Abstract
Curcumin is a natural product found in the rhizome of Curcuma longa (L.) and other Curcuma spp. As a lipophilic molecule, it has greater affinity for polar, non-polar, alkaline, or extremely acidic organic solvents. Several studies indicate that curcumin has several benefits for human health, for example, against degenerative diseases, cancer, and infectious diseases. To obtain a quality product with nutraceutical properties, it is necessary to know its physicochemical characteristics and preserve it from cultivation until ingestion by the human. However, its low solubility leads to low absorption; in this context, nanotechnological systems can contribute to increase curcumin bioavailability. This review aims to highlight important issues in all stages that curcumin goes through: from aspects related to its extraction to its association with nanotechnology. Although curcumin extraction process is already well established, it is possible to observe more and more research focused on increasing yield and being more environmentally friendly. Further, curcumin’s low absorption is notable due to its physicochemical characteristics, mainly due to its low aqueous solubility. However, its association with nanotechnology shows to be promising and an increasingly growing trend because the use of this “Indian solid gold” is the hope of many patients.
1. Introduction
Although research showing the potential of foods (such as curcumin) is old (in the 1949s, the first research on curcumin benefits to human health was carried out), in the last decade there has been an increase in the population’s knowledge and consumption of food to promote health. In this sense, a directly proportional relationship is observed between the reduction of synthetic additives and the increase in the consumption of functional foods, such as nutraceuticals.[1-3] Nutraceuticals are a class of food-derived products that have beneficial properties to health and wellness to the body. Although its use is already a trend nowadays because the nutraceuticals market is a multimillion-dollar and high-impact branch, it is expected that this market will grow even more in the next decade.[2, 4]
Among the various nutraceuticals that have been the focus of research, emphasis must be placed on curcumin as it has ≈249,260 documents results in Scopus, with 33,371 only in the year 2023 (search performed in November 12, 2023). It is also worth highlighting that this yellow-colored polyphenol, found primarily in the rhizome of Curcuma longa (L.) and other Curcuma spp., is extremely used (for centuries) in the human diet as dye and seasoning (like curry), with an extensive range of nutraceutical properties very well documented in the literature.[5, 6]
Curcumin (C21H20O6, Figure 1) presents a molecular weight of 368.39 g mol−1 and melting point at 183 °C.[6] This compound possesses keto-enol tautomerism depending on the pH (in acidic pH, the ketone form is the dominant one [also in the cells]), being enol the more stable form. Temperature also seems to influence this issue as higher temperatures favor the formation of the keto form. It is also worth highlighting that curcumin presents cis–trans isomerism.[7, 8] Curcumin is soluble in polar and nonpolar organic solvents and in alkali or extremely acidic solvents (such as glacial acetic acid), being insoluble in water, neutral and acidic pH (however; it is unstable in alkaline conditions).[9] Knowing the physicochemical characteristics of a component is crucial when the development of a nutraceutical is desired because, with the help of new technologies, some factors such as poor solubility in water can be circumvented. Thus, this review article seeks to highlight all the steps that curcumin goes through for its activity as a nutraceutical: extraction, purification, absorption, and activities, including the most recent studies of its association with nanotechnology.
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Curcuma Longa: Nutraceutical Use and Association With Nanotechnology
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G. Corrêa Carvalho, G. D. Marena, M. Gaspar Gonçalves Fernandes, G. Ricci Leonardi, H. A. Santos, M. Chorilli, Curcuma Longa: Nutraceutical Use and Association With Nanotechnology. Adv. Healthcare Mater. 2024, 13, 2400506. https://doi.org/10.1002/adhm.202400506
