Totaranes

Podolactones are considered to be a group of natural products whose basic skeleton contains a y-lactone between carbons 19-6 and a 6-lactone between carbons 12-14, which are their characteristic functions Fig. (1) [1]. The numbering of the podolactone skeleton has been assigned on the basis of the totarane skeleton from which most of podolactones have been proposed to be derived. 

Appearance of podolactones in the extracts of Podocarpus species along with various derivatives with a totarane skeleton (totarol, 12-... 

Ginkgolide A (ginkgolide diterpene) Nagilactone C (totarane-like diterpene)... 

Abietanes may formally be derived from pimaranes by migration of the methyl group C-17 from C-13 to C-15. In plants, however, they emerge from cyclization of geranylgeranyl diphosphate. Related parent diterpene hydrocarbons include 13,16-cycloabietanes, 17(15-16)-aZ)eo-abietanes in which the methyl group C-17 has shifted from C-15 to C-16, and totaranes. The latter formally arise from abietane when the isopropyl group migrates from C-13 to C-14. 

More than 20 quinoid 13,16-cycloabietanes, named as eoleones A-Z, oeeur in the yellow glands in the leaves of Afriean Coleus speeies (Labiatae). Lanugone A isolated from Plectranthus lanuginosis (Labiatae) represents a quinoid n(lS)-abeo-abietane. Totaranes sueh as (-l-)-totarol and the derived biphenyl-type dimer (-t)-podototarine are found in the wood of Podocarpus totara (Cupressaeeae). 

---