Evernia prunastri lichen as a source of bioactive glucans with potential for topical applications.

Microwave hydrothermal treatment was selected to extract valuable fractions with bioactive and gelling properties from Evernia prunastri lichen with potential for topical applications. The impact of the extraction processing conditions on the soluble extracts, mucilage fraction and residual solid phase was analyzed within a lichen global valorization approach. A particular stress was made on the thermo-rheological and structural characteristics of the extracted glucan and galactomannan polymers, the corresponding gelled matrices, and their cosmetic feasibility. Results revealed that the proposed microwave-assisted treatment showed a relevant influence on the phytochemical features of the aqueous soluble extracts, accounting the major protein content at 120 °C and the enhanced antioxidant and anti-tyrosinase properties at 140 °C. Extracts at 200 °C showed the highest anti-inflammatory (COX-1 and COX-2 inhibition) efficacies. The biopolymer analyses indicated that those recovered after lichen hydrothermal treatment at 160 °C featured a good extraction performance, the highest molecular weight, apparent viscosity, and antiproliferative potential. The thermo-rheological properties of the corresponding matrices formulated at 10 % and 60 or 80 °C exhibited the strongest and most thermo-reversible characteristics, as well as antifreezing feasibility. Another advantage of the selected fractions was the absence of skin irritation according to the in vitro skin irritation assay.

Microwave-assisted extraction of Ulva spp. including a stage of selective coagulation of ulvan stimulated by a bio-ionic liquid.

Microwave-assisted hydrothermal processing was proposed to recover high valuable compounds with antioxidant and gelling features from Ulva spp. green seaweed. The influence of the extraction conditions on the solubles, ulvan fraction and residual solid phase was studied to achieve a global valorization of the seaweed. A particular emphasis was placed on the selective coagulation of ulvan stimulated by a bio-ionic liquid during the extraction process. The achieved outcomes indicated that the selected microwave treatment exhibited a notable impact on the phytochemical properties of the soluble extracts, with the highest values of sulfate and protein content at 160 °C, and the highest antioxidant features at 200 °C. The most prominent molecular weight distributions were also identified for systems hydrothermal treated at 160 °C. The ulvan analyses showed that those extracted after microwave treatment at 160 °C showed the highest yields, molecular weight and the strongest gel features from the rheological point of view. The presence of the chloride chlorine during the extraction process favored the ulvan performance and the enhancement of the corresponding viscoelastic properties.

Spray-drying microencapsulation of tea extracts using green starch, alginate or carrageenan as carrier materials.

Tea industry generates many by-products which could be used to produce and incorporate bioactive tea extracts (TE) into nutraceuticals, cosmetics and/or clinical applications. However, sensibility to external factors is a major disadvantage hindering its utilization. This study deals with the implementation and characterization of suitable biopolymer delivery systems based on starch, carrageenan or alginate, as microencapsulation, to stabilize and protect TE through innovative thin-carbohydrate-coated formulations. TE were spray-dried and microencapsulated in recycled carrier materials (alginate, carrageenan or starch). Product yields varied from 55 to 58%. High microencapsulation and loading efficiencies were achieved (60-93% and 65-84%, respectively). Antioxidant capacity varied from 32 to 46 g Trolox/100 g extract, within different carrier-systems; which also showed promising rheological and UV-protective properties when transformed into gels. Total phenolic content, particle-size distribution, HPSEC-analysis, SEM-analysis and FTIR-analysis were also performed. In sum, this paper characterizes and discusses the high potential of these recycled carbohydrate-coated microparticles for future applications.

Microwave hydrothermal processing of Undaria pinnatifida for bioactive peptides.

Microwave hydrothermal processing was employed to obtain valuable gelling or bioactive fractions from U. pinnatifida, assessing the processing conditions following a biorefinery concept. It was identified a relevant impact on the antioxidant properties, sulfate, protein and oligosaccharides content, with the highest values above 200 °C, although the maximum in fucose was obtained at 160 °C. The lowest temperature involved the highest minerals and sulfate content of the solid phases. Rheology indicated that hydrothermal treatment at 160 °C is adequate to extract alginates with structural and viscoelastic properties similar to those commercially available. The incorporation of the hydrothermal residual solids in the proposed alginate matrices favored the development of systems with potential non-food applications applications. Selected extracts, after an intensification stage using ultrasound, featured interesting biological activities for two human cancer cell lines (A2780; HeLa 229) with percentage of cellular inhibition > 83 and 57%, without positive effects on A549 and HCT-116.

Chondrus crispus treated with ultrasound as a polysaccharides source with improved antitumoral potential.

