# Cosmeceutical Potentials of _Equisetum debile_ Roxb. ex Vaucher Extracts
## 4 Discussion
Additionally, quercetin could down-regulate the expression of MMP-1 via an inhibition of activator protein-1. This study shows that the inhibition activities of MMP-1 and MMP-2 could be partially explained by total phenolic content with the coefficient of determination (R\({}^{2}\)) of 0.4127 and 0.5101, respectively (Figure 6). Moreover, phenolic compounds found in CE by LCMS (Q-TOF) qualification analysis, such as naringenin-7-O-\(\beta\)-D-glucuronide, luteolin 7-glucose, and kaempfer, could be the candidates for further study due to their previously reported involvements in the inhibitions against collagenases [67; 68; 69]. Collectively, this study demonstrates that _E. debile_ extracts may be well suited for skin care and treatments. EF is the most attractive fraction for skin-whitening and anti-wrinkle applications. _E. debile_ phenolics and flavonoids could be responsible for the inhibitions of tyrosinase and collagenases. Although quercetins were previously identified in _E. debile_[55], further studies are still required to assess the total flavonoid content in the present study. The identification and quantification analysis of quercetins and other phenolic compounds shown in Supplementary Table S1 should also be investigated in the semi-purified fractions in order to infer their potential association with the observed inhibitory activities against tyrosinase and collagenases. Dihydrotostosterone (DHT) is a potent androgen derivative. It is an essential hormone for normal male growth. However, highly expressed DHT is a major cause of androgenic alopecia [50]. The 5\(\alpha\)-reductase is a microsomal enzyme that is responsible for the reduction of testosterone to DHT. Therefore, the anti-hair loss activities of _E. debile_ extracts were assessed via the inhibitions against 5\(\alpha\)-reductase (Figure 9 and Table 3). All extracts of _E. debile_ exerted inhibitions against 5\(\alpha\)-reductase, ranging from 44.59 \(\pm\) 0.40 to 83.07 \(\pm\) 3.46%. DF displayed the strongest inhibition (FEA of 1.48 \(\pm\) 0.06 mg finasteride/g). CE and MF exhibited comparative inhibitions and were the lowest at 44.59 \(\pm\) 0.40 and 48.60 \(\pm\) 3.27%, respectively. HF and EF showed comparative inhibition potencies of 60.86 \(\pm\) 0.39 and 62.45 \(\pm\) 0.83%, respectively. The anti-5\(\alpha\)-reductase activity of _Equisetum_ plants was previously reported from only _E. debile_ species [32]. The findings in this present study agree with the previous investigation of _E. debile_, which reported the extracts from ethyl acetate, hexane, and ethanol exhibiting inhibitions against 5\(\alpha\)-reductase. However, this study is the first to report the inhibitory activities of semi-purified fractions of _E. debile_ crude extracts against 5\(\alpha\)-reductase. Moreover, it is the first to express the activities of _E. debile_ extract as an FEA value. In this study, dichloromethane rather than either hexane or ethyl acetate was able to sequester the strongest 5\(\alpha\)-reductase inhibitors, suggesting that phytochemicals conferring the most potent inhibitions preferred the solvents with the low range of moderate polarity indices. This study also shows that the total phenolic content was not related to the inhibition activity of 5\(\alpha\)-reductase (Figure 6). Fatty acids and phytosterols were speculated to be the compounds exerting anti-5\(\alpha\)-reductase activities due to their presences and potential mechanisms. Generally, hair growth treatments incorporate the active ingredients of lipophilic compounds containing several fatty acids including palmitic acid, stearic acid, oleic acid, linoleic acid, arachidonic acid, and myristic acid. This is probably due to certain aliphatic free fatty acids exerting inhibitions against 5\(\alpha\)-reductase [70]. The structure of fatty acids, including chain length, unsaturation, oxidation, and esterification are factors that influenced the inhibition potencies.