Raúl Rodríguez-Herrera

Ultrasound-assisted extraction of phenolic compounds from Laurus nobilis L. and their antioxidant activity.

Bay leaves (BL) (Laurus nobilis L., Family: Laureceae) are traditionally used to treat some symptoms of gastrointestinal problems, such as epigastric bloating, impaired digestion, eructing and flatulence. These biological properties are mainly attributed to its phenolic compounds. In this paper, ultrasound-assisted extraction of phenolic compounds from Laurus nobilis L. (Laureceae) was studied. Effects of several experimental factors, such as sonication time, solid/liquid ratio and concentration of solvent on extraction of phenolic compounds were evaluated through a randomized complete block design with factorial treatment arrangement (3(3)). The best extraction conditions were: 1g plant sample with 12 mL of 35% ethanol, for 40 min, obtaining a yield of phenolic compounds of 17.32±1.52 mg g(-1) of plant. In addition, free radical-scavenging potential of DPPH and lipid oxidation inhibition, by linoleic acid peroxidation of the selected extract was measured in order to evidence their antioxidant properties. Results indicated that high amounts of phenolic compounds can be extracted from L. nobilis by ultrasound-assisted extraction technology.

Halophilic hydrolases as a new tool for the biotechnological industries.

Halophilic micro-organisms are able to survive in high salt concentrations because they have developed diverse biochemical, structural and physiological modifications, allowing the catalytic synthesis of proteins with interesting physicochemical and structural properties. The main characteristic of halophilic enzymes that allows them to be considered as a novel alternative for use in the biotechnological industries is their polyextremophilicity, i.e. they have the capacity to be thermostable, tolerate a wide range of pH, withstand denaturation and tolerate high salt concentrations. However, there have been relatively few studies on halophilic enzymes, with some being based on their isolation and others on their characterisation. These enzymes are scarcely researched because attention has been focused on other extremophile micro-organisms. Only a few industrial applications of halophilic enzymes, principally in the fermented food, textile, pharmaceutical and leather industries, have been reported. However, it is important to investigate applications of these enzymes in more biotechnological processes at both the chemical and the molecular level. This review discusses the modifications of these enzymes, their industrial applications and research perspectives in different biotechnological areas.

Microbial Enzymes Involved in Polyurethane Biodegradation: A Review

Plastics are present in a lot of aspects of everyday life. They are very versatile and resistant to microbial attack. Polyurethanes are used in several industries and are divided in polyester and polyether polyurethanes and there are different types among them. Despite their microbial resistance, they are susceptible to the attack of fungi and bacteria but the mechanism to elucidate its biodegradation are unknown. There are reports from bacteria and fungi that are capable of degrading polyurethane but the studies about the enzymes that attack the plastic are focused on bacterial enzymes only. The enzymes reported are of type esterase and protease mainly since these enzymes are very unspecific and can recognize some regions in the polyurethane molecule and hydrolyze it. Fungal enzymes have been studied prior the 1990s decade but recently, some authors report the use of filamentous fungi to degrade polyurethane and also report some characteristics of the enzymes involved in it. This review approaches polyurethane biodegradation by focusing on the enzymes reported to date.

Novel strategies for upstream and downstream processing of tannin acyl hydrolase.

Tannin acyl hydrolase also referred as tannase is an enzyme with important applications in several science and technology fields. Due to its hydrolytic and synthetic properties, tannase could be used to reduce the negative effects of tannins in beverages, food, feed, and tannery effluents, for the production of gallic acid from tannin-rich materials, the elucidation of tannin structure, and the synthesis of gallic acid esters in nonaqueous media. However, industrial applications of tannase are still very limited due to its high production cost. Thus, there is a growing interest in the production, recovery, and purification of this enzyme. Recently, there have been published a number of papers on the improvement of upstream and downstream processing of the enzyme. These papers dealt with the search for new tannase producing microorganisms, the application of novel fermentation systems, optimization of culture conditions, the production of the enzyme by recombinant microorganism, and the design of efficient protocols for tannase recovery and purification. The present work reviews the state of the art of basic and biotechnological aspects of tannin acyl hydrolase, focusing on the recent advances in the upstream and downstream processing of the enzyme.

Total phenolic content, in vitro antioxidant activity and chemical composition of plant extracts from semiarid Mexican region

OBJECTIVE To determine the extraction suitable conditions of total phenolic content (TPC) by heat-reflux system, antioxidant activities and HPLC characterization of the aqueous-ethanolic extracts of Jatropha dioica (J. dioica) (Dragons blood), Flourensia cernua (F. cernua) (Tar bush), Eucalyptus camaldulensis (E. camaldulensis) (Eucalyptus) and Turnera diffusa (T. diffusa) (Damiana). METHODS TPC was evaluated by the well-known colorimetric assay using Folin-Ciocalteu reagent. The antioxidant activities were assayed by three methods based on scavenging of DPPH, ABTS and by lipid oxidation inhibition. The chemical composition of the extracts obtained was subject to HPLC analysis. RESULTS TPC in the plant extracts ranged from 2.3 to 14.12 mg gallic acid equivalents/g for J. dioica and E. camaldulensis, respectively. The plant extracts of F. cernua, E. camaldulensis and T. diffusa showed similar strong antioxidant activities on scavenging of DPPH and lipid oxidation inhibition. In contrast, J. dioica extracts had lowest potential antioxidant in three assays used. HPLC assay showed the presence of several phenolic compounds in the extracts used. CONCLUSIONS The results obtained suggest that F. cernua, E. camaldulensis and T. diffusa are potential sources to obtain bioactive phenolic compounds with high antioxidant properties which can be used in the factories as antioxidant agents or for treatments in diseases.

