On the structure of prostratin: An X-ray study

Tigliane Diterpenoids from the Stem Bark of Neoboutonia macrocalyx

“…The presence of four diastereotopic protons at δ 2.49 (d, 2.3, H-5b), 2.29 (d, 12.3, H-5a), 4.39 (d, J = 13.8, H-20a), and 4.27 (d, J = 13.8, H-20b) suggested a 12-deoxyphorbol 5 skeleton, in which the C-20 hydroxyl group is free and an ester moiety is attached to C-13. Comparison of the 1 H NMR spectrum of 3 with the literature data revealed close similarity to the known compound 12-deoxyphorbol-13-hexadecanoate. , A comparison of the 1 H NMR data of 3 with those of 12-deoxyphorbol 8 and 13- O -acetyl-12-deoxyphorbol (prostatin) revealed additional signals at δ 0.89 (3H, t, J = 5.6, H-15‘), 1.26 (22H, br s, H-4‘−H-14‘), 1.59 (2H, m, H-3‘), and 2.30 (2H, dd, J = 7.3, 7.5 Hz, 2‘), suggesting that the compound is an ester of 12-deoxyphorbol and pentadecanoic acid. Comparison of the 1 H NMR data of 3 to those of other tigliane diterpenoids established the stereochemistry as 4β-OH, 8β-H, 9α-OH, 10α-H, 11α-CH 3 , 13α-OR, and 14α-H. , The 13 C NMR spectrum of 3 (Table ) revealed minor differences from that of 2 .…”

“…Tigliane diterpenoids have been isolated from many plants in Thymelaeaceae and Euphorbiaceae. − They have interesting biological properties such as irritant, cytotoxic, carcinogenic, and antitumor activity. , Their presence in N. macrocalyx coupled with the reported cytotoxicity may be responsible for the observed antiplasmodial activity of the extracts, although this will have to be further investigated.…”

On the Active Principles of the Thymelaeaceae

“…Ingestion of the plant leads, along with other acute toxic symptoms, to inflammation and blistering of the alimentary tract. Previous trials to characterize the toxic principles of Pimelea prostrata lead to the isolation of 13-O-acetyl-12-deoxyphorbol (Prostratin, I) from air dried plant material [3,4]. However, Prostratin (I), being practically non-irritant to mouse skin [3], does not account for the high irritant activity on the mouse ear of extracts of the plant material.…”

Tigliane and daphnane diterpenoids from Thymelaeaceae family: chemistry, biological activity, and potential in drug discovery

“…The chemical structures of tigliane and daphnane diterpenoids have been primarily determined through NMR spectral analysis. Generally, these diterpenoids exhibit poor crystallinity, and there are limited reports of X-ray crystallographic analyses [25][26][27][28]. The 1 H and 13 C-NMR spectra of tigliane and daphnane diterpenoids share similarities but can be readily differentiated by observing the characteristic signals derived from the gem-dimethylcyclopropane group in tiglianes or the isopropenyl group in daphnanes, respectively.…”