Antibacterial activity of plant extracts and phytochemicals on antibiotic-resistant bacteria

The antimicrobial activity of plant extracts and phytochemicals was evaluated with antibiotic susceptible and resistant microorganisms. In addition, the possible synergistic effects when associated with antibiotics were studied. Extracts from the following plants were utilized: Achillea millifolium (yarrow), Caryophyllus aromaticus (clove), Melissa offficinalis (lemon-balm), Ocimun basilucum (basil), Psidium guajava (guava), Punica granatum (pomegranate), Rosmarinus officinalis (rosemary), Salvia officinalis (sage), Syzygyum joabolanum (jambolan) and Thymus vulgaris (thyme). The phytochemicals benzoic acid, cinnamic acid, eugenol and farnesol were also utilized. The highest antimicrobial potentials were observed for the extracts of Caryophyllus aromaticus and Syzygyum joabolanum, which inhibited 64.2 and 57.1 ( per cent) of the tested microorganisms, respectively, with higher activity against antibiotic-resistant bacteria 83.3 ( per cent). Sage and yarrow extracts did not present any antimicrobial activity. Association of antibiotics and plant extracts showed synergistic antibacterial activity against antibiotic-resistant bacteria. The results obtained with Pseudomonas aeruginosa was particularly interesting, since it was inhibited by clove, jambolan, pomegranate and thyme extracts. This inhibition was observed with the individual extracts and when they were used in lower concentrations with ineffective antibiotics.

Antioxidant activity of ethanolic extracts of Pothomorphe umbellata L. Miq. (Pariparoba)

Oxidative stress has been implicated in many pathological conditions such as cancer, aging inflammation and cell death. The Brazilian flora is particularly rich in medicinal plants employed for many purposes. Among them the Piperaceae family and specially the "pariparobas" are widely used in the treatment of liver diseases. In vitro antioxidant activity of Pothomorphe umbellata L. Miq. was evaluated and compared with that of Piper regnellii, another plant from the Piperaceae family commonly used as it were P. umbellata. A purified fraction of the ethanolic extract of P. umbellata, containing 4-nerolidylcatechol was also assayed for antioxidant activity and compared with that of alpha-tocopherol. Rat brain homogenates were incubated with increasing aliquots of crude extracts of different parts of the plants or 4-nerolidylcatechol/alpha-tocopherol for 1 h at 37 degrees Celsius. Both malondialdehyde (MDA) and chemiluminescence (CL) were assayed to evaluate brain tissue autoxidation. The Q1/2 for MDA assay for root, stem and leaves were 4.4, 19.3 and 38.5 mug/mL for P. umbellata and 26.0,64.4 and 13.3 mug/mL for P regnellii, respectively. Calculated MDA and CL Q1/2 values for 4-nerolidylcatechol and alpha-tocopherol were O.75 and O.68 muM for 4-nerolidylcatechol and 14.4 and 1O.9 muM for alpha-tocopherol, respectively. These results indicate high antioxidant activity of P. umbellata root extract as compared to that of vitamin E, which was attributed to the presence of 4-nerolidylcatecho1.