New Insights into the Efficacy of Aspalathin and Other Related Phytochemicals in Type 2 Diabetes—A Review

Abstract

In the pursuit of bioactive phytochemicals as a therapeutic strategy to manage metabolic risk factors for type 2 diabetes (T2D), aspalathin, C-glucosyl dihydrochalcone from rooibos (Aspalathus linearis), has received much attention, along with its C-glucosyl flavone derivatives and phlorizin, the apple O-glucosyl dihydrochalcone well-known for its antidiabetic properties. We provided context for dietary exposure by highlighting dietary sources, compound stability during processing, bioavailability and microbial biotransformation. The review covered the role of these compounds in attenuating insulin resistance and enhancing glucose metabolism, alleviating gut dysbiosis and associated oxidative stress and inflammation, and hyperuricemia associated with T2D, focusing largely on the literature of the past 5 years. A key focus of this review was on emerging targets in the management of T2D, as highlighted in the recent literature, including enhancing of the insulin receptor and insulin receptor substrate 1 signaling via protein tyrosine phosphatase inhibition, increasing glycolysis with suppression of gluconeogenesis by sirtuin modulation, and reducing renal glucose reabsorption via sodium-glucose co-transporter 2. We conclude that biotransformation in the gut is most likely responsible for enhancing therapeutic effects observed for the C-glycosyl parent compounds, including aspalathin, and that these compounds and their derivatives have the potential to regulate multiple factors associated with the development and progression of T2D.

Hibiscus, Rooibos, and Yerba Mate for Healthy Aging: A Review on the Attenuation of In Vitro and In Vivo Markers Related to Oxidative Stress, Glycoxidation, and Neurodegeneration

“…Rooibos is prepared from either leaves or stems, and consumption of it has been increasing because of its health benefits and caffeine-free composition, compared to other teas [ 103 ]. In addition, this plant has a unique flavonoid profile including dihydrochalcone aspalathin in both fermented and non-fermented rooibos, which has been demonstrated to help with type-2 diabetes slowdown [ 104 ]. Non-exclusive polyphenols, such as orientin, isoorientin, isoquercitrin, rutin, and quercetin, have also been described in rooibos [ 105 ].…”

Aspalathin and Other Rooibos Flavonoids Trapped α-Dicarbonyls and Inhibited Formation of Advanced Glycation End Products In Vitro

“…An important aspect that should be considered is the fact that aspalathin, despite its high antiglycation as well as trapping properties, has an extremely low level of bioavailability—at less than 1% [ 75 ]. However, aspalathin as a C-glycoside is metabolized with the involvement of bacterial enzymes in the large intestine, where low-molecular metabolites, such as phloroglucinol, have the chance to be absorbed into the circulation and can have a systemic antiglycation and trapping effect [ 76 ].…”

Aspalathus linearis (Rooibos) Targets Adipocytes and Obesity-Associated Inflammation

“…Aspalathin is the specific flavonoid to Rooibos, and it is abundantly present in Aspalathus linearis , which explains the huge amount of interest in the potential health benefits of this flavonoid. The other four main flavonoids (nothofagin, orientin, isoorientin and vitexin) in Rooibos extract are not specific and may occur in other medicinal plants such as Leandra dasytricha [ 25 ]. The Rooibos extract used in our study contains 80 g·kg −1 aspalathin, which is in the range of the natural products containing Rooibos (8–12%) [ 31 , 32 ].…”

“…Rooibos tea has been consumed since the late 1700s, but its potent antioxidant activity and health-giving properties have only been reported in the past two decades, increasing its popularity [ 24 ]. Thus, Rooibos has attracted the attention of several research groups, and multiple in vivo and in vitro studies have demonstrated its significant effect on insulin resistance, diabetes, cardiovascular complications (mainly as an anti-hypertensive, through inhibition of angiotensin-converting enzyme), inflammation, viral infections, ovarian function, and others [ 24 , 25 ]. The anti-obesity potential of Rooibos extract was first reported in 2011 [ 26 ]; then, a research group demonstrated its effect on murine preadipocyte cells, but no more data were found on its impact on human adipocytes [ 27 ].…”