Metabolism / Metabolites
Anaerobic incubation of phorbol (1) from Croton tiglium with human intestinal bacteria afforded five metabolites: isophorbol (2), deoxyphorbol (3), 4beta,9alpha,20-trihydroxy-13,15-seco-1,6,15-tigliatriene-3,13-dione (4), 4beta,9alpha,20-trihydroxy-15,16,17-trinor-1,6-tigliadiene-3,13-dione (5) and 4beta,9a,20-trihydroxy-14(13-->12)-abeo-12alphaH-1,6-tigliadiene-3,13-dione (6). All these metabolites (2-6) were identified and characterized by spectroscopic means, including two-dimensional (2D)-NMR. Nine defined strains from the human intestine showed an ability to transform 1 to these metabolites.

Toxicity Summary
IDENTIFICATION AND USE: Phorbol is a powder. It is used in biochemical and medical research. HUMAN EXPOSURE AND TOXICITY: Phorbol lacked the lymphocyte-activating inducing properties found in phorbol esters. Unlike phorbol esters, phorbol lacks tumor-promoting activity and it was either inactive or elicited poor response in inhibition of growth and stimulation of differentiated functions in human melanoma cells. ANIMAL STUDIES: Phorbol (20 ug/mL) was devoid of biological activity and had no effect on binding sites in prepn from mouse brain. Phorbol did not stimulate prostaglandin E2 synthesis in bone and bone resorption in neonatal mouse calvaria in organ culture. Phorbol showed no erythroid differentiation in Friend virus-transformed proerythroid C1 745 cells. Thus phorbol is inactive analog of phorbol esters.
The term 'phorbol' is used to describe the family of naturally occurring compounds that can be referred to as tigliane diterpenes. Phorbol esters are the tetracyclic diterpenoids generally known for their tumor promoting activity. The phorbol esters mimic the action of diacyl glycerol (DAG), activator of protein kinase C, which regulates different signal transduction pathways and other cellular metabolic activities. The biological activities of the phorbol esters are highly structure specific. The phorbol esters, even at very low concentrations, show toxicological manifestations in animals fed diets containing them. This toxicity limits the use of many nutritive plants and agricultural by-products containing phorbol esters to be used as animal feed. Besides, possessing antinutritional and toxic effects, few derivatives of the phorbol esters are also known for their antimicrobial and antitumor activities. The molluscicidal and insecticidal properties of phorbol esters indicate its potential to be used as an effective biopesticide and insecticide. The phorbols themselves do not induce tumors but promote tumor growth following exposure to a subcarcinogenic dose of a carcinogen. TPA and related phorbols were reported to be a potent stimulator for plasminogen activator synthesis. A good correlation was observed between plasminogen activator induction and tumor promotion with TPA, phorbol 12,13-didecanoate (PDD), and TPA beta-oxide (a derivative of TPA) in bioassays. The phorbol does not involve covalent binding to the cellular DNA, in fact it mimics the effects of transformation such as alteration in membrane morphology, increased saturation density, altered cell surface fucose glycopeptides, and increased the level of plasminogen activator and ornithine decarboxylase. (A15429) Various esters of phorbol have important biological properties, the most notable of which is the capacity to act as tumor promoters through activation of protein kinase C. They mimic diacylglycerols, glycerol derivatives in which two hydroxyl groups have reacted with fatty acids to form esters. The most common phorbol ester is 12-O-tetradecanoylphorbol-13-acetate (TPA), also called phorbol-12-myristate-13-acetate (PMA), which is used as a biomedical research tool in models of carcinogenesis. TPA, together with ionomycin, can also be used to stimulate T-cell activation, proliferation, and cytokine production, and is used in protocols for intracellular staining of these cytokines. (Wikipedia)

