Plants extraction has been used since ancient times to recover bioactive substances used as medicaments or cosmetic products. The multifaced variety of molecules constituting the phyto-complex can be extracted through different methods and with the aid of various solvents depending on the nature of the plant derived ingredients. Leaves, petals, flowers, stems, roots, and barks are an inexhaustible source of botanical active ingredients that can be included in a cosmetic formulation to treat minor skin conditions, beautify, moisturize, clean, cover up blemishes and so on.
Bio-based ingredients are generally extracted from plants but their abundance can be heavily dependent on the seasonal change. Nowadays it is sometimes possible to circumvent this issue through techniques such as recombinant DNA technology or natural fermentation in order to produce the desired compound. [1]
Recent developments of cosmetic industry include the progressive substitution of petrochemical ingredients with bio-based substances and the design of new extraction methods avoiding organic solvents or reducing their waste and negative impact on the environment. Among bio-based solvents there is ethanol, produced from the fermentation of sugar beet or cereals and highly versatile and biodegradable although flamable and potentially explosive. [2] Terpenes such as α-pinene or d-limonene extracted from pine and citrus plants respectively can be used as bio-solvents to extract low-polarity substances like fat and oils. Water can be used to extract polar substances but also low polarity ones by tuning its pressure and temperature: techniques such as pressurised hot water extraction (PHWE) or sub-critical water extraction in dynamic mode offer a promising green modern approach to extract bioactive compounds from plants. [2]
Ultrasounds and microwaves assisted extraction technologies can largely enhance the yield of botanical ingredients, while reducing the extraction duration and the solvent waste. Supercritical fluid extraction employing solvents such as carbon dioxide (CO2) or refrigerant gases like tetrafluorethane (R134) are innovative extraction methods carried out in closed-loop systems and capable of producing clean extracts, preserving thermolabile molecules as low molecular weight terpenes among others.
The move of cosmetic instustry towards always more eco-friendly products is already started, but beacuse of the large scale production and the intense demand, the design of new technologies and sustainable cultivation and processing methods is needed. Extraction will stay a crucial step in botanical ingredient isolation and during synthetic cosmetics purification, but the attempt of a continuous sustainable development will be always a goal to preserve this world for future generations.
References:
[1] Goyal, N. et al. Biocosmetics: Technological Advances and Future Outlook. Environ. Sci. Pollut. Res. (2021); No. 0123456789. https://doi.org/10.1007/s11356-021-17567-3. [Journal impact factor = 4.223 ] [Times cited = 5]
[2] Chemat, F. et al. Green Extraction of Natural Products: Concept and Principles. International Journal of Molecular Sciences, (2012); 13(12), 8615–8627. doi:10.3390/ijms13078615 [Journal impact factor = 5.923] [Times cited = 1216]
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