PARTE UTILIZADA= Used part: Hojas. 

ACCIÓN FARMACOLÓGICA= Pharmacological action: Antiescorbútica, emoliente, pectoral, antioftálmico. 

COMPOSICIÓN QUÍMICA= Chemical composition:Na sua composiçao química foi registrada a presença de nitrato de potássio, sais de cálcio e fósforo, além de polifenóis. 

ZONA GEOGRÁFICA= Geografical zone: Cosmopolita.

DIVERSIDAD GENÉTICA Y MEJORAMIENTO DE PLANTAS MEDICINALES= Medicinal plants and improvement of medicinal herbs

We test competing hypotheses of relationships among Aroids (Araceae) and duckweeds (Lemnaceae) using sequences of the trnL-trnF spacer region of the chloroplast genome.  Included in the anal. were 22 aroid genera including Pistia and five genera of Lemnaceae including the recently segregated genus Landoltia.  Aponogeton was used as an outgroup to root the tree.  A data set of 522 aligned nucleotides yielded max. parsimony and max. likelihood trees similar to those previously derived from restriction site data.  Pistia and the Lemnaceae are placed in two sep. and well-supported clades, suggesting at least two independent origins of the floating aquatic growth form within the aroid clade.  Within the Lemnaceae there is only partial support for the paradigm of sequential morphol. redn., given that Wolffia is sister to Wolffiella + Lemna.  As in the results of the restriction site anal., pantropical Pistia is placed with Colocasia and Typhonium of southeastern Asia, indicative of Old World affinities.  Branch lengths leading to duckweed terminal taxa are much longer relative to other ingroup taxa (including Pistia), evidently as a result of higher rates of nucleotide substitutions and insertion/deletion events.  Morphol. redn. within the duckweeds roughly correlates with accelerated chloroplast genome evolution. 

ÚLTIMOS AVANCES EN LA QUÍMICA Y ACTIVIDADES BACTERIOLÓGICAS EN LAS PLANTAS MEDICINALES= Medicinal plants, last advances on chemistry and bacteria activities on the medicinal herbs

1) Free radical stress leads to tissue injury and progression of disease conditions such as arthritis, hemorrhagic shock, atherosclerosis, diabetes, hepatic injury, aging and ischemia, reperfusion injury of many tissues, gastritis, tumor promotion, neurodegenerative diseases and carcinogenesis.  The present study was aimed to investigate the antioxidant activity of methanolic exts. of Pistia stratiotes leaves by different methods like reductive ability, nitric oxide radical assay and superoxide scavenging activity.  PSLE showed strong antioxidant activities in different systems like reducing power, superoxide anion scavenging and nitric oxide radical scavenging activities when compared with different stds. such as ascorbic acid and BHT.  Plant ext. showed concn.- dependent scavenging activity on all reactive species used.  Presumably, Pistia stratiotes leaves ext. (PSLE) functions as an antioxidant to scavenge free radicals and reduces free radical induced cell injury.

2) Background, aim, and scope Water quality impairment by nutrient enrichment from agricultural activities has been a concern worldwide.  Phytoremediation technol. using aquatic plants in constructed wetlands and stormwater detention ponds is increasingly applied to remediate eutrophic waters.  The objectives of this study were to evaluate the effectiveness and potential of water lettuce (Pistia stratiotes L.) in removing nutrients including nitrogen (N) and phosphorus (P) from stormwater in the constructed water detention systems before it is discharged into the St.  Lucie Estuary, an important surface water system in Florida, using phytoremediation technologies.  Materials and methods In this study, water lettuce (P. stratiotes) was planted in the treatment plots of two stormwater detention ponds (East and West Ponds) in 2005-2007 and water samples from both treatment and control plots were weekly collected and analyzed for water quality properties including pH, elec. cond., turbidity, suspended solids, and nutrients (N and P).  Optimum plant d. was maintained and plant samples were collected monthly and analyzed for nutrient contents.  Results Water quality in both ponds was improved, as evidenced by decreases in water turbidity, suspended solids, and nutrient concns.  Water turbidity was decreased by more than 60%.  Inorg. N (NH4 + and NO3 -) concns. in treatment plots were more than 50% lower than those in control plots (without plant).  Redns. in both PO4 3- and total P were approx. 14-31%, as compared to the control plots.  Water lettuce contained av. N and P concns. of 17 and 3.0 g kg-1, resp., and removed 190-329 kg N ha-1 and 25-34 kg P ha-1 annually.  Discussion Many aquatic plants have been used to remove nutrients from eutrophic waters but water lettuce proved superior to most other plants in nutrient removal efficiency, owing to its rapid growth and high biomass yield potential.  However, the growth and nutrient removal potential are affected by many factors such as temp., water salinity, and physiol.
limitations of the plant.  Low temp., high concn. of salts, and low concn. of nutrients may reduce the performance of this plant in removing nutrients.  Conclusions The results from this study indicate that water lettuce has a great potential in removing N and P from eutrophic stormwaters and improving other water quality properties.

