Epitulipinolide

Molecules. 2014 Apr 3;19(4):4234-45.

Antioxidant and anticancer constituents from the leaves of Liriodendron tulipifera.[Pubmed: 24705566]

METHODS AND RESULTS:
Sixteen compounds were extracted and purified from the leaves of Liriodendron tulipifera. These compounds include aporphines, oxoaporphine, coumarin, sesquiterpene lactone, benzenoids, cyclitol and steroids. (+)-Norstephalagine (2) (an aporphine) and scopoletin (8) (a coumarin) were isolated from Liriodendron tulipifera leaves from the first time. The identified compounds were screened for their antiradical scavenging, metal chelating and ferric reducing power activities. The results have showed that these compounds have antioxidative activity. The study has also examined the chemopreventive property of the isolated compounds against human melanoma cells A375. The results shown that (-)-anonaine (1), (-)-liridinine (3), (+)-lirinidine (6), lysicamine (7) and Epitulipinolide diepoxide (9) significantly inhibited the proliferation of melanoma cells.
CONCLUSIONS:
These results revealed that these compounds have antioxidative activity and chemopreventive activity in skin melanoma cells.

J. Organic Chem.,1972,37(17):2740-4.

Antitumor agents. VI. Sesquiterpene lactones tulipinolide and epitulipinolide from Liriodendron tulipifera.[Reference: WebLink]

The dihydro derivatives 3 and 4 of tulipinolide (1) and Epitulipinolide (2) were prepared by NaBH4 reduction since catalytic hydrogenation gave other reduction products.
METHODS AND RESULTS:
The stereochemistry at the reduced center of these derivatives was determined by cyclization to the already known β-cyclo compounds 6 and 7. Minor alkaline-hydrolysis products of Epitulipinolide (2) were established as the methoxy Michael adducts 13 and 15 if methanol was a cosolvent. Without methanol the eudasmanolide diol 16 was formed along with the unusual cadinene lactone 22, but in no case was the C-8 cis γ-lactone germacranolide (isoeupatolide) detected.
CONCLUSIONS:
A product of alkaline hydrolysis of tulipinolide (1) was desacetylisotulipinolide (23), a C-8 trans γ-lactone which was also obtained by treatment of eupatolide methanesulfonate (25) with hydroxide ion. The acetate of 23 (isotulipinolide) was shown to be identical with the recently isolated germacranolide, laurenobiolide.