Analytical Standards of Boswellic Acids and Their Separation

Matthias Nold, Hugh Cramer

AnaltyiX Volume 4, 2014

Getting to the Heart of Frankincense

The trees of the genus boswellia have been used in traditional medicine for thousands of years as an anti-inflammatory agent. Its resin is known as frankincense or olibanum and is still widely used in dietary supplements and in herbal medicinal products. The most characteristic components are a group of pentacyclic triterpene acids of which β-boswellic acids are the major biologically active constituents. Sigma-Aldrich offers six boswellic acids as analytical standards and two neat standards of α+β mixtures for use in research and quality control.

Figure 1. Chemical Structure of Boswellic Acids

Separation of Boswellic Acids

Several conditions, using a variety of solid phases, have been screened for their suitability to separate six boswellic acids. The shortest analysis time was achieved using an Ascentis^® Express Column (2.7 µm particle size, L × I.D. 10 cm × 3.0 mm) and acetonitrile/phosphoric acid as eluents.

Figure 2 shows the chromatograms of the ethanolic extract of a boswellia herbal supplement as well as of a mixture of the six analytical standards.

Figure 2. Experimental Conditions and Chromatograms for the Separation of Boswellic Acids

A. Boswellia Extract

B. Analytical Standards at 50 µg/mL of Each Component

Peak Ids
1) 11-Keto-ß-boswellic-acid 2) 3-O-Acetyl-11-keto-ß-boswellic-acid 3) α-boswellic-acid 4) ß-boswellic-acid 5) 3-O-Acetyl-α-boswellic-acid 6) 3-O-Acetyl-ß-boswellic-acid

	Conditions
Column:	Ascentis Express Phenyl-Hexyl, 10 cm x 3.0 mm I.D., 2.7 µM (53345-U)
Mobile Phase:	(A) 0.1% phosphoric acid; (B) acetonitrile
Gradient:	50% B for 0.5 min; to 100% B in 4.5 min; held at 100% B for 5 min
Flow Rate:	0.6 mL/min
Pressure:	2390 psi (165 bar)
Column temp.:	35 °C
Detection:	UV at 210 nm
Injection:	5 µL
Sample(s):	A: Boswellia extract in 50:50 water:ethanol B: Boswellic acid standards at 50 µg/mL in 70:30 water:methanol
Extraction:	1. Weigh 100 mg Bosewellia Herbal Supplement 2. Add 10 mL ethanol 3. Sonicate for 30 min at 40 °C 4. Dilute: 100 µL extract in ethanol, 400 µL ethanol, 500 µL water

Table 1.Analytical Standards of Boswellic Acids and Column Used

Product No.	Description	Package Size
74607	3-O-Acetyl-11-keto-ß-boswellic acid	5 mg
56208	3-O-Acetyl-α-boswellic acid	5 mg
49873	3-O-Acetyl-ß-boswellic acid	5 mg
96729	3-O-Acetylboswellic acid, mixture of α and ß	5 mg
06813	α-Boswellic acid	10 mg
80342	ß-Boswellic acid	5 mg
63850	Boswellic acid, mixture of α and ß	5 mg
78535	11-Keto-ß-boswellic acid	5 mg
53345-U	Ascentis Express Phenyl-Hexyl, 2.7 Micron HPLC Column	10 cm × 3.0 mm

We are continuously expands its offering of analytical standards for plant constituents, intended for the analysis of medicinal plants and herbal medicinal products.

On our Web page at sigma-aldrich.com/medicinalplants, you will find an up-to-date list of all phytopharma standards sorted in alphabetical order; by substance class and by genus of a large number of the most popular medicinal plants.

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