Ultrasound-assisted extraction was used to recover gelling biopolymers and antioxidant compounds from Chondrus crispus with improved biological potential. The optimal processing conditions were evaluated using a Box-Behnken design, and the impact on the biological and thermo-rheological properties of the carrageenan fraction and on the bioactive features of the soluble extracts were studied. The optimum extraction parameters were defined by extraction time of ~34.7 min; solid liquid ratio of ~2.1 g/100 g and ultrasound amplitude of ~79.0% with a maximum power of 1130 W. The dependent variables exhibited maximum carrageenan yields (44.3%) and viscoelastic modulus (925.9 Pa) with the lowest gelling temperatures (38.7 °C) as well as maximum content of the extract in protein (22.4 mg/g), gallic acid (13.4 mg/g) and Trolox equivalents antioxidant capacity (182.4 mg TEAC/g). Tested hybrid carrageenans exhibited promising biological activities (% of growth inhibition around 91% for four human cancer cellular lines: A549; A2780; HeLa 229; HT-29).

Eco-friendly extraction of Mastocarpus stellatus carrageenan for the synthesis of gold nanoparticles with improved biological activity.

Carrageenan was extracted from Mastocarpus stellatus using hot water extraction under atmospheric and pressurized conditions. The influence of heating temperature during a non-isothermal heating profile up to temperatures in the range 70-190 °C was studied to evaluate the extraction yields and properties of the carrageenan fraction. Under the selected conditions (130 °C), extracted carrageenan (CMs) was used for the green synthesis of gold nanoparticles (AuNPs). After the optimization of the reaction conditions, the synthesized gold nanoparticles (Au@CMs) were characterized by UV-Vis spectroscopy, Z potential measurements, electron microscopy, and X-ray diffraction analysis, which confirmed the formation of spherical, polycrystalline, and negatively charged nanoparticles with a mean diameter of 14.3 ± 2.1 nm. The study conducted by scanning transmission electron microscopy, energy dispersive X-ray analysis and mapping confirmed the presence of carrageenan stabilizing AuNPs. Finally, Fourier transformed infrared spectroscopy was performed to analyze the functional groups of CMs involved in the reduction and stabilization of AuNPs. The selective cytotoxicity and the antioxidant activity of the Au@CMs were evaluated in different cell lines and compared to the CMs. Au@CMs showed an improved antioxidant capacity in cells under oxidative stress and the induction of apoptosis in a monocytic cell line, while no antitumor effect was observed in a lung endothelial cell line.

Valorisation of Camellia sinensis branches as a raw product with green technology extraction methods.

This work deals with the study of tea stalks from pruning debris using environmental friendly extraction technology to offer new healthy properties. In the manufacturing tea industry, tea trees require to be pruned every year and most of their remains are discarded as a waste with no economic value. Microwave aqueous extraction and pressurized hot water extraction process (autohydrolysis) were used to recover bioactive compounds from the tea branches. Operating at a fixed solid: liquid ratio (1:15), the effect of the maximum heating temperatures from 140 to 220 °C was studied. Liquid extracts were analysed for total phenolic, oligosaccharides, protein, mineral and heavy metals content, as well as for antioxidant capacity. The antitumoral possibilities were also determined for selected samples. The obtained results indicated that both processes could be used as an alternative to recover bioactive compounds from tea wastes, although microwave-assisted extraction allowed saving time when compared with autohydrolysis processing. The temperature exhibited a relevant effect on the total phenolic content and antioxidant capacity, decreasing with the microwave treatment and increasing with the autohydrolysis temperature. The obtained extracts could be adequate for incorporation in food and non-food fields.

Tailoring hybrid carrageenans from Mastocarpus stellatus red seaweed using microwave hydrodiffusion and gravity.

This work deals with the use of microwave hydrodiffusion and gravity (MHG) for the recovery of hybrid carrageenans with specific mechanical features together with bioactive compounds. For this purpose, Mastocarpus stellatus red seaweed was used as raw material and the most adequate MHG processing conditions were studied. The physicochemical properties of the algae and the corresponding biopolymers, the fundamental characterisation of the bioactive compounds from the extracts (antioxidant capacity, sulfate content, protein content, among others) and the rheological features of the formulated gels were analysed. Results indicated that MHG is an adequate technique for obtaining functional extracts with potential applications in the food and non-food fields. Hybrid carrageenans with a wide range of viscoelastic features were recovered by MHG, saving time compared to conventional methods. The yields obtained for the recovered hybrid carrageenans and bioactive fractions were comparable to those obtained in red algae with conventional techniques.

A green approach for alginate extraction from Sargassum muticum brown seaweed using ultrasound-assisted technique.

Ultrasound assisted aqueous extraction of alginate from Sargassum muticum was proposed to minimize the use of chemicals, high temperatures and prolonged times, with comparable extraction yields to conventional acid/alkali procedures. The alginate, precipitated from the liquors obtained after ultrasound assisted extraction of fucoidan and phlorotannin fractions, and converted to alginic acid sodium salt by a green treatment was characterized by FTIR-ATR, 1H NMR, HPSEC, MALDI-TOF, rheology and citotoxitity. A clear influence of the sonication time was observed on the alginate molar mass, block structure, thermo-rheological and tumoral cell growth inhibition features. All tested hydrogels featured stable and thermo-reversible characteristics.