Three novel seco-prezizaane-type sesquiterpenoids, jiadifenolide (1), jiadifenoxolane A (2), and jiadifenoxolane B (3), were isolated from the pericarps of Illicium jiadifengpi. Their pentacyclic cage structures were determined by 2D-NMR methods, chemical conversion, and single-crystal X-ray analysis. Compounds 1 and 2 strongly promote neurite outgrowth in primary cultured rat cortical neurons at concentrations ranging from 0.01 to 10 muM.

Two new seco-prezizaane-type sesquiterpenes, 1,2-dehydroneomajucin (1) and jiadifenin (2), were isolated from the methanol extract of the pericarps of Illicium jiadifengpi, indigenous to the southern part of China. Their structures were elucidated on the basis of NMR data. Compound 2, which is an equilibrated mixture of the epimers 2a and 2b on the C-10 acetal carbon, is the first example of a majucin-type seco-prezizaane with an oxo-function at the C-10 position. The proposed structure for 2 was unambiguously confirmed by chemical conversion of the known sesquiterpene (2S)-hydroxy-3,4-dehydroneomajucin (5) to 2. Compounds 2 and 5 were found to significantly promote neurite outgrowth in primary cultures of fetal rat cortical neurons at concentrations from 0.1 to 10 microM.

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An extract of the pericarps of Illicium merrillianum has yielded four new sesquiterpenes: 3 alpha-hydroxycycloparvifloralone (1), 1,2-dehydrocycloparvifloralone (2), (11) 7,14-ortholactone-3 alpha-hydroxyfloridanolide (3), and 11-O-debenzoyltashironin (4) along with cycloparvifloralone (5), merrillianone (6), and tashironin (7). The structures of 1--4 were determined on the basis of spectroscopic analyses. 11-O-Debenzoyltashironin (4) showed neurotrophic activity in primary culture of rat cortical neurons at 0.1--10 microM. However, cycloparvifloralone-type sesquiterpenes (1, 2, 5, and 6) and tashironin (7) had no neurotrophic activity at these concentrations.

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Diabetic retinopathy, a leading cause of visual loss and blindness, is characterized by microvascular dysfunction. Hyperglycemia is considered the major pathogenic factor for diabetic retinopathy and is associated with increased oxidative stress in the retina. In this study, we investigated the potential protective effects of Panax notoginseng Saponins (PNS) in retinal capillary endothelial cells (RCECs) exposed to high glucose conditions. We found a pronounced increase in cell viability in rat RCECs incubated with both PNS and high glucose (30 mM) for 48 h or 72 h. The increased viability was accompanied by reduced intracellular hydrogen peroxide (H2O2) and superoxide (O2 −), decreased mitochondrial reactive oxygen species (ROS), and lowered malondialdehyde (MDA) levels. PNS also increased the activities of total superoxide dismutase (SOD), MnSOD, catalase (CAT), and glutathione peroxidase (GSH-PX). The glutathione (GSH) content also increased after PNS treatment. Furthermore, PNS reduced NADPH oxidase 4 (Nox4) expression. These results indicate that PNS exerts a protective effect against high glucose-induced injury in RCECs, which may be partially attributed to its antioxidative function.

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