HU-331 is a

quinone The quinones are a class of organic compounds that are formally "derived from aromatic compounds uch as benzene or naphthalene">benzene.html" ;"title="uch as benzene">uch as benzene or naphthalene] by conversion of an even number of –CH= group ...

anticarcinogenic An anticarcinogen (also known as a carcinopreventive agent) is a substance that counteracts the effects of a carcinogen or inhibits the development of cancer. Anticarcinogens are different from anticarcinoma agents (also known as anticancer or ant ...

drug synthesized from

cannabidiol Cannabidiol (CBD) is a phytocannabinoid discovered in 1940. It is one of 113 identified cannabinoids in cannabis plants, along with tetrahydrocannabinol (THC), and accounts for up to 40% of the plant's extract. , clinical research on CBD in ...

, a

cannabinoid Cannabinoids () are several structural classes of compounds found in the cannabis plant primarily and most animal organisms (although insects lack such receptors) or as synthetic compounds. The most notable cannabinoid is the phytocannabinoid tet ...

in the ''

Cannabis sativa ''Cannabis sativa'' is an annual herbaceous flowering plant indigenous to Eastern Asia, but now of cosmopolitan distribution due to widespread cultivation. It has been cultivated throughout recorded history, used as a source of industrial fibe ...

'' plant. It showed a great efficacy against

oncogenic Carcinogenesis, also called oncogenesis or tumorigenesis, is the formation of a cancer, whereby normal cells are transformed into cancer cells. The process is characterized by changes at the cellular, genetic, and epigenetic levels and abnor ...

human cells. HU-331 does not cause arrest in

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 sub ...

, cell apoptosis or

caspase Caspases (cysteine-aspartic proteases, cysteine aspartases or cysteine-dependent aspartate-directed proteases) are a family of protease enzymes playing essential roles in programmed cell death. They are named caspases due to their specific cyste ...

activation. HU-331 inhibits DNA

topoisomerase II Type II topoisomerases are topoisomerases that cut both strands of the DNA helix simultaneously in order to manage DNA tangles and supercoils. They use the hydrolysis of ATP, unlike Type I topoisomerase. In this process, these enzymes change th ...

even at nanomolar concentrations, but has shown a negligible effect on the action of DNA

topoisomerase I DNA topoisomerases (or topoisomerases) are enzymes that catalyze changes in the topological state of DNA, interconverting relaxed and supercoiled forms, linked (catenated) and unlinked species, and knotted and unknotted DNA. Topological issues i ...

. The cannabinoid quinone HU-331 is a very specific

inhibitor Inhibitor or inhibition may refer to: In biology * Enzyme inhibitor, a substance that binds to an enzyme and decreases the enzyme's activity * Reuptake inhibitor, a substance that increases neurotransmission by blocking the reuptake of a neurotra ...

of topoisomerase II, compared with most known anticancer quinones. One of the main objectives of these studies is the development of a new

derived compound that produces anti- neoplasm, neoplastic activity while maintaining low toxicity at therapeutic doses.

Mechanism of action

Inhibitors of

topoisomerase DNA topoisomerases (or topoisomerases) are enzymes that catalyze changes in the topological state of DNA, interconverting relaxed and supercoiled forms, linked (catenated) and unlinked species, and knotted and unknotted DNA. Topological issues i ...

s can act at two different levels. First inhibiting topoisomerase, which stabilize the topoisomerase-DNA complex and thus introduce DNA breaks in the wires that lead to

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 in ...

, then inhibiting the catalytic activity of topoisomerase, which hinders the activity of these enzymes without introducing breaks into the DNA chains. HU-331 seems to be a

catalytic Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

inhibitor of topoisomerase II, probably by enzymatic ligation to the protein. This molecule does not cause damage to DNA, but protects cells from damage, natural, or induced by other inhibitors of topoisomerase II that act as inhibitors of topoisomerase. Even when 60% of the target cells are killed by treatment with HU-331, other cells' nucleic content remains unharmed, with less breakage of DNA chains that control important cellular functions.

Doxorubicin Doxorubicin, sold under the brand name Adriamycin among others, is a chemotherapy medication used to treat cancer. This includes breast cancer, bladder cancer, Kaposi's sarcoma, lymphoma, and acute lymphocytic leukemia. It is often used toge ...

, like other anticancer quinones, was used for

chemotherapy Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs (chemotherapeutic agents or alkylating agents) as part of a standardized chemotherapy regimen. Chemother ...

in human cancers for many years. The mechanism of action of these drugs has been the subject of considerable controversy since

chemotherapeutic Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs (chemotherapeutic agents or alkylating agents) as part of a standardized chemotherapy regimen. Chemotherap ...

drugs exert their

cytotoxic Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are an immune cell or some types of venom, e.g. from the puff adder (''Bitis arietans'') or brown recluse spider (''Loxosceles reclusa''). Cell physiology Treating c ...

effect on target cells by nonspecific mechanisms. The doxorubicin damages DNA by intercalation, the generation of

reactive oxygen species In chemistry, reactive oxygen species (ROS) are highly reactive chemicals formed from diatomic oxygen (). Examples of ROS include peroxides, superoxide, hydroxyl radical, singlet oxygen, and alpha-oxygen. The reduction of molecular oxygen () p ...

