Table 9.

Biological activity of C. limon fruit extracts, essential oil and its ingredients compounds significant from the cosmetics point of view, confirmed by scientific research.

Activity	Extracts and Compounds Tested	Mechanism of Action	References
Antioxidant activity	C. limon essential oil	Strong lipid peroxidation reduction and free radical reduction effect in vitro and in vivo.	[79,80]
	C. limon var. pompia fruit extracts	Extract enclosed in hyalurosomes and glycerosomes reduces oxidative stress caused by hydrogen peroxide and the viability of keratinocytes and fibroblasts.
Depigmenting activity	Essential oil ingredients (e.g., citral, β-pinene, D-limonene)	Essential oil components show tyrosinase inhibitory activity. Mixture of essential oil ingredients has a stronger inhibitory effect due to their synergistic effect.	[80]
Effect of increasing the penetration of substances	C. limon essential oil	Acc. to in vitro study on human epidermal cells (SkinEthic), C. limon essential oil increased the penetration of α-tocopherol. Modification of TEWL (Trans Epidermal Water Loss) was transient. C. limon essential oil enhanced the penetration of locally administered lipids and water-soluble vitamins.	[81]
Preservative effect in cosmetics	C. limon essential oil	Antibacterial activity and increasing the fungistatic effect of synthetic preservatives.	[7,52,53]