Diosgenin content is a novel criterion to assess memory enhancement effect of yam extracts.

Several studies have suggested that some kind of Dioscorea species (yam) or yam-contained herbal medicines have cognitive enhancement effect. However, it has been unknown what is a crucial factor for cognitive enhancement in each Dioscorea species. In this study, we aimed to investigate whether one of the main and brain-penetrating components in yams, diosgenin, can be a novel criterion to assess memory enhancement effect of yam extracts. Although our previous studies showed that administration of diosgenin or diosgenin-rich yam extract enhanced cognitive function in normal mice and healthy humans, we have never evaluated whether the effect depends on diosgenin content or not. Therefore, we compared memory enhancement effects of low diosgenin-contained general yam water extract with diosgenin-rich yam extract on cognitive function in normal mice. We found that unlike diosgenin-rich yam, administration of general yam water extract did not enhance object recognition memory in normal mice. LC-MS/MS analyses revealed that after administration of general yam, diosgenin concentration in the brain did not reach to the effective dose because of the low diosgenin content in the original yam extract. On the other hand, when diosgenin was artificially added into general yam, the extract showed memory enhancement in normal mice and promoted neurite outgrowth in neurons. Our study suggests that diosgenin is actually an active compound in yams for memory enhancement, and diosgenin content can be a criterion for predicting cognitive enhancement effect of yam extracts.

Serum Brain-derived Neurotrophic Factor Levels Mirror Bone Mineral Density in Amenorrheic and Eumenorrheic Athletes.

Amenorrhea and osteoporosis are strongly associated in female athletes. Amenorrheic women show lower serum levels of brain-derived neurotrophic factor (BDNF) than eumenorrheic women. BDNF is known to regulate bone tissue development and remodeling; thus, athletes with low serum BDNF levels may show low bone mass. This study investigated the associations between serum BDNF, estradiol, and bone mineral density (BMD) in female athletes. This study included 160 elite female athletes (21.7±4.3 years). Serum levels of BDNF and estradiol were in 195 blood samples obtained from 132 eumenorrheic athletes (EA) and 63 amenorrheic athletes (AA). BMD was measured in the radius, lumbar spine, pelvis, and legs using dual-energy X-ray absorptiometry. AA showed significantly lower serum BDNF levels than EA (p=0.017). Serum BDNF levels were positively and significantly associated with both serum estradiol levels (p=0.0004) and the BMD measured at all sites (all p<0.05). 10 AA received transdermal estrogen therapy, and serum BDNF levels were measured at baseline and 6 months after therapy. Hormone-treated AA demonstrated a significant increase in serum BDNF levels after 6 months (p=0.022). Thus, serum BDNF levels may be associated with decreased BMD and serve as an indicator of the therapeutic effect of estradiol supplementation in female athletes with osteoporosis.