Paola Arfaioli

Quantitative Determination of Some Essential Oil Components of Selected Artemisia absinthium Plants

ABSTRACT The essential oils obtained by steam distillation of leaves and flowers of 49 selected Artemisia absinthium mother plants of different geographical origins which were grown in Tuscany (Carmignano, Firenze), were analyzed by GC. More than 90 compounds were found in the oils, most of which occurred only in trace amounts. Eight components, which have been reported to have antibacterial activity (α- and β-thujone, terpinen-4-ol, linalool, nerol, geraniol, α-pinene, 1,8-cineole) were identified and their percentages in each of the oils were determined. From these results, oil composition variations both within and between the accessions were found. Some genotypes were characterized by particularly high percentages of active principles.

Conventional, organic and biodynamic farming: differences in polyphenol content and antioxidant activity of Batavia lettuce

BACKGROUND Lactuca sativa L. ssp. acephala L., cv. Batavia red Mohican plants were cultivated under intensive conventional, organic and biodynamic farming and were analyzed for their polyphenol content and antiradical activity in order to demonstrate the influence of farming on yield, polyphenol content and antiradical activity. RESULTS The yield of plants from conventional farming was the highest (2.89 kg m⁻²), while polyphenol content, measured by spectrophotometry, of these plants was lower at P < 0.05 (1.36 mg g⁻¹) than the content of plants from organic and biodynamic farming (1.74 and 1.85 mg g⁻¹, respectively). The antiradical activity, measured by DPPH · assay, was positively correlated to flavonoid and hydroxycinnamic acid contents. CONCLUSION Flavonoid, hydroxycinnamic acid and anthocyan patterns were not affected by the type of cultivation, while quantitative differences were demonstrated and some differences were found between conventional farming and organic or biodynamic farming. The yield of conventionally grown salads was the highest.

Polyphenol Content of Modern and Old Varieties of Triticum aestivum L. and T. durum Desf. Grains in Two Years of Production

Antiradical activity and total polyphenol and flavonoid contents of modern and old varieties of durum (9 varieties) and soft (17 varieties) wheat grains, sampled over two years (summer 2007 and 2008) in the same site, were determined in order to point out differences among varieties and between old and modern varieties. Nine compounds were identified by means of HPLC/MS, and their amount was determined. No correlation was found between antiradical activity and polyphenol or flavonoid contents. The temperature conditions in the 30 days before harvesting were the principal factor which differentiated the quantitative profile of polyphenols and the antiradical activity of the seeds (p < 0.001): high temperatures cause a drop in polyphenol content.

Study of the Maillard reaction products formed by glycine and D-glucose on different mineral substrates

Abstract This work deals with the formation of humic-like compounds, products of the Maillard reaction between glycine and D-glucose, on clay (K+, Ca2+ and Al3+-saturated montmorillonite and kaolinite) and quartz systems in the presence of the same cations. Natural quartz was used as the control while the effect of cation type, mineral substrate and CEC was evaluated. All the systems form humic-like substances that are probably responsible for the decrease in the pH (H2O) after 30 d. The type of cation does not influence the overall production of humic substances, while the amount of cations controls the formation of humic-like material especially in the presence of clays. A mineral surface is necessary to synthesize molecules with this high degree of complexity. Fulvic-like compounds are produced in great amounts on natural quartz and their formation is hampered by the presence of ‘free’ cations, regardless of their amount. Humic substances do not penetrate the interlayer of montmorillonite.

Study of the humic-like compounds formed from L-tyrosine on homoionic clays

Abstract The ability to produce humic-like polymeric compounds, with L-tyrosine as the starting material, was evaluated using different mineral systems, e.g. on Ca-, Al- and Cu(II)-saturated montmorillonite, nontronite and kaolinite, and on quartz. Clay minerals proved to be effective in the formation of these compounds, but not quartz, except in the presence of Cu(II). The newly formed compounds were fractionated by alkaline extraction. With clay systems, the amounts of substances produced appear to be related more to the interlayer cation than to the clay type. Copper cations appear to be more effective when not associated with the clay structure.