Euphorbia antisyphilitica residues as a new source of ellagic acid

In this study, a new source of ellagic acid (EA) is reported. Euphorbia antisyphilitica or “candelilla” was used to extract phenolic dilactone. Cereous layers and fibrous tissue were analyzed. A completely randomized experimental design with a treatment factorial arrangement was employed. The factors considered were: plant/extracting agent ratio, extraction temperature and time. Candelilla wax does not contain EA. Temperature and the ratio plant/extracting agent were determinant during the EA extraction process. Around 20 mg of free EA per gram of fibrous tissue were found. Residues of candelilla are a good source of EA.

Biotechnological production and application of fructooligosaccharides

Abstract Currently, prebiotics are all carbohydrates of relatively short chain length. One important group is the fructooligosaccharides (FOS), a special kind of prebiotic associated to the selective stimulation of the activity of certain groups of colonic bacteria. They have a positive and beneficial effect on intestinal microbiota, reducing the incidence of gastrointestinal infections and also possessing a recognized bifidogenic effect. Traditionally, these prebiotic compounds have been obtained through extraction processes from some plants, as well as through enzymatic hydrolysis of sucrose. However, different fermentative methods have also been proposed for the production of FOS, such as solid-state fermentations utilizing various agro-industrial by-products. By optimizing the culture parameters, FOS yields and productivity can be improved. The use of immobilized enzymes and cells has also been proposed as being an effective and economic method for large-scale production of FOS. This article is an overview of the results considering recent studies on FOS biosynthesis, physicochemical properties, sources, biotechnological production and applications.

Utilization of molasses and sugar cane bagasse for production of fungal invertase in solid state fermentation using Aspergillus niger GH1.

Agro-industrial wastes have been used as substrate-support in solid state fermentation for enzyme production. Molasses and sugarcane bagasse are by-products of sugar industry and can be employed as substrates for invertase production. Invertase is an important enzyme for sweeteners development. In this study, a xerophilic fungus Aspergillus niger GH1 isolated of the Mexican semi-desert, previously reported as an invertase over-producer strain was used. Molasses from Mexico and Cuba were chemically analyzed (total and reducer sugars, nitrogen and phosphorous contents); the last one was selected based on chemical composition. Fermentations were performed using virgin and hydrolyzate bagasse (treatment with concentrated sulfuric acid). Results indicated that, the enzymatic yield (5231 U/L) is higher than those reported by other A. niger strains under solid state fermentation, using hydrolyzate bagasse. The acid hydrolysis promotes availability of fermentable sugars. In addition, maximum invertase activity was detected at 24 h using low substrate concentration, which may reduce production costs. This study presents an alternative method for invertase production using a xerophilic fungus isolated from Mexican semi-desert and inexpensive substrates (molasses and sugarcane bagasse).

Fungal cultures of tar bush and creosote bush for production of two phenolic antioxidants (Pyrocatechol and Gallic acid)

Abstract‘Tar bush’ and ‘creosote bush’ were substrates of fungal cultivation for tannase production and gallic acid and pyrocatechol accumulation. Aspergillus niger GH1 grew similarly on both plant materials under solid state culture conditions, reaching maximal levels after 4 d. Fungal strain degraded all tannin content of creosote bush after 4 d of fermentation and >75 % of tar bush after 5 d. Higher level of tannase activity was detected in tar bush fermentation. Biotransformation of tannins to gallic acid was high (93 % in creosote bush and 89 % in tar bush). Pyrocatechol was released poorly. Kinetic parameters of tannin conversion were calculated.

The complete biodegradation pathway of ellagitannins by Aspergillus niger in solid‐state fermentation

Our research group has found preliminary evidences of the fungal biodegradation pathway of ellagitannins, revealing first the existence of an enzyme responsible for ellagitannins degradation, which hydrolyzes pomegranate ellagitannins and it was called ellagitannase or elagitannin acyl hydrolase. However, it is necessary to generate new and clear information in order to understand the ellagitannin degradation mechanisms. This work describes the distinctive and unique features of ellagitannin metabolism in fungi. In this study, hydrolysis of pomegranate ellagitannins by Aspergillus niger GH1 was studied by solid‐state culture using polyurethane foam as support and pomegranate ellagitannins as substrate. The experiment was performed during 36 h. Results showed that ellagitannin biodegradation started after 6 h of fermentation, reaching the maximal biodegradation value at 18 h. It was observed that ellagitannase activity appeared after 6 h of culture, then, the enzymatic activity was maintained up to 24 h of culture reaching 390.15 U/L, after this period the enzymatic activity decreased. Electrophoretic band for ellagitannase was observed at 18 h. A band obtained using non‐denaturing electrophoresis was identified as ellagitannase, then, a tandem analysis to reveal the ellagitannase activity was performed using Petri plate with pomegranate ellagitannins. The extracts were analyzed by HPLC/MS to evaluate ellagitannins degradation. Punicalin, gallagic acid, and ellagic acid were obtained from punicalagin. HPLC/MS analysis identified the gallagic acid as an intermediate molecule and immediate precursor of ellagic acid. The potential application of catabolic metabolism of ellagitannin hydrolysis for ellagic acid production is outlined.