Dr. Hepp-Castro, Matías

Radiata pine bark is a widely available organic waste, requiring alternative uses due to its environmental impact on soil, fauna, and forest fires. Pine bark waxes could be used as cosmetic substitutes, but their toxicity requires evaluation since pine bark may contain toxic substances or xenobiotics, depending on the extraction process. This study evaluates the toxicity of radiata pine bark waxes obtained through various extraction methods on human skin cells grown in vitro. The assessment includes using XTT to evaluate mitochondrial activity, violet crystal dye to assess cell membrane integrity, and ApoTox-Glo triple assay to measure cytotoxicity, viability, and apoptosis signals. Pine bark waxes extracted via T3 (acid hydrolysis and petroleum ether incubation) and T9 (saturated steam cycle, alkaline hydrolysis, and petroleum ether incubation) exhibit non-toxicity up to 2% concentration, making them a potential substitute for petroleum-based cosmetic materials. Integrating the forestry and cosmetic industries through pine bark wax production under circular economy principles could promote development while replacing petroleum-based materials. Extraction methodology affects pine bark wax toxicity in human skin cells due to the retention of xenobiotic compounds including methyl 4-ketohex-5-enoate; 1-naphthalenol; dioctyl adipate; eicosanebioic acid dimethyl ester; among others. Future research will investigate whether the extraction methodology alters the molecular structure of the bark, affecting the release of toxic compounds in the wax mixture.

The bark of Pinus radiata D. Don is a bioresource of great worldwide abundance. While various forms of use have been studied, it is still a little-used bioresource. Due to its great accumulation, significant solid emissions of this residue generate environmental problems such as changes in soil chemistry, ecological problems such as the alteration of arthropod communities and fire risk. The opportunity to take advantage of this bioresource could be in its wax content, which could be a replacement for the main raw materials used in the production of cosmetics. These currently correspond to petroleum-derived substances, such as petroleum jelly, paraffin, or mineral oil. The importance of replacing these raw materials is that several studies report that they are the main causes of human skin diseases, such as chemical hypersensitivity syndrome and allergic contact dermatitis. This study seeks to prove that lipophilic extracts (waxes) from pine bark can replace petroleum-derived raw materials used in cosmetics. To achieve this, pine bark at drying conditions was characterized, and the performance of wax extraction by various treatments was studied. The density, viscosity, melting point, and solubility in culture media of the obtained waxes were determined. The waxes were chemically characterized by FT-IR and GC–MS analysis. The results reveal that the maximum moisture of the bark is 14.54 %, the best extraction yields are obtained by using water at 120 ◦C and 1.2 atm, and petroleum ether (3.12 %), alkaline hydrolysis 1 mol L− 1 (NaOH) and petroleum ether (3.53 %) ethyl acetate (3.23 %). Values were close to the reference study using the rapid lipid extraction method. The density of the wax is 0.845 g mL− 1 and its viscosity of 530 cP (24 ◦C), and the melting point varied according to the extractive treatment at between 25 and 40 ◦C. Solubility tests made it possible to determine that the 10/50/1000 μL ratio of modified Eagle Dulbecco wax/dimethylsulfoxide/medium allows homogeneous solubilization of the wax without the presence of precipitates. Chemical characterization identified typical functional groups of plant-based waxes such as long-chain alkanes, alkyls, methyl groups, esters, and carbonyls, with the most abundant fatty acids being C:22 and C:24.