## 4 Discussion
The hydroxylated unsolic acid is corosolic acid. Corosolic acid is known to the main active constituents of Banach, _Lagerstroemia speciosa_, that exhibit antidiabetic activity. With the oleanolic and maslinic acid, corosolic acid could inhibit the glycogen phosphorylase and consequently lower the blood glucose level in adrenaline-induced diabetic mice [33; 34]. Asiatic acid is also one of the most abundant triterpenoids in SF leaves. With the madecasic acid, asiatic acid is a major functional phytochemical in _Centella asiatica_. It has been used cosmetically and pharmaceuticals in skin and dermatological diseases. Cantella asiatica has currently been used as a commercial cosmeceutical ingredient. Compare to the _C. asiatica_ grown in south and east Asia, _S. formosum_ leaves were found to have more diverse and higher amounts of triterpenoids. While only asiatic and made-assic acid were identified, nine different triterpenoids were found from SF leaves extract. The asiatic acid and madecasic acid concentrations in SF leaves were similar or higher concentrations than those in _C. asiatica_. Only madecasic acid in the _C. asiatica_ grown in Indonesia contained 5- to 10-fold more than SF leaves showing a similar amount to the asiatic acid. Seven additional triterpenoids in SF leaves were extraordinary, however, their amounts were not negligible as well. The concentrations of betulinic and corosolic acid were 3.2-6.1 mg/g dry leaf that was a similar amount of asiatic acid. Betulinic acid and corosolic acid have strong beneficial functionalities. Recent studies have provided evidence that betulinic acid ameliorates psoriatic symptoms and skin inflammation in psoriatic mice, thereby suggesting the compound could be a natural anti- psoriaticatic drug for treating human psoriasis [35; 36]. Corosolic acid is also a triterpenoid widely found in plants and is known to regulate various cellular processes such as cellular oxidative stress and signaling kinase in some diseases, including skin cancer [37]. For analysis of phenolic compounds, myricetin-3-O-hamnoside, a member of the flavonoid class of the flavonoids, was the most abundance compound with \(\sim\)50% of total flavonoids in _S. formosum_ leaves, followed by quercetin-3-O-arabinoside with 20% of the total. Meanwhile, catechin, a flavonal, was found to be a dominant component with 20-60% of the total flavonoids in this plant. Myricetin-3-O-hamnoside is thought to offer a variety of potential health benefits, displaying anti-mutagenic, anti-inflammatory, antioxidant, and antinociceptive activities [38]. Catechin is widely known to be a biologically active compound of green tea. Catechins have many benefits including prevention or reduction of skin damage [39; 40]. Additionally, the three components of phenolic acids including gallic acid, 3,4-dihydrobenzoic acid, and _p_-coumaric acid were found in _S. formosum_ leaves. Among them, gallic acid consisted of 95% of total phenolic acid content in _S. formosum_ leaves. Recently, some studies have reported that gallic acid brought new perspective efficacy in cosmetics and nanocomposites [41]. Its anti-inflammatory properties make it valuable components to prevent inflammatory-status diseases such as skin inflammation, wound healing, skin infections [42; 43; 44]. In summary, the quantitative analysis of bioactive phytochemicals in _S. formosum_ leaf extract was first performed in our study. _S. formosum_ exhibited high levels of phytochemicals as well as its anti-inflammatory effect and antibacterial capacity, which make the SF leaves attractive for pharmacological and cosmetic applications in the future.