Boswellia serrata
DEFINITION
Boswellia serrata is the oleogum resin obtained by incision or produced by spontaneuos exudation from the stem and branches of Boswellia serrata Roxb. (Fam. Burseraceae). It contains NLT 1.0% of the keto derivatives of -boswellic acid, calculated on the dried basis as the sum of 11-keto--boswellic acid and 3-acetyl-11-keto--boswellic acid.
IDENTIFICATION
•  A. Thin-Layer Chromatographic Identification Test 201
Standard solution:  Treat a quantity of USP Boswellia serrata Extract RS with gentle heating in methanol to obtain a solution having a known concentration of 30 mg/mL, cool, centrifuge, and use the supernatant.
Sample solution:  Use the Sample solution, prepared as directed in the test below for Content of Keto-Derivatives of -Boswellic Acids, and concentrate to 10% of the volume.
Adsorbent:  0.25-mm layer of chromatographic silica gel
Developing solvent system:  A mixture of hexane and ethyl acetate (6:4)
Dipping reagent:  Prepare a solution of 10% sulfuric acid in methanol. [Note—Prepare fresh immediately before use. ]
Application volume:  10 µL
Analysis 
Samples:  Standard solution and Sample solution
Apply the samples as bands to a suitable thin-layer chromatographic plate (see Chromatography 621). Use a saturated chamber. Develop until the solvent front has moved up about 90% of the plate. Remove, dry, and examine under UV light at 254 nm. Dip in the Dipping reagent, heat for 5–10 min at 100, and examine under visible light.
Acceptance criteria:  Under UV light at 254 nm, the Sample solution exhibits two main zones due to 11-keto--boswellic acid and 3-acetyl-11-keto--boswellic acid at RF values of about 0.30 and 0.36, respectively, corresponding to zones from the Standard solution. Under visible light, the Sample solution exhibits two additional zones due to -boswellic acid and 3-acetyl--boswellic acid at RF values of about 0.49 and 0.58, respectively, corresponding to zones from the Standard solution. Other, less intense zones are observed for the Sample solution and the Standard solution.
•  B. The 210-nm chromatogram of the Sample solution, in the test for Content of Keto-Derivatives of -Boswellic Acids, exhibits peaks for 11-keto--boswellic acid, 3-acetyl-11-keto--boswellic acid, -boswellic acid, and 3-acetyl--boswellic acid at retention times that correspond to those in the 210-nm chromatogram of Standard solution B and the 210-nm Reference Chromatogram provided with the USP Boswellia serrata Extract RS.
COMPOSITION
•  Content of Keto-Derivatives of -Boswellic Acids
Standard solution A:  Dissolve a quantity of USP 3-Acetyl-11-keto--Boswellic Acid RS in methanol to obtain a solution having a known concentration of 0.1 mg/mL.
Standard solution B:  Treat a quantity of USP Boswellia serrata Extract RS with gentle heating in methanol to obtain a solution having a known concentration of 10 mg/mL. Before injection, pass through a filter of 0.45-µm pore size.
Sample solution:  Transfer about 2.0 g of crushed Boswellia serrata to a round-bottom flask, and reflux in 50 mL of methanol in a water bath for 15 min, stirring with a magnetic stirrer. Repeat till the last extract turns colorless. Evaporate the combined extracts to about 50 mL, transfer to a 100-mL volumetric flask, and dilute with methanol to volume. Before injection, pass through a filter of 0.45-µm pore size, and discard the first few mL of the filtrate.
Mobile phase:  Prepare a a filtered and degassed mixture of acetonitrile, water, and glacial acetic acid (900:100:0.1). Make adjustments if necessary.
Chromatographic system 
Mode:  LC
Detector:  UV 254 nm
Column:  4.6-mm × 25-cm; packing L1
Flow rate:  See the gradient table below.
Time
(min)
Flow Rate
(mL/min)
0 1
5 1.5
10 2
30 2
32 1
45 1
Injection size:  20 µL
System suitability 
Samples:  Standard solution A and Standard solution B
[Note—The relative retention times for 11-keto--boswellic acid and 3-acetyl-11-keto--boswellic acid are about 1.0 and 1.4, respectively. ]
Suitability requirements:  The chromatogram of Standard solution B is similar to the 254-nm Reference Chromatogram provided with the USP Boswellia serrata Extract RS.
Relative standard deviation:  NMT 2.0% of the 3-acetyl-11-keto--boswellic acid peak response for replicate injections, Standard solution A
Tailing factor:  NMT 1.5, 11-keto--boswellic acid peak, Standard solution A
Analysis 
Samples:  Standard solution A, Standard solution B, and Sample solution
Using the chromatogram of Standard solution B and the 254-nm Reference Chromatogram provided with the lot of USP Boswellia serrata Extract RS, identify the retention times of the peaks of 11-keto--boswellic acid and 3-acetyl-11-keto--boswellic acid in the Sample solution.
Separately calculate the percentages of the two analytes in the portion of Boswellia serrata taken:
Result = (rU/rS) × (CS/W) × 10F
rU== peak area of each analyte from the Sample solution
rS== peak area of 3-acetyl-11-keto--boswellic acid from Standard solution A
CS== concentration of USP 3-Acetyl-11-keto--Boswellic Acid RS in Standard solution A (mg/mL)
W== weight of Boswellia serrata taken to prepare the Sample solution (g)
F== conversion factor for each analyte (0.93 for 11-keto--boswellic acid and 1.0 for 3-acetyl-11-keto--boswellic acid)
Acceptance criteria:  Add the percentages calculated for 11-keto--boswellic acid and 3-acetyl-11-keto--boswellic acid: NLT 1.0% on the dried basis.
IMPURITIES
Inorganic Impurities 
•  Heavy Metals, Method II 231: NMT 20 ppm
SPECIFIC TESTS
•  Botanic Characteristics
Macroscopic:  It occurs as small ovoid tears, sometimes forming agglomerated masses up to 5 cm long and 2 cm thick; whitish to golden yellow; fracture is brittle, and fractured surface is waxy and translucent; characteristic aromatic odor; aromatic, slightly mucilaginous taste.
•  Loss on Drying 731: Dry 1.0 g of finely powdered Boswellia serrata at 105 for 2 h: it loses NMT 12.0% of its weight.
•  Articles of Botanical Origin, Total Ash 561: NMT 2.0%, determined on 2.0 g of finely powdered Boswellia serrata.
ADDITIONAL REQUIREMENTS
•  Packaging and Storage: Preserve in well-closed containers, protected from light and moisture, and store in a cool place.
•  Labeling: The label states the Latin binomial of the species of Boswellia from which the oleogum resin was obtained.
•  USP Reference Standards 11
USP 3-Acetyl-11-keto--Boswellic Acid RS Click to View Structure
USP Boswellia serrata Extract RS
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