Azodicarbonamide (HPH116): the only “virucide” ever used in clinical trial

HPH116 is a small chemical compound designed to target the HIV nucleocapsid p7 (NCp7) zinc finger protein which is involved in packaging viral RNA (RNA is the genetic material of the virus). Zinc finger inhibitors cause viral inhibition by covalent modification of the sulphur atoms of the zinc-coordinating cysteine residues in the two CCHC zinc fingers, resulting in ejection of zinc inactivating cell-free virions . In vitro, ADA is broadly inhibitory to retroviruses, including drugresistant strains, clinical isolates and monocytotropic strains of HIV- 1, as well as HIV-2 and SIV, albeit at "relatively high" concentrations. The compound caused direct inactivation of cell-free HIV-1 virus particles through cross-linkage of viral nucleocapsid proteins. Another very important clinical feature: National Cancer Institute (NCI; USA) has been unable to create drug-resistant strains of the virus in over three years of testing it with these compounds. Dr. Rice said, "there has been increasing interest in the zinc finger,NCI went on to show that these drugs could infiltrate mature virus particles and disrupt the zinc finger, rendering HIV non infectious.”

Virucidal activity against other viruses

In all orthoretroviruses, these proteins are characterized by the presence of one or two Zn2_ finger domains with a common sequence motif, -Cys-X2-Cys-X4-His-X4-Cys- (CCHC). Comparison between HIV and SIV zinc protein

The human T cell leukemia virus-1 and 2 (HTLV-1) and (HTLV2)

They are retroviruses that causes adult T cell leukemia (ATL) and neurological disorder, the tropical spastic paraparesis (HAM/TSP). As for HIV, the three major modes of transmission for HTLV-1 and HTLV-2 infection are perinatal, sexual and by blood transfusion. HTLV-1 zinc finger protein

Human Hepatitis C Virus (HCV). (HCV is not a retrovirus)

In 2002, Professor De Clercq suggests the interest of testing Azodicarbonamide against an other sexually transmitted virus Human Hepatitis C Virus (HCV). Persons who received blood transfusions or an organ transplant before 1992 and hemophiliacs who received clotting factor concentrates produced before 1987 are also at risk for HCV. At moderate risk are those who have received chronic hemodialysis. Others at risk are infants born to infected mothers, healthcare workers exposed to needlesticks contaminated with HCV+ blood and persons with high-risk sexual practices. Hepatitis C Virus Proteins Ns3 Ns4A Zinc Finger De Clercq E (2002) Highlights in the development of new antiviral agents. Mini Rev Medicinal Chemistry 2(2):163–175.

HUMAN PAPILLOMAVIRUSES (HPV) (HPV is not a retrovirus)

HPV is a small DNA tumour virus; there are 100 known different types Genital infections of HPV are sexually transmitted HPV is the most common sexually transmitted viral infection, about 2/3 of young adults acquire HPV infections of genital tract during first two years of sexual activity

Types 6 and 11: provoke condyloma accuminata
Types 16, 18 and 31: provoke uterus cervical cancer

Data are extracted from

Potential Drugs Against Cervical Cancer: Zinc-Ejecting Inhibitors of the Human Papillomavirus Type 16 E6 Oncoprotein Walter Beerheide, Hans-Ulrich Bernard, Yee-Joo Tan, Arasu Ganesan, William G. Rice, Anthony E. Ting Journal of the National Cancer Institute, Vol. 91, No. 14, July 21, 1999

In conclusion

Azodicarbonamide is showing activity against a host of viruses sexually transmitted and represent an interesting molecule alone or in combination to be useful for a vaginal protective preparation.

Currently, a broad range of compounds is being considered for development as HIV microbicides. Most of these compounds are binding- or entry inhibitors, but also the use of nucleotide and non-nucleoside reverse transcriptase inhibitors (RTI) is gaining increased interest in the microbicides field.

Most probably, the first generation of microbicides will be formulated as a single compound. In case an entry inhibitor will be used, antiviral potency will be limited. In contrast, substantial higher activity is expected from the use of reverse transcriptase inhibitors (RTI) as microbicides.  However, both entry inhibitors and RTI have one important drawback in common, being the emergence of drug resistant viral mutants. Therefore, new classes of compounds with the potential for development as HIV microbicides should be evaluated.

Especially the a-carbonyl azoic compound HPH116 (1,1’ azobisformamide, azodicarbonamide) is here of interest . HPH116 is an anti-HIV compound selectively targeting the retroviral NCp7 nucleocapsid zinc finger domains, without affecting mammalian nucleic and cytoplasmic zinc finger proteins. The mechanism of action of HPH116 is believed to involve the ejection of zinc from the NCp7 protein. The nucleocapsid protein of HIV is a small (55-amino acid), very basic and highly conserved nucleic acid binding protein that contains two copies of the conserved sequence Cys-X2-Cys-X4-His-X4-Cys (with X being a conservatively substituted amino acid). NCp7 participates in numerous obligate stages of the viral replication cycle and mutations in its primary structure have been observed to result in the production of non-infectious virions. Moreover, the sensitivity of HIV to HPH116 is independent of the phenotype (syncytium inducing or non-syncytium inducing).  Importantly, HPH116 has been shown to have antiviral effect against a large group of retroviruses, including HIV type 1 and 2.

Additionally, HPH116 also has antiviral activity against other sexually transmitted viruses like human papilloma virus (HPV) and hepatitis C virus (HCV), which is an important advantage for the development of HPH116 as a compound for the prevention of HIV and (co-occurring) other STDs. 

Animal Reproductive Toxicology Data

A cGCP compliant study (study SMVCE-86-071) was conducted by Lovelace Inhalation Toxicology Research Institute, Albuquerque NM, USA and Environmental Health Research and Testing Inc. Lexington KY, USA, for The National Toxicology Program ( USA).

Abstract :
  There were no adverse effects with respect to right caudal weight, right epididymal weight, right testicular weight, sperm motility, sperm count per 'g' caudal tissue, incidence of abnormal sperm except a small but significant increase in sperm count in rats at 50 and 100 mg/m³ levels. Azodicarbonamide did not interfere with oestrous cyclicity and the average oestrous cycle length in both mice and rats under the present experimental conditions.

A cGLP test was performed by the Hatano Research Institute, Food and Drug Safety Center, 729-5 Ochiai, Hadano-shi, Kanagawa, 257-0025, Japan. Tel +81-463-82-4751 Fax +81-463-82-9627

Abstract :
  One-generation reproduction toxicity was investigated for 1,1'-azobisformamide by daily oral administration of 0, 100, 300 and 1000 mg/kg to 5 week-old male and to 10 week-old female Sprague-Dawley strain (Crj:CD) rats (25 animals each sex/group). The test substance was given to the males for 10 weeks before mating and thereafter in total for 14 weeks, and to the females for 2 weeks before mating, and throughout the mating, gestation and lactation periods, thus in total 8 weeks. The treatment did not affect their reproductive ability, including the oestrous cycle, mating, parturition of the animals and viability, growth and morphology of offspring.


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