3) An efficient and rapid in vitro regeneration protocol via organogenesis was developed for water lettuce (Pistia stratiotes).  Different explants of the plant, e.g., leaves, condensed stems and stolons, were tested for in vitro regeneration.  Calli could be initiated only from the condensed stems on Murashige and Skoog (MS) agar medium supplemented with 30 g L-1 sucrose plus 2.26 mmol/L of 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.88 mmol/L of 6-benzylaminopurine (6-BA), while calli could not be formed from the leaves and stolons on the media with different combinations of plant growth regulators.  Shoots emerged when the calli were transferred onto shoot initiation medium (MS agar medium modified with 4.44 mmol/L BA and 0.54 mmol/L alpha-naphthaleneacetic acid, NAA) in two weeks.  The regenerated shoots were rooted spontaneously on this medium or when transferred to rooting medium (MS agar medium supplemented with 0.54 mmol/L NAA).  The rooted plants were transferred to different liq. media without plant growth regulator for comparing their multiplication, and it was found that the medium with two-fold macroelements of Schenk and Hildebrandt (SH) was the best.  The regenerated plants were multiplied rapidly in this liq. medium and 10 new plants were produced from each parent plant in two weeks.  This is the first report on in vitro regeneration of water lettuce.  The regeneration and clonal propagation protocol described here has the potential not only to provide an axenic model system for biochem. studies of this aquatic monocotyledonous plant, but also to be widely applied in many fields, such as genetic modification of this plant, prodn. of pharmaceutical recombinant proteins and bioremediation of contaminated water.

1) TOURSARKISSIAN, Martín. Plantas medicinales de Argentina : sus nombres botánicos, vulgares, usos y distribución geográfica. Buenos Aires : Hemisferio Sur, 1980, p.9.

2) LORENZI, Harri; MATOS, ABREU, José de . Plantas medicinais no brasil: nativas e exóticas. Nova Odessa, SP: Instituto Plantarum, 2002. p. 76.

3) ROTHWELL, Gar W., et al.  Molecular phylogenetic relationships among Lemnaceae and Araceae using the chloroplast trnL-trnF intergenic spacer. Molecular Phylogenetics and Evolution. 2004, vol.30, nº2, p.378-385.
 
4) JHA, Megha; GANESH, N.; SHARMA, Versha. In vitro evaluation of free radical scavenging activity of Pistia stratiotes. International Journal of ChemTech Research. 2010, Vol.2, nº1, p.180-184.
 
5) LU, Qin, et al.. Phytoremediation to remove nutrients and improve eutrophic stormwaters using water lettuce (Pistia stratiotes L.). Environmental Science and Pollution Research. 2010, vol.17, nº1, p.84-96.
 
6) ZHANG, Yong, et al.  In vitro regeneration and propagation of Pistia stratiotes: an ideal aquatic plant for biomanufacturing and bioremediation. Yingyong Yu Huanjing Shengwu Xuebao. 2008, vol.14, nº4, p.445-449.