Potential Use of Essential Oils and Their Individual Components in Cosmeceuticals: A Review

The cosmetic industry is searching for new active ingredients from renewable natural sources to make more environmentally friendly and safe products. Botanical extract is a nearly limitless source of these new actives due to the current consumer demands as well as international regulations. Due to both their fragrant nature for the creation of fragrances and perfumes and the numerous advantageous properties of their individual components (EOCs), such as anti-inﬂ ammatory, antimicrobial


Introduction
Essential oils (EOs) are biologically active volatile molecules that are produced in a variety of plant organs, including lowers, buds, leaves, branches, stems, seeds, fruits, forests, roots, etc. [1].Additionally, several active substances are found in EOs, including alkaloids, tannins, steroids, glycosides, resins, phenols, volatile oils, and lavonoids [2,3].To address consumer concerns about the negative effects of synthetic antioxidants, which have hazardous side effects on consumers and subsequently cause numerous cancers, EOs are currently gaining popularity as natural alternatives to synthetic antioxidants.Therefore, new and affordable sources of natural antioxidants are becoming more accessible in order to preserve and improve customers' health and generate food security [4].
Due to the high concentration of volatile, aromatic, and bioactive components, EOs and extracts play a signi icant role in many sectors [5].Additionally, these powerful substances play a crucial role in the pharmaceutical, food, agricultural, cosmetic, and health industries and have inherent antioxidant and antibacterial capabilities [6].Additionally, changing to a more "natural cosmetic" has become necessary due to current international regulations, which forbid the use of many conventional chemicals in the production of goods for human consumption and recommend gradually replacing them with alternative substances, preferably derived from renewable natural sources, such as plants and microorganisms (biotechnological sources) [7][8][9][10][11].A wide variety of cosmetically acceptable active ingredients are produced by plants and microorganisms, and these ingredients can be used to make a variety of cosmetics and toiletries, such as creams that protect against UV radiation and pollution, produce fragrances, or lessen the effects of aging on the skin [1,9,12,13].
An essential piece of research exploring the advantages connected with the use of botanical extracts in the formulation of various cosmetic products has been inspired by current consumer interests and market trends.The goal of this is to use their biological characteristics to create new goods that can improve human health, beauty, and wellness.The most valued https://doi.org/10.29328/journal.abse.1001023goods for meeting some of the demands made in the design of new products are essential oils (EOs) and their individual components (EOCs), in particular [14][15][16][17].In order to take advantage of some of their capabilities, such as analgesic, antibacterial, and antimicrobial properties, but mostly their pleasant aroma, EOs have been widely incorporated in a wide range of cosmetic items, perfumes, and home products [18].This review strives to offer a current viewpoint on the use of EOs and each of their component parts in the cosmetic business today.Additionally, some fundamental issues regarding the potential need for safety measures while using EOs and EOCs in the creation of cosmetics and toiletries will also be covered.

General characteristics of essential oils
Essential oils (Eos) are highly hydrophobic natural substances that are widely used in the food and pharmaceutical industries, pest management, perfumery, cosmetics, and toiletries.They are derived from aromatic plants, which can include lowers, roots, bark, leaves, seeds, peel, fruits, wood, and whole plants [16,[19][20][21][22].They comprise a large family of compounds known as essential oil components (EOCs), each of which has its own distinct chemical ingerprint [22][23][24][25][26][27][28][29][30].Therefore, a single essential oil should be considered as a complex mixture of bioactive compounds, with their inal compositional pro ile, and hence their bioactivity, dependent on different factors: (i) method of extraction, drying, and storage; (ii) time of harvest and climate conditions, and (iii) plant species and which part of the plant was used for their isolation [11].This compositional richness is a crucial component in the wide spectrum of essential oil applications, and it promotes better wellness, hygiene, and aesthetics [31].
Commonly, EOs are liquids that have a density below that of water.They can also be combined with alcohols, ethers, and lipids but are not water-soluble.The majority of EOs come from angiosperm plants, such as those in the Apiaceae, Asteraceae, Lamiaceae, Lauraceae, Myrtaceae, and Rutaceae families [1,32], which play a very important role in defense, signaling, or as part of their secondary metabolism [19,33].Figure 1 includes some examples of EOs, with their origin, properties, and active components.
EOs should be considered as a renewable bio-resource of active ingredients that can be exploited for the production of eco-sustainable products, with their antioxidant, bactericidal, virucidal, fungicidal, anti-parasitical, insecticidal, and medicinal properties being a very important bene it for this type of applications [34][35][36][37][38][39].They can be used in the manufacture of a wide variety of cosmetic goods, such as creams, gels, and ointments, without the requirement for the addition of chemical preservatives, in particular, because some of their constituent components have bactericidal and fungicidal properties [40].It is important to note that EOs have a number of disadvantages, including high volatility, poor water solubility, and thermal and chemical lability (the majority of these molecules are vulnerable to oxidation when exposed to the environment), which makes their handling challenging for a logical design of cosmetic products [17,19,41], It necessitates careful management of their conditioning, storage, and packaging processes.A careful quanti ication of their maximum concentrations in a given formulation is required to ensure the production of safe cosmetic products because the role of EOs, and their individual components, in the formulations is not always positive and represents a potential source of allergenic reactions [30].

