Alessandra Bertoli

Rubia tinctorum a source of natural dyes: agronomic evaluation, quantitative analysis of alizarin and industrial assays

Common madder (Rubia tinctorum L.) produces anthraquinone pigments in its roots, one of them being alizarin (1,2 dihydroxy anthraquinone) which has been used for dyeing textiles since 2000 B.C. Four madder genotypes were evaluated for their agronomic characteristics as well as for their industrial value in order to test this species domestication potential for the Mediterranean area and to assess its value as a new industrial dye crop. Pigments were separated from methanolic and ethereal extracts and quantified by HPLC. Good agronomic performance was observed in the different accessions of R. tinctorum which were tested. Root yield increased from young (5 months old) to mature plants (30 months old) reaching a mean value of 120 g plant−1, which corresponds to a yield of 8 t ha−1. Variation in yield capacity was observed among the different accessions. Young roots showed a higher alizarin content than 15 and 30 month old plants. However, the total amount of alizarin present in a plant increased from 181.8 mg plant−1 to 917.8 mg plant−1 in 5 to 30 month old plants. A range of variation in alizarin content was established for genetic differences within madder. Industrial assays demonstrated good performance when using a weight of dry powder which is 30% of the weight of material to be dyed for dyeing cotton, wool and silk yarns. Resistance to fading appears to be fairly good for dyed wool.

Agronomic potential of Reseda luteola L. as new crop for natural dyes in textiles production

Abstract Six weld genotypes ( Reseda luteola L.) were evaluated for their agronomic characteristics in a 4-year field study carried out under rainfed condition in Central Italy in order to point out productive potential and the best harvest time to maximise yield of dye. Good agronomic performances were observed with an overall dry yield of about 40 g per plant and an estimated dry yield per hectare of 2.8 tons. Differences were found among the six accessions and some of them withstanded well to drought conditions experienced in drier growing seasons. The harvest of plants during flowering or during beginning of fruit ripening did not affect overall dry yield (40 and 45 g per plant at flowering and fruit maturity, respectively). The luteolin amount (expressed in mg g −1 dry weight) was affected by climatic conditions as experienced in two different growing seasons (1993 and 1994) and by the plant phenological stages at harvest being luteolin most abundant in the dryest year and in plants harvested during flowering. Genetic variability existed for the luteolin content in leaves plus reproductive structures (inflorescences and fruits) that varied from 13.6 to 28.7 mg g −1 dry weight in the six accessions tested in 1994. The dry powder from leaves and reproductive structures was used in the dyeing of cotton, wool and silk yarns. Good and bright yellow colours were observed using a ratio 30:100 (weight/weight) of weld on the textile materials. Separated weld organs showed different dyeing capacities being the leaves, inflorescences and fruits the most effective ones. Weld showed a progressive decrease in resistance to fading going from cotton, to the other kind of yarns. Finally, all dyed specimens exhibited good resistance to light and wash fastness making the use of weld a viable alternative to synthetic yellow dyes.

Plant Cell Cultures: Bioreactors for Industrial Production

The recent biotechnology boom has triggered increased interest in plant cell cultures, since a number of firms and academic institutions investigated intensively to rise the production of very promising bioactive compounds. In alternative to wild collection or plant cultivation, the production of useful and valuable secondary metabolites in large bioreactors is an attractive proposal; it should contribute significantly to future attempts to preserve global biodiversity and alleviate associated ecological problems. The advantages of such processes include the controlled production according to demand and a reduced man work requirement. Plant cells have been grown in different shape bioreactors, however, there are a variety of problems to be solved before this technology can be adopted on a wide scale for the production of useful plant secondary metabolites. There are different factors affecting the culture growth and secondary metabolite production in bioreactors: the gaseous atmosphere, oxygen supply and CO2 exchange, pH, minerals, carbohydrates, growth regulators, the liquid medium rheology and cell density. Moreover agitation systems and sterilization conditions may negatively influence the whole process. Many types ofbioreactors have been successfully used for cultivating transformed root cultures, depending on both different aeration system and nutrient supply. Several examples of medicinal and aromatic plant cultures were here summarized for the scale up cultivation in bioreactors.

Antimicrobial and antifungal activity of crude extracts and isolated saponins from Astragalus verrucosus

The antimicrobial and antifungal properties of several crude extracts and pure saponins, astraverrucins I-VI, from the aerial parts of Astragalus verrucosus were investigated by the disc diffusion method. Antimycotic activity was observed on more polar extracts, but only one saponin showed an appreciable activity.

