Rosemary, Sage & Oregano Lamiaceae family

Summary

Sample preparation

Dried rosemary and sage were ground on a cutter at up to 28,000 rpm to a particle diameter of ≤1 mm. The residues left after their steam distillation (post-distillation or PD material) and oregano (Origanum onites) were included in the same series. The moisture content of all samples was ≤12 % for SFE compatibility.

Extraction

Supercritical CO₂ extractions ran on a SuperEx SC-1000 system with a 1 L vessel rated to 500 bar and 200 °C, in two sequential stages at 45 °C and a CO₂ flow of 100 mL min^-1. Stage 1 used pure CO₂ at 100–450 bar for 240 minutes in dynamic mode to strip residual waxes from the dried herbs and their PD residues. Stage 2 then extracted the de-waxed material with 10–15 % ethanol as co-solvent at 200–350 bar for 180 minutes, targeting the two phenolic diterpenes carnosic acid and carnosol. Rosmarinic acid was recovered separately by subcritical water extraction on the same system, at 50 bar and 110–150 °C with a water flow of 30 mL min^-1, in static and dynamic modes for 20–60 minutes, so the two routes could be compared on the same material.

Analysis

Carnosic acid, carnosol and rosmarinic acid were quantified by HPLC-DAD on a Shimadzu i-Series LC-2050-3D with a C18 column (250 × 4.6 mm, 5 µm) and 10 µL injections. Carnosic acid and carnosol were run isocratically in acetonitrile : water with 0.5 % H₃PO₄ (65 : 35 v/v) at 1.5 mL min^-1 and 25 °C over 35 minutes, with detection at 230 nm; rosmarinic acid by a water–methanol gradient (each with 0.1 % H₃PO₄) at 1.0 mL min^-1 and 30 °C, with detection at 330 nm.

Measured yields, compositions and chromatograms are reported in the full application note (PDF above).

At a glance

Plant material

Rosemary, Sage & Oregano — Lamiaceae family

Target compounds

Carnosic acid, carnosol, rosmarinic acid, ursolic acid

Compound class

Polyphenols

Published

December 2024

Document

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