## 1 Introduction  
Human skin consists largely of two layers of tissue. The outer layer is the epidermis, which contains keratinocytes, and the inner layer is the dermis, which contains fibroblasts and an extracellular matrix. Skin aging is a complex process involving both layers. The cause of skin aging is the degradation of the structure and physiological functions of the skin by various exogenous (exterior) and endogenous (interior) factors. Exogenous aging is caused by environmental factors such as ultraviolet (UV) radiation, alcohol ingestion, pollutants, and severe physical stress [1, 2]. These factors cause oxidative damage to skin lipids, proteins, and DNA through the formation of free radicals, leading to loss of skin elasticity. UV accounts for up to 80% of exogenous aging. Endogenous skin aging is caused by accumulated intrinsic damage due to the persistent formation of reactive oxygen species (ROS) [3; 4]. Free radicals damage the connective tissue of the skin, leading to premature skin aging (photoaging) [3; 4; 5]. Previous studies have indicated that sustained ROS exposure can stimulate skin aging through antioxidant system destruction, wrinkling, and melanin overproduction [5]. To delay such aging of the skin, methods of strengthening and protecting skin cells have been studied as an important issue in the cosme industry. Innovative formulations of cosmetic raw materials are being developed. In particular, nanotechnology in the cosmetic industry has a very small particle size, so it is possible to increase the surface area to increase skin absorption of active ingredients [6; 7; 8]. Plant-derived active ingredients such as polyphenols have been used to prevent skin aging [9] because they have strong antioxidant activity against ROS. Bioactive compounds such as isoflav, anthocyanins, and catechins protect the epidermis of the skin from external stimuli and oxidative stress. These plant-derived active ingredients with antioxidant activity were mostly obtained through plant cultivation. However, plant cultivation generally requires a great deal of space and a long period of time. In addition, it is difficult to obtain consistent plant extracts because control of the cultivation conditions is relatively difficult. As an alternative, growing plant calluses in an environment where cultivation conditions are easy to control allows for management of changes in the external environment, thus enabling high productivity and a fast turnover rate. Calluses, parts of which have the same roles as animal stem cells, is a mass of plant stem cells with properties that help stimulate and regenerate plants after injury [10]. A plant stem cell is an undifferentiated cell that has the genetic potential to produce an entire mature plant, strong proliferative capacity, and high differentiation potential, so it is possible to produce a mature plant from a specific plant callus [11; 12; 13]. Plant stem cells exhibit excellent anti-aging properties because fibroblasts stimulate collagen synthesis and promote skin regeneration, among other activities. These unique properties of plant stem cells are focused on the development of new cosme. Although active research is being conducted on the use of plant callus materials called plant stem cells as functional natural materials with excellent physiological activity in the cosmetic field, plant stem cell materials have not been developed [14]. The anti-aging effects of grapes, raspberries, tomatoes, medicinal material, and many plant stem cells have been previously reported. However, the anti-aging efficacy of stem cells obtained from rice embryonic cells has hardly been reported [15; 16; 17]. Rice (_Oryza sativa_) is composed of many phytochemicals such as \(\gamma\)-oryzanol, vitamin E homologues, and phenolic acids that produce beneficial health properties [18; 19]. Rice Stem Cell Extract (RSCE) is a callus extract derived from embryonic cells of rice seeds. It has a high vitamin content and excellent antioxidant effect.