Evaluation of the Authenticity and Quality of Top-Selling Boswellia Products by HPLC-Triple Quadrupole Mass Spectrometry

Reviewed: Meins J, Artaria C, Riva A, Morazzoni P, Schubert-Zsilavecz M, Abdel-Tawab M. Survey on the quality of the top-selling European and American botanical dietary supplements containing boswellic acids. Planta Med. 2016;82(6):573-579. doi: 10.1055/s-0042-103497.

Keywords: Boswellia serrata, Boswellia sacra, Boswellia carteri, Boswellia frereana, adulteration, boswellic acids, HPLC-MS

Frankincense is the name of the aromatic resin obtained from a number of trees in the Boswellia genus (Burseraceae), including B. carteri, B. frereana, B. papyrifera, B. sacra, and B. serrata. The American Herbal Products Association’s Herbs of Commerce, 2nd edition, lists frankincense as the common name for B. sacra, while Indian frankincense is used for B. serrata. Boswellia serrata is the only Boswellia species listed as official in the Ayurvedic Pharmacopoeia of India, the European Pharmacopoeia, and the United States Pharmacopeia.

Extracts of the resin of Indian frankincense are popular as dietary supplements due to anti-inflammatory properties, which have been ascribed to triterpenoid acids known as boswellic acids (BAs). In order to evaluate the quality of products, the six top-selling (based on data from the market research company SPINS; Chicago, Illinois) Boswellia dietary supplements in the United States and the 11 most popular products from Europe were analyzed by high-performance liquid chromatography using triple quadrupole mass spectrometric detection (HPLC-QQQ-MS). The most abundant BAs (alpha-boswellic acid [α-BA], acetyl-alpha-boswellic acid [AαBA], acetyl-beta-boswellic acid [AβBA], acetyl-11-keto-boswellic acid [AkBA], beta-boswellic acid [β-BA], and 11-keto-boswellic acid [kBA]) were quantitatively measured. In addition, the compositions of these products were compared to data from authentic B. serrata, B. carteri, B. sacra, and B. frereana reported by Frank and Unger.¹ According to that paper,¹ B. frereana does not contain BAs, and B. sacra and B. carteri can be distinguished from B. serrata by the ratio of non-acetylated BAs (α-BA, β-BA) to acetylated BAs (AαBA, AβBA). This ratio is greater than 1 in B. serrata, but below 1 in B. carteri and B. sacra (these latter two species can be regarded as the same from a chemotaxonomic and botanical point of view; however, their growing range is different, with B. carteri growing in Somalia and B. sacra in Yemen and Oman).

Based on the label, all products with one exception (a product from the USA, labeled to contain Boswellia extract, but the exact species was not indicated) claimed to be made from B. serrata. Two products (one from Italy and one from the USA) contained little to no BAs, suggesting the use of a Boswellia species lacking BAs, e.g., B. frereana, or material from an altogether different genus. Another Italian product had a ratio of non-acetylated to acetylated BAs below 1, suggesting the presence of B. carteri or B. sacra. Two products (one from Spain, one from Italy) were enriched in AkBA, containing up to 66% of this particular BA. Extracts with such high amounts of AkBA do not occur in nature and are usually made by oxidation and subsequent acetylation of the major BAs.²

Comment: The authentication of B. serrata extracts is challenging due to the fact that B. carteri and B. sacra contain the same major BAs, and that manufacturing steps, in addition to solvent extraction of the Boswellia tree resin, have produced Boswellia-derived ingredients that do not represent the naturally occurring BA pattern. Many methods available to authenticate B. serrata are based on high-performance thin-layer chromatography (HPTLC), and have been developed to distinguish Indian frankincense from other potential adulterating species such as guggul (Commiphora wightii syn. C. mukul, Burseraceae), myrrh (Commiphora molmol, C. myrrha, and other Commiphora spp.), or benzoin tree (Styrax benzoin, S. paralleloneurus, or S. tonkinensis, Styracaceae).

An HPTLC method to distinguish B. serrata from other Boswellia spp. was published in 2012.³ This newly published validated HPLC-QqQ-MS method provides a more sophisticated tool to characterize Boswellia extracts. The use of the (α-BA+β-BA)/(AαBA+AβBA) ratio to distinguish B. serrata from B. sacra/B. carteri in the paper by Frank and Unger¹ is based on a small number of non-authenticated materials, but has been confirmed with a larger sample size in the work by Paul.⁴

References

1. Frank A, Unger M. Analysis of frankincense from various Boswellia species with inhibitory activity on human drug metabolising cytochrome P450 enzymes using liquid chromatography mass spectrometry after automated on-line extraction. J Chromatogr A. 2006;1112(1-2):255-262.
2. Gokaraju G, Gokaraju R, Gottumukkala V, Golakoti T, Pratha S. Process for producing a fraction enriched up to 100% of 3-O-acetyl-11-keto-beta boswellic acid from an extract containing a mixture of boswellic acids. US Patent No. 20040073060. April 15, 2004.
3. Paul M, Brüning G, Bergmann J, Jauch J. A thin-layer chromatography method for the identification of three different olibanum resins (Boswellia serrata, Boswellia papyrifera and Boswellia carterii [sic], respectively, Boswellia sacra). Phytochem Anal. 2012;23(2):184-189.
4. Paul M. Chemotaxonomic investigations on resins of the frankincense species Boswellia papyrifera, Boswellia serrata and Boswellia sacra, respectively, Boswellia carterii [sic]. PhD thesis. Saarbrücken, Saarland, Germany: Saarland University; 2012. Available at: http://scidok.sulb.uni-saarland.de/volltexte/2012/4999/pdf/Dissertation_Fertig_211112.pdf. Accessed September 19, 2016.