Indole-3-carbinol (
C9 H9 N O), sometimes referred to as I3C, is produced by the breakdown of the
glucosinolate
Glucosinolates are natural components of many pungent plants such as mustard, cabbage, and horseradish. The pungency of those plants is due to mustard oils produced from glucosinolates when the plant material is chewed, cut, or otherwise damaged. T ...
glucobrassicin
Glucobrassicin is a type of glucosinolate that can be found in almost all cruciferous plants, such as cabbages, broccoli, mustards, and woad. As for other glucosinolates, degradation by the enzyme myrosinase is expected to produce an isothiocya ...
, which can be found at relatively high levels in
cruciferous vegetables
Cruciferous vegetables are vegetables of the family Brassicaceae (also called Cruciferae) with many genera, species, and cultivars being raised for food production such as cauliflower, cabbage, kale, garden cress, bok choy, broccoli, Brussels spr ...
such as
broccoli
Broccoli (''Brassica oleracea'' var. ''italica'') is an edible green plant in the cabbage family (family Brassicaceae, genus ''Brassica'') whose large flowering head, stalk and small associated leaves are eaten as a vegetable. Broccoli is cl ...
,
cabbage
Cabbage, comprising several cultivars of ''Brassica oleracea'', is a leafy green, red (purple), or white (pale green) biennial plant grown as an annual vegetable crop for its dense-leaved heads. It is descended from the wild cabbage ( ''B.&nb ...
,
cauliflower
Cauliflower is one of several vegetables in the species ''Brassica oleracea'' in the genus ''Brassica'', which is in the Brassicaceae (or mustard) family. It is an annual plant that reproduces by seed. Typically, only the head is eaten – the ...
,
brussels sprouts
The Brussels sprout is a member of the Gemmifera cultivar group of cabbages (''Brassica oleracea''), grown for its edible buds. The leaf vegetables are typically 1.5–4.0 cm (0.6–1.6 in) in diameter and resemble miniature cabbages ...
,
collard greens
Collard is a group of certain loose-leafed cultivars of ''Brassica oleracea'', the same species as many common vegetables including cabbage ( Capitata group) and broccoli ( Italica group). Collard is a member of the Viridis group of ''Brassica ...
and
kale
Kale (), or leaf cabbage, belongs to a group of cabbage (''Brassica oleracea'') cultivars grown for their edible leaves, although some are used as ornamentals. Kale plants have green or purple leaves, and the central leaves do not form a head ...
. It is also available in
dietary supplement
A dietary supplement is a manufactured product intended to supplement one's diet by taking a pill, capsule, tablet, powder, or liquid. A supplement can provide nutrients either extracted from food sources or that are synthetic in order ...
s. Indole-3-
carbinol is the subject of on-going
biomedical research
Medical research (or biomedical research), also known as experimental medicine, encompasses a wide array of research, extending from "basic research" (also called ''bench science'' or ''bench research''), – involving fundamental scientif ...
into its possible
anticarcinogenic,
antioxidant
Antioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals. This can lead to polymerization and other chain reactions. They are frequently added to industrial products, such as fuels and lubricant ...
, and anti-
atherogenic
Atherosclerosis is a pattern of the disease arteriosclerosis in which the wall of the artery develops abnormalities, called lesions. These lesions may lead to narrowing due to the buildup of atheroma, atheromatous plaque. At onset there are usu ...
effects. Research on indole-3-carbinol has been conducted primarily using
laboratory animals
Animals used by laboratories for testing purposes are largely supplied by dealers who specialize in selling them to universities, medical and veterinary schools, and companies that provide contract animal-testing services. It is comparatively rare ...
and
cultured cells.
Limited and inconclusive human studies have been reported. A recent review of the biomedical research literature found that "evidence of an inverse association between cruciferous vegetable intake and breast or prostate cancer in humans is limited and inconsistent" and "larger
randomized controlled trial
A randomized controlled trial (or randomized control trial; RCT) is a form of scientific experiment used to control factors not under direct experimental control. Examples of RCTs are clinical trials that compare the effects of drugs, surgical te ...
s are needed" to determine if supplemental indole-3-carbinol has health benefits.
Indole-3-carbinol and cancer
Investigation of mechanisms by which consumption of indole-3-carbinol might influence
cancer
Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
incidence focuses on its ability to alter
estrogen
Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal acti ...
metabolism
Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...
and other cellular effects. Controlled studies have been performed on such animals as
rats,
mice
A mouse ( : mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...
