Boswellic Acid Contents in Commercial Boswellia Dietary Supplements for Humans and Animals

Reviewed: Miscioscia E, Shmalberg J, Scott KC. Measurement of 3-acetyl-11-keto-beta-boswellic acid and 11-keto-beta-boswellic acid in Boswellia serrata supplements administered to dogs. BMC Vet Res. 2019;15:270.

Keywords: 3-O-acetyl-11-keto-β-boswellic acid, Boswellia serrata, boswellic acids, Indian frankincense, 11-keto-β-boswellic acid, HPLC-UV

Using a validated high-performance liquid chromatography method with ultraviolet detection (HPLC-UV) at 250 nm, 11-keto-β-boswellic acid (KBA) and 3-O-acetyl-11-keto-β-boswellic acid (AKBA) contents were determined in 13 dietary supplements from the US labeled to contain “boswellia” or “Boswellia serrata” in powdered form or as extracts. Seven supplements were marketed as animal supplements, predominantly for joint support in the canine market, while six supplements were for human use.

All the formulas contained one or both of the boswellic acids, although one formula contained only 0.7 mg/g of total boswellic acids. Animal dietary supplements contained an average of 5.2 mg/g (± 9.2 mg/g) and 10.3 mg/g (± 20.4 mg/g) KBA and AKBA, respectively. The dietary supplements for human consumption had a similar average content of KBA (5.1 ± 20.4 mg/g), but much higher AKBA contents (79.6 ± 68.2 mg/g). The reason for this is that several of the human dietary supplement contained 5-Loxin^® (Laila Nutra, Vijayawada, India), a formulation in which the native Indian frankincense extract is oxidized and acetylated to convert the major boswellic acids into AKBA.

Comment: This paper gives an insight into the composition of some of the Indian frankincense supplements on the US market. While the monograph of the United States Pharmacopeia¹ specifies that the contents in keto boswellic acids has to be at least 1%, the European Pharmacopoeia² requires 1% of both, KBA and AKBA. When using the latter specifications, only two out of the 13 dietary supplements were compliant. The lack of data on additional boswellic acids (i.e., α-boswellic acid, 3-O-acetyl-α-boswellic acid, β-boswellic acid, and 3-O-acetyl-β-boswellic acid) prevent an assessment if any of these products was adulterated, since absence of KBA may be explained by a different manufacturing process, as indicated above. Interestingly, the authors decided to publish the brand names together with the results, providing a rare insight into the composition of these brands.

The validation might have benefitted from a bit more thorough work. The calculation of the detection limit is difficult to follow, and despite the authors’ claim that “no interfering peaks were observed,” it is not clear how the absence of co-elution was ensured. Since there are a lot of compounds that absorb at 250 nm, the addition of a more specific detection method (e.g., the addition of mass spectrometric data) would have been helpful.

References

1. United States Pharmacopeial Convention. Boswellia serrata. In: United States Pharmacopeia 40 and National Formulary 35. Rockville, MD, USA: United States Pharmacopeial Convention, 2017.
2. Council of Europe. Indian Frankincense. In: European Pharmacopoeia (Ph. Eur.), 10th edition. Strasbourg, France: Council of Europe, 2019.