X-ray structure investigation of (20S)-20-O-beta-D-glucopyranosyl-protopanaxadiol and antitumor effect on Lewis lung carcinoma in vivo.

(20S)-20-O-beta-D-Glucopyranosyl-protopanaxadiol (1) has been isolated as a metabolite of ginseng saponins by Paecilomyces bainier. The compound crystallizes in the monoclinic space group P2(1) with unit cell parameters a=11.523(6) A, b=12.383(6) A, c=14.233(7) A, beta=96.862(9) degrees , and Z=2. The crystal structure has been solved by direct methods and refined to R=0.0536 for 4569 observed reflections. In the crystal structure, the water and methanol molecules link the molecules into infinite supramolecular layers through hydrogen bonds. The antitumor property of 1 was tested in vivo towards the inhibition of Lewis lung carcinoma growth. The results indicated that the antitumor effect of 1 was ordinary on monotherapy. However, comparing the antitumor activity of 1 plus cyclophosphamide (CTX) with that of CTX alone, the combination effect was significantly superior and synergistic. This may due to immunoloregulation activity of 1 by improving the WBC, IL-2 and INF-gamma degraded by CTX.