, and
rainbow trout
The rainbow trout (''Oncorhynchus mykiss'') is a species of trout native to cold-water tributaries of the Pacific Ocean in Asia and North America. The steelhead (sometimes called "steelhead trout") is an anadromous (sea-run) form of the coasta ...
, introducing various controlled levels of
carcinogens
A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive substan ...
, and levels of indole-3-carbinol into their daily diet. Results showed dose-related decreases in
tumor
A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
susceptibility due to indole-3-carbinol (inferred by decreases in
aflatoxin
Aflatoxins are various poisonous carcinogens and mutagens that are produced by certain molds, particularly ''Aspergillus'' species. The fungi grow in soil, decaying vegetation and various staple foodstuffs and commodities such as hay, sweetcorn ...
–
DNA binding). The first direct evidence of pure anti-initiating activity by a natural
anticarcinogen (indole-3-carbinol) found in human diet was claimed by Dashwood ''et al.'' in 1989.
Indole-3-carbinol induces a
G1 growth arrest of human reproductive cancer cells.
This is potentially relevant to the prevention and treatment of cancer, as the
G1 phase
The G1 phase, gap 1 phase, or growth 1 phase, is the first of four phases of the cell cycle that takes place in eukaryotic cell division. In this part of interphase, the cell synthesizes mRNA and proteins in preparation for subsequent steps leadi ...
of
cell growth
Cell growth refers to an increase in the total mass of a cell, including both cytoplasmic, nuclear and organelle volume. Cell growth occurs when the overall rate of cellular biosynthesis (production of biomolecules or anabolism) is greater than ...
occurs early in the cell life cycle, and, for most cells, is the major period of
cell cycle
The cell cycle, or cell-division cycle, is the series of events that take place in a cell that cause it to divide into two daughter cells. These events include the duplication of its DNA (DNA replication) and some of its organelles, and subs ...
during its lifespan. The G1 phase is marked by synthesis of various enzymes that are required in the next (
"S") phase, including those needed for DNA replication.
Overuse of indole-3-carbinol supplements in the hope of preventing cancer may be unwise, as the hormone balance should be tested (via simple blood test) before regular consumption. Such caution is advised, due to its effect on
estrogen
Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal acti ...
levels (estrogen has a significant impact on brain function).
It promotes liver cancer in
trout
Trout are species of freshwater fish belonging to the genera '' Oncorhynchus'', ''Salmo'' and ''Salvelinus'', all of the subfamily Salmoninae of the family Salmonidae. The word ''trout'' is also used as part of the name of some non-salmoni ...
when it is combined with
aflatoxin B1
Aflatoxin B1 is an aflatoxin produced by ''Aspergillus flavus'' and '' A. parasiticus''. It is a very potent carcinogen with a TD50 3.2 μg/kg/day in rats. This carcinogenic potency varies across species with some, such as rats and monkeys, seem ...
and demotes
metastasis
Metastasis is a pathogenic agent's spread from an initial or primary site to a different or secondary site within the host's body; the term is typically used when referring to metastasis by a cancerous tumor. The newly pathological sites, then, ...
.
Melanoma
Indole-3-carbinol causes proliferation arrest and
apoptosis
Apoptosis (from grc, ἀπόπτωσις, apóptōsis, 'falling off') is a form of programmed cell death that occurs in multicellular organisms. Biochemical events lead to characteristic cell changes (morphology) and death. These changes incl ...
in human
melanoma
Melanoma, also redundantly known as malignant melanoma, is a type of skin cancer that develops from the pigment-producing cells known as melanocytes. Melanomas typically occur in the skin, but may rarely occur in the mouth, intestines, or eye ( ...
cells. Kim ''et al.'' (2011) showed that the master regulator of melanoma biology,
microphthalmia-associated transcription factor
Microphthalmia-associated transcription factor also known as class E basic helix-loop-helix protein 32 or bHLHe32 is a protein that in humans is encoded by the ''MITF'' gene.
MITF is a basic helix-loop-helix leucine zipper transcription factor ...
