Quantitative and qualitative analyses of rosmarinic acid in South African Salvia species using two chromatographic techniques

The genus Salvia (Lamiaceae) encompasses about 900 species worldwide of which 26 are indigenous to southern Africa. The South African species are used in traditional medicines [1], as spice or tea due to reported good anti-oxidant properties [2]. The anti-oxidant capacity of these plants has been ascribed to the presence of phenolic compounds such as rosmarinic acid (RA), caffeic acid, carnosic acid and carnosol [2]. HPTLC-densitometric and HPLC-UV chromatographic techniques were used for qualitative and quantitative analyses of RA in 18 methanol:chloroform extracts from sixteen Salvia species. Polynomial and linear regression analyses were used to estimate the amount of RA in solvent extracts by HPTLC-densitometric and HPLC-UV techniques, respectively. RA was identified in all the samples investigated and ranged from 13.1µg/mg (S. stenophylla Burch. ex Benth.) to 113.0µg/mg (S. muirii L.Bolus). The paired sample t-test showed no statistical significant difference in the estimation of the amount of RA in the solvent extracts using the two chromatographic techniques. A strong correlation (r2=0.93) was found between the estimation using the HPTLC-densitometric and the HPLC-UV calibrations.

Acknowledgement: National research Foundation (South Africa); Tshwane University of Technology, South Africa National Biodiversity Institute (Pretoria).

References: 1. Watt JM, Breyer-Brandwijk MG (1962) The Medicinal and Poisonous Plants of Southern and Eastern Africa. 2nd edition. E and S. Livingstone, Edinburgh.

2. Kamatou GPP et al. (2010) Food Chem 119: 684–688.