The main compounds constituting essential oils
From a chemical point of view, EOs are very complex mixtures of low molecular weight volatile compounds (in some cases more than 100), the so-called essential oil components (EOCs), which appear at quite different concentrations [24].However, the biological features of EOs, which are often controlled by two or three components present at the highest concentrations (20% -70% w/w), do not, however, re lect the compositional richness of EOs [34].On the other hand, the makeup and consequently the quality of a particular essential oil depend on a variety of factors, including genetics, the season of harvest, the location of the crop, the section of the plant used, and the technique of manufacturing [42,43].
Lipophilic terpenoids, phenylpropanoids (aromatic chemicals), and short-chain aliphatic hydrocarbon derivatives (terpenes) make up the majority of essential oils.The latter are aromatic or hydrocarbons generated from phenols, ethers, esters, aldehydes, ketones, alcohols, oxides, and alcohols [11,42,44].Figure 2 shows some representative molecular structures of different essential oil components (EOCs) that can appear in EOs.The composition of EOs is associated with the existence of speci ic biosynthetic pathways in plants [45].The biosynthesis of the many types of necessary components follows extremely precise pathways, which are typically classi ied based on the speci ic chemical composition of the component [11].Thus, aromatic phenylpropanoids are obtained from the shikimic acid pathway, which results in the formation of phenylalanine, terpenoids derived from the isopentenyl diphosphate (IPP), and its isomer dimethylallyl diphosphate (DMAPP) [44,46].On the other hand, terpenoids are composed of different isoprene units (C 5 H 8 ) which are commonly assembled in a head-to-tail fashion following a direct assembly process, or by cyclization, rearrangements, or other types of conversions from aliphatic isoprenoid precursors [42].Repeated addition of IPP units results in prenyl diphosphate precursors, which are then changed by terpene-speci ic synthetases to produce the terpene skeleton.To create the inal terpene molecules with the desired chemical structures and characteristics, these go through secondary enzymatic modi ication, typically by a redox process [11].
It should be noted that in addition to the unique compositional diversity of EOs linked to their biosynthetic pathways, it is also possible to isolate extracts with various compositions from a given plant type; thus, the inal composition of the EOs may vary depending on the methods used for their extraction.This can be explained by the unique characteristics of the different constituents found in essential oils, particularly their volatility.Since terpenoids, such as sterols or carotenoids, remain in the non-volatile fraction found in plant resins or gums, remaining as a residue in the distillation process, genuine essential oils obtained by distillation contain a high amount of low volatile components, such as diterpenes [42].It should be noted that the weight ratio between volatile and non-volatile compounds is strongly dependent on the speci ic essential oil, and ranges from 99:1 for grapefruit oil to 60:40 for bergamot oil [47,48].

