Effect of Kaempferia parviflora extract and its polymethoxyflavonoid components on testosterone production in mouse testis-derived tumour cells

Low testosterone is associated with late-onset hypogonadism, age-related disease, type 2 diabetes, and cardiovascular disease. In this study, we investigated the effects of Kaempferia parviflora extract and two of its components, 5,7-dimethoxyflavone and 5-hydroxy-3,7,3′,4′-tetramethoxyflavone, on testosterone production in mouse testis-derived tumour cells I-10. K. parviflora fractions containing 5,7-dimethoxyflavone elicited testosterone production in these cells, as did nobiletin, a polymethoxyflavonoid found in citrus species, but not K. parviflora, which was used as a comparative control. Furthermore, we found that these compounds enhanced testosterone production via cyclic AMP (cAMP)/cAMP response element binding protein signalling. In particular, the compounds inhibited activation of phosphodiesterase and thereby increased production of cAMP. These findings support the possibility that K. parviflora extract, 5,7-dimethoxyflavone, and nobiletin may mitigate age-related disease and hypogonadism by enhancing testosterone production.