Isovitexin

Isovitexin is a flavone C-glycoside known chemically as apigenin-6-C-glucoside. It consists of the flavone aglycone apigenin linked to a β-D-glucopyranose moiety via a carbon-carbon bond at the 6-position. Its molecular formula is C21H20O10. Isovitexin is an isomer of vitexin, which is apigenin-8-C-glucoside.

Occurrence and distribution: Isovitexin has been identified in a variety of plant species and plant-derived foods. It is particularly associated with certain medicinal plants and dietary sources where flavone C-glycosides are present. Compared with many O-glycosides, C-glycosides such as isovitexin tend to exhibit greater chemical stability under physiological conditions.

Chemistry and biosynthesis: In plants, isovitexin is formed when a UDP-glucose moiety is attached to apigenin by a C-glycosyltransferase at the 6-position, producing the 6-C-glucoside. This contrasts with vitexin, where glycosylation occurs at the 8-position. In vivo, isovitexin can be deglycosylated to apigenin by enzymatic activity or gut microbiota, contributing to potential metabolic interconversions.

Biological activity: In vitro studies have reported antioxidant activity for isovitexin, along with anti-inflammatory and neuroprotective effects in cellular models. Some preclinical research has suggested possible antidiabetic and anticancer activities, but clinical evidence is limited and findings are not yet conclusive.

Pharmacokinetics and safety: As a C-glycoside, isovitexin is relatively resistant to acid hydrolysis and may be absorbed in part in its glycosylated form, with metabolism to apigenin contributing to bioavailability. Typical dietary levels pose no known safety concerns, while the pharmacokinetics and safety of pharmacological doses require further investigation.