Minor constituents from Bupleurum fruticosum roots

A new triterpenoid saponin, 23-acetoxy,16 alpha-hydroxy-13,28-epoxyolean-11-en-3 beta-yl--beta-D-glucopyranosyl- (1-->2)---beta-D-glucopyranosil(1-->3)-beta-D-fucopyranoside, has been isolated from the roots of Bupleurum fruticosum, along with eight coumarins, scopoletin, scoparone, prenyletin, capensin, fraxetin, aesculetin,7-(3-methyl-2-butenyloxy-6-methoxycoumarin, 7-(2-hydroxy-3-methyl-3-butenyloxy)-6-methoxycoumarin and 5,7-dihydroxy-6-methoxy-8-(3-methyl-2-butenyl)coumarin. The last compound has not been previously encountered in nature. The structures were determined by analysis of NMR spectral data including two-dimensional techniques.

Hairy Root Cultures for Secondary Metabolites Production

Hairy roots (HRs) are differentiated cultures of transformed roots generated by the infection of wounded higher plants with Agrobacterium rhizogenes. This pathogen causes the HR disease leading to the neoplastic growth of roots that are characterized by high growth rate in hormone free media and genetic stability. HRs produce the same phytochemicals pattern of the corresponding wild type organ. High stability and productivity features allow the exploitation of HRs as valuable biotechnological tool for the production of plant secondary metabolites. In addition, several elicitation methods can be used to further enhance their accumulation in both small and large scale production. However, in the latter case, cultivation in bioreactors should be still optimized. HRs can be also utilised as biological farm for the production of recombinant proteins, hence holding additional potential for industrial use. HR technology has been strongly improved by increased knowledge of molecular mechanisms underlying their development. The present review summarizes updated aspects of the hairy root induction, genetics and metabolite production.

Synthesis and properties of glycerylimidazolium based ionic liquids: a promising class of task-specific ionic liquids

A series of task-specific ionic liquids (TSILs) based on glycerylimidazolium cations have been prepared by reaction of 1-chloropropanediol, a compound obtainable from glycerol (a widely available and in-expensive waste product), with the appropriate base (1-H-imidazole, 1,2-dimethylimidazole and 1-methyl-1-H-imidazole). The reaction of 3-(1H-imidazol-1-yl)propane-1,2-diol with chloroalkanes, bromoalkanes and alkyl mesylates gave the corresponding salts which were characterized. The possibility to use these ILs in palladium catalyzed reactions was evaluated, evidencing good catalyst stability and a high recyclability.

Antimicrobial activity of crude extracts and pure compounds of Hypericum hircinum

The antimicrobial activity of the n-hexane (H) and chloroform (C) extracts, the methanol extract (M) and its ethyl acetate (E) and n-butanol (B) fractions, and six isolated constituents of the aerial parts of Hypericum hircinum was investigated using an agar diffusion method. The maximum activity was exhibited by the methanolic extract against Staphylococcus aureus, while all pure constituents showed no antimicrobial activity against the tested microorganisms.

Bioactive Constituent Production in St. John’s Wort in Vitro Hairy Roots. Regenerated Plant Lines†

A wild strain of Agrobacterium rhizogenes was used to regenerate twelve in vitro plant lines from different hairy roots of H. perforatum (St. Johns Wort). The production of the main bioactive constituents was observed even though their yields varied in the different plant lines. Two lines were selected for the hyperoside production (4.9-4.6 mg/gdw) while nine were characterized by significant yields of chlorogenic acid (ranged from 0.47 to 1.09 mg/gdw). Furthermore, one out of twelve lines showed a 10-fold higher hypericin content (0.25 mg/gdw) than that reported for the in vitro shoots in the literature. Morphological and phytochemical features were determined in order to select H. perforatum genotypes enriched in valuable bioactive compounds.

Estradiol-antagonistic Activity of Phenolic Compounds from Leguminous Plants

Natural flavonoids are currently receiving much attention because of their estrogenic and antiestrogenic properties. Six isoflavones (isoprunetin, isoprunetin 7‐O‐β‐d‐glucopyranoside, isoprunetin 4′,7‐di‐O‐β‐d‐glucopyranoside, genistein, genistein 7‐O‐β‐d‐glucopyranoside, daidzein), four flavones (luteolin, luteolin 7‐O‐β‐d‐glucopyranoside, luteolin 4′‐O‐β‐d‐glucopyranoside, licoflavone C), isolated from Genista morisii and G. ephedroides (two Leguminosae plants of the Mediterranean area) together with two structurally related pterocarpans, bitucarpin A and erybraedyn C, isolated from Bituminaria bituminosa (Leguminosae), were tested for the antagonist activity by a yeast based estrogen receptor assay (Saccharomyces cerevisiae RMY326 ER‐ERE). Most compounds inhibited the estradiol‐induced transcriptional activity in a concentration dependent manner. In particular, for the flavone luteolin 77% inhibition of the induced β‐galactosidase activity was observed. Interestingly, licoflavone C exhibited a dose‐dependent antagonistic activity at concentrations up to 10−4 m, but stimulated β‐galactosidase expression at higher concentrations resulting in a U‐shaped‐like dose‐response curve. Copyright