Betalains: A Narrative Review on Pharmacological Mechanisms Supporting the Nutraceutical Potential Towards Health Benefits

Abstract

Betalains are naturally occurring pigments sourced mainly from Beta vulgaris (beetroot), Hylocereus spp. (dragon fruit), Amaranthus spp., and Opuntia spp. Betalains are widely used for their vibrant colors and health-promoting properties. These nitrogenous, water-soluble pigments are crucial colorants in the food industry, responsible for the red, purple, and yellow plant tissues, predominantly in the order Caryophyllales. They are grouped into betacyanins, with reddish-violet hues, and betaxanthins, yellow to orange. Examples include beetroot stems for betacyanins and yellow pitaya pulp for betaxanthins. Several pharmacological activities were reviewed in the scientific literature, describing their potential implications for human health. In this review, we focused on the main and latest studies on the pharmacological effects and mechanisms of betalains, including antioxidant, anti-inflammatory, antihypertensive, hypolipidemic, antidiabetic, hepatoprotective, neuroprotective, anticancer, and antimicrobial properties, in both in vitro and in vivo studies. Overall, betalain consumption is considered safe, with no major adverse effects or allergic reactions reported. We also approached topics such as the pharmacokinetics, bioavailability, stability, and enhanced stabilization of betalains. This article provides a comprehensive overview of bioactive potential of betalains, highlighting the biochemical mechanisms involved. The current knowledge broadens the clinical applicability of betalains, making them potential sources of nutraceutical compounds that can be used to develop functional foods.

Keywords: anti-inflammatory; anticancer; antidiabetic; antihypertensive; antimicrobial; antioxidant; betacyanin; betaxanthin; hepatoprotective; hypolipidemic.

Figure 1

Chemical structures of the main subclasses of betalains. In the center, betalamic acid, the common precursor of betalains, gives rise to two main subclasses: betaxanthins (left, yellow/orange), which result from the conjugation of betalamic acid with amino acids or amines, and betacyanins (right, red/purple), formed by conjugation with cyclo-DOPA groups. Examples of betaxanthins include indicaxanthin, vulgaxanthin I, and tryptophan-betaxanthin, while examples of betacyanins include betanin, isobetanin, and neobetanin. The arrows indicate the biosynthetic pathways between betalamic acid and its derived subclasses. Adapted from Khan et al., 2015 [9].

Figure 2

A representative diagram highlights oxidative stress and inflammation as participants in the pathophysiological mechanisms of diseases and the inhibition of these processes by betalains. The excessive generation of free radicals triggers important molecular alterations including genetic mutation, lipid peroxidation, and the impairment of the endogenous antioxidant system. In addition, it can activate inflammatory signaling routes, resulting in inflammatory components that aggravate the damage. ROS: reactive oxygen species. RNS: reactive nitrogen species. Nrf2: nuclear factor erythroid 2-related factor 2. GSH: glutathione. SOD: superoxide dismutase. MDA: malondialdehyde. STAT3: signal transducer and activator of transcription 3. NF-κB: nuclear transcription factor kappa B. COX-2: cyclooxygenase-2. iNOS: inducible nitric oxide synthase. TNF-α: tumor necrosis factor-alpha. IL: interleukin. Created using http://BioRender.com (accessed on 21 November 2024).

Figure 3

Representative scheme of the main biological properties and plant sources of betalains. Created using https://BioRender.com (accessed on 30 October 2024).