and inhibition of DNA topoisomerase I and II. This leads to breaking the chains of DNA single and double strands. The protein associated with these ruptures are the topoisomerase II and DNA damage is catalyzed by this enzyme. Thus, while doxorubicin and other

anthraquinone Anthraquinone, also called anthracenedione or dioxoanthracene, is an aromatic organic compound with formula . Isomers include various quinone derivatives. The term anthraquinone however refers to the isomer, 9,10-anthraquinone (IUPAC: 9,10-dioxoan ...

s act through many mechanisms such as apoptosis, abrogation of the cell cycle cell, activation of caspases, generation of ROS, inhibition of both topoisomerases, activation of

intracellular This glossary of biology terms is a list of definitions of fundamental terms and concepts used in biology, the study of life and of living organisms. It is intended as introductory material for novices; for more specific and technical definitions ...

secondary messengers Second messengers are intracellular signaling molecules released by the cell in response to exposure to extracellular signaling molecules—the first messengers. (Intercellular signals, a non-local form or cell signaling, encompassing both first m ...

, etc. Hu-331 is more active and less toxic, since it generates reactive oxygen species in the

heart The heart is a muscular Organ (biology), organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as ca ...

and has a specific activity that gives great potential to develop as a new anticancer drug, according to Kogan ''et al.'' Cannabinoids can act as anticancer compounds killing several

cells followed by direct interaction with cannabinoid receptors. The growth of

glioma A glioma is a type of tumor that starts in the glial cells of the brain or the spine. Gliomas comprise about 30 percent of all brain tumors and central nervous system tumours, and 80 percent of all malignant brain tumours. Signs and symptoms ...

is inhibited by a selective activation of the CB2 cannabinoid receptor and endogenous cannabinoids such as

anandamide Anandamide (ANA), also known as ''N''-arachidonoylethanolamine (AEA), is a fatty acid neurotransmitter. Anandamide was the first endocannabinoid to be discovered: it participates in the body's endocannabinoid system by binding to cannabinoid r ...

inhibit the proliferation of cells involved in

lung cancer Lung cancer, also known as lung carcinoma (since about 98–99% of all lung cancers are carcinomas), is a malignant lung tumor characterized by uncontrolled cell growth in tissues of the lung. Lung carcinomas derive from transformed, mali ...

. The reason behind the antitumor effect of HU-331 appears unknown as

cannabinoid receptor antagonist A cannabinoid receptor antagonist, also known simply as a cannabinoid antagonist or as an anticannabinoid, is a type of cannabinoidergic drug that binds to cannabinoid receptors (CBR) and prevents their activation by endocannabinoids. They includ ...

s do not inhibit HU-331, despite being mediated by a cannabinoid receptor. The HU-331 exerts an

antiangiogenic An angiogenesis inhibitor is a substance that inhibits the growth of new blood vessels (angiogenesis). Some angiogenesis inhibitors are endogenous and a normal part of the body's control and others are obtained exogenously through pharmaceutical dr ...

effect accompanied by apoptosis of

endothelial cells The endothelium is a single layer of squamous endothelial cells that line the interior surface of blood vessels and lymphatic vessels. The endothelium forms an interface between circulating blood or lymph in the lumen and the rest of the vessel ...

. Although in some studies. HU-331 has not caused the death of cells by oncogenic apoptosis. The conclusion that would lead cells to apoptosis based on treatment with the drug did not increase the proportion of cells containing DNA

Lues The first recorded outbreak of syphilis in Europe occurred in 1494/1495 in Naples, Italy, during a French invasion. Because it was spread by returning French troops, the disease was known as "French disease", and it was not until 1530 that the te ...

in the sub-

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 ...

and have not found the expression of

caspase-3 Caspase-3 is a caspase protein that interacts with caspase-8 and caspase-9. It is encoded by the ''CASP3'' gene. ''CASP3'' orthologs have been identified in numerous mammals for which complete genome data are available. Unique orthologs are also p ...

in cancer cells.

Legal status

United States

HU-331 is not scheduled at the federal level in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

Florida

"HU-331 (3-hydroxy-2- 1''R'',6''R'')-3-methyl-6-(1- methylethenyl)-2-cyclohexen-1-yl5-pentyl-2,5-cyclohexadiene-1,4-dione)" is a Schedule I

controlled substance A controlled substance is generally a drug or chemical whose manufacture, possession and use is regulated by a government, such as illicitly used drugs or prescription medications that are designated by law. Some treaties, notably the Single ...

in the state of

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and ...

making it illegal to buy, sell, or possess in Florida.Florida Statutes - Chapter 893 - DRUG ABUSE PREVENTION AND CONTROL
/ref>

Wisconsin

"3-hydroxy-2- 1R,6R)-3-methyl-6-(1-methylethenyl)-2-cyclohexen-1-yl5-pentyl-2,5-cyclohexadiene-1,4-dione, commonly known as HU-331" is a Schedule I controlled substance in the state of

Wisconsin Wisconsin () is a state in the upper Midwestern United States. Wisconsin is the 25th-largest state by total area and the 20th-most populous. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake M ...

making it illegal to buy, sell, or possess in Wisconsin.2013 Wisconsin Act 351
/ref>

Hungary

HU-331 is included on the list of novel psychoactive substances (''55/2014. II. 30.EMMI rendelet'') in Hungary.

References

{{Cannabinoids HU cannabinoids Cyclohexenes Hydroxybenzoquinones