Anthocyanin from black rice was reported to have beneficial effects on diabetes, but the molecular mechanisms are still largely unknown. Black rice cultivated from different regions in Taiwan (Hualien and Changhua) were included in this study. Concentrations of anthocyanin were significantly higher using the ethanol extraction method than those using water; therefore, ethanol extracts from Hualien and Changhua black rice (HBRE and CBRE) were used for further investigation. 2-NBDG glucose uptake analysis revealed that both HBRE and CBRE promote glucose uptake in C2C12 myotubes. The membrane expression levels of GLUT4 and phosphorylation of IRS-1 also had been markedly increased by both HBRE and CBRE, which was in accordance with the glucose uptake results. CBRE did not affect the downstream of IRS-1 but significantly enhanced protein levels of p-AMPK/AMPK. In contrast, HBRE was shown to target various signaling participated in GLUT4 glucose uptake, including PI3K/Akt and the p38 MAPK/ERK. Overall, we demonstrated that anthocyanin-rich extracts from black rice stimulate GLUT4 glucose uptake via upregulation of PI3K/Akt and AMPK/p38 MAPK signaling in C2C12 myotubes. Our findings revealed that anthocyanin-rich black rice might be a promising functional food for the prevention and treatment of insulin resistance and diabetic hyperglycemia.

Type 2 diabetes mellitus (T2DM) is a chronic disease characterized by hyperglycemia that can lead to long-term complications including heart diseases, stroke, retinopathy, and renal failure. Treatment strategies include stimulating glucose uptake and controlling blood glucose level. Bofutsushosan (BOF) and Daisaikoto (DAI) are two herb-based kampo medicines that have been demonstrated to improve metabolism-associated disorders including obesity, hyperlipidemia, and nonalcoholic fatty liver. Given their bioactivities against metabolic syndromes, we explored in this study the effect of BOF and DAI extracts on glucose absorption and used them as source to identify phytochemical stimulator of glucose absorption. Glucose uptake and mechanistic studies were evaluated in differentiated C2C12 skeletal muscle cells, and HPLC analysis was used to determine the molecular bioactive constituents. Our results indicated that the ethanolic extracts of BOF and DAI (BOFEE and DAIEE, respectively) enhanced the glucose uptake ratio in the differentiated C2C12 cells, and further analysis identified the flavone baicalin as a major constituent capable of efficiently stimulating glucose absorption. Mechanistic studies revealed that the effect from baicalin involved the activation of IRS-1 and GLUT-4, and implicated the AMPK, PI3K/Akt, and MAPK/ERK signaling cascades. Due to its potency, we suggest that baicalin merit further evaluation as a potential candidate anti-hyperglycemic agent for the treatment and management of T2DM.

The emergence of SARS-CoV-2 variants highlights the urgent need for novel therapeutic strategies, particularly entry inhibitors that could efficiently prevent viral infection. Medicinal herbs and herbal combination formulas have long been recognized for their effects in treating infectious diseases and their antiviral properties, thus providing abundant resources for the discovery of antiviral candidates. While many candidates have been suggested to have antiviral activity against SARS-CoV-2 infection, few have been validated for their mechanisms, including possible effects on viral entry. This study aimed to identify SARS-CoV-2 entry inhibitors from medicinal herbs and herbal formulas that are known for heat-clearing and detoxifying properties and/or antiviral activities. A SARS-CoV-2 pseudoparticle (SARS-CoV-2pp) system was used to assess mechanism-specific entry inhibition. Our results showed that the methanol extract of Anemarrhena asphodeloides rhizome, as well as the water extracts of Cimicifuga foetida rhizome, Xiao Chai Hu Tang (XCHT), and Sheng Ma Ge Gen Tang (SMGGT), have substantial inhibitory effects on the entry of SARS-CoV-2pps into host cells. Given the observation that Cimicifuga foetida exhibited the most potent inhibition and is a constituent of SMGGT, we further investigated the major compounds of the herb and identified caffeic acid as a bioactive component for blocking SARS-CoV-2pp entry. Entry inhibition of Cimicifuga foetida and caffeic acid was validated on both wild-type and the currently dominant JN.1 strain SARS-CoV-2pp systems. Moreover, caffeic acid was able to both inactivate the pseudoparticles and prevent their entry into pretreated host cells. The results support the traditional use of these herbal medicines and underscore their potential as valuable resources for identifying active compounds and developing therapeutic entry inhibitors for the management of COVID-19.