Synthesis of 20S-protopanaxadiol β-D-galactopyranosides
20S-Protopanaxadiol (3β,12β,20S-trihydroxydammar-24-ene) 3-, 12-, and 20-O-β-D-galactopyranosides were synthesized for the first time. Condensation of 12β-acetoxy-3β,20S-dihydroxydammar-24-ene (1) and 2,3,4,6-tetra-O-acetyl-α-D-galactopyranosylbromide (α-acetobromogalactose) (2) under Koenigs–Knorr conditions with subsequent removal of the protecting groups resulted in regio- and stereoselective formation of 20S-protopanaxadiol 3-O-β-D-galactopyranoside, an analog of the natural ginsenoside Rh2. Glycosylation of 12β,20S-dihydroxydammar-24-en-3-one (5) by 2 with subsequent treatment of the reaction products with NaBH4 in isopropanol and deacetylation with NaOMe gave 20S-protopanaxadiol 12- and 20-O-β-Dgalactopyranosides.
A ginseng saponin metabolite suppresses tumor necrosis factor-α-promoted metastasis by suppressing nuclear factor-κB signaling in murine colon cancer cells
SC-514, an inhibitor of IkappaB kinase beta (IKKbeta), blocked the TNF-alpha-induced activation of nuclear factor-kappaB (NF-kappaB) as well as the TNF-alpha-promoted metastasis of murine colon adenocarcinoma cells. We investigated the effect of 20-O-beta-D-glucopyranosyl-20(S)-protopanaxadiol (M1), a main intestinal bacterial metabolite of ginseng, on the NF-kappaB-dependent metastasis. M1 was effective in suppressing the TNF-alpha-induced activation of NF-kappaB, expression of matrix metalloprotease-9 (MMP-9), migration and invasion. The TNF-alpha-evoked increase in lung and liver metastasis of colon carcinoma was also abrogated by treatment with M1 in vitro. These results suggest that ginseng has potential to suppress inflammation-related metastasis by downregulating the NF-kappaB signaling pathway.
THE IRON-ACETOCARMINE METHOD OF FIXING AND STAINING CHROMOSOMES
A short description of this procedure was given in Vol. 55 of the American Naturalist, pp. 573â€”574. The method has now been used almost daily for five years, and certain improvements have suggested themselves. The solution can be prepared by mixing about equal volumes of glacial acetic acid and water. To this is added powdered carmine in excess. The liquid is then â€ ? just brought to boil, cooled, and decanted. To the red solution there are then added a few drops of a solution of ferric hydrate in 50 per cent. acetic acid, to act as a mordant. The amount of iron varies with different objects. Too much produces a precipitate in a short time. The more