Unknown Precipitate

To form the iron-curcumin complex, stoichiometric ratios are calculated and volumes of curcumin solution and iron solution are mixed.  Before the iron is added to the curcumin, the pH of the curcumin is adjusted to approximately 7.5 with triethylamine.  It was observed that when this solution is left overnight, a precipitate appears.  When centrifuged, it was discovered that the precipitate was actually a denser fluid and not a solid.  This dense fluid was dark in color and oily in consistency.  It was not soluble in the solvents typically used for FeCl₃ or curcumin.  After testing the oily fluid using HPLC it was discovered that it was not the iron-curcumin complex as had been reported in several papers, but just iron hydroxide.  

In order to further prove that the oily precipitate is not the iron-curcumin complex, different ratios of curcumin and iron(III) were mixed.  If the dense oil is iron hydroxide, then the test tubes containing more iron will have more precipitate.

7/31/18

-Alex Griffith

Trip to NJIT

On Wednesday, July, 25th, we went to NJIT to do mass spectrometry on a few samples of curcuminoids and curcuminoid complex we had prepared the day prior. We were greeted by Dr. Zhang, a research professor, and his post-doctoral assistant. They brought us to a Liquid Chromatography Mass Spectrometry machine to complete the experiments which would identify the masses of fragments of our samples.

We learned that, with the method used, the complex would not appear at its hypothesized molecular weight, and that the mass of one curcumin and one iron appeared to be the most stable fragment. An ongoing topic of interest is the phase, gaseous, or solvated, of the complex.

-Alexander Czechowicz

Microbiology Controls

This week marked an expansion of focus upon plating our hypothetical complex onto various TSA media containing various bacteria. Much of what we analyzed on this side of the project looked like the following:

We saw that the hypothetical complexes did not exhibit larger zones of inhibition across Al3+, Cu2+, Fe3+ and Fe2+ than curcumin alone. Dr. K hypothesized that the formation equilibrium had to be pushed to the right and we increased the mol:mol ratio of cation to curcumin for the next plates. This showed mild evidence supporting Dr. K's hypothesis.

We had more questions about achieving a high concentration of complex in solution and attempted to accomplish that goal by considering the time since mixing our curcumin and the cation. Dr. K had Isaac, who normally runs our HPLC, mix the solution in his syringe which produced results consistent with greater amounts of complex. We decided to try to apply this to the microbiology side of things.

Hypothetically, if we accept that the rate of decomposition of the complex is greater than its rate of formation shortly after mixing, then its concentration should be highest right when mixed. We will check back in next week to see whether or not the plates we streaked today support this hypothesis.

7/19/2018
-Alexander Czechowicz

Crystalization

After crystals were extracted from turmeric solution, it was noted that the crystals were not pure orange in color.  There were several very small flecks of yellow and red.  The lab supplied separated curcuminoids were all slightly different in color, one being yellow, another being orange, and the last being red.  From this information, it was hypothesized that if these crystals were separated by color, they could be used as seed crystals in a super saturated curcumin solution to produce larger single color crystals.  These single colors could possibly be the individual curcuminoids.  If true, this would mean there would be a much easier and cheaper way to separate curcuminoids.

Curcumin Crystals Before Separation

Separating the small crystals by hand had to be accomplished using a dissection microscope, a metal spatula, and tweezers.  Because the extremely low percentage of demethoxycurcumin and bisdemethoxycurcumin in turmeric, the amount of yellow and red crystals in the yield was very small.

Yellow, Orange, and Red Crystals: Seperated

7/18/18
-Alex Griffith

Melting Points

Several solids have been filtered from solutions containing both metal cations and curcumin.  Especially when it comes to iron(III), the identity of the filtered solid has been questionable.  It was possible that the solid was iron oxide and not the curcumin-iron complex.  As a method of identifying the solid, we attempted to find the melting point of the black crystals that were removed from solution.
The melting point of curcumin is 183°C.  The melting point of iron oxide is far beyond the limitations of the melting point apparatus at 1500°C.  The black crystals did not melt at 250°C, although they did begin to change color.  The limitations of the machine made further analysis of the black crystals impossible.

The melting point apparatus was also utilized to confirm the identity of orange crystals extracted from a turmeric solution.  

The melting point of the crystals was 179°C.  Because the melting points of the curcuminoids are all slightly different, the "impurity" caused by having all three curcuminoids together reduced the melting point, meaning that the crystals were confirmed as curcumin by the melting point testing.

7/12/18

-Alex Griffith

Solar Cells and Decomposition

Using solar cells, we tested for current with curcuminoids and the Fe 3+ curcumin complex. This endeavor was inspired by the search for applications of the curcumin complex. We found that there was a significant reduction in potential difference when the curcumin and iron complex was used, which is proof that the Fe 3+ curcumin complex is forming. The change in voltage can be attributed to a loss in conjugation.

The solar cell project has been testing raspberry solar cells due to favorable conjugation. While raspberries are effective, they are not efficient as they are expensive. Curcumin may yield similar voltages for a fraction of the cost.

We considered that our curcumin samples may be degrading, and occasionally caught scents of vanilla. The following skeletal structure is of vanillin, a vanilla plant derivative that resembles a potential "metabolite."

The following is another candidate:                        

                                                                                                       

Curcumin

                 




Vanillin and the cinnamaldehyde derivative might not be what is actually being produced by natural degradation or leaving our samples is ambient temperature, but we have suspicions that they may be. Further experiments may involve identification of the nature of degradation of curcumin.

"Degradation of curcumin: From mechanism to biological implications" by Schneider, et al, explores this topic. It can be found at this link.

We were having some issues with the IR spec machine. At first in troubleshooting, we tried to re-calibrate the machine to the environment, but this proved ineffective in affording a sound IR graph. We then reset all of the hardware which also proved inconclusive. Using new salt crystals rectified the error. We produced a good overlay of three spectra.

7/3/18
-Alexander Czechowicz

Removing Complexes From Solution

When the complex is dissolved in ethanol, the IR results are changed.  The additional alcohol leads to a greatly exaggerated peak in the IR spectrum around 3500(cm-1).  To combat this, the complex was removed from solution and dried in order to use it in a solvent that did not contain alcohol.

Four complexes were prepared using aluminium, copper, iron (III), and iron (II).  Laboratory supplied curcuminoids (all three were used) were dissolved in methanol.  The cation solutions were then added.  Finally, a drop of triethylamine was added before the solutions were refluxed for an hour.

After refluxing, the solutions were left to evaporate over the weekend.

Curcumin-Aluminum Complex	Curcumin-Copper Complex	With the exception of the iron(III), all complexes were slightly sticky.
Curcumin-Iron(II) Complex	Curcumin-Iron(III) Complex	The complexes were all dissolved in dichloromethane for use with IR spectroscopy.  They were much more soluble in ethanol than dichloromethane.

7/2/18

-Alex Griffith