Chemical analysis and evaluation of antioxidant and antimicrobial activities of fruit fractions of Mauritia flexuosa L. f. (Arecaceae).

BACKGROUND: Fruit consumption is currently considered beyond the nutritional aspects because of the important roles in disease prevention and benefits to health. The objective of this study was to characterize the chemical profile and evaluate the antioxidant and antimicrobial properties of different fractions obtained from fruit pulps of Mauritia flexuosa (MFFs). METHODS: Initially, chloroform, ethyl acetate and ethanol fractions were obtained from the pulps. Quantifications of total phenols and flavonoids were performed using the methods of Folin-Ciocalteu and complexation with aluminum chloride, respectively. Standard samples were used to identify and quantify phenolic acids and flavonoids using high-performance liquid chromatography with a diode-array detector (HPLC-DAD). The antioxidant capacity of the fractions was verified by sequestration of the free radical 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS) and iron chelating activity. The antimicrobial activity was determined using the microdilution method and the modulating activity was determined using sub-inhibitory concentrations of the fractions in association with antibiotics. RESULTS: The chemical analyzes revealed the presence of catechin, caffeic acid, rutin, orientin, quercetin, apigenin, luteolin and kaempferol, where all are present in the ethyl acetate fraction. The fractions exhibited moderate antioxidant and antimicrobial activities against Gram-positive and Candida strains in addition to modulating the activity of conventional antibiotics. The most expressive result was obtained from the association of the chloroform fraction with cefotaxime, which produced a synergistic effect, reducing the minimum inhibitory concentration (MIC) of the antibiotic from 1,024 to 256 µg/mL. DISCUSSION: The fractions presented a constitution rich in phenolic compounds, especially flavonoids. The data obtained demonstrated that the fractions presented moderate antioxidant activity by acting both as primary and secondary antioxidants. The fractions presented antimicrobial and antibiotic potentiating activities, being the first record of modulating effect of fractions of this species against the studied microbial strains, but failed in modulating the activity of antifungal drugs, indicating that this plant has the potential to be used in the development of therapeutic alternatives against resistant bacteria. The constitution phenolic the fractions may be responsible for their pharmacological properties in vitro.

Chemical composition of the essential oil of Lippia gracilis Schauer leaves and its potential as modulator of bacterial resistance.

Lippia gracilis Schauer (Verbenaceae) is an aromatic plant widely used in folk medicine in the Brazilian semi-arid region. This work aims at evaluating the anti-microbial activity of essential oils from the leaves of L. gracilis (EOLG) when associated with commercial antibiotics against bacterial resistance. The essential oil obtained by hydrodistillation has 38 chemical constituents with thymol (44.4%), carvacrol (22.2%), p-cymene (6.2%) and α-pinene (5.6%) as major constituents. Microbiological assays were conducted by direct and gaseous contacts. We demonstrated that EOLG has significant synergism with all antibiotics tested. EOLG decreased the minimal inhibitory concentration of the aminoglycosides and improved their zone of inhibition more than 300% against Staphylococcus aureus and 270% against Pseudomonas aeruginosa. These results demonstrate that natural substances present in EOLG have the capacity to modulate bacterial resistance and can be used as an adjuvant therapy against multi-resistant microorganisms such as S. aureus, Escherichia coli and P. aeruginosa.

Biological screening of araripe basin medicinal plants using Artemia salina Leach and pathogenic bacteria.

BACKGROUND: Many medicinal plant species from the Araripe Basin are widely known and used in folk medicine and for commercial manufacturing of phytotherapeutic products. Few ethnobotanical and pharmacological studies have been undertaken in this region, however, in spite of the great cultural and biological diversity found there. MATERIALS AND METHODS: Extracts of 11 plant species collected from Ceará state, Brazil, were subjected to the brine shrimp lethality test in order to detect potential sources of novel cytotoxic, antitumor compounds. The larvicidal activity, based on the percentage of larval mortality, was evaluated after 24 h exposure to the treatments. RESULTS: All species tested showed good larvicidal activity as compared to a reference compound and literature data. The extract from Vanillosmopsis arborea was the most active with an LC(50) of 3.9 µg/ml. Best results were shown by Lantana montevidensis against Pseudomonas aeruginosa [minimum inhibitory concentration (MIC) 8µg/ml] and Escherichia coli (MIC 32 µg/ml), Zanthoxylum rhoifolium against E. coli (MIC, 256 µg/ml) and Staphylococcus aureus (MIC 64 µg/ml) and Croton zenhtneri against S. aureus (MIC 64 µg/ml). CONCLUSION: Chemical tests indicated that a wide variety of natural product classes was present in those extracts that showed significant activities in the bioassays.