Tumor inhibitors. LVI. Cucurbitacins O, P, and Q, the cytotoxic principles of Brandegea bigelovii

Abstract

the acetonitrile solution (after filtration) gave an oil which was chromatographed over tic plates (silica gel G; benzene-ethyl acetate, 4:1). A band (R¡ 0.65) afforded 13 as an oil which did not crystallize after long standing: yield 30 mg; ir bands (CHCla) 3450 (hydroxyl), 1750 (carbonyl), and 1250 (acetate) cm-1. The nmr spectrum (Table I) indicated that the substance was pure and clearly indicated a vinylic methyl group as shown in the formula of 13.

New Cucurbitacin Glycosides fromPicrorhiza kurrooa

“…Cucurbitacin Q, reported by Kupchan as a constituent of Brandegea bigelovii(12), to our knowledge, has been isolated only as an aglycone but never as a glycoside. Since the 1H-NMR data of the aglycone reported in the literature are fragmentary and 13CNMR data are completely lacking, the NMR data of the 2-0glycoside, compound 6, are given in…”

Cucurbitacins and cucurbitane glycosides: structures and biological activities

“…72 The 2,3-cis-diol system was originally, and erroneously, assigned as a-configured 72 and was subsequently revised to be b-configured. 72 The 2,3-cis-diol system was originally, and erroneously, assigned as a-configured 72 and was subsequently revised to be b-configured.…”

“…From Brandegea bigelovii (Cucurbitaceae), cucurbitacins O (73), P (74), and Q (75) were isolated, and their cytotoxicity against Eagle's KB human carcinoma of the nasopharynx was determined. 72 The 2,3-cis-diol system was originally, and erroneously, assigned as a-configured 72 and was subsequently revised to be b-configured. 73 From Picrorhiza kurrooa 18 and Ecballium elaterium, 39 cucurbitacin Q 2-O-glucoside (76) and 16-deoxy-D 16 -hexanorcucurbitacin O (77) were obtained, respectively.…”

Separation of Cucurbitacins by Overpressure Layer Chromatography fromHemsleya gigantha1

“…Since only one of the two spots was UV-active, mixtures of saturated and unsaturated cucurbitacins were suggested. This was further supported by the presence of ion peaks at m/z = 96 and 111 (from cucurbitacins with 23,24-unsaturated side-chains), as well as peaks at m/z = 113 and 142 (from cucurbitacins with saturated side-chains) (17,18). In addition, both A and B displayed significant ion peaks at m/z =369, 387, and 405, consistent with a 2,3-diol structure (18).…”

“…This was further supported by the presence of ion peaks at m/z = 96 and 111 (from cucurbitacins with 23,24-unsaturated side-chains), as well as peaks at m/z = 113 and 142 (from cucurbitacins with saturated side-chains) (17,18). In addition, both A and B displayed significant ion peaks at m/z =369, 387, and 405, consistent with a 2,3-diol structure (18). The 1H-NMR spectrum of mixture A revealed a strong signal at ö = 2.05 ppm, indicating the presence of an acetyl group in the compounds, while compounds in mixture B were not acetylated.…”