Development of high-performance thin layer chromatography method for identification of phenolic compounds and quantification of rosmarinic acid content in some species of the Lamiaceae family

Aim: Representatives of Nepetoideae Burnett subfamily are promising species of the Lamiaceae Martinov family because of accumulating such valuable groups of secondary metabolites as terpenoids and polyphenols. A high-performance thin layer chromatography (HPTLC) fingerprint method for the qualitative determination of phenolic compounds and for the quantification of rosmarinic acid (RA) content in methanol extracts of five species of this subfamily was developed for the first time.

Materials and methods: Dried aerial parts of Dracocephalum moldavica L., Ocimum americanum L., Lophanthus anisatus (Nutt.) Benth., Monarda fistulosa L., and Satureja hortensis L. collected in flowering period were macerated with methanol. The HPTLC analysis was conducted using the CAMAG analytical system (Muttenz, Switzerland). The comparative analysis of RA contents was performed by HPTLC densitometric detection at λ = 366nm.

Results: Identification of polyphenols in the investigated herbs was performed by comparison of a color and R _f of the chromatographic zones with six reference standards: rutin, apigenin, luteolin, caffeic acid, chlorogenic acid, and RA. HPTLC method was also validated for the quantification of RA in the extracts of investigated herbs. RA contents decreased in such a sequence: D. moldavica (24.83 ± 0.78mg/g) > M. fistulosa (20.32 ± 0.64mg/g) > O. americanum (19.59 ± 0.61mg/g) > S. hortensis (18.77 ± 0.52mg/g) > L. anisatus (12.61 ± 0.43mg/g).

Conclusion: Obtained data can facilitate the differentiation of investigated species using the chromatographic fingerprints of their phenolic compounds. Developed and validated HPTLC method provides an approach to estimate RA content as a common marker of investigated herbs.

Keywords: Lamiaceae; chromatographic fingerprints; high-performance thin layer chromatography; phenolic compound; rosmarinic acid.