Isolation of a new 15-membered macrocyclic glycolipid lactone, Cuscutic Resinoside a from the seeds of Cuscuta chinensis: a stimulator of breast cancer cell proliferation.

While searching for new estrogenic compounds from the plant kingdom, we investigated an extract of the seeds of Cuscuta chinensis (Convolvulaceae) which showed potency for stimulating MCF-7 cell proliferation. A novel resin glycoside, cuscutic resinoside A ( 6) was isolated along with five known compounds from the extract. The structure was deduced from its spectral data as (11 S)-hydroxyhexadecanoic acid 11- O-alpha- L-(4- O-2 R,3 R-nilylrhamnopyranosyl)-(1-->2)- O-alpha- L-rhamnopyranosyl-(1,2-lactone) forming a unique 15-membered macrocyclic lactone. The compound significantly stimulated not only MCF-7 cell proliferation but also T47D human breast cancer cells at a concentration of 10 microM. Along with cuscutamine ( 1) and kaempferol ( 4), 6 was tested in the transient luciferase reporter assay and was found to have different luciferase inducing activity characteristics from the other compounds. These results suggest that 6 stimulated cancer cell proliferation by a different mechanism from 1 and 4.