Incensole acetate

Another striking difference relates to the diterpenes (Figure 16.3) B. carterii reveals strong peaks that have been assigned to verticilla-4 (20),7,ll-triene (compound 1), incensole acetate (compound 2), and incensole (compound 3) and, on the other hand, Boswellia serrata shows peaks of m- and / -camphorene (compoimd 4 and compound 5) as well of cembrenol (= serratol) (compound 6). 

The brownish colored zone (Rj 0.28) of incensole (compound 3), which occurs in both the resin and the volatile fractions of B. carterii, draws the hue between the volatile diterpenes and the nonvolatile triterpenes. B. carterii reveals two further colored prominent spots, a yellowish-ochre (Rf 0.65) of incensole acetate (compound 2) and a violet-colored spot (Rj 0.98) of verticilla-4(20),7,ll-triene (compound 1). Lane 2 and lane 3 reveal a light blue area (Rj 0.60) of 1,8-cineol that is only visible in freshly distilled oils. 

FIGURE 16.6 Purification steps of fraction 2 and 3 from B. carterii. (A) GC and TLC data of fractions 2 and 3. (B) GC data of incensole acetate after separation and purification of the zone Rf 0.50. (C) Mass spectrum of incensole acetate (compound 2). 

FIGURE 16.9 An overview of the marker substances of (A) B. carterii and (B) B. serrata. (A) Lane 1 incensole (compound 3), lane 2 and 3 hexane extract of B. carterii, lane 4 incensole acetate (compound 2), lane 5 verticilla-4(20),7,ll-triene (compound 1). (B) Lane 1 m-camphorene (compound 4) and p-camphorene (compound 5), lane 2 cembrenol (compound 6), lane 3 Hexane extract of B. serrata. 

The isolation of the second violet zone (Rf 0.55) succeeded more easily with B. serrata resins because there was no interference with incensol acetate. 

The GC-MS chromatogram, obtained after SPME of the traditional incense from a monastery of Mount Athos, is presented in Figure 10.7a. The occurrence of octanol (18), octyl acetate (40), incensole (127), incensole acetate (129), incensole oxide (130) and incensole oxide acetate (131), allowed the identification of a B. papyrifera olibanum (Figure 10.7b) in a mixture with other substances, most probably Damask rose and jasmine. 

Frankincense, also called olibanum, is a natural oleo gum resin that exudes from incisions in the bark of Boswellia trees [46, 47]. Diterpenes like incensole or isoincensole and their oxide or acetate derivatives (see Figure 10.3) are characteristic biomarkers of olibanum [48]. Although diterpenoid hydrocarbons possessing the cembrane skeleton have been isolated from a variety of terrestrial and marine organisms, their occurrence and particularly that of cembrenes A and C (see Figure 10.3) is supplementary proof of the presence of olibanum in a sample. Optimisation of the SPME conditions was done with the aim of trapping these low volatile diterpenes. 

The samples coming from Eritrea, Jerusalem and Liban could be undoubtedly attributed to B. papyrifera, because of their characteristic constituents octanol (18), octyl acetate (40), linear caboxylic acids (10, 20, 36, 49, 63), incensole (127) and its acetate and oxide derivatives (129-131). 

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