Cucurbitane structure

From the rhizomes of Hemsleya panacis-scandens and H carnosiflora (Cucurbitaceae) and the leaves of Cowania mexicana (Rosaceae), nineteen cucurbitane type triterpenoids (109 - 127) had been isolated and their structural elucidation had been reported [56-58]. 

Further, many kinds of 29-nor-cucurbitane glycosides, cayaponosides (128 - 143), had been isolated from the root of Cayaponia tayuya (Cucurbitaceae) which have been used as laxatives, diuretics and antirheumatics in Brazilian traditional medicine, and their structural elucidation had also been reported [59]. 

Cueurbitacins tetracyclic triterpenes found as their glycosides in the Cucurbitaceae and Cruciferae. These toxic, bitter compounds are structurally related to the parent hydrocarbon, cucurbitane [19(10-9P)-abeo-5p-lanostane], which differs from lanostane (see Lanosterol) in the formal shift of the 10-methyl group to the 9p-position. Cucurbitacin E was formerly known as elaterin. C. have a laxative action some serve as insect attractants, and a few have antineo-plastic and antigibberellin activity. 

---