Pentacyclic Triterpenoids from Sabia discolor Dunn and Their α-Glycosidase Inhibitory Activities.

Four new pentacyclic triterpenoids named Sabiadiscolor A-D (1 and 7-9) together with eleven known ones were isolated by repeated column chromatography. Their structures were identified and characterized by NMR and MS spectral data as 6 oleanane-type pentacyclic triterpenoids (1-6), 7 ursane-type ones (7-13), and 2 lupanane-type ones (14-15). Except for compound 15, all other compounds were isolated from Sabia discolor Dunn for the first time. Their α-glycosidase inhibitory activities were evaluated, which showed that compounds 1, 3, 8, 9, 13, and 15 implied remarkable activities with IC50 values ranging from 0.09 to 0.27 µM, and the preliminary structure-activity relationship was discussed.

Plasmon-modulated bistable four-wave mixing signals from a metal nanoparticle-monolayer MoS2 nanoresonator hybrid system.

We present a study for the impact of exciton-phonon and exciton-plasmon interactions on bistable four-wave mixing (FWM) signals in a metal nanoparticle (MNP)-monolayer MoS2 nanoresonator hybrid system. Via tracing the FWM response we predict that, depending on the excitation conditions and the system parameters, such a system exhibits 'U-shaped' bistable FWM signals. We also map out bistability phase diagrams within the system's parameter space. Especially, we show that compared with the exciton-phonon interaction, a strong exciton-plasmon interaction plays a dominant role in the generation of optical bistability, and the bistable region will be greatly broadened by shortening the distance between the MNP and the monolayer MoS2 nanoresonator. In the weak exciton-plasmon coupling regime, the impact of exciton-phonon interaction on optical bistability will become obvious. The scheme proposed may be used for building optical switches and logic-gate devices for optical computing and quantum information processing.

Effect of Intravenous Glucose Tolerance Test on Bone Turnover Markers in Adults with Normal Glucose Tolerance.

BACKGROUND It is well known that enteral nutrients result in acute suppression of bone turnover markers (BTMs), and incretin hormones are believed to play a significant role in this physiological skeletal response. However, there is limited research exploring the impact of parenteral nutrients on BTMs. Our aim was to assess the influence of intravenous glucose on BTMs in adults with normal glucose tolerance (NGT). MATERIAL AND METHODS We conducted 1-h intravenous glucose tolerance test (IVGTT) in 24 subjects with NGT. Blood samples were collected before and 5, 10, 15, 20, 30, 60 min after administration of glucose, then serum levels of bone formation marker procollagen type I N-terminal propeptide (P1NP) and resorption marker C-terminal cross-linking telopeptides of collagen type I (CTX) were measured. RESULTS During IVGTT, the fasting CTX level fell gradually and reached a nadir of 80.4% of the basal value at 60 min. Conversely, the fasting P1NP level decreased mildly and reached a nadir of 90.6% of the basal value at 15 min, then gradually increased and reached 96.6% at 60 min. The CTX-to-P1NP ratio increased slightly and reached a peak of 104.3% of the basal value at 10 min, then fell gradually and reached a nadir of 83% at 60 min. CONCLUSIONS Our study indicates that intravenous glucose results in an acute suppression of BTMs in the absence of incretin hormones. The mechanism responsible for this needs further investigation.