Seong-Cheol Bang

Pulsatilla saponin D: The antitumor principle fromPulsatilla koreana

By bioassay-guided separation, an already known saponin,Pulsatilla saponin D was isolated from the root ofPulsatilla koreana Nakai as a antitumor component when evaluated byin vivo antitumor activity as well asin vitro cytotoxic activity test. It showed potent inhibition rate of tumor growth (IR, 82 %) at the dose of 6.4 mg/kg on the BDF1 mice bearing LLC cells.

Evaluation of anticancer activity of 4-vinyl-1-arylsulfonylimidazolidinones.

To continue exploration of structure activity relationship of novel 1-(indoline-5-sulfonyl)-4-phenylimidazolidinones (1) reported as anticancer agent with broad spectrum, three 1-(arylsulfonyl)-4-vinylimidazolidinones (2) were synthesized from methyl serinate (3) in 8 steps. Reaction of intermediate 2-phenoxycarbonylaminobut-3-enyl p-toluenesulfonate (10) with arylsulfonamide in the presence of potassium carbonate produced corresponding2 andN-(4-vinyloxazolidin-2-yl)arylsulfonamide11 in approximately equal ratio. This reaction is believed to undergo through urea intermediate16 as shown in scheme 3. 1-Arylsufonyl-4-vinylimidazolidinones2 show much reduced activity against human colon carcinoma (Colo205), human chronic myelogenous leukemia (K562), and human ovarian adenocarcinoma (SK-OV-3) and compatible activity against human lung carcinoma (A549) compared to1. Therefore phenyl at 4-position should be the optimum planar motif for the activity of1.

A convenient preparation of a disaccharide motif and its role in the cytotoxicity of the triterpenoid saponin, α-hederin

The sugar structures of triterpenoid saponins, such as α-hederin, are intimately associated with their antitumor activities and other biological activities. The α-l-rhamnopyranosyl-(1→2)-α-l-arabinopyranoside group of α-hederin alters the cytotoxicity of its aglycon, hederagenin. This study explored the role of this saccharide unit in the cytotoxic effect of α-hederin and the possibility of its use as a carrier moiety in prodrugs of anticancer agents. A new convenient and practical procedure for the preparation of 4-methoxybenzoyl-2,3,4-tri-O-benzoyl-α-l-rhamnopyranosyl-(1→2)-3,4-O-dibenzoyl-β-l-arabinopyranoside (2) from 4-methoxybenzoyl-β-l-arabinopyranoside was accomplished using four steps with an overall yield of 63%. The use of BF3-OEt2 as a catalyst in the glycosylation step in this procedure had a large advantage over the TMSOTf catalyst used in the usual method. Moreover, the key intermediate obtained in this procedure, 4-methoxybenzoyl-2,3,4-tri-O-benzoyl-α-l-rhamnopyranosyl-(1→2)-α-l-arabinopyranoside (7), was selectively transformed to 4-methoxybenzoyl-2,3,4-tri-O-benzoyl-α-l-rhamnopyranosyl-(1→2)-4-O-acetyl-α-l-arabinopyranoside (9) and 4-methoxybenzoyl-2,3,4-tri-O-benzoyl-α-l-rhamnopyranosyl-(1→2)-3-O-benzoyl-β-l-arabinopyranoside (10). These derivatives did not show any cytotoxicity against human cancer cell lines. Thus the 3-O-α-l-rhamnopyranosyl-(1→2)-α-l-arabinopyranoside could be used as a nontoxic carrier moiety to enhance the activity of anticancer drugs.