Table 2.

Bioavailability studies of aspalathin (ASP) and nothofagin (NOT) in human subjects after a single dose.

Dosage Form	ASP (mg) 1	NOT (mg) 1	Compound and Metabolites 2		ASP Excretion in Urine	Ref.
			Plasma	Urine
Green rooibos infusion (300 mL; 14 g/L, added to boiling water and infused for 10 min)	91	nq 3	nd 4	Methylated ASP; methylated and glucuronidated ASP	Max. conc. reached <2 h after ingestion; 0.74% excreted during 0–24 h	[49]
Green rooibos ‘ready-to-drink’ beverage (500 mL)	41	7	nd	Glucuronidated ASP (2); methylated and glucuronidated ASP (3); methylated and sulphated ASP; sulphated ASP; NOT & metabolites not detected	Most excreted <5 h after ingestion; 0.22% excreted during 0–24 h	[50]
Fermented rooibos ‘ready-to-drink’ beverage (500 mL)	3.6	0.8	nd	methylated and glucuronidated ASP (3); methylated and sulphated ASP; sulphated ASP; NOT & metabolites not detected	0.09% excreted during 0–24 h	[50]
Green rooibos infusion (20 g/L; 10 min infused in freshly-boiled water)	287	34	ASP	ASP; glucuronidated ASP; methylated ASP; methylated and glucuronidated ASP (3); methylated and sulphated ASP; sulphated ASP; glucuronidated 3-hydroxyphoretin; NOT; glucuronidated NOT; glucuronidated phloretin	0.17% recovery rate at tmax	[48]
Isolated fraction 5 of green rooibos, reconstituted in 500 mL water to similar phenolic content as green rooibos infusion			ASP	As for infusion, except for glucuronidated nothofagin	0.10% recovery rate at tmax	[48]

¹ Dose. ² Number in brackets indicate number of metabolite derivatives. ³ Not quantified. ⁴ Not detected. ⁵ Fraction was isolated by high-speed counter-current chromatography; contained 0.3 g ASP/0.5 g fraction added to 500 mL water; fraction also contained nothofagin, orientin, isoorientin and isovitexin.