Phorbol diesters

Figure 1. General structure of the tumor-promoting component, phorbol, of croton oil. 12-O-tetradecanoyl-phorbol-l3-acetate (TPA) is the most potent promoter of the phorbol diesters. Phorbol didecanoate and phorbol dibenzoate, among others, have promoting ability but to a lesser extent than TPA. Phorbol alone has been reported to have no capacity to induce tumors as ODC.

R12. Rokutan, K., Thomas, J. A., and Johnston, R. B. J., Phagocytosis and stimulation of the respiratory burst by phorbol diester initiate S-thiolation of specific proteins in macrophages. J. Immunol. 147, 260-264 (1991). 

The oil of Croton tiglium (croton) has a violent purgative action and contains tumor-promoting phorbol diesters and triesters. 

Trager, W., and Gill, G. S. (1989). Plasmodium falciparum gametocyte formation in vitro Its stimulation by phorbol diesters and by 8-bromo cyclic adenosine monophosphate. ]. Protozool. 36,451-454. 

SOD-mimetic activity of Cu(II)(3,5-DIPS)2 also led to studies of this compound s ability to inhibit interleukin-2 (IL-2) synthesis by a mouse thymoma cell line, EL4 [379]. Cu(IIX3,5-DIPS)2 did inhibit phorbol diester-induced synthesis of IL-2 (IC50 = 10 /xM), but it did not inhibit phorbol-diester-induc-ed attachment of these cells to substrate. While 3,5-DIPS also inhibited IL-2 synthesis (IC50 value = 15 /xM), CUCI2 was ineffective (100 /xM). Mechanistically, the inhibition of IL-2 synthesis by Cu(IIX3,5-DIPS)2 was suggested to be due to an inhibition of IL-2 messenger RNA transcription [379]. 

Subsequent developments led to the observation that the application of a less concentrated solution, which was high enough to initiate hyperplasia but too low to promote tumour development, could be used to produce tumours if its application was followed by the application of an irritant, such as a phorbol diester, capable of promoting neoplastic tumour development. The... 

Induction of ornithine decarboxylase is another feature of epidermal exposure to the phorbol diester. Induction of this enzyme is also inhibited by... 

It has been understood for many years that exposure to ionizing radiation increases the incidence of neoplasia in various tissues. Such exposures induce malignant transformations in mouse lOTl/2 cells in a dose-related fashion [496]. X-Ray induced transformations can be enhanced by post-irradiation incubation with a phorbol diester tumour promoter. 

When it was recognized that the clastogenic effect of this phorbol diester involved the release of superoxide, clastogenicity was suppressed and cell survival increased by concomitant incubation with Cu-Zn SOD [497-499]. Pretreatment with Cu-Zn SOD also reduced X-ray and phorbol diester promoted transformations and increased survival of culture hamster embryo cells [493, 500]. In still another study it was found that Cu-Zn SOD reduced transformation of lOTl/2 cells produced by concomitant X-ray irradiation and exposure to misonidazole, a hypoxic cell radiosensitizer [501]. These observations were most pronounced when Cu-Zn SOD was present during fixation and expression periods [502], consistent with the observation that Cu-Zn SOD protects DNA [503] and proteins [474] against ionizing radiation. Effective radiation protection as a result of superoxide removal does offer anticlastogenic activity as well. 

The mechanism of promoting action in the epidermis relates to the ability of the compounds to cause irritation, inflammation and cell proliferation. The phorbol diester 12-0-tetradecanoylphorbol-13-acetate (TPA) when applied to mouse epidermis in nanomolar quantities produces dramatic histopathological changes (Boutwell, 1964) and biochemical changes in the epidermis (Diamond al., 1980). Irritation and hyperplasia are insufficient properties aTone... 

In animal cells accelerated turnover of phosphatidylcholine (PC) was fiist described as a wide spread cellulai response to phorbol diester treatment and related agonists [11]. 

However, the major phorbol diester-activated enzymatic event is the phospholipase D (PLD)-catalyzed cleavage of PC, giving phosphatidic acid (PA) and bis-phosphatidic acid (bis PA), thus provoking cell proliferation. Dkect evidence for phospholipase D signalling in plants was recently provided [12]. 

Niedel, JE, Kuhn, LJ and Vandenbark, GR (1983) Phorbol diester receptor copurifies with protein kinase C. Proceedings of the National Academy of Sciences of the United States of America, 80, 36-40. 

Rider, LG, Dougherty, RW and NiedeL JE (1988) Phorbol diesters and dioctanoylglycerol stimulate accumulation of both diacylglycerols and alky lacy Iglycerols in human neutrophils. Journal of Immunology, 140, 200-207. 

Napoli, L (1993) Prostaglandin E and phorbol diester are negative modulators of retinoic acid synthesis. Arch. Biochem Biophys. 300, 577-581. 

As with analytical OPLC, off-line and on-line methods can be distinguished in preparative OPLC applications. In the off-line OPLC method, the steps of preparation after development are similar to conventional TLC methods drying, scraping of the sorbent layer, elution, and crystallization. Phorbol diester constituents of croton oil were identified by off-line OPLC separation followed by extraction and chemical ionization mass spectrometry (CI-MS) (90). The on-line method is more effective for preparative applications because time-consuming scraping and elution can be eliminated. 

Takeda, N., Ohigashi, H., Hirai, N., Koshimizu, K., Suzuki, M., Tatematsu, A., Osato, T., and Mizuno, F. (1991). Mass spectrometric identification of a phorbol diester 12-0-hexadecanoylphorbol-13-acetate, an Epstein-Barr virus-activating substance, in the soil collected from under Sapium sehiferum. Cancer Lett. 59, 153-158. 

Goerig M, Habenicht AJR, Heitz R, Zeh W, Katus H, Kommerell B, Ziegler R, Glomset JA (1987) Sn-1,2-diacylglycerols and phorbol diesters stimulate thromboxane synthesis by de novo synthesis of prostaglandin H synthase in human promyelocytic leukemia cells. J Clin Invest 79 903-911... 

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