Plant Fibers and Phenolics: A Review on Their Synthesis, Analysis and Combined Use for Biomaterials with New Properties

Abstract

Devising environmental-friendly processes in biotechnology is a priority in the current economic scenario. We are witnessing a constant and steady push towards finding sustainable solutions to societal challenges by promoting innovation-driven activities minimizing the environmental impact and valorizing natural resources. In bioeconomy, plants are among the most important renewable sources of both fibers (woody and cellulosic) and phytochemicals, which find applications in many industrial sectors, spanning from the textile, to the biocomposite, medical, nutraceutical, and pharma sectors. Given the key role of plants as natural sources of (macro)molecules, we here provide a compendium on the use of plant fibers functionalized/impregnated with phytochemicals (in particular phenolic extracts). The goal is to review the various applications of natural fibers functionalized with plant phenolics and to valorize those plants that are source of both fibers and phytochemicals.Fibers 2019, 7, 80 2 of 17 secreting enzymes acting on cell wall polysaccharides [7] (e.g., pectinases degrading the middle lamellas which "glue" together the bundles of bast fibers).Fibers 2019, 7, x FOR PEER REVIEW 2 of 17 (fungi, such as Ascomycota, Basidiomycota, and Zygomycota and bacteria belonging to the phyla Proteobacteria, Bacteroidetes, Actinobacteria, and Firmicutes [6]) secreting enzymes acting on cell wall polysaccharides [7] (e.g., pectinases degrading the middle lamellas which "glue" together the bundles of bast fibers). Figure 1. Cross section of the stem of a representative fiber crop, stinging nettle (Urtica dioica L.), and details of enzyme-treated cortical peels with some separated bast fibers. (a) Transversal cross section stained with Safranin and Alcian blue (FASGA staining), showing in blue the cellulosic bast fibers and in red lignin; (b) cortical peels separated from the stem bottom internodes and treated for 24 h at 50 °C with TEXAZYM BFE (INOTEX Ltd, Czech Republic) showing some separated bast fibers; the inset shows one separated bast fiber.The use of plant fibers provides several advantages, namely breathability and comfort in case of skin irritations/allergies [8]. Adding to them anti-microbial and anti-oxidant effects greatly widens their spectrum of applications to, for example, the manufacture of technical textiles, such as those used for wound healing. Notably, plants are also rich sources of phytochemicals showing antioxidant and bactericidal/fungicidal effects. Some plant species, such as the fiber crops hemp and nettle, are multi-purpose, as they produce both high yields of cellulosic fibers and phytochemicals [2,9].In this review we will illustrate recent examples of natural fibers functionalized (i.e., with a chemical bond) or impregnated with phytochemicals (more specifically phenolics which show strong antimicrobial activities thanks to their chemical heterogeneity [10]). The goal is to highlight the value of plants as renewable resources of biomass (fibers) on one hand and of molecules with biological effe...

Anticancer Activities of Marine-Derived Phenolic Compounds and Their Derivatives

“…Since the only difference between 43 and 44 is the absence and presence of the acetoxy group, it can be assumed that acetylation of 43 decreased biological activities. Interestingly, 43 and 44 were remarkably active against Chinese hamster fibroblasts (V79), unlike stypodiol (45), which showed little effect on normal cells [181]. The neurotoxicity of meroditerpenes from S. flabelliforme was also demonstrated by Sabry and co-workers [183].…”

“…The highest activity of almost 100% inhibition of cell proliferation was observed against human neuroblastoma cells (SH-SY5Y) for all compounds. Even though the authors did not provide the exact IC 50 values, they can be clearly seen from the reported graphical representations as 6.25-12.5, <12.5 and 12.5-25 µM for epitaondiol (43), epitaondiol monoacetate (44) and stypodiol (45), respectively. Since the only difference between 43 and 44 is the absence and presence of the acetoxy group, it can be assumed that acetylation of 43 decreased biological activities.…”

“…The development of the efficient syntheses of the desired biologically active metabolites, with the aim of preserving the marine ecosystem, is thus often essential [44]. The understanding of secondary metabolites biosynthesis in organisms could aid to the establishment of bioinspired synthesis and development of new synthetic strategies [45].…”

“…The key enzyme is phenylalanine ammonia-lyase (PAL), which is responsible for the formation of cinnamic acid. Next, cinnamic acid is transformed into p-coumarid acid by cinnamate 4-hydroxlyase (C4H) [45,48,49].…”

Vegetable Additives in Food Packaging Polymeric Materials

“…In this review, various applications of plants used as bioresources are discussed, providing valuable raw materials used as additives in polymeric matrices, such as lignocellulosic fibers [69] and nano-cellulose [70], as well as plant extracts containing bioactive phenolic compounds [42] used in the pharmaceutical and cosmetic industries [71]. The increasing environmental concerns draw attention on their use as active compounds, instead of synthetic ones.…”