Introduction and History

Turmeric, known scientifically as Curcuma longa, is an herbaceous plant of the Zingiberaceae family, which it shares with ginger. This plant can attain a height of up to three feet and has beautiful flowers.
Turmeric Fresh and Powdered

The primary value of turmeric resides in the roots, which are harvested in late fall to early winter. These roots have been a popular spice for thousands of years, and are commonly used as a condiment, dye, and herbal medicine. In Hinduism, turmeric is associated with fertility, prosperity, and purity. Considering the popularity of Hinduism in India, it should come as no surprise that India currently provides nearly the  entire global supply of turmeric. Turmeric has been used in India for over 4000 years, with evidence of its presence found in ancient Indian pots dating back to 2500 BCE. The known history of turmeric, however, extends back only to 500 BCE, with its first recorded appearance in Ayurvedic medicine. Since then, many other countries have also adopted its use, including but not limited to China, Japan, Iraq, and Egypt. Ayurvedic medicine believed turmeric helps strengthen the body, relieve gas, dispel worms, improve digestion, dissolve gallstones, and relieve arthritis. 

Today, research has validated many of these traditional beliefs, demonstrating that it possesses anti-inflammatory properties, acts as an antioxidant, and boosts the immune system. Turmeric is available in various forms, ranging from fresh roots to supplement capsules. The high availability of turmeric makes it very easy to obtain for those wanting to experience its benefits.

However, each form of turmeric has a unique chemical composition, with some forms providing more benefits to health relative to other forms.

Joey Li

My name is Joey Li, and I am volunteering in the John L. Holmes Mass Spectrometry Facility in summer of 2024. I just finished my first year of Biomedical Science at the University of Ottawa, and I am going into my second year in September 2024. I volunteered in this lab with the goal of gaining more experience in the field of chemistry and getting an insight into research. My ultimate goal is to get admitted to medical school, where I wish to specialize in rheumatology so I can help improve the lives of those unfortunate enough to be diagnosed with autoimmune conditions. Volunteering in this lab not only allowed me to apply the skills I have learned in my first-year chemistry classes, but also allowed me to explore the diverse world of mass spectrometry and its vast range of applications in science research. Throughout the course of the summer, I learned how to prepare and analyze samples, identify and quantify different compounds in the samples using both the GC-MS and LC-MS, and the fascinating ways in which mass spectrometry instrumentation works
 

Joey Li Summer 2024
Joey Li Summer 2024

Fun Fact

The name “turmeric” has multiple pronunciations. According to the Merriam-Webster dictionary, the original pronunciation emphasizes the first “R,” resulting in the pronunciation ‘tər-mə-rik. Nevertheless, due to many people omitting this “R,” a newly accepted pronunciation is ‘tü-mə-rik. The British pronunciation puts additional emphasis on the “U,” resulting in the pronunciation ‘tyü-mə-rik.

https://dictionary.cambridge.org/us/pronunciation/english/turmeric

Turmeric pronounciation
Turmeric pronounciation

Objective

The original objective of this study was to examine the abundance of the molecule curcumin in different extraction solvents. Curcumin is reported to be the most abundant molecule in turmeric and is responsible for its bright orange colour. Many studies show the anti-inflammatory effects of curcumin. Due to the extensive research on curcumin, the study was redirected to focus on a different set of molecules. The new objective still involved the comparison of molecule abundance; however, this time the focus was on different sources of turmeric and a different series of molecules known as turmerones

Tumerones
Tumerones

The sources of turmeric chosen were fresh turmeric, turmeric powder, and turmeric supplement capsules. The fresh turmeric was dried and ground up in the lab. Nothing needed to be done with the turmeric powder, as it was already in a powdered form ready to be mixed with the solvents. The turmeric capsules had to be opened to get the powder out. Since the fresh turmeric was dried and ground up to the same fineness as the store-bought turmeric powder, the two should contain the same constituents. For the turmeric capsules, the Amazon listing claims that each capsule contains 500 mg of turmeric root powder and 50mg of turmeric root extract, equivalent to 2500 mg of raw root. Once again, this should contain the same constituents as fresh turmeric based on what is advertised.

Turmeric Sources

Extraction Methods.

Each source of turmeric was extracted in acetonitrile, ethanol, hexanes, and ethyl acetate. The extracted samples were analyzed using the GC-MS, with two trials run on each sample. Initially, the starting temperature was set to 40°C, and the final temperature was set to 320°C, with increments of 20°C per minute. This produced chromatograms that were very condensed, so the initial and final temperatures were then set to 100°C and 250°C respectively, along with increments of 10°C per minute for the second trial. Fresh ginger, being a close relative of turmeric, was also analyzed using the same method. However, the results were irrelevant to the pattern found between the turmeric samples.

