Sergio Sorbo

Antibacterial and allelopathic activity of extract from Castanea sativa leaves.

Following the extraction of Castanea sativa with an aqueous solution of sulfuric acid (pH 3.0), the ethyl acetate soluble fraction was tested for its antibacterial and allelopathic activity. The extract was shown to have pronounced antibacterial effects against seven of the eight strains of Gram-positive and Gram-negative bacteria used (MIC in the range of 64-256 microg/ml and MBC in the range of 256-512 microg/ml). The active fraction was analyzed by TLC and HPLC showing the presence of rutin, hesperidin, quercetin, apigenin, morin, naringin, galangin and kaempferol. Standards of the identified flavonoids were tested against the same bacterial strains. The highest activity was shown by quercetin, rutin and apigenin. The allelopathic effect was tested against Raphanus sativus seed germination. The extract, quercetin, rutin and apigenin caused a decrease in the percentage of seed germination and root and epicotyl growth.

Antimicrobial and antioxidant activities of coumarins from the roots of Ferulago campestris (Apiaceae).

We report the isolation of several coumarins and the stereochemical assessment of some pyranocoumarins, as well as the antibacterial and antioxidant activities of the three most abundant ones (grandivittin, agasyllin and aegelinol benzoate) isolated from the roots of Ferulago campestris collected in Sicily and of the hydrolysis product (aegelinol). Aegelinol and agasyllin showed antibacterial activity against nine ATCC and the same clinically isolated Gram-positive and Gram-negative bacterial strains. At a concentration between 16 and 125 μg/mL both coumarins showed a significant antibacterial effect against both Gram-negative and Gram-positive bacteria. In particular the ATCC strains Staphylococcus aureus, Salmonella thypii, Enterobacter cloacae and Enterobacter earogenes (MIC = 16 and 32 μg/mL for aegelinol and agasyllin, respectively) were the most inhibited. Antibacterial activity was also found against Helicobacter pylori: a dose-dependent inhibition was shown between 5 and 25 μg/mL. The antioxidant activity of the coumarins was evaluated by their effects on human whole blood leukocytes (WB) and on isolated polymorphonucleate (PMN) chemiluminescence (CL), PMA-stimulated and resting.

Comparison of the heavy metal bioaccumulation capacity of an epiphytic moss and an epiphytic lichen

This study compared the heavy metal bioaccumulation capacity in the epiphytic moss Scorpiurum circinatum and the epiphytic lichen Pseudevernia furfuracea, exposed in bags for 3 months in the urban area of Acerra (S Italy). The content of Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Ti, V, and Zn was measured by ICP-MS. The results showed that both species accumulated all the heavy metals assayed. The moss had the highest bioaccumulation capacity for all metals and showed a more constant and linear accumulation trend than the lichen. Intra-tissue heavy metal bioaccumulation was assessed by X-ray microanalysis applied to ESEM operated in high and low vacuum and ESEM modes.

Biodiversity and trace element content of epiphytic bryophytes in urban and extraurban sites of southern Italy

In the present study epiphytic bryophytes were employed as a model system in an integrated way both as bioindicators at species, population and community levels and as bioaccumulators of airborne trace elements. Twenty sites with Quercus ilex trees were chosen in a Mediterranean area both in urban and natural locations, with an altitude ranging from 0 to about 500 m a.s.l., in coastal and inland areas (Campania, Italy). Data on the presence of species, cover values and phenology were recorded for each site and the Index of Atmospheric Purity (IAP) was calculated. The data matrix of frequency/cover × species was analysed by multivariate methods. Data obtained clearly show that in urban sites the number of species and IAP values are lower, and that acrocarpous mosses and vegetative reproduction occur more frequently. Contents of trace elements (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Ti, V, Zn) were measured in four species and concentrations were normalised to the soil pattern by calculating the Enrichment Factor (EF). The results show the large contribution of resuspended soil particles to the chemical composition of the analysed bryophytes. All the examined species were enriched in Cd, Cu and Zn, and in some cases showed high EF for Pb. The differences among epiphytic bryophyte vegetation are discussed in order to evaluate suspected alterations due to human impact and/or environmental change.

Effects of seven pure flavonoids from mosses on germination and growth of Tortula muralis HEDW. (Bryophyta) and Raphanus sativus L. (Magnoliophyta)

Dried mosses (five moss species) were progressively extracted and subjected to a four-step Craig distribution. Seven pure flavonoids were isolated and identified. The flavonoids were the flavones apigenin, apigenin-7-O-triglycoside, lucenin-2, luteolin-7-O-neohesperidoside, saponarine and vitexin; and the biflavonoid bartramiaflavone and they were submitted to biological tests. The tests were performed in vitro on spore germination and protonemal growth of the moss Tortula muralis and on seed germination and root growth of Raphanus sativus. Flavonoids caused a decrease in the percentage of spore germination, protonemal development and root growth. In addition they caused morphological alterations, such as forked tips, swollen apices, rounded cells and early formation of brood cells in the protonemata. Data were discussed in relation to the presence of allelochemicals in mosses.

