Effect of Elderberry (Sambucus nigra L.) Extract Intake on Normalizing Testosterone Concentration in Testosterone Deficiency Syndrome Rat Model Through Regulation of 17β-HSD, 5α-Reductase, and CYP19A1 Expression.

Background/Objectives. Men experience Leydig cell and mitochondrial dysfunction due to the accumulation of reactive oxygen species during aging, leading to hormonal imbalances in the body. This results in symptoms of testosterone deficiency syndrome (TDS) as testosterone levels decline. Consequently, there is a growing need for alternative therapies, such as phytotherapy, to regulate testosterone secretion. Methods. In this study, we evaluated the potential of elderberry extract powder (KSB191) as a functional ingredient for improving TDS by analyzing its mechanism in regulating testosterone imbalance. The major compounds of KSB191 were rutin and fructose-leucine, and the efficacy of KSB191 was confirmed by observing increases in total testosterone, free testosterone, and sperm motility in an aged rat model with decreased testosterone levels. Additionally, we assessed safety by analyzing levels of prostate-specific antigen, alanine aminotransferase, aspartate aminotransferase, and creatinine. Results. To confirm the effectiveness of KSB191 in increasing testosterone synthesis and inhibiting its breakdown, we analyzed the expression levels of genes related to testosterone synthesis and degradation in the testis tissue. KSB191 not only increases the expression levels of enzymes (3β-HSD, CYP17A1, and 17β-HSD) that catalyze testosterone synthesis in Leydig cells, but also reduces the expression of enzymes (5α-reductase and CYP19A1) that degrade testosterone, thereby enhancing testosterone production in the body. Conclusions. KSB191 is predicted to be a novel functional ingredient that acts on Leydig cells and increases testosterone synthesis (particularly, the increase in free testosterone), ultimately alleviating the symptoms of TDS.