# Michael acceptor in gambogic acid--Its role and application for potent antitumor agents.
> ガンボギン酸のマイケル受容体部位の役割と抗腫瘍活性への応用


## Abstract

Gambogic acid (GA) is a structurally distinctive natural compound exhibiting broad antiproliferative effects against cancer cell lines. Its C-10 position functions as a reactive Michael acceptor, rendering it vulnerable to nucleophilic attack and thereby restricting clinical utility. An intramolecular hydrogen bond between the C-6 hydroxyl and the C-8 carbonyl was found to enhance the electrophilicity of the C-9/C-10 double bond. Two structural modification strategies were evaluated. Strategy A introduced a methyl group at C-10 to increase steric hindrance; this abolished both electrophilicity and antiproliferative activity. Strategy B replaced the C-6 hydroxyl with neutral or basic substituents, substantially reducing electrophilicity while preserving antitumor potency against cancer cell lines. These findings clarify the mechanistic role of the Michael acceptor in GA and provide a rational basis for designing improved analogues.

### Mechanism

An intramolecular hydrogen bond between the C-6 hydroxyl and C-8 carbonyl increases the electrophilicity of the C-10 Michael acceptor site, simultaneously driving antiproliferative activity and susceptibility to nucleophilic inactivation.

## Bibliographic

- **Authors**: Wang J, Shen W, Yuan Z, Lan L, Xu J, Wang CY, et al.
- **Journal**: Bioorg Med Chem Lett
- **Year**: 2015 (2015-07-15)
- **PMID**: [26009165](https://pubmed.ncbi.nlm.nih.gov/26009165/)
- **DOI**: [10.1016/j.bmcl.2015.04.100](https://doi.org/10.1016/j.bmcl.2015.04.100)
- **Study type**: in vitro study
- **Delivery route**: in vitro
- **Effect reported**: mixed

## Delivery context

This is basic research at the cellular or molecular level. For human application, inhalation is the most promising delivery route, but inhalation carries explosion risk and concentration matters (empirical LFL of 10%; high-concentration devices are not recommended).

## Safety notes

This is basic research at the cellular or molecular level. For human application, inhalation is the most promising delivery route, but inhalation carries explosion risk and concentration matters (empirical LFL of 10%; high-concentration devices are not recommended).

See also:
- [Inhalation concentration and LFL / UFL](https://h2-papers.org/en/safety-notes/inhalation-concentration)
- [Consumer Affairs Agency accident cases](https://h2-papers.org/en/safety-notes/accident-cases)
- [Inhalation safety threshold lineage](https://h2-papers.org/en/safety-notes/lineage)

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> **Cite as**: H2 Papers — PMID 26009165. https://h2-papers.org/en/papers/26009165
> **Source**: PubMed PMID [26009165](https://pubmed.ncbi.nlm.nih.gov/26009165/)