Orthosphenia mexicana

In general, very little has been written about diterpenes from the Latin American Celastra-ceaeas these structures are not often found. Abietriene type diterpenes have been the general rule in the Celastraceae although the chemical study of the minor constituents of Orthosphenia mexicana and Rzedowskia tolantonguensis did enable pimarane type diterpenes to be isolated and chemically characterized [43,45] and the second of these species afforded a series of new diterpenes with an isopimarane skeleton, described for the first time in the Celastraceae. 

The structure of the diterpene 107 (C20H30O3) was established by spectroscopic methods and confirmed by x ray diffraction studies while, under nmr, the nor-diterpenes 109-113 proved to be structures with an exocyclic methylene and no carboxylic groups at C-4 and are assumed to be the result of an oxidative decarboxylation process as has occurred elsewhere. Orthosphenia mexicana yielded another new diterpene of the nor-isopimaradiene type (C19H28O3) related to the above-mentioned products [43] spectroscopic analysis and chemical trans-formations established its structure with a tertiaiy hydroxyl, an a,P-unsaturated keto group and the presence of a typical vinyl system of the ABX type. 

Particularly interesting has been the case of Orthosphenia mexicana which yielded five new triterpene methylene quinones with a new carbon skeleton, a greater degree of conjugation than hitherto reported, an extra 14-15 double bond and a rearranged methyl at C-15. Its structure was elucidated by a succession of chemical transformations, spectroscopic methods and X ray diffraction which determined the absolute configuration of this compound [49,50],... 

O.m. Orthosphenia mexicana Stand Leg. R.t. Rzedowskia tolantonguensis Med. M.b. Maytenus boaria Mol. 

Orthosphenin (49), Fig. (16), the first example of an evoninol nucleus with an 0x0 group at C-8 and residual cassinic acid, was isolated from the hexane extract of the roots of Orthosphenia mexicana Standley and was found to have a lethal dosis (LD oo) of 0.01 p.g/cm2 against the fith-instar larvae of the Egyptian cotton leafworm Spodoptera littoralis [143]. 

Di-Ac, 1-cinnamoyl 6P,9p-Diacetoxy-Iot-cinnamoyloxy-2p,4p-hydroxydihydro-p-agarofuran O28H36O9 M 516.587 Constit. of Orthosphenia mexicana. 

---