Inhibitory effects on mushroom tyrosinase by flavones from the stem barks of Morus lhou (S.) Koidz.

Five flavones displaying tyrosinase inhibitory activity were isolated from the stem barks of Morus lhou (S.) Koidz., a cultivated edible plant. The isolated compounds were identified as mormin (1), cyclomorusin (2), morusin (3), kuwanon C (4), and norartocarpetin (5). Mormin (1) was characterized as a new flavone possesing a 3-hydroxymethyl-2-butenyl at C-3. The inhibitory potencies of these flavonoids toward monophenolase activity of mushroom tyrosinase were investigated. The IC50 values of compounds 1-5 for monophenolase activity were determined to be 0.088, 0.092, 0.250, 0.135 mM, and 1.2 microM, respectively. Mormin (1), cyclomorusin (2), kuwanon C (4) and norartocarpetin (5) exhibited competitive inhibition characteristics. Interestingly norartocarpetin (5) showed a time-dependent inhibition against oxidation of L-tyrosine: it also operated under the enzyme isomerization model (k5 = 0.8424 min(-1), k6 = 0.0576 min(-1), K(app)(i) = 1.354 microM).

A new guaianolide as apoptosis inhibitor from Chrysanthemum boreale.

The 8-O-acetyl-3,10-dihydroxy-4(15),11(13)-guaiadien-12,6-olide, named borenolide, was isolated from Chrysanthemum boreale M. Borenolide inhibits the etoposide-induced apoptosis in U937 cell with an IC(50) value of 6.2 microg/ml. Structural assignment was based on NMR-spectroscopic methods and X-ray crystallographic analysis.

Estrogenic regulation of HSP90 kD synthesis in rat urinary bladder.

The role of heat shock protein (HSP90 kD) has been investigated in regard to its association with steroid receptors. HSP90 kD may play a role in steroid receptor stabilization and activation. Oophorectomized Sprague-Dawley rats (n = 25) were placed into five groups and injected subcutaneously with 30 microg beta-estradiol 17-benzoate in sesame oil, with one group injected with carrier oil (control). After estrogen administration, the rats were killed, and their bladders removed for immunostaining, immunoblotting and enzyme-linked immunosorbent assay (ELISA). Immunoblot analysis demonstrated a 90-kD band in bladder homogenates, even in the absence of estrogen. However, the bands were more intense 12 and 24 h after administering estrogen. ELISA showed significant differences in HSP90 kD synthesis as early as 6 h compared to controls (P< 0.05). After 48 h the estrogen-treated rats and controls were identical. The above results were confirmed by immunostaining for HSP90 kD. HSP90 kD synthesis in the rat urinary bladder is under estrogenic regulation. These findings may be relevant in the etiology and pathobiology of interstitial cystitis and menopausal voiding dysfunctions since the bladder is enriched with estrogenic receptors and is under estrogenic influence.

Hemistepsins with cytotoxic activity from Hemisteptia lyrata.

Two sesquiterpene lactones were isolated from Hemisteptia lyrata Bunge (Compositae). Their structures were elucidated by spectroscopic methods as recently known hemistepsin and the new 6-O-(2-methylpropenoyl)-3-hydroxy-4(15), 10(14), 11(13)-guaiatrien-12,8-olide. The two hemistepsin derivatives were examined for their in vitro cytotoxic activity against human cell lines such as UACC 62, HCT 15, UO-31, PC-3 and A549. Growth inhibitory property was determined by in vitro treatment of the respective cell lines using the sulforhodamine B assay (SRB). Both compounds exhibited significant cytotoxic activity (IC50 < 4.3 micrograms/ml) on all five human cell lines tested.

Structural analogues of cumambrin B from the flower of Chrysanthemum boreale.

The structural analogues of cumambrin B (1, 2, 3, 4) were isolated from the flower of Chrysanthemum boreale Makino. The structures of compounds were determined by two-dimensional 1H-1H COSY and 13C-1H COSY spectra with the aid of homonuclear and heteronuclear double resonance experiment. The stereochemistry of compounds has been verified from single crystal X-ray diffraction of cumambrin A (2). The antimicrobial activities of these guaianolides have been studied.