α boswellic acid

Boswellia serrata Roxb. and Boswellia sacra Flueck gum resins were purchased from Bauer S.r.l. (Udine, Italy). The origin of B. sacra samples was from Ethiopia, whereas B. serrata samples originated from India. The gum resins were milled to coarse powder and used for all extractions. All chemicals were of analytical reagent-grade unless stated otherwise. Pure standards were purchased for the quantification by external calibration curves: 11-Keto-β-Boswellic acid, α-Boswellic acid and β-Boswellic acid (ExtraSynthese, Lyon, France), 3-O-Acetyl-11-Keto-β-Boswellic acid (Merck, Darmstadt, Germany), 3-O-Acetyl-α-Boswellic acid, 3-O-Acetyl-β-Boswellic acid (Sigma-Aldrich, St. Louis, MO. USA).

All solvents and chemicals were of analytical reagent grade. The solvents used for the extraction and for HPLC-MS/MS analysis were methanol, acetic acid (both HiPerSolv Chromanorm, VWR chemicals, Fontenay-sous-Bois, France), and ultrapure water (reverse-osmosis type water (pureAqua, Schnaitsee, Germany) coupled to a Milli-Q station (Millipore, Eschborn, Germany)). The reference substances, acetyl-α-boswellic acid (α-ABA), acetyl-β-boswellic acid (β-ABA), α-boswellic acid (α-BA), β-boswellic acid (β-BA), acetyl-11-keto-β-boswellic acid (AKBA), 11-keto-β-boswellic acid (KBA), and maslinic acid (MA) were purchased from Extrasynthese (Genay Cedex, France). Acetyl-lupeolic acid (ALA) and lupeolic acid (LA) were isolated and characterized as previously published [7 (link),8 (link),10 (link)].