(MITF-M) was downregulated by indole-3-carinol to induce apoptosis. Kundu ''et al.'' (2017) demonstrated that the anticancer property of indole-3-carbinol is driven by specific targeting of oncogenic pathways. In two different studies using xenografted mouse model of melanoma, they observed that subcutaneous injection of indole-3-carbinol could bring down tumor burden significantly. The underlying molecular mechanism of this anti-tumor effect was found to be by the specific inhibition of activity of oncogenic
BRAFV600E V600E is a mutation of the BRAF gene in which valine (V) is substituted by glutamic acid (E) at amino acid 600. It is a driver mutation in a proportion of certain diagnoses, including melanoma, hairy cell leukemia, papillary thyroid carcinoma, ...
in tumors that harbored the mutation. However, in tumors that expressed wild type BRAF, indole-3-carbinol did not cause any comparable antiproliferative effect. Additionally indole-3-carbinol did not cause antiproliferation even in normal epidermal melanocytes underscoring the specificity and selectivity of its action. Kundu ''et al.'' further showed that inhibition of BRAF V600E activity by indole-3-carbinol resulted in downregulation of MITF-M by downstream signaling which caused a G1
cell cycle
The cell cycle, or cell-division cycle, is the series of events that take place in a cell that cause it to divide into two daughter cells. These events include the duplication of its DNA (DNA replication) and some of its organelles, and subs ...
arrest leading to the observed antiproliferative effect.
In a second study Kundu ''et al.'' showed that in melanoma cells where
PTEN is downregulated, indole-3-carbinol directly interacts with
NEDD41 to prevent PTEN ubiquitination and subsequent proteasomal degradation. This results in stabilization of PTEN and inhibition of proliferation by downstream
AKT
Protein kinase B (PKB), also known as Akt, is the collective name of a set of three serine/threonine-specific protein kinases that play key roles in multiple cellular processes such as glucose metabolism, apoptosis, cell proliferation, tran ...
signaling. Overall scientific evidence shows that in melanoma, indole-3-carbinol specifically inhibits the two most commonly associated driver mutation signaling pathways to cause proliferation, a fact that can be used to design clinical trial to treat human patients with indole-3-carbinol in future.
Systemic lupus erythematosus
Indole-3-carbinol can shift
estrogen
Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal acti ...
metabolism towards less estrogenic metabolites.
Systemic lupus erythematosus
Lupus, technically known as systemic lupus erythematosus (SLE), is an autoimmune disease in which the body's immune system mistakenly attacks healthy tissue in many parts of the body. Symptoms vary among people and may be mild to severe. Comm ...
(SLE, or lupus), an
autoimmune disease
An autoimmune disease is a condition arising from an abnormal immune response to a functioning body part. At least 80 types of autoimmune diseases have been identified, with some evidence suggesting that there may be more than 100 types. Nearly a ...
, is associated with estrogen. In a study using mice bred to develop lupus, indole-3-carbinol was fed to one group while another group was fed a standard mouse diet; the group fed the indole-3-carbinol diet lived longer and had fewer signs of disease.
Another study of lupus-prone mice with indole-3-carbinol defined the mechanism for the improvement of their disease to be due to sequential blocks in the development of
B and
T cell
A T cell is a type of lymphocyte. T cells are one of the important white blood cells of the immune system and play a central role in the adaptive immune response. T cells can be distinguished from other lymphocytes by the presence of a T-cell r ...
s of these mice. The maturation arrests resulted in a fall in
autoantibody
An autoantibody is an antibody (a type of protein) produced by the immune system that is directed against one or more of the individual's own proteins. Many autoimmune diseases (notably lupus erythematosus) are associated with such antibodies.
Pr ...
production, thought to be a crucial component of lupus causation. In addition, I3C supplementation of the disease prone mice led to a normalization of their T cell function.
Women with lupus can manifest a metabolic response to indole-3-carbinol and might also benefit from its antiestrogenic effects. Clinical trials are currently underway to determine the efficacy of treating human patients with lupus using indole-3-carbinol.
Effect in recurrent respiratory papillomatosis
There is evidence suggesting that indole-3-carbinol may have an effect on
human papillomavirus
Human papillomavirus infection (HPV infection) is caused by a DNA virus from the ''Papillomaviridae'' family. Many HPV infections cause no symptoms and 90% resolve spontaneously within two years. In some cases, an HPV infection persists and res ...
-infected cells in both pediatrics and adult patients.
Research is ongoing.
References
Further reading
*
*
External links
MSDS at Fischer Scientific
{{Cruciferous Biochemistry
Indoles
Hydroxymethyl compounds
Oncology
Histone deacetylase inhibitors