Seco-diterpenes

A.C. Pinto, S.K. Do Prado, R.B. Filho, W.E. Hull, A. Neszmelyi, and G. Lukacs, Natural abundance C- C coupling constants observed via double quantum coherence. Structural elucidation by the one-and the two-dimensional NMR experiments of velloziolone, a new seco-diterpene. Tetrahedron Lett. 23(50), 5267... 

Another tetracyclic carbon skeleton, named cumbiane, has been isolated from Pseudopterogorgia elisahethae. Its representatives are the diterpenoids cumbiasin A (33) and B (34) [20] their structures and relative configurations were elucidated by interpretation of a combination of spectral data. The six-membered ring D was formed by connecting CIO and C16 of an elisabethane carbon skeleton. The carbocyclic skeleton of the cumbiasins is unprecedented and represents a new class of C20 rearranged diterpenes. The tricyclic seco-cumbiane skeleton is derived from the cumbiasins by cleavage of the C15-C16 bond. Due to intramolecular cyclizations two additional oxo-heterocycles are present in cumbiasin C (35) [20] (Fig. 7). 

Pseudopterosins coexist with the seco-pseudopterosins, suggesting that these two classes of diterpenes are produced from a single cyclase product. Elisabethatriene (42) undergoes aromatization to erogorgiaene (1) presumably a series... 

The pseudopterosins and seco-pseudopterosin isolated from Bahamian specimens of Pseudopterogorgia elisabethae display strong anti-inflammatory and analgesic activity. These diterpene glycosides had potencies superior to those of... 

Isodon diterpenes. Highly oxygenated.- -seco-ent-kaurane diterpenoids, the isodons (Figure 7), isolated from species of Isodon (now Rhabdosia)... 

Yokoyama, R., Huang, J.M., Hosoda, A., Kino, K., Yang, C.S. and Fukuyama, Y. (2003) Seco-prezizaane-type sesquiterpenes and an abietane-type diterpene from lllicium minwanense. Journal of Natural Products... 

Sanchez JA, Ortega-Barria E, Gonzalez J. New pseudopterosin 134. and seco-pseudopterosin diterpene glycosides from two Colombian isolates of Pseudopterogorgia elisabethae and their diverse biological activities. J. Nat. Prod. 2004 67 1672-1680. 

A group of challenging target molecules with important biological activities are the pseudopterosins [23] and the seco-pseudopterosins [24], marine diterpene glycosides with strong anti-inflammatory properties (Fig. 3). 

The helioporins, a group of marine diterpenes with antiviral and cytotoxic properties, are structurally closely related to the (seco-) pseudopterosins and all possess a characteristic benzodioxole unit [29]. Their stereostructure was assigned as shown in Fig. 4 with a cfs-relationship of the two benzylic sidechains at the tetralin nucleus. 

Figure 1. Structures of Diterpenes 27. Nomial-Labdane-20,12-Lactone, 5,10-Seco-... 

Segawa, M., Enoki, N., Ikura, M., Hikichi, K., Ishida, R., Shirahama, H., and Matsumoto, T. (1987) Dictymal, a new seco-fusicoccin type diterpene from the brown alga Dictyota dichotoma. Tetrahedron Lett., 28, 3703-3704. 

Look, S.A. and Fenical, W. (1987) Seco-pseudopterosins, antiinflammatory diterpene-glycosides from gorgonians octocoral genus Pseudopterogorgia. Tetrahedron, 43, 3363-3370. 

Rodriguez, A.D., Cobar, O.M., and Martinez, N. (1994b) The first seco-asbestinin a novel class of diterpene from the Caribbean gorgonian Briareum asbestinum (Pallas). Tetrahedron Lett., 35, 5793-5796. 

The blue coral, Heliopora coerulea, harvested in Japan has yielded a series of diterpenes with antiviral (herpes simplex type 1, HSVl) and cytotoxic (P-388) activities. The series includes both amphilectanes and seco-amphilec-tanes (helioporin C, Figure 20.59) (seco-amphilectane = serrulatane). The helioporin aglycones are very similar to those of pseudopterosins, but helioporins are not glycosides. 

Several types of triqrdic diterpenes are formed by the association of a cydopentane, a cydohexane and a cydo-heptane, for whidi there are at least five different carbon skeletons, all represented in the genus Sinularia (Figure 20.59). The most widespread carbon skeleton is that of mandapamate and isomandapamate, which were isolated from Sinularia dissecta, S. maxima, and S. conferta. Formally related to mandapamate and isomandapamate, havellockate is a seco-spiroditerpene isolated from Sinularia granosa from Havelock Island, Andaman and Nicobar (Indian Ocean). Two original derivatives were extracted... 

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