###### Abstract  
_Momordia charantia_ (_M. charantia_) is rich in flavonoids, which possess a strong antioxidant capacity and may help prevent hair loss. This study aims to develop the microemulsion of _M. charantia_ with antioxidant activity and 5\(\alpha\)-reductase (5\(\alpha\)R) inhibitory activity. The total phenolic content (TPC), antioxidant activity, and 5\(\alpha\)R inhibitory activity of ethanolic and aqueous extracts of the fruit were investigated. The preparation of _M. charantia_ extract-loaded microemulsion (MELM) was optimized and characterized the MELM. The aqueous extract of _M. charantia_ fruit flesh displayed a TPC of 780.75 \(\pm\) 24.82 mg Gallic acid equivalence/g of extract. ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid), DPPH (2,2-diphenyl-1-picrylhydrazyl)), and nitric oxide (NO) radical scavenging activities were observed in all the extracts. About 0.461 \(\pm\) 0.003 mg finasteride equivalence/g of extract of 5\(\alpha\)R inhibitory activity was detected in the aqueous extract of the inner tissue of _M. charantia_ fruit. Based on NO radical scavenging and 5\(\alpha\)R inhibitory activity, an aqueous extract of the inner tissue (pericarp with seed) of _M. charantia_ fruit was used to prepare the MELM. The MELM was prepared using a different ratio of tween 80 and ethanol as Smix. The results showed that the 1:1 ratio of tween 80: ethanol produced microemulsion of an optimum size, zeta potential, and polydispersity index. The MELM samples were stored at 5, 30, and 40 \({}^{\circ}\)C for 12 weeks, and the stability was assessed. The results revealed that the size, zeta potential, and polydispersity index of the formulated MELM remained unchanged during the investigated time. This study primarily reports the 5\(\alpha\)R inhibitory activity of _M. charantia_ extract and the development of microemulsion. The prepared MELM could be further developed into cosmetic or pharmacological preparations to manage hair loss. The pathology of AGA is associated with the activity of the 5\(\alpha\)-reductase (5 aR) enzyme in hair follicles and the sebaceous gland. 5 aR converts testosterone into dihydrotestosterone (DHT), which is a more potent androgen than testosterone. A high level of DHT can induce many effects, such as acne, hair loss, and enlargement of the prostate [2]. AGA is likely to occur in males and females but is most often found in males. It can be treated with 5 aR inhibitors such as finasteride and Mutasteride [3]. However, these medicines may cause unacceptable adverse effects such as sexual dysfunction and reduced sexual confidence. The topical minoxidil lotion is another medicine used to treat AGA. It also has side effects such as irritation, itching, rash, and dry skin. There are two isoforms of 5 aR, types 1 and 2 (5 aR1 and 5 aR2). Several phytochemicals were reported with 5 aR inhibitory activity. These include catechins and epicatechin gallate. Flavonoids were reported to inhibit 5 aR1 enzymes such as myricetin, quercetin, baialcein, and fisetin. Biochanin A, kaempfer, genistein, and daidzein can also inhibit 5 aR activity [4]. Antioxidants such as polyphenols are reported for hair loss prevention and hair growth-promoting activities [5]. Transforming growth factor (TGF)-\(\beta\)1 is a catagen phase inducer released by ROS-inducible and inhibits epithelial cell growth that causing shortening of the human hair cycle [6]. Reactive oxygen species (ROS) are known as radical oxygen, an unstable molecule that can easily react with other molecules in the cell. The reaction of ROS when building up in cells is the cause of damaged DNA, RNA, and proteins, through cell death. ROS also causes hair loss via a reaction with cellular protein in hair. From previous studies, the relationship between ROS and TGF-\(\beta\)1 in epithelial cells has been reported, in which ROS can induce TGF-\(\beta\). The report showed that antioxidants have the potential to be used as a treatment. _M.