## 4 Discussion  
Androgenetic alopecia (AGA) is the most common type of progressive hair loss in men and women, typically occurring after puberty, and its prevalence and incidence vary by age and race. The causes of AGA are known to include genetic factors, age, and androgens [83]. The most important cause of the disease is androgen, and the complete molecular and cell biological mechanism for the cause has not been revealed. Androgens, including testosterone and dihydrotestosterone, exert their effects through the androgen receptor (AR), a ligand-dependent nuclear transcription factor belonging to the steroid hormone nuclear receptor family. Dihydrotestosterone (DHT), converted from testosterone by 5\(\alpha\)- reductase, is more biologically active than testosterone and binds AR with a 2-fold higher affinity and a 5-fold reduced dissociation rate [84; 85]. The high binding affinity of DHT and AR results in changes in hair-growth-stimulating factors such as VEGF and IGF1 and hair growth inhibitory factors such as transforming growth factor beta 2 (TGF-\(\beta\)2) and Dickkopf-1 (DKK-1). Changes in these factors cause a gradual miniaturization of hair follicles and shorten the anagen phase, causing hair loss [86]. As mentioned above, there are currently only three medications approved by the FDA to treat hair loss: minoxidil, finasteride, and baricitinib [2; 3; 4]. However, as mentioned above, these drugs require continuous use for treatment and may cause serious side-effects [5; 6; 7]. Therefore, there is a need to develop a hair loss treatment using natural substances that can be used continuously and have fewer side-effects. According to the National Center for Complementary and Integrative Health (NC-CII), low-risk complementary and alternative medicine (CAM) treatments are being proposed as options for managing hair loss. Currently, research is being actively conducted to develop hair loss treatments using natural-product-derived substances for CAM  
Figure 7: UPLC-ESI-Q-TOF-MS analysis of HE-specific upregulated peak. (**a**) ESI-MS (\(-\)) BPI profile, (**b**) ESI-MS (\(+\)) BPI profile, and (**c**) diode array. treatment, and among them, hair loss treatment research using extracts derived from microalgae and bioactive compounds is being actively conducted [87]. Bioactive compounds (me-meijiococcene and C32 botryococcene) derived from _Botryococcus terribilis_ increase the expression of genetic markers important for hair growth (CTNNB1, ALPL, FGFI, and RBPJ) [34]. _Schizochytrium_ sp-extracted lipids show effectiveness in treating hair loss by preventing ROS-induced damage to HDP cells and suppressing ferroptosis through antioxidant effects [35]. Algal Oligosaccharides (AOSs) increased the expression of several hair-growth-stimulating factors, such as VEGF and \(\beta\)-catenin, and inhibited several hair growth inhibitory factors, such as AR, TGF-\(\beta\)2, and DKK-1, in HDP cells [86]. In addition, it shows that it has the effect of promoting hair growth by extending the anagen phase of mice. In the case of extracts derived from _Gratelupia elliptica_, it inhibits the activity of 5\(\alpha\)-reductase, promotes PGE 2 production in HaCaT keratinocytes, and promotes the proliferation of keratinocytes. Additionally, it shows a high inhibitory effect on LPS-stimulated IL-12, IL-6, and TNF-\(\alpha\) expression in bone marrow-derived dendritic cells [88]. We noted that extracts and bioactive compounds derived from microalgae are effective in treating hair loss, and confirmed whether they are effective in treating hair loss using microalgae extracts with high industrial availability. While previous studies examined the hair-growth-promoting effects of loligide in HDP cells and the photoprotective properties of _S. deserticola_ JD052 extract [21; 66], our study takes a different approach. We found that heterotrophically cultured _S. deserticola_ JD052 extract exhibited enhanced hair-growth-promoting effects in HDP cells compared to the conventionally used extract from the photoautotrophic condition.