Turmeric Extracts
Turmeric Extracts

Results.

Fresh Turmeric Results Each of the four solvents used yielded roughly the same results. However, it is noteworthy that the hexane extraction is missing quite a few more peaks overall compared to the other solvents. The ethyl acetate extraction brings out all the peaks found in other solvents, while also showing an extra peak with a retention index of 1243. The ethyl acetate extraction contains everything from the other extractions as well as a few more molecules, so the focus of this section will be on that extraction. The table here lists all the identified compounds, along with their retention times and percent abundances. Since the mass of the turmeric sample was not measured for the extractions, the concentration cannot be quantified. The GC identified the presence of R-carvone with high confidence. However, carvone is not typically found in turmeric and was not found in any other samples. Cross-contamination was not possible, as the acetonitrile, ethanol, and hexane extractions were run before the ethyl acetate extraction. If carvone was present, it would have been identified in all fresh turmeric extracts. Vanillin is found in turmeric in very small amounts in all extracts of fresh turmeric. 

Fresh Turmeric Chromatogram
Fresh Turmeric Chromatogram

Tumerones!

Three molecules stood out in all fresh turmeric extracts. These molecules are ar-turmerone, α-turmerone, and β-turmerone. α-turmerone can simply be referred to as turmerone, while a more common name for βturmerone is curlone. In the ethyl acetate extract for fresh turmeric, the percent abundances for arturmerone, α-turmerone, and β-turmerone were 21.26%, 20.56%, and 15.00%, respectively.

Table of Fresh Turmeric Molecules
Table of Fresh Turmeric Molecules

A Closer Look at ar-turmerone, α-turmerone, and β-turmerone

The image here shows the structure of each form of turmerone, as well as their mass spectra identified by the GC and their retention indices found in the NIST Chemistry Webbook. Since α-turmerone and βturmerone have one fewer double bond than ar-turmerone, they have a molecular weight of 218 as opposed to 216. According to the National Institutes of Health, ar-turmerone has neuroprotective effects, is an antioxidant, and decreases inflammation. α-turmerone is antimicrobial and also works as an anti-inflammatory but works through a different pathway and is less potent due to its lower stability than ar-turmerone. β

Tumerones and Mass Spec
Tumerones and Mass Spec

A Study on the Anti-inflammatory Properties of Ar-turmerone

This graph shows the effect of aromatic-turmerone on the inflammatory response in microglial cells in mice. Aβ 1-42 induces the release of pro-inflammatory cytokines, thereby reducing cell viability. Treatment with ar-turmerone helped to offset the damage done by inflammatory cytokines and increase the cell’s viability. One criticism of the study that I may add is related to the experimental setup. Two groups were set in this study, one treated with only ar-turmerone and the other treated with both ar-turmerone and Aβ 1-42. This setup was intended to demonstrate the effect of ar-turmerone on cell viability. However, a more effective setup for this study would be to include a control group treated with only Aβ 1-42 and an experiment group treated with both ar-turmerone and Aβ 1-42. This would help demonstrate that ar-tumerone increases cell viability relative to the group treated with only Aβ 1-42.

Turmeric paper
Turmeric paper

Turmeric Powder Results Four extractions were performed on the store-bought turmeric powder using the same solvents as those used for the other turmeric sources. To maintain consistency, the focus was placed on the ethyl acetate extraction. Overall, the results from the turmeric powder are quite consistent with those from the fresh turmeric. This was expected, as the turmeric powder used claims to be simply ground turmeric. The main difference lies in the abundance of the turmerones. The percent abundances for ar-turmerone, αturmerone, and β-turmerone were 31.00%, 12.87%, and 17.77%, respectively, indicating that more arturmerone was extracted relative to α-turmerone in the store-bought turmeric powder. The abundance of β-turmerone was higher than that found in the fresh turmeric, though this discrepancy does not seem to be significant. 

Turmeric Culinary Powder
Turmeric Culinary Powder

Turmeric Culinary Powder Results

Other notable differences were in the presence of molecules that were found in the fresh turmeric. This time, no carvone was observed, which was expected. The store-bought turmeric powder also lacks vanillin and linoleic acid. In place of linoleic acid, hexadecanoic acid is present in the turmeric powder. Both molecules have 32 hydrogens and 2 oxygens, but hexadecanoic acid has 2 fewer carbons than linoleic acid.

