml), while the dichloromethane and methanol extracts were prooxidant. Activity in the aqueous extract was confirmed by determination of thiobarbituric acid-reactive substances (TBARS), showing an IC50 = 556 microg/ml. On the other hand, studies on the cytotoxic activity demonstrated a 78% crown gall tumour inhibition and an ED50 = 4. 2 microg/ml in KB cells growth for the dichloromethane extract. A 56% decrease in the initial absorbance of DNA-Methyl Green complex could also be observed at 1000 microg/ml, suggesting the presence of compounds that interact with DNA.

Neotropics and natural ingredients for pharmaceuticals: why isn't South American biodiversity on the crest of the wave?

Despite the advent of biotechnology and modern methods of combinatorial chemistry and rational drug design, nature still plays a surprisingly important role as a source of new pharmaceutical compounds. These are marketed either as herbal drugs or as single active ingredients. South American tropical ecosystems (or the Neotropics) encompass one‐third of the botanical biodiversity of the planet. For centuries, indigenous peoples have been using plants for healing purposes, and scientists are making considerable efforts in order to validate these uses from a pharmacological/phytochemical point of view. However, and despite the unique plant diversity in the region, very few natural pharmaceutical ingredients from this part of the world have reached the markets in industrialized countries. The present review addresses the importance of single active ingredients and herbal drugs from South American flora as natural ingredients for pharmaceuticals; it highlights the most relevant cases in terms of species of interest; and discusses the key entry barriers for these products in industrialized countries. It explores the reasons why, in spite of the regions competitive advantages, South American biodiversity has been a poor source of natural ingredients for the pharmaceutical industry. Copyright

Biological studies of Bolax gummifera, a plant of the Falkland Islands used as a treatment of wounds

Aqueous and dichloromethane extracts of Bolax gummifera (Lam.) Sprengel (Apiaceae), a plant of the Falkland Islands used as a treatment of wounds, were studied in order to support the ethnopharmacological information related to the medicinal use of this plant. The antimicrobial, antioxidant and red blood cells membrane stabilizing activities were analyzed. The antimicrobial bioassay was carried out using the test turbidity method (OD 620 nm), the aqueous extract showing an 82% inhibition of Staphylococcus aureus but no activity against Pseudomonas aeruginosa. The dichloromethane extract inhibited both microorganisms: S. aureus in 94% and P. aeruginosa in 32%. No antioxidant activity could be observed using hydroperoxide-initiated chemiluminescence in rat liver homogenates. Investigations into the membrane stabilizing activity of the extracts were carried out using human red blood cells subjected to hypotonic- and heat-induced lyses. The aqueous extract showed an important stabilizing activity of the red blood cell membrane.

Inhibition of lipid peroxidation and iron (II)-dependent DNA damage by extracts of Pothomorphe peltata (L). Miq.

Leaves of Pothomorphe peltata (L.) Miq. (Piperaceae) are used locally as anti-inflammatory, antipyretic, hepatoprotective and diuretic infusions and to treat external ulcers and local infections in several parts of the Peruvian, Bolivian and Brazilian Amazon region. The antioxidant activity of different extracts of P. peltata was studied using the hydroperoxide-initiated chemiluminescence assay in liver homogenates, and the methanolic extract was found to have the highest antioxidant activity, with an IC50 = 4 micrograms/ml. Aqueous and dichloromethane extracts did not show antioxidant activity. The extracts were further evaluated using the thiobarbituric acid-reactive substances (TBARS) assay. Finally, an assay of DNA sugar damage induced by Fe (II) salt was used to determine the capacity of the extracts to suppress the oxidative degradation of DNA. All the extracts showed antioxidant activity in the latter two bioassays. The methanolic extract showed the highest activity in reducing oxidative damage to DNA, with an IC50 = 5 micrograms/ml. Since this extract was highly effective in reducing chemiluminescence and DNA damage, and because the latter activity could be due to the presence of compounds that bind to DNA, DNA-binding activity was studied using the DNA-methyl green (DNA-MG) bioassay. A 30% decrease in the initial absorbance of DNA-MG complex was observed in the methanolic extract at 1000 micrograms/ml, suggesting the presence of compounds that bind to genetic material. No DNA-binding activity was observed in the aqueous or dichloromethane extracts.

Extracts of Bolivian plants, Copaifera reticulata and Heisteria pallida inhibit in vitro free radical-mediated DNA damage

The presence of different extracts of antiinflammatory plants Copaifera reticulata and Heisteria pallida in a reaction medium containing calf thymus DNA in a free radical generating system protected DNA against oxidative damage in terms of deoxyribose oxidation. The highest antioxidant activity was obtained using the methanol extract of C. reticulata (IC50=3 μg/mL), followed by the aqueous extracts of H. pallida (IC50=257 μg/mL) and C. reticulata (IC50=380 μg/mL). Both dichloromethane extracts and the methanol extract of H. pallida showed a decreased antioxidant activity at higher concentrations. These results suggest that these extracts are capable of suppressing the in vitro oxidative degradation of DNA.