# Blyproducts as a Sustainable Source of Cosmetic Ingredients
## 2 Byproducts in Cosmetics
### Plant-Based Byproducts  
When considering the application of plant byproducts in cosmetics, the possible sources are vast, with applications in almost all aspects of cosmetics. Plant-based byproducts in the agro-food industry are estimated to produce 1.3 billion tons of residues yearly, with skins, peels, seeds, leaves, and other inedible factions being the main residues produced [49]. These byproducts have the advantage of being rich in a plethora of so-called \"secondary\" metabolites which are known to exert beneficial effects in human health [4]. Of these metabolites, the most known ones are phenolic compounds, and their application in cosmetics can be either as promising bioactive compounds, such as photoprotective agents that can prevent photodamage, skin melanoma, and UV-induced skin ageing, or as structural elements capable of preserving the integrity of the cosmetic formulation through their antimicrobial or antioxidant potential [50]. Another family of compounds attained from plant byproducts with potential for cosmetic application are carotenoids. These pigments can also be used for UV protection due to their antioxidant activity, thus preventing photodamage [51]. Polysaccharides can also be attained from plant residues, and their application in cosmetics can be divided into two categories, structural and bioactive. In the first, polysaccharides application is centered upon the moisture absorption capacities, which allows their application in formulations as a moisturizing agent [52]. In the second, polysaccharides are used as bioactive agents within the formulation, capable of skin immunomodulation, wound healing, and even skin whiteners due to their antioxidant activity [51]. Plant-based lipids are also among the compounds attained from plant byproducts with potential cosmetic applications. These compounds are mainly used as barrier repair agents due to their potential to immerse themselves in the lipidic component of the skin stratum corneum, but they can also be used as moisturizers, anti-inflammatory, and wound healing compounds [53; 54]. The main applications for compounds attained from plant byproducts can be seen in Table 3. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Source**} & **Byproduct** & \multirow{2}{*}{**Compounds Extracted**} & \multirow{2}{*}{**Application**} & \multirow{2}{*}{**Types of Products**} & \multirow{2}{*}{**References**} \\  & **Example** & & & & \\ \hline \multirow{4}{*}{Ovine} & Fleece. & \multirow{2}{*}{Lanolin.} & Emolilient, emulsifying, skin/hair conditioner. & Skin and hair care products. & [44] \\ \cline{2-6}  & Cartilages and trimmings. & Collagen and peptides & Antimicrobial and moisture. & Antiacne. & [38; 45] \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._ \begin{table}
\begin{tabular}{c c c} \hline \hline \multicolumn{2}{c}{**Compound**} & \multicolumn{1}{c}{**Potential Cosmetic Use**} & \multicolumn{1}{c}{**References**} \\ \hline \multicolumn{2}{c}{Phenolic compounds} & Photoprotective agent, anti-skin aging, preservative agent. & [50] \\ \hline \multicolumn{2}{c}{Carotenoids} & Photoprotective agent. & [51] \\ \hline \multicolumn{2}{c}{Polysaccharides} & Moisturizer agents, anti-inflammatory, skin whitening, and wound healing. & [52] \\ \hline \multicolumn{2}{c}{Lipids} & Barrier repair, moisturizer, anti-inflammatory, antioxidant, and wound healing activity. & [53; 54; 55] \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Main compounds attained from plant byproducts and their potential cosmetic applications. One source of the aforementioned compounds are wine and grape byproducts. From this source, pomace, stalks, skin, and seeds are the main byproducts generated, with an estimated 14.5 million tons per year produced in the EU [56].