Structure of Kaurane-Type Diterpenes fromParinari spruceiand their Potential Anticancer Activity

Abstract

Twenty-three kaurane-type diterpenes 1 - 23, including twenty new natural products 1 - 20, have been isolated from the leaves of Parinari sprucei and their structures elucidated by spectroscopic and chemical analysis. The isolated compounds were tested for their cytotoxic activity towards a panel of cancer cell lines. Compounds 9 and 10 showed activity against all cell lines with ED (50) values in the range of 10 - 20 microg/mL. The previously known 13-hydroxy-15-oxozoapatlin 21 was evaluated in an in vivo hollow fiber test, and found to be active with KB and LNCaP cells at the concentrations used.

Modulation of the G2Cell Cycle Checkpoint by Sesquiterpene Lactones Psilostachyins A and C Isolated from the Common RagweedAmbrosia artemisiifolia

“…Therefore, the psilostachyins do not appear promising as agents to enhance the sensitivity of tumour cells to DNA damage. However, OZ was recently shown to have antitumour activity in vivo in a mouse hollow fibre model when used as a single agent [30] and it would be interesting to determine the effects of psilostachyins on tumour growth in vivo when used as single agents.…”

Selective Oxidations in the Synthesis of Complex Natural ent-Kauranes and ent-Beyeranes

“…Taking advantage of the allylic C–H bond reactivity, diterpenes 1 and 7 were converted directly to enones 8 and 9 in 38% and 54% yield, respectively, using Py 2 Se 2 and PhIO 2 (Scheme ). Selective dihydroxylation of compounds 8 and 9 (OsO 4 , NMO) gave diastereoisomerically pure 16α,17-dihydroxy-15-oxo- ent -kauran-19-oic acid ( 2 ) and methyl 16α,17-dihydroxy-15-oxo- ent -kauran-19-oate ( 3 ), natural products isolated from Parinari sprucei , in 42% and 78% yield, respectively. One- and two-dimensional NMR experiments were performed to confirm the relative stereochemistry of the products (see the Supporting Information for comparison tables).…”

Characterization of New Ent-kaurane Diterpenoids of Yunnan Arabica Coffee Beans

“…The compound 4 displayed similar characteristic signals to 10α,16α,17-trihydroxy-9α-methyl-15-oxo-20-nor-kauran-19-oic acid γ-lactone ( A ) [16, 17] except for the absence of the carbonyl groups at C-15. This was confirmed by the chemical shift at C-15 ( δ C 50.9) in 4 which was upfield shifted comparing to that in A ( δ C 224.0).…”