Diindolylmethane (DIM) spontaneously forms from indole-3-carbinol (I3C) during cell culture experiments.
Indole-3-carbinol (I3C) when given orally is converted to diindolylmethane (DIM) and other oligomers catalyzed by stomach acid. This suggests that DIM is the predominant active agent and that I3C is a precursor, 'pro-drug' in vivo. However, in cell culture studies carried out in neutral solutions, I3C has been considered fully active.


METHODS
The stability of I3C in cell culture media was studied.


RESULTS
In the 8 different cell culture media tested, greater than 50% dimerization of I3C into DIM occurred in 24 hours. At 48 hour, greater than 60% conversion was found. When neutral synthetic cerebrospinal fluid (CSF) or peritoneal fluid (PF) was studied, a large peak, tentitively identified as I3C's linear trimer (LTR) conversion product by mass spectra, and two smaller peaks, were seen. When CSF or PF was diluted 1:1 with media, the formation of these additional peaks was diminished.


CONCLUSIONS
Because of the greater biologic potency of DIM when studied in parallel with I3C in vitro, this extent of dimerization shows that DIM rather than I3C is the active agent in cell culture studies.
Bradlow
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HL
David and Alice Jurist Institute for Medical Research, HUMC Hackensack, NJ 07601, USA. bradlowhl@gmail.com
Zeligs
M A
MA
D000818:Animals; D001711:Biotransformation; D001943:Breast Neoplasms / Q000378:metabolism; D002138:Calibration; D018929:Cell Culture Techniques / Q000379:methods; D003470:Culture Media; D019281:Dimerization; D005260:Female; D005744:Gastric Acid / Q000378:metabolism; D006801:Humans; D007211:Indoles / Q000378:metabolism*; D008297:Male; D011355:Prodrugs / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000378:metabolism; D013045:Species Specificity; D002583:Uterine Cervical Neoplasms / Q000378:metabolism
D003470:Culture Media; D007211:Indoles; D011355:Prodrugs; C016517:indole-3-carbinol; C016392:3,3'-diindolylmethane