## 4 Discussion  
For many decades, medicinal herbs have attracted the interest of scientists as they possess various bioactive phytochemicalenical constituents including phenolics, alkaloids, flavonoids, tannins, saponins, and triterpenoids which exhibit positive pharmacological functionalities on the human body. In this study, we have aimed to provide more comprehensive information of bioactive compounds in _Syzygium formosum_ regarding the cosmetic or dermatological uses for soothing or relieving the rashes, itching, atopic dermatitis or psoriasis, anti-inflammatory, and anti-bacterial activities. By the UVB-induced HaCaT inflammation model, it has been clearly demonstrated that the extract of _S. formosum_ has great anti-inflammatory effects. When compared with _C. asiatica_ which is currently proven to be effective, _S. formosum_ leaf extract exhibited higher efficacy in the down-regulations of IL-1\(\beta\), IL-6, and IL-8 expressions. In the stratum corneum and fibroblasts, IL-1\(\beta\) is a major cytokine affecting skin condition. IL-6 and IL-8 are also important in proinflammatory responses of skin. In addition, _S. formosum_ leaf extract also showed a great antibacterial effect on _S. aureus_ and _C. acnes_ that is commensal skin bacteria species. Especially, by adding the _S. formosum_ leaf extract, the growth of _C. acnes_ growth was significantly suppressed showing the efficacy of \(10^{5}\) magnitudes that suggest the 99.999% sterilization. _S. aureus_ generates toxins which could aggravate symptoms of atopic dermatitis. Proliferation of _C. acnes_ is regarded as the main factor correlated with a severe form of acne. Therefore, controlling _S. aureus_ and _C. acnes_ is very important for skin health. Despite the effective functionalities, there have been few in-depth studies on the comprehensive and systemic analysis of phytochemical components in _S. formosum_ leaves. In our study, twenty phytochemical components including eight flavonoids (catechin, epigallocatechin gallate, quercetin aglycone, glycoconjugates of quercetin, and myricetin), three phenolic acids (gallic acid, 3,4-dihydrobenzoic acid, _p_-coumaric acid), and nine triterpenoids (madecassic acid, asiatic acid, hederagenin, maslinic acid, corosolic acid, betulin, betulinic acid, oleanolic acid, and unsolic acid) were identified in _S. formosum_ leaves. Besides, four different glycoconjugates of quercetin and myricetin were determined as well. Each component of flavonoids, phenolic acids, and triterpenoids was quantified by the MRM using QQQ-MS/MS. Among the twenty-four compounds identified in the SF leaves, epigallocatechin gallate, _p_-coumaric acid, madecassic acid, hederagenin, and betulin were the five phytochemical components firstly recognized in our study. _S. formosum_ leaf contained a broad spectrum of triterpenoids derived from lupeol and amyrin. Betulin and betulinic acid, which is one of the major triterpenoids in the SF leaves, are derived from lupeol and are known to be major functional constituents in birch extract that has been used in cosmetic and herbal essence products [26; 27]. Derived from \(\beta\)-amyrin, oleanolic acid is a precursor of maslinic acid and hederagenin, and importantly, ginseng Peg, Pq, and Pj [28]. Maslinic acid is abundant in the wax-like coating of the leaves and fruits of olive and is reported to exhibit anti-cancer and anti-inflammatory activities [29; 30]. Instead of \(\beta\)-conformation, unsolic, corosolic, asiatic, and madecasic acids are synthesized by the sequential hydroxylation from the \(\alpha\)-amyrin. Ursolic acid was a precursor of madecasic and asiatic acid and has been widely found in the peels of fruits and herbs [31]. Although the systematic human clinical trial has not been evaluated, numerous beneficial effects on health and disease were reported such as anti-inflammatory, antioxidant, anti-carcinogenic, antiobesity, antidiabetic, cardioprotective, neuroprotective, hepatoprotective, anti-skeletal muscle atrophy, and thermogenic effects [31; 32].