Turmeric Results Powder
Turmeric Results Powder

Turmeric Capsule Results Once again, the focus will be on the ethyl acetate extraction of turmeric capsules. Recall that the turmeric capsule claims to contain 500 mg of turmeric powder and 50 mg of turmeric root extract that is equivalent to 2500 mg of turmeric powder. This implies that the results from the turmeric capsules should be consistent with those from the fresh turmeric root and store-bought turmeric powder. Although we expected to find the same molecules as in the fresh turmeric and turmeric powder, the turmeric capsules present some interesting differences. 

Turmeric Capsule Results
Turmeric Capsule Results

While both fresh turmeric and turmeric powder contain significant amount of α-turmerone, no trace of α-turmerone was found in the turmeric capsules. Instead, nearly half of the capsule is composed of ar-turmerone, which accounts for 46.68%. β-turmerone is still present in the turmeric capsules, with the lowest percent abundance of all three turmeric sources at 10.76%. Other notable differences in the turmeric capsules include the absence of zingiberene and the presence of octadecanoic acid

Turmeric Capsules Result Table
Turmeric Capsules Result Table

Summarizing the Results: A Discernable Trend:

The tables summarize the percent abundances of each form of turmerone in the different sources of turmeric. Fresh turmeric serves as the baseline, as it has undergone no processing. The turmeric capsule represents the most processed form, while turmeric powder falls in between. A closer look at the tables reveals a striking trend: as the level of processing increases, the abundance of ar-turmerone rises while the abundance of α-turmerone drops. β-turmerone is a bit of a third wheel here, as there is no pattern for its abundance

Results Comparison
Results Comparison

Why Do We See This Trend? An explanation for the higher abundance of ar-turmerone in processed sources of turmeric is the extraction process. In the extraction process, chemical stability is a crucial factor that affects the amount of a chemical in the extract. Ar-turmerone’s complete benzene ring provides it with much greater stability than α-turmerone, allowing it to remain intact and retain its bioactivity throughout the extraction process while also being less affected by storage conditions. Another explanation for the higher abundance of ar-turmerone is that it is a major part of turmeric essential oil and is generally present in higher concentrations than α-turmerone. Because of this, it is not surprising that an extraction would yield a higher proportion of ar-turmerone. A third explanation for the higher relative abundance of ar-turmerone relates to its superior health benefits over α-turmerone. In other words, the company may be purposely seeking to attain higher concentrations of ar-turmerone so that people can benefit from its effects. Refer to the graph shown earlier on the effects of Aβ 1-42 on cell viability in the presence of ar-turmerone. According to the same study, ar-turmerone’s superior stability allows it to bind to and inhibit more pro-inflammatory cytokines at a given moment in time compared to alpha-turmerone, making it a more effective anti-inflammatory molecule.

Tumerone
Tumerone

Conclusion Turmeric is an intriguing plant with a long history and a variety of use cases. The most notable use is as a medicinal herb, as turmeric provides a range of health benefits. The medicinal effects of turmeric are attributed to numerous different molecules found within the plant. One such set of molecules is turmerones, which occur in three different forms. Ar-turmerone is anti-inflammatory, neuroprotective, and acts as an antioxidant; α-turmerone is anti-inflammatory and antimicrobial; and β-turmerone shares similar effects with ar-turmerone but is less researched. Turmerones vary in relative abundance depending on the source of turmeric. A general pattern observed is that ar-turmerone tends to be more abundant in highly processed forms of turmeric, while α-turmerone is less abundant in these processed forms. A pattern was not identified for the abundance of β-turmerone between different sources of turmeric. Several explanations exist for the observed pattern in the abundance of ar-turmerone and α-turmerone. Three potential explanations are: the extraction process favouring ar-turmerone’s higher stability, arturmerone being naturally greater in proportion compared to α-turmerone in nature, or health supplement companies are purposely trying to attain higher concentrations of ar-turmerone to provide greater health benefits. GC-MS is an excellent tool for analyzing volatile compounds in a sample. However, it struggles with larger, less volatile compounds. Since this study used only GC-MS, some molecules were not detected. An example is curcumin, a molecule found in high abundance in turmeric. Curcumin is the molecule responsible for turmeric’s orange colour. Because curcumin is a large molecule, GC-MS could not detect it. Future research can combine GC-MS findings with those of the LC-MS to create a more comprehensive view of turmeric’s medicinal properties

Joey Li
Joey Li