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Interactions
12-O-tetradecanoylphorbol 13-acetate (I) & phorbol (II) incr the recovery of ouabain-resistant mutants in N-methyl-N'-nitro-N-nitrosoguanidine- and methylazoxyethanol acetate-treated V79 chinese hamster cell cultures. In both cases I was more effective than II in promoting the mutant recovery.
Studies on the mechanism of skin tumor promotion. Phorbol given simultaneously with 12-o-tetradecanoylphorbol 13-acetate after 7,12-dimethylbenz[a]anthracene (DMBA) initiation in female mice had no effect on promotion.
A single s.c. injection of 200 uCi ((3)H)-thymidine into pregnant BALB/c mice followed by i.p. injections of phorbol twice weekly for 25 wk, in the offspring, resulted in higher tumor development in the lungs and livers of male and, to a lesser extent, of female offspring, than in their untreated littermates. The difference in overall tumor incidence was statistically significant, but the increases of the individual tumor types were only of borderline significance. Slight carcinogenic activity of ((3)H)thymidine alone was observed in the mothers and in the offspring without phorbol treatment. ((3)H)-thymidine may be useful as a broad spectrum initiator for transplacental 2-stage carcinogenicity studies to determine the organ specificity of different promoting agents.
Twice-weekly i.p. injections of 4 mg phorbol for 10 wk, after a single feeding of 6 mg dimethylbenz(a)anthracene (DMBA) in female Wistar rats, led to a significant augmentation of mammary adenocarcinoma incidence and of lymphatic leukemia incidence as compared to 6 mg DMBA alone. In female Sprague-Dawley rats, using the same doses of DMBA and phorbol and the same injection schedule, phorbol given after DMBA did not augment mammary adenocarcinoma incidence or lymphatic leukemia incidence as compared to DMBA given alone. There is a strain-related sensitivity between Wistar and Sprague-Dawley rats with regard to the promoting activity of phorbol when phorbol treatment follows DMBA treatment, and mammary adenocarcinoma incidence and lymphatic leukemia incidence are studied. Phorbol did not promote mammary fibroadenoma incidence in DMBA-treated rats, mammary adenocarcinoma incidence in procarbazine-treated rats and mammary adenocarcinoma incidence or mammary fibroadenoma incidence in X-ray-treated rats. DMBA and procarbazine, with or without phorbol, tended to induce more mammary neoplasms in the anterior (thoracic) than in the posterior (abdominal) mammary glands. X-Irradiation tended to induce mammary neoplasms in approximately equal numbers in the anterior and posterior mammary glands. Regional differences in chemically induced mammary carcinogenesis were due to a difference in the transport and delivery of the chemical carcinogens to the regions rather than a difference in the amount of mammary gland tissue in the regions. An analysis of the numbers of Sprague-Dawley rats that developed either no mammary neoplasms, or only mammary adenocarcinomas, or only mammary fibroadenomas, or both mammary adenocarcinomas and mammary fibroadenomas in response to DMBA, procarbazine and X-ray, suggested that the development of a mammary adenocarcinoma or the development of a mammary fibroadenoma are independent processes.
For more Interactions (Complete) data for PHORBOL (7 total), please visit the HSDB record page.

Isakov N. Protein kinase C (PKC) isoforms in cancer, tumor promotion and tumor suppression. Semin Cancer Biol. 2017 May 29. pii: S1044-579X(17)30108-6. doi: 10.1016/j.semcancer.2017.04.012. [Epub ahead of print] Review. PubMed PMID: 28571764.

Phorbol is a white solid. (NTP, 1992)
Phorbol is a diterpenoid with the structure of tigliane hydroxylated at C-4, -9, -12(beta), -13 and -20, with an oxo group at C-3 and unsaturation at the 1- and 6-positions. It is a tetracyclic diterpenoid, an enone, a cyclic ketone, a tertiary alcohol and a tertiary alpha-hydroxy ketone. It derives from a hydride of a tigliane.
Phorbol has been reported in Rehmannia glutinosa, Croton tiglium, and Euphorbia tirucalli with data available.
Phorbol is a natural, plant-derived organic compound. It is a member of the tigliane family of diterpenes. Phorbol was first isolated in 1934 as the hydrolysis product of croton oil, which is derived from the seeds of the purging croton, Croton tiglium. The structure of phorbol was determined in 1967. It is very soluble in most polar organic solvents, as well as in water.

C20H28O6

364.4327

364.189

17673-25-5

17673-25-5;

442070

Off-white to light yellow solid powder

1.415 g/cm3

572ºC at 760 mmHg

250-251ºC DECOMP

313.8ºC

1.83E-15mmHg at 25°C

1.648

-0.8

5

6

1

26

753

8

C[C@@H]1[C@H]([C@@]2([C@@H](C2(C)C)[C@H]3[C@]1([C@@H]4C=C(C(=O)[C@]4(CC(=C3)CO)O)C)O)O)O

QGVLYPPODPLXMB-UBTYZVCOSA-N

InChI=1S/C20H28O6/c1-9-5-13-18(24,15(9)22)7-11(8-21)6-12-14-17(3,4)20(14,26)16(23)10(2)19(12,13)25/h5-6,10,12-14,16,21,23-26H,7-8H2,1-4H3/t10-,12+,13-,14-,16-,18-,19-,20-/m1/s1

(1S,2S,6R,10S,11R,13S,14R,15R)-1,6,13,14-tetrahydroxy-8-(hydroxymethyl)-4,12,12,15-tetramethyltetracyclo[8.5.0.02,6.011,13]pentadeca-3,8-dien-5-one

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment (e.g. under nitrogen), avoid exposure to moisture.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ~50 mg/mL (~137.20 mM)
H2O : ≥ 20 mg/mL (~54.88 mM)

Solubility in Formulation 1: ≥ 1.67 mg/mL (4.58 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 16.7 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 1.67 mg/mL (4.58 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 16.7 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 1.67 mg/mL (4.58 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 16.7 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 4: 5 mg/mL (13.72 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with ultrasonication (<60°C).

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 (Please use freshly prepared in vivo formulations for optimal results.)