Aspalathin health benefit
Aspalathin is a green rooibos tea component. A dihydrochalcone and C-glycoside, it is the most abundant flavonoid in rooibos (Aspalathus linearis), which is well known as an herbal tea in many countries. Aspalathin appears to have in vitro antioxidant and antimutagenic effects. Aspalathin may also be helpful in blood sugar control.
Antioxidant activity of the dihydrochalcones Aspalathin and Nothofagin and their corresponding flavones in relation to other Rooibos ( Aspalathus linearis ) Flavonoids, Epigallocatechin Gallate, and Trolox.
J Agricultural Food Chem. 2009; Snijman PW, Joubert E, Ferreira D, Li XC, Ding Y, Green IR, Gelderblom WC. Snijman PW, Joubert E, Ferreira D, Ding Y, Green IR, Gelderblom WC. Departments of Chemistry, Stellenbosch University, Matieland (Stellenbosch), South Africa.
The antioxidant activity of rooibos flavonoids, including the dihydrochalcones aspalathin and nothofagin and their corresponding flavone glycosides, was evaluated using the ABTS radical cation, metal chelating, and Fe(II)-induced microsomal lipid peroxidation assays. Epigallocatechin gallate (EGCG) and Trolox were used as reference standards. Optimized geometric conformers of aspalathin and nothofagin, in addition to calculated physicochemical properties, were considered to explain interaction with the microsomal membrane structure and thus relative potency of the dihydrochalcones. The most potent radical scavengers were aspalathin and EGCG, followed by quercetin and nothofagin. The least effective radical scavengers were isovitexin and vitexin. Quercetin and EGCG were the most effective inhibitors of lipid peroxidation. Aspalathin and catechin displayed similar potencies. Nothofagin was almost as ineffective as its flavone glycoside analogues.
For blood sugar
Hypoglycemic effect of aspalathin, a rooibos tea component from Aspalathus linearis, in type 2 diabetic model db/db mice.
Phytomedicine. 2009. Kawano A, Nakamura H, Hata SI, Minakawa M, Miura Y, Yagasaki K. Department of Applied Biological Science, Tokyo University of Agriculture and Technology, Fuchu, Tokyo, Japan.
Effects of aspalathin on glucose metabolism were studied in vitro and in vivo. We first examined the effect of aspalathin on glucose uptake by cultured L6 myotubes and on insulin secretion from cultured RIN-5F pancreatic beta-cells in vitro, and then investigated the effect of dietary aspalathin on fasting blood glucose level and conducted an intraperitoneal glucose tolerance test using type 2 diabetes model mice in vivo. Aspalathin dose-dependently and significantly increased glucose uptake by L6 myotubes. It also significantly increased insulin secretion from cultured RIN-5F cells at 100muM. Dietary aspalathin (0.1-0.2%) suppressed the increase in fasting blood glucose levels of db/db mice for 5 weeks. Our results suggest that aspalathin has beneficial effects on glucose homeostasis in type 2 diabetes through stimulating glucose uptake in muscle tissues and insulin secretion from pancreatic beta-cells.
In Vitro Hepatic Biotransformation of Aspalathin and
Nothofagin, Dihydrochalcones of Rooibos (Aspalathus linearis), and Assessment of
Metabolite Antioxidant Activity.
J Agric Food Chem. 2009. van der Merwe JD, Joubert E, Manley M, de Beer D, Malherbe CJ, Gelderblom WC.
Aspalathin (2',3,4,4',6'-pentahydroxy-3'-C-beta-d-glucopyranosyldihydrochalcone) is the major flavonoid present in the South African herbal tea rooibos. In vitro metabolism of aspalathin and a structural analogue nothofagin, lacking the A ring catechol group, was investigated by monitoring the formation of glucuronyl and sulfate conjugates using Aroclor 1254 induced and uninduced rat liver microsomal and cytosolic subcellular fractions. Following glucuronidation of both aspalathin and nothofagin, HPLC-DAD, LC-MS, and LC-MS/MS analyses indicated the presence of two metabolites: one major and one minor. Only one aspalathin metabolite was obtained after sulfation, while no metabolites were observed for nothofagin. Two likely sites of conjugation for aspalathin are 4-OH or 3-OH on the A-ring. For nothofagin, the 4-OH (A-ring) and 6'-OH (B-ring) seem to be involved. The glucuronyl conjugates of aspalathin lack any radical scavenging properties in online postcolumn DPPH radical and ABTS radical cation assays. Deconjugation assays utilizing glucuronidase and sulfatase resulted in the disappearance of the metabolites, with the concomitant formation of the unconjugated form in the case of the glucuronidated product. The balance between conjugated and unconjugated forms of aspalathin could have important implications regarding its role in affecting oxidative status in intra- and extracellular environments in vivo.
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