Diterpenes from the Genus Amaracus

Abstract

Continuing our work on the terpenoids occurring in plants of the Labiatae family, we report now on the diterpenoids isolated from Amaracus akhdarensis (Ietswaart et Boulos) Brullo et Furnari (syn. Origanum akhdarensis) and Amaracus pampanini Brullo et Furnari, both growing in Libya.

The taxonomy and chemistry of Origanum

“…This, disagrees with other workers that report several free flavonoids of O. vulgare, from Russia (Antonesku et al, 1983;Peshkova and Mirovich, 1984;Mirovich, 1987), from Japan (Kanazawa et al, 1995), from China (Zheng et al, 1997) and from Greece (Vekiari et al, 1993); unfortunately in all these studies no subspecies are named. On the other hand Tomas- Barberan et al (1988b) also state that species in the sections Amaracus, Anatolicon and Majorana do accumulate external flavonoids, and this is confirmed by other researchers (Passannanti et al, 1984;Voirin et al, 1984;Harvala and Skaltsa, 1986;Souleles, 1990). Inter-sectional hybrids seem to accumulate free flavones too (Palomino et al, 1997;Bosabalidis et al, 1998).…”

“…In O. compactum, 21␣-dihydroxyursolic and 21␣-dihydroxyoleanolic acids, ␤-amyrin, betulin and betulinic acid have also been found (Bellakhdar et al, 1988). The triterpenic alcohol uvaol was isolated from O. pampaninii and was also found present in the flowers of O. dictamnus but absent from the leaves (Passannanti et al, 1984;Piozzi et al, 1986). Figure 3.14 Diterpenoids found in Origanum spp.…”

“…These diterpenes are isoprimara-7,15-dien-19-ol (akhdarenol), isoprimara-15-en-8␤,19-diol (akhdardiol), isoprimara-15-en-8␤,11␣,19-triol (akhdartriol) and isoprimara-15-en-3␤,8␤,19-triol (isoakhdartriol), all found in O. akhdarense while only akhdardiol was found in O. pampaninii (Passannanti et al, 1984;Piozzi et al, 1985). Figure 3.14 shows the diterpenoids found in the genus.…”

“…The major triterpenoids that have been reported are ursolic and oleanolic acids from O. dictamnus, O. akhdarense, O. pampaninii, O. majorana, O. vulgare, and O. compactum; possibly these are present in other Origanum taxa as well, since they are common to most Labiatae (Hegnauer, 1966(Hegnauer, , 1989Passannanti et al, 1984;Piozzi et al, 1985;Bellakhdar et al, 1988;Chung et al, 2001). Ursolic acid constituted 1.8 per cent w/w and oleanolic acid constituted 0.4 per cent w/w of the dried leaves of O. dictamnus (Revinthi-Moraiti et al, 1985).…”

Virescenols: Sources, Structures and Chemistry

“…Acremonium species seem to be a very good source of altrose (26) as it is present in almost all of virescenosides. Virescenosides F (7) and G (8) are the first and, as far as we know, the only terpenic glycosides containing altruronic acid (27) as the sugar moiety.…”