Two diterpene rhamnosides, mimosasides B and C, from Mimosa hostilis.

Two new diterpene rhamnosides, mimosasides B and C (1, 2) were isolated together with mimosaside A (3), a known diterpene rhamnoside (4), four known flavones (5-8), five known flavanones (9-13), and four known chalcones (14-17) from the leaves and twigs of a Brazilian medicinal plant, Mimosa hostilis.

Seco-prezizaane-type sesquiterpenes and an abietane-type diterpene from Illicium minwanense.

A methanol extract of the pericarps of Illicium minwanense afforded seven new seco-prezizaane-type sesquiterpenes (2-8) and a new abietane-type diterpene (9), together with six previously known compounds (1 and 10-14). The structures of the new compounds, (1S)- and (1R)-minwanenone (2 and 3), 1alpha-hydroxy-6-deoxypseudoanisatin (4), (2S)-hydroxy-6-deoxypseudoanisatin (5), 3-oxopseudoanisatin (6), (3S,6R)-4,7-epoxy-6-deoxypseudoanisatin (7), 7-O-methylpseudomajucin (8), and (+)-8,11,13,15-abietatetraene (9), were elucidated by spectroscopic data analysis and chemical transformations. The absolute configurations of 1 and 5 were established by X-ray crystallographic analysis of their p-bromobenzoyl derivatives.

Studies of the mechanism of action of the aerolysin-like hemolysin of Aeromonas sobria in stimulating T84 cells to produce cyclic AMP.

We previously reported that the aerolysin-like hemolysin of Aeromonas sobria stimulates T84 cells to produce cyclic AMP, which then emerges in the culture medium. In order to clarify the mechanism of action of the hemolysin, we examined the involvement of adenosine nucleotide. The results show that the hemolysin stimulates T84 cells to release ATP, which is then converted to adenosine by ectonucleotidase. The adenosine generated might stimulate the P1 adenosine receptors of T84 cells to produce cyclic AMP.

Physicochemical and biological properties of an extracellular serine protease of Aeromonas sobria.

Previously, we cloned a protease gene of Aeromonas sobria, determined its nucleotide sequence and established a method of purifying its product. In this study, we examined the properties of the purified protease. The protease was temperature-labile and had an optimal pH of 7.5. Metallo-protease inhibitors and a cysteine protease inhibitor did not block the proteolytic activity of the enzyme. The treatment with reagents to modify sulfhydryl group did not reduce the activity. But, serine protease inhibitors did, showing that it was a serine protease. Subsequently, we examined the ability of the protease to enhance vascular permeability in dorsal skin. The protease showed activity and the reaction was inhibited by a simultaneously injected antihistaminic agent. Histopathological examination showed that mast cells appeared around the site where the protease was injected. These findings show that the vascular permeability-enhancing effect of the protease is due to histamine released at the site. Furthermore, we found that a soybean trypsin inhibitor (Kunitz) did not block the proteolytic action of the protease in vitro, but inhibited its vascular permeability-enhancing activity in skin. This suggests that a trypsin-like protease from skin mediates the activity of the protease to enhance its vascular permeability.

Neurotrophic activity of honokiol on the cultures of fetal rat cortical neurons.

Honokiol, a main biphenyl neolignan of the traditional crude medicine, Magnoliae cortex, was found to show neurotrophic activity on the cultures of rat cortical neurons at concentration from 0.1 to 10 microM. In the cortical neurons cultured in serum-free medium supplemented with B27, honokiol could promote neurite outgrowth. In addition, the survival and growth of neurons were significantly enhanced by adding honokiol to the primary cultures in serum-free medium supplemented with N2. Its neurotrophic activity was comparable to 40 ng mL(-1) of bFGF at concentration of 10 microM.

New seco-prezizaane-type sesquiterpenes, jiadifenin with neurotrophic activity and 1,2-dehydroneomajucin from Illicium jiadifengpi.

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.