Turmeric: from spice to medicine

By Giannis Konstantinou

Turmeric powder is a world popular spice that has found its way into kitchens all over the globe. The ground rhizomes of the turmeric plant, named Curcuma longa L., originate from southeast Asia, and have garnered interest for thousands of years, not only for its culinary use but also for its medicinal capabilities . 

Turmeric has been a part of traditional medicine in India for more than 2000 years (Tilak et al., 2004). The main active component found in the turmeric rhizome is Curcumin (with chemical formula 1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione), also called diferuloylmethane, which gives it its yellow colour. Curcumin is nowadays used worldwide in a variety of forms for a variety of health benefits, from Malaysia where it is used as antiseptic to Pakistan where it is used as an anti-inflammatory agent, while also being available in the form of capsules, energy drinks and ointments (Hewlings & Kalman, 2017). However, there is strong evidence to suggest that the health capabilities of curcumin are far more wider reaching than this.

Curcumin first became an interest to scientists when it was separated from turmeric in 1815 without devoting much research to it. However, after a 1995 report on curcumin and its anticancer properties, research in curcumin has increased greatly and has revealed the variety of health benefits that it can have (Priyadarsini, 2014). Today, evidence exists to suggest that curcumin, with its antioxidant and anti-inflammatory properties, has the capability to help in a variety of conditions, namely: arthritis, hyperlipidaemia, cancer, neurological disorders, and depression (Hewlings & Kalman, 2017).

The blood brain barrier, which is the border of endothelial cells that separate the blood in the vessels and the brain, has high selectivity for what goes in and out of the brain, and this creates a challenge when manufacturing drugs to treat brain disorders, due to the difficulty in crossing this barrier (Keener, 2017). Curcumin, being insoluble in water and highly soluble in lipids, can cross the blood brain barrier and treat neurological diseases, especially those that are due to oxidation and inflammation of neurons (Liczbiński et al. 2020). Another study concluded that curcumin-loaded nanoparticles were able to cause neural stem cells to undergo neurogenesis, a mechanism that could have the potential to serve as treatment for Alzheimer’s disease (Tiwari et al., 2013). Curcumin has thus showed promising capabilities in treating neurological diseases (Liczbiński et al. 2020)

Moreover, in a randomised control trial in 2013 the efficacy and safety of curcumin use in major depressive disorder was investigated for the first time on patients, after antidepressant capabilities were shown in animal studies. In this study, a sample of 60 patients which were diagnosed with major depressive disorder were used. In this sample the efficacy of a treatment using fluoxetine, a widely used antidepressant, was compared against a treatment using solely curcumin and a treatment that included both. All treatments had similar effects, with the combination treatment having a slightly higher efficacy. This study is in accordance with the animal studies that it preceded and shows that curcumin has an antidepressant effect  comparable to that of fluoxetine, a prescribed antidepressant medication (Sammukhani et al., 2014).

Studies on the molecular signalling of curcumin have also revealed anticancer properties. It was found that curcumin was able to control the cell cycle and induce cell apoptosis in cancer cells when present in a specific concentration, but not in healthy cells. These signalling properties have also shown possible activity in other pathologies like liver and spleen toxicity, pathogenic infections and cardiological diseases. (Liczbiński et al. 2020)

The majority of drugs that have developed over the past years for diseases like cancer, CVDs, metabolic, neurological and more, have been mono targeted drugs. However, conditions such as these are linked to disorders in a multitude of chemical and biological  pathways; hence, a mono targeted drug may not be the most effective way to address these diseases. Curcumin, being able to interact with a number of signalling molecules, has been shown to possess a variety of healing properties, ranging from anti-inflammatory to antioxidant effects, to hypoglycaemic and antimicrobial activities. In addition, curcumin has the added benefit of being an inexpensive and widely available dietary agent (Gupta et al., 2013). All in all, animal studies and limited clinical studies have shown significant evidence of the potential of curcumin as a therapeutic agent, and have highlighted the potential yield from further research on curcumin and its therapeutic proficiencies. 

References:

Tilak, J.C., Banerjee, M., Mohan, H. and Devasagayam, T.P.A. (2004), Antioxidant availability of turmeric in relation to its medicinal and culinary uses. Phytotherapy Research. 18(10): 798-804. Available from: doi:10.1002/ptr.1553 [Accessed 15^th September]

Hewlings, S. J., & Kalman, D. S. (2017). Curcumin: A Review of Its Effects on Human Health. Foods. 6(10): 92. Available from: https://doi.org/10.3390/foods6100092 [Accessed 15th September 2020]

Priyadarsini, I. K. (2014) The Chemistry of Curcumin: From Extraction to Therapeutic Agent. Molecules. 19(12): 20091-20112. Available from: https://doi.org/10.3390/molecules191220091 [Accessed 15th September 2020]

Sanmukhani, J., Satodia, V., Trivedi, J., Patel, T., Tiwari, D., Panchal, B., Goel, A. and Tripathi, C.B. (2014), Efficacy and Safety of Curcumin in Major Depressive Disorder: A Randomized Controlled Trial. Phytotherapy Research. 28(4): 579-585. Available from: https://doi.org/10.1002/ptr.5025 [Accessed 16th September]

Liczbiński, P, Michałowicz, J, Bukowska, B. (2020),Molecular mechanism of curcumin action in signaling pathways: Review of the latest research. Phytotherapy Research. 34(8): 1992– 2005. Available from: https://doi.org/10.1002/ptr.6663 [Accessed 16th September]

Keener A.B. (2017) Getting Drugs Past the Blood-Brain Barrier. Available from: https://www.the-scientist.com/features/getting-drugs-past-the-blood-brain-barrier-30196 [Accessed 16th September]

Tiwari, K.S., Agarwal, S., Seth, B., Yadav, A., Nair, S., Bhatnagar, P., Karmakar, M., Kumari, M., Chauhan, S.K.L., Patel, K.D., Srivastava, V., Singh, D., Gupta, K.S., Tripathi, A., Chaturvedi, K.R., and Gupta, C.K. (2014). Curcumin-Loaded Nanoparticles Potently Induce Adult Neurogenesis and Reverse Cognitive Deficits in Alzheimer’s Disease Model via Canonical Wnt/β-Catenin Pathway. ACS Nano. 8(1): 76-103. Available from: DOI: 10.1021/nn405077y [Accessed 16th September]

Gupta, S.C., Patchva, S. & Aggarwal, B.B. (2013), Therapeutic Roles of Curcumin: Lessons Learned from Clinical Trials. AAPS  15: 195–218.  Available from: https://doi.org/10.1208/s12248-012-9432-8 [Accessed 16th September]