Applications of EOs in cosmetic products
People have been interested in using essential oils and herbal extracts as cosmetics for a long time, and active ingredients derived from plants have been employed in perfumes and cosmetics.Historical evidence from the nations where these plants were irst cultivated, including India, China, Egypt, and Iran, attests to the long-standing use of medicinal plants in cosmetics.In order to address their health needs, it is estimated that more than 80% of the world's population uses conventional medicine (plant extracts or their active ingredients) [49].For example, in ancient Egypt, the oil of medicinal plants was extracted by steaming, while the Romans and Greeks used the distillation method for extraction.The use of medicinal herbs also increased with the rise of Islamic culture thanks to creative methods, and technologies for extracting oil, EO, and their substance advanced in a useful direction.Additionally, the essential oils (EO) derived from plants like Cedrus libani, Ocimum kilimandscharicum, Artemisia annua, Acacia vestita, Piper angustifolium, Sassafras albidum, and Rosmarinus of icinalis contain camphor, which has been known to have aromatic properties for centuries and was used as a medicine in ancient China and Japan.It has been employed in numerous Asian and European nations for medical, gastronomic, and aesthetic purposes [50,51].
Currently, consumers' tendency to purchase herbal cosmetics, which are both environmentally friendly and renewable, has increased [52].In recent years, "natural cosmetics" recorded a large quota of cosmetics (about $40 billion by 2021, which is about 10% of the global cosmetics market) [53].Plant EOs are utilized in a variety of cosmetic products such moisturizers, lotions, and cleansers for the skin because of their anti-in lammatory, antibacterial, and antioxidant characteristics.Hair care products, lipsticks, and perfumes all employ cosmetics, conditioners, masks, or antidandruff products [53].
By adding rosemary and chamomile EOs to shampoo, EOs can quickly penetrate the scalp, feed the hair follicles, moisturize the hair, strengthen the hair, and eliminate the adverse molecules that block the pores of the skin [54].EOs signi icantly in luence hair growth stimulation and hair loss prevention [55].According to a report, topical mint oil made from Mentha piperita is normally applied at a modest dose (3% weight on weight) to promote hair growth [56].One of the most common applications of EOs in skin care is to prevent acne from appearing, using the ability of EOs to inhibit Propionibacterium acnes, which Citronella's EO has the ability to do [57].Due to their ability to block the majority of UV photons between the wavelengths of 290 and 400 nm, EOs can be used in sunscreen products to shield the skin against sunburn, wrinkles, and other skin-damaging effects [58].Calendula of icinalis essential oils were used in a cream formulation that was tested in a lab setting.The outcomes showed that the cream formulation had good sun protection qualities [59].
Cosmetic products have preservatives added to them to keep bacteria from spoiling them and lengthen their shelf lives.The customer must also be shielded from any pathogens.Although chemical preservatives stop germ growth, customers are skeptical about their safety.Producing preservative-free or self-preserving cosmetics is therefore of great interest [60].Therefore, the use of plant essences and extracts in the manufacture of cosmetics as multipurpose antimicrobial substances, both as an alternative to natural preservatives and with anti-pathogenic qualities, can aid in improving the quality of these products.In herbal cosmetics, some Nepta species, such as Nepeta cataria var (Citriodora), Nepeta cataria, and Nepeta grandi lora, are utilized.Nepetalactone and geraniol in N. cataria, citronellol and geraniol in N. citrodora, and o-cymene, c-terpinene, carvacrol, and p-cymene in N. grandi lora were the principal chemicals in these three species [61].Table 1 shows a Potential application of some EOs in the design of different cosmetic formulations.

Conclusion
The cosmetic industry is becoming more and more interested in the family of compounds known as essential oils (EOs) and their speci ic components (EOCs).This is a result of their numerous biological qualities, which can be used to promote well-being, attractiveness, and health.These features include those that are antibacterial, antifungal, antiin lammatory, and antioxidant.Due to this, essential oils are now widely used in products for hair and skin care as well as natural preservatives in many formulations.This has expanded the spectrum of uses for essential oils beyond the fragrance industry, creating an almost unlimited list of applications that are constantly expanding.Therefore, essential oils have become essential components contributing to the optimal balance of physical wellness.However, the safety concerns related to the use of EOs and EOCs in the inal products cannot be hidden due to their signi icant contribution to the present growth of the cosmetic industry towards greener and eco-sustainable products, making it vital to be cautious with their dose.Therefore, it is clear that EOs and EOCs are a very important source of bioactive molecules for the cosmetic industry, even though it is mandatory a careful analysis of their application conditions.On the other hand, the use of essential oils in cosmetics and toiletries is advantageous not only in terms of the cosmetic advantages of the products and their function as preservatives but also because it enhances the brand image of commercial goods.This necessitates advancing study in order to better understand the biological functions of these compounds and any potential toxicological implications, which will pave the way for the creation of essential oil-based cosmetic products.Therefore, considering the interest of the cosmetic industry in replacing traditional actives with greener bioactive ingredients, it is necessary to perform more systematic tests evaluating the real performance of essential oils in inal formulations.

Figure 1 :
Figure 1: Diff erent forms of EOs' eff ects on microorganisms and their mechanisms.