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Formulation, Characterization, and Antitumor Properties of Trans- and Cis-Citral in the 4T1 Breast Cancer Xenograft Mouse Model



Citral is composed of a random mixture of two geometric stereoisomers geranial (trans-citral) and neral (cis-citral) yet few studies have directly compared their in vivo antitumor properties. A micelle formulation was therefore developed.


Geranial and neral were synthesized. Commercially-purchased citral, geranial, and neral were formulated in PEG-b-PCL (block sizes of 5000:10,000, Mw/Mn 1.26) micelles. In vitro degradation, drug release, cytotoxicity, flow cytometry, and western blot studies were conducted. The antitumor properties of drug formulations (40 and 80 mg/kg based on MTD studies) were evaluated on the 4T1 xenograft mouse model and tumor tissues were analyzed by western blot.


Micelles encapsulated drugs with >50% LE at 5–40% drug to polymer (w/w), displayed sustained release (t1/2 of 8–9 h), and improved drug stability at pH 5.0. The IC50 of drug formulations against 4T1 cells ranged from 1.4 to 9.9 μM. Western blot revealed that autophagy was the main cause of cytotoxicity. Geranial at 80 mg/kg was most effective at inhibiting tumor growth.


Geranial is significantly more potent than neral and citral at 80 mg/kg (p < 0.001) and western blot of tumor tissues confirms that autophagy and not apoptosis is the major mechanism of tumor growth inhibition in p53-null 4T1 cells.

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Body weight


Critical micelle concentration


Dynamic light scattering


Dulbecco’s modified eagle medium


Enhanced permeability and retention


Fetal bovine serum






Loading efficiency


Maximum tolerated dose








Phosphate buffered saline




Polydispersity index


Poly(ethylene glycol)-block-polycaprolactone


Sodium dodecyl sulfate


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This research was supported by NIH grant R01DK099596 and startup funds from the University of Wisconsin-Madison, School of Pharmacy.

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Correspondence to May P. Xiong.

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Zeng, S., Kapur, A., Patankar, M.S. et al. Formulation, Characterization, and Antitumor Properties of Trans- and Cis-Citral in the 4T1 Breast Cancer Xenograft Mouse Model. Pharm Res 32, 2548–2558 (2015).

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  • breast cancer
  • citral
  • geranial
  • micelle
  • neral