Radix Astragali (RA) is commonly used as a health food supplement to reinforce the body vital energy. Flavonoids, including formononetin, ononin, calycosin, and calycosin-7-O-β-d-glucoside, are considered to be the major active ingredients within RA. Here, we provided different lines of evidence that the RA flavonoids stimulated the expression of erythropoietin (EPO), the central regulator of red blood cell mass, in cultured human embryonic kidney fibroblasts (HEK293T). A plasmid containing hypoxia response element (HRE), a critical regulator for EPO transcription, was tagged upstream of a firefly luciferase gene, namely, pHRE-Luc, which was being transfected into fibroblasts. The application of RA flavonoids onto the transfected cells induced the transcriptional activity of HRE. To account for the transcriptional activation after the treatment of flavonoids, the expression of hypoxia-inducible factor-1α (HIF-1α) was markedly increased: The increase was in both mRNA and protein levels. In addition, the degradation of HIF-1α was reduced under the effect of flavonoids. The regulation of HIF-1α therefore could account for the activation of EPO expression mediated by the RA flavonoids. The current results therefore reveal the function of this herb in enhancing hematopoietic functions.

Chinese date, the fruit of Ziziphus jujuba Mill., has thousands of years cultivation history, and about 700 cultivars of dates in China. Two types of dates are commonly found in the market: (i) fresh immature dates consumed as fruits, and (ii) dried mature dates used as Chinese medicines. Here, chemical and biological properties of these dates were revealed. Different sources of dates showed similar chemical profiles; however, the amounts of identified chemicals showed a great variation. The amount of nucleotides, flavonoids and polysaccharides in dates could be affected by its maturity and drying process. In parallel, the antioxidative functions of their extracts were compared. The date extracts protected PC12 cells against tBHP-induced cytotoxicity, and which also stimulated the transcriptional activity of antioxidant response element. The antioxidative effects were varied among different dates. The current results suggested the optimization of sources and specific usage of different maturity dates.

Flavonoids, a group of compounds mainly derived from vegetables and herbal medicines, share a chemical resemblance to estrogen, and indeed some of which have been used as estrogen substitutes. In searching for possible functions of flavonoids, the neuroprotective effect in brain could lead to novel treatment, or prevention, for neurodegenerative diseases. Here, different subclasses of flavonoids were analyzed for its inductive role in neurite outgrowth of cultured PC12 cells. Amongst the tested flavonoids, a flavonol aglycone, isorhamnetin that was isolated mainly from the leaves of Ginkgo biloba L. showed robust induction in the expression of neurofilament, a protein marker for neurite outgrowth, of cultured PC12 cells. Although isorhamnetin by itself did not show significant inductive effect on neurite outgrowth of cultured PC12 cells, the application of isorhamnetin potentiated the nerve growth factor- (NGF-)induced neurite outgrowth. In parallel, the expression of neurofilaments was markedly increased in the cotreatment of NGF and isorhamnetin in the cultures. The identification of these neurite-promoting flavonoids could be very useful in finding potential drugs, or food supplements, for treating various neurodegenerative diseases, including Alzheimer's disease and depression.