Cucurbitacins From Bryonia Verrucosa. Isomerization of 2-Hydroxy-3-Keto-Cucurbitacins

Abstract

Three new cucwbitacins as well as thirteen know ones were isolated from the h i t s of B v n i a vemcosa. The new compounds were characterized by chemical and qxxtral methods.An effective and simple method to isomerize 2-hydroxy-3-ketocucurbiracins in acid media is described.

Cucurbitacins and cucurbitane glycosides: structures and biological activities

“…19 It was shown that 2 and 6 have a hepatoprotective effect in rats with experimental cholestasis. 22 Compound 9 was subsequently shown to be identical to the aglycone of 22-deoxocucurbitosides A and B from B. alba. 22 Compound 9 was subsequently shown to be identical to the aglycone of 22-deoxocucurbitosides A and B from B. alba.…”

“…20 Other congeners of cucurbitacin B, including dihydroisocucurbitacin B 3-glucoside (7) from Wilbrandia ebracteata (Cucurbitaceae), 21 23,24-dihydro-3-epiisocucurbitacin B (8), and the 23-epimeric pairs 9 and 10 from Bryonia verrucosa (Cucurbitaceae), were also reported. 22 Compound 9 was subsequently shown to be identical to the aglycone of 22-deoxocucurbitosides A and B from B. alba. 23…”

“…36 From the methanolic seed extracts of four species of the genus Physocarpus (Rosaceae), 3-epi-isocucurbitacin D (14) was obtained and found to antagonize the action of insect steroid hormones. 37 Other members belonging to the cucurbitacin D group include 23,24-dihydro-epi-isocucurbitacin D (20) from Acanthosicyos horridus (Cucurbitaceae), 38 22-deoxocucurbitacin D (21) from Wilbrandia ebracteata (Cucurbitaceae), 21 anhydro-22deoxo-3-epi-isocucurbitacin D (22) from Ecballium elaterium (Cucurbitaceae), 39 25-O-acetyl-2-deoxycucurbitacin (amarinin) (24) from Luffa amara (Cucurbitaceae), 40 and compound 25 from W. ebracteata. 37 Other members belonging to the cucurbitacin D group include 23,24-dihydro-epi-isocucurbitacin D (20) from Acanthosicyos horridus (Cucurbitaceae), 38 22-deoxocucurbitacin D (21) from Wilbrandia ebracteata (Cucurbitaceae), 21 anhydro-22deoxo-3-epi-isocucurbitacin D (22) from Ecballium elaterium (Cucurbitaceae), 39 25-O-acetyl-2-deoxycucurbitacin (amarinin) (24) from Luffa amara (Cucurbitaceae), 40 and compound 25 from W. ebracteata.…”

New Cucurbitane-Type Triterpenoids fromBryonia aspera

“…In analogy to the previously iso-lated neocucurbitacins, we named compound 1which represents only the third example of a lactone-type norcucurbitacinneocucurbitacin C (l " Fig. The structures of the known compounds (see Supporting Information) were identified as the pentacyclic triterpene bryonolic acid (5) [11]; 23,24-dihydrocucurbitacin B (6) [12]; 23,24-dihydro-epi-isocucurbitacin B (7) [13,14]; cucurbitacin E (8) [15][16][17]; 23,24-dihydrocucurbitacin D (9) [15,18]; cucurbitacin L (10) [16,19] Our results show that B. aspera is a rich source of cucurbitanetype triterpenoids, most of which are derivatives of 23,24-dihydrocucurbitacin D, whereas 23,24-unsaturated congeners were obtained only as minor constituents. Compound 2 was obtained as a white amorphous solid.…”

“…1). Because bryonolic acid (5) as well as several cucurbitacin derivatives are known to possess strong antiproliferative activity [14,23,24], these compounds might be responsible for the traditional use of B. aspera as an anticancer remedy. Its HR-E-SI-TOF-MS showed a quasi-molecular ion peak at m/z = 557.3493 [M + Na] + , which corresponded to the molecular formula C 30 H 45 O 8 .…”