The remarkable life-extending activity of the high curcumin concentrations requires additional experimental data for evaluation. Aqueous solutions of curcumin are not stable over three days (see decreased toxicity in zebrafish embryo); there are even reports on curcumin half-life to be less than 30 minutes and on phototoxicity of the aqueous solutions. How did the authors determine thioflavin and curcumin concentration in the agar plates at day 10, 20, or 30? This can be achieved by calibrated UV/VIS absorption.
Did the agents alter the E. coli cultures in any way? Curcumin is known to inhibit E. coli growth at far lower concentrations! Maybe some of the nematodes entered the Dauer stage due to restricted growth of E. coli, which recovers after curcumin depletion. Could this result in the observation of "extended lifespan," which is actually due to an extended Dauer stage? The later Dauer stage results in a related paralysis that may result in a false-positive "dead" assignment. Thus, the reports of their "death may be greatly exaggerated."
Wu JY, Lin CY, Lin TW, Ken CF, Wen YD. Curcumin affects development of zebrafish embryo. Biol Pharm Bull. 2007 Jul;30(7):1336-9. Abstract
Wang YJ, Pan MH, Cheng AL, Lin LI, Ho YS, Hsieh CY, Lin JK. Stability of curcumin in buffer solutions and characterization of its degradation products. J Pharm Biomed Anal. 1997 Aug;15(12):1867-76. Abstract
Kaur S, Modi NH, Panda D, Roy N. Probing the binding site of curcumin in Escherichia coli and Bacillus subtilis FtsZ—A structural insight to unveil antibacterial activity of curcumin. European Journal of Medicinal Chemistry, Volume 45, Issue 9, September 2010, 4209-4214. Abstract
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