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Carnosic acid


1.      Introduction

Name: Carnosic acid

CAS No.: 3650-09-7

Molecular Weight: 332.43

Molecular Formula: C20H28O4, 

Appearance: off-white to yellow brown powder or cream.

Specification: 5%-95%

Solubility: Lipid-soluble


Rosemary extracts are derived from Rosmarinus officinalis L. and contain several compounds which have been shown to exert antioxidative functions. These compounds belong mainly to the classes of phenolic acids, flavonoids, diterpenoids and triterpenes.

The present opinion refers to rosemary extracts prepared using solvent extraction (ethanol, hexane, acetone and supercritical carbon dioxide techniques).

The principal antioxidative components of the extracts are the phenolic diterpenes carnosol (CAS No 5957-80-2, molecular formula C20H28O4) and carnosic acid (CAS No 3650-09-7, formula C20H28O4)


                            Carnosol                        Carnosic acid


Dried leaves of rosemary contain between 1.5%-2.5% carnosic acid and only about 0.3%-0.4% carnosol.


2.  Mechanism

Carnosic acid is the starting element of a unique antioxidant mechanism called the “Carnosic Acid Cascade” (See below figure). The cascade is an exceptional series of chemical reactions that involve the transformation of carnosic acid into carnosol; carnosol into rosmanol; and rosmanol into galdosol. With each of these transformations, free radicals are quenched.



3. Isolation and Chromatogram

3.1 One way for isolation of carnosic acid 95%

Dried leaves (500g) were extracted with ethanol at room temperature, and the ethanol was evaporated to dryness under reduced pressure. The dried extract then was mixed with 1L of n-hexane for 70h and filtered. The extract was concentrated to one-third of its volume and extracted three ties with 0.5L of 5% NaHCO3 solution. The combined bicarbonate fractions were treated with H3PO4 to achieve PH 2.2. The acidic solution was then reextracted with n-hexane, dried over Na2SO4, and concentrated under reduced pressure until off-white crystals appeared. Evaporative recrystallization from n-heptane yielded off-white crystals of Carnosic acid with a melting point of 190 and purity greater than 95% as indicated by HPLC and NMR.


3.2 Chromatogram (285 nm) of Rosemary Extract enriched in Carnosic acid (40%)

The chromatographic profile (285 nm) of the RE

HPLC-DAD-MS/MS analysis of the RE extract revealed that a total of 15 phenolic compounds were present in the extract distributed in three major categories: phenolic acids, diterpenes and flavonoids.

The structure and peak identification of carnosol (peak 10, content 6.5%) and Carnosic acid (peak 14, content 39%) are indicated. 


4. Potential Aplication:

1. Antioxidant, antisepticand antibacterial, its antioxidant ability is far higher than VC, VE and Teapolyphenols, and 2 to 4 time stronger than BHA and BHT. It is stable andendures high temperature of 190-240C.

2. Prevents senescence, eliminates free radicals.
3. Antisepsis, antibioticand anti-inflammatory.

4. Skincare - skinrestoring and moisturizing, eliminates freckles.

5. Reducesserum totalcholesterol and fatty tissue: not only effectively decreases serumcholesterollevels, but also reduces the cholesterol content in differenttissues such asliver, heart and fatty tissue


Rosemary extracts are a 100% natural product approved by:

- FDA Revision of 21 Code of Federal Regulation 21 CFR, Part 182-20

- FEMA GRAS 3001 and 2992

- CEE 88/388/ECC and 88/344/ECC list 1 no 406

- E 392 and 2002/46/EC