Development of liquid crystal formulations containing rosa damascena mill. leaf extract from environmentally friendly extraction technique for cosmeceutical applications

Abstract

Large quantity of Rosa damascena Mill. leaves have been disposed of as agricultural waste every year during pruning for flowering. Therefore, this study aimed to investigate the potential of utilizing R. damascena leaves as a natural source of bioactive ingredients and incorporating into liquid crystal (LC) formulations for cosmetic and cosmeceutical applications. The dried leaves of R. damascena were subjected to extraction using environmentally friendly methods with 50% v/v or 95% v/v ethanol, or DI water. These methods included conventional maceration (3 cycles of 24 h), infusion, digestion, ultrasonication, microwave extraction, micellar extraction, and pulsed electric field (PEF) extraction at 10 kV/cm. The extracts were analyzed for chemical compositions using high-performance liquid chromatography, Folin Ciocalteu, and aluminum chloride methods. Their antioxidant activities were determined using spectrophotometric methods to measure the radical scavenging and ferric-reducing antioxidant capacity. Whitening effects were assessed for anti-tyrosinase activities, while anti-aging activities were evaluated through inhibition against collagenase and elastase. Their irritation profiles were examined using the hen's egg-chorioallantoic membrane (HET-CAM) test. The R. damascena leaf extract with the most promising cosmeceutical activities and safety profiles was incorporated into LC systems when various factors affecting the LC development were evaluated, including the types and amounts of the oil phase and the surfactant. Each LC was identified using a polarized light microscope and characterized for its physical appearance, viscosity, pH, and stability. The findings indicated that ethanol extraction yielded significantly greater yields (p < 0.05), while the levels of total phenolic and flavonoid content varied depending on the solvent and extraction methods. However, specific bioactive compounds such as rutin and rosmarinic acid were exclusively detected in aqueous extracts. Notably, aqueous extracts obtained through ultrasonication and microwave extraction exhibited outstanding inhibition of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+). Conversely, aqueous extracts from PEF extraction exhibited significantly strong inhibition of collagenase and elastase, with a collagenase inhibition of 69.1 ± 10.1%, comparable to that of epigallocatechin gallate (76.0 ± 1.2%). Besides, all extracts were considered safe as they did not induce any irritation in the HET-CAM test. Due to their notable anti-skin aging properties and safety, the aqueous extract of R. damascena leaves obtained through PEF was chosen for further development of LC formulations. LC formulations were successfully developed, yielding a homogenous transparent yellow gel, with the birefringence under the polarizing light microscope indicating the LC formation. Squalane was found to be more suitable for LC formulation compared to jojoba oil due to the resulting appealing appearance. However, temperature was found to affect the stability of all LC formulations. Only some LCs were stable after the centrifugation. Therefore, the LC exhibited a good stability, which composed of 2.5% w/w squalene and 35% w/w Tween® 85, were selected for the further incorporation of the extract. Various quantities of R. damascena leaf extract (0.1, 0.5, and 1% w/w) were successfully incorporated into the selected LC but resulted in a stronger color and higher viscosity depending on the extract concentration. All LCs were found to be stable in the room temperature since there was no change in the appearance, crystallinity, pH, and viscosity. Additionally, LC emphasized their capability to improve the stability of R. damascena leaf extract both physically and chemically. Therefore, it could be concluded that LC containing R. damascena leaf extract exhibited promising potential for further use in cosmetics and cosmeceuticals, contributing to the anti-skin wrinkles.