Eupalinin A isolated from Eupatorium chinense L. induces autophagocytosis in human leukemia HL60 cells.

Eupalinin A, a natural phytoalexin included in Eupatorium chinense L., exhibited a marked inhibitory effect on cell growth in HL60 cells. The morphological aspects of eupalinin A-treated cells evaluated by Hoechst 33342 nuclear staining indicated cell death, only a small part of which showed a typical apoptosis with nuclear fragmentation and condensation. To determine what type of cell death is caused by eupalinin A, we examined the contribution of caspases, Bcl-2 family proteins, MAP kinase, and PI3K/Akt, and mitochondrial membrane potential to this cell death. As a result, most part of the cell death was not associated with apoptosis because of caspase independence and no death factor released from mitochondria. Electron microscopic study indicated a characteristic finding of autophagy such as the formation of autophagosomes. Furthermore, the level of microctubule-associated-protein light chain 3 (LC3) II protein and monodancylcanaverin (MDC) incorporation were gradually increased with reduction of mitochondrial membrane potential by the accumulation of intracellular ROS after eupalinin A treatment. From these results, we can conclude that eupalinin A-induced cell death was mainly due to autophagy, which was initiated by increased ROS, resulting in the perturbation of mitochondrial membrane potential. Since the class III PI3K inhibitor such as 3-MA or LY294002 did not inhibit the eupalinin A-induced type II programmed cell death (PCD II), it was suggested that the PCD II was executed by Beclin-1 independent pathway of damage-induced mitochondrial autophagy (mitophagy).

Laxative effect of agarwood leaves and its mechanism.

We investigated the laxative activity of an extract of agarwood leaves from Aquilaria sinensis. The laxative activity was measured in mice by counting the stool frequency and stool weight, and the drugs were orally administered. An acetone extract of agarwood leaves and senna (a representative laxative drug) both increased the stool frequency and weight, but a methanol extract did not. The laxative effect of the acetone extract was milder than that of the anthraquinoid laxative, senna, and the former did not induce diarrhea as a severe side effect. We identified the main constituent contributing to the laxative effect of the acetone extract as genkwanin 5-O-beta-primeveroside (compound 4). Compound 4 strengthened the spontaneous motility and induced contraction in the ileum. This ileal contraction induced by compound 4 was inhibited by atropine, but not by azasetron, suggesting that the effect of compound 4 was mediated by acetylcholine receptors, and not by serotonin. The laxative mechanism for compound 4 may in part involve stimulation of intestinal motility via acetylcholine receptors.

Flavonol glycosides in leaves of two Diospyros species.

Fourteen flavonol glycosides including two new compounds were isolated from the leaves of two Diospyros plants (D. cathayensis and D. rhombifolia). The structures of isolated compounds were determined by spectroscopic analysis. The scavenging activity of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical of the isolated compounds was also investigated.