Toxicity, Accumulation, and Removal of Heavy Metals by Three Aquatic Macrophytes

A comprehensive understanding of the uptake, tolerance, and transport of heavy metals by plants will be essential for the development of phytoremediation technologies. In the present paper, we investigated accumulation, tissue and intracellular localization, and toxic effects of cadmium (Cd), lead (Pb), zinc (Zn), and copper (Cu) in three aquatic macrophytes (the angiosperms Lemna minor and Elodea canadensis, and the moss Leptodictyum riparium). We also tested and compared their capacity to absorb heavy metal from water under laboratory conditions. Our data showed that all the three species examined could be considered good bioaccumulators for the heavy metals tested. L. riparium was the most resistant species and the most effective in accumulating Cu, Zn, and Pb, whereas L. minor was the most effective in accumulating Cd. Cd was the most toxic metal, followed by Pb, Cu, and Zn. At the ultrastructural level, sublethal concentrations of the heavy metals tested caused induced cell plasmolysis and alterations of the chloroplast arrangement. Heavy metal removal experiments revealed that the three macrophytes showed excellent performance in removing the selected metals from the solutions in which they are maintained, thus suggesting that they could be considered good candidates for wastewaters remediation purpose.

Trace element accumulation in Pseudevernia furfuracea (L.) Zopf exposed in Italy’s so called Triangle of Death.

Trace element accumulation in the lichen Pseudevernia furfuracea (L.) Zopf was studied in the district of Acerra (province of Naples, southern Italy), one of the points forming Italys Triangle of Death. P. furfuracea thalli, collected from Mt. Faito (province of Naples), were transplanted and exposed in bags at different sites in Acerra district, classified into three different site types (urban, rural and industrial). We aimed to test the hypothesis that P. furfuracea, when transplanted in the district of Acerra, would respond to air pollution accumulating trace elements and that element concentrations in the exposed lichens were different in relation to the three different environments, characterised by different pollution sources. Samples were exposed for six months, periodically collected and examined by ICP MS spectrometer assays to measure concentrations of 10 trace elements (Al, As, Cd, Cr, Cu, Fe, Mn, Pb, V and Zn). The exposed samples showed increases in concentrations of all the examined elements; the trace element concentrations were evaluated by calculating exposed to control (EC) ratios, for each site and each trace element, to better understand the accumulation rates. EC ratios were evaluated after 3 and 6 month exposures, at the end of spring and summer respectively: 6 month EC values were the highest. The urban sites showed EC ratios generally higher than industrial and rural; the most accumulated elements were Pb and Cu (at the urban sites), Cu and Zn (at the industrial sites), and Cu and As (at the rural sites). The chemical data were then processed using a multivariate approach (ordination, PCA) to better understand environmental gradients. Bioaccumulation data and PCA analysis showed the sampling sites separated by different trace element abundance. Trace element abundance patterns in the three site types are discussed in relation to the land use and the pollution sources.

Ultrastructural changes and Heat Shock Proteins 70 induced by atmospheric pollution are similar to the effects observed under in vitro heavy metals stress in Conocephalum conicum (Marchantiales – Bryophyta)

Changes in ultrastructure and induction of Heat Shock Proteins 70 have been studied in Conocephalum conicum (Marchantiales) collected in different urban and country sites in Italy. These results were compared to the effects in vitro of exposition to different heavy metals for several days. At urban sites, cellular ultrastructure was modified, and heavy metals could be observed accumulating in cell walls. Simultaneously, a strong increment in Hsp70 was detected, compared with results observed on control specimens. When C. conicum was exposed to heavy metals in vitro, comparable effects as in polluted sites were observed: Cd and Pb accumulated mostly within parenchyma and, within cells, were absorbed to cell walls or concentrated in vacuoles. Moreover, severe alterations were observed in organelles. Concomitantly, a progressive accumulation of Hsp70 was detected following heavy metals exposition. These effects are discussed in order to describe the dose and time-dependent response to heavy metal stress in C. conicum.

Physiological and morphological responses of Lead or Cadmium exposed Chlorella sorokiniana 211-8K (Chlorophyceae)

The heavy metal pollution in soils and aquatic environments is a serious ecological problem. In the green-microalga Chlorella sorokiniana 211-8K (Chlorophyceae) exposed to ions of lead (Pb) and cadmium (Cd) we studied the metabolic responses to the toxicity of these two heavy metals. Our data indicate that both the pollutants alter the alga cell ultrastructure and its physiological characteristics (growth, photosynthesis, respiration, enzyme activities). The toxic effects of the two metals resulted time-dependent to the exposure. After 24 h of treatment with 250 μM Pb or Cd, photosynthesis was inhibited until to 77 and 86%, however respiration was strongly enhanced up to 300 and 350%, respectively. In the algal cells Pb or Cd exposure induced a reduction in the content of the total chlorophylls and a decrease of the soluble protein levels, significantly compromising the growth, particularly in cultures cadmium-treated. We report data on ultrastructural changes induced by the two heavy metals; they affected overall chloroplast ultrastructure of the alga. Most importantly, the O-acetyl-L-serine(thiol)lyase (OASTL) activity was appreciably increased after only 2 h of Cd exposure, indicating the existence of a link between the metal contamination and cysteine synthesis. Then, Chlorella sorokiniana cells seem to better tolerate high concentrations of Pb while appear to be more sensitive to Cd ions. These results provide some additional information that can lead to better understand consequences of heavy metal poisoning in microalgae.

Antibacterial activity in Pleurochaete squarrosa extract (Bryophyta)

An acetone extract of the moss Pleurochaete squarrosa was tested against eleven bacterial strains, some of which are pathogenous for man. The extract was active on some Gram-negative strains. Antibacterial activity of the extract, expressed as MICs, was compared with three reference antibiotics. Acute toxicity assay was performed in Balb C mice.