Effects of slope exposure on soil physico-chemical and microbiological properties along an altitudinal climosequence in the Italian Alps

Due to their sensitivity to changing environmental conditions sub- and alpine soils are often monitored in the context of climate change, usually, however, neglecting slope exposure. Therefore, we set up a climosequence-approach to study the effect of exposure and, in general, climate, on the microbial biomass and microbial diversity and activity, comprising five pairs of north (N)- and south (S)-facing sites along an altitudinal gradient ranging from 1200 to 2400m a.s.l. in the Italian Alps (Trentino Alto Adige, Italy). Soil physico-chemical properties were related to microbiological properties (microbial biomass: double strand DNA yield vs. substrate-induced respiration; diversity of bacterial, fungal and archaeal communities: genetic fingerprinting DGGE vs. real-time PCR; microbial activity: basal respiration vs. multiple hydrolytic enzyme assays) to monitor shifts in the diversity and activity of microbial communities as a function of slope exposure and to evaluate the most determinant chemical parameters shaping the soil microbiota. The exposure-effect on several hydrolytic key-enzymes was enzyme-specific: e.g. acid phosphomonoesterase potential activity was more pronounced at the N-facing slope while the activities of alkaline phosphomonoesterase, pyrophosphate-phosphodiesterase and arylsulfatase were higher at the S-facing slope. Furthermore, this exposure-effect was domain-specific: bacteria (S>N, altitude-independent); fungi (N~S); and archaea (N>S; altitude-dependent). Additionally, the abiotic parameters shaping the community composition were in general depending on soil depth. Our multidisciplinary approach allowed us to survey the exposure and altitudinal effects on soil physico-chemical and microbiological properties and thus unravel the complex multiple edaphic factor-effects on soil microbiota in mountain ecosystems.

Humic-like compounds formed from l-tryptophan and d-glucose in the presence of CU (II)

Abstract This study concerns the humic-like polymeric compounds formed by D-glucose plus L-tryptophan and by L-tryptophan alone, both on Cu-saturated nontronite, montmorillonite and kaolinite and on quartz in the presence of Cu(II) ions. These mineral-organic systems were kept in thermostat at 70°C for 30 days and submitted to alternate wetting-drying cycles. Higher amounts of humic-like compounds were extracted from quartz-organic than from clay-organic systems, showing the remarkable action of Cu(II), which even overcame the high catalytic power of clays.

Adsorption of the herbicides alachlor and metolachlor on two activated charcoals

Abstract The adsorption-desorption processes of two anilidic herbicides, alachlor and metolachlor, that can produce residue problems in soils, on two activated carbons commercially available Norit W 52 and Gro-Safe have been studied. Adsorption isotherms are of type H1 according to the Giles classification and fit the Langmuir equation. The results show high adsorption values at low concentrations: the adsorption capacity of Norit was always greater than Gro-Safe one and the affinity for the carbons was higher for alachlor than for metolachlor. In all cases we can suggest the formation of a monomolecular film of herbicide adsorbed on the two charcoals considered.

Interactions of two acetanilide herbicides with clay surfaces modified with Fe(III) oxyhydroxides and hexadecyltrimethyl ammonium

Abstract The adsorption at 22° and 5°C of two acetanilide herbicides (Alachlor and Metolachlor) on montmorillonite saturated with HDTMA+ cation or coated with Fe(III) oxyhydroxides (modified clays) was studied. The isotherms were of L, S and C type depending on the type of the adsorbent. The calculated values of isosteric adsorption heat (ΔH) and desorption experiments suggest that weak bonds take place. FT-IR analyses showed that both molecules are adsorbed on clays by hydrogen bond between the C-O group and OH groups of Fe(III) oxyhydroxy cation coating the clay. Also on HDTMA-Montmorillonite the C-O group is involved in the adsorption but with lower strenght. Alachlor is only partially decomposed to 2-chloro-2′,6′-diethylacetanilide when the dirty clays complexes are heated at 70°C for 18 h. X-ray analyses showed that both herbicides were unable to penetrate into the inter-layers of the clays.

Synthesis and Characterization of Maillard Compounds Formed under Sterile Conditions on Sand‐ and Silt‐Sized Mineral Substrates

Abstract Maillard compounds were synthesized from D‐glucose and glycine to mimic the separation of particles during a volcanic eruption so that the role of quartz and volcanic ash, fractionated into silt‐ and sand‐size particles, could be tested under sterile conditions. The obtained polymers were separated into two fractions of 1000–8000 and >8000 Daltons. The results evidence the formation of humus‐like polymers from simple compounds and show the importance of substrate mineralogy. Specifically, a) humic‐like polymers can form in the absence of microbial life, b) the role of particle size is important, c) mineral substrates enhance their yields, d) the polymers on volcanic ash and quartz show differences, e) their structure changes with time, f) at the end of the experiments there is an increase of unsaturation while the aliphaticity decreases, and g) the yields of the compounds of 1000–8000 Daltons decrease with time unlike those >8000.