Olibanum

The following materials may be ground at ordinary temperatures if only the regular commerci fineness is required amber, arabac, tragacanth, rosin, olibanum, gum benzoin, myrrh, guaiacum, and montau wax. If a finer product is required, hammer mills or attrition mills in closed circuit, with screens or air classifiers, are used. 

The final chapter (Chapter 16) shows how PLC can be used to isolate and identify unknown terpenoic compounds from the frankincense resin (olibanum) and to find marker diterpenes. The novel development at low temperamres is included in the PLC methods described. 

The Use of PLC for Isolation and Identification of Unknown Compounds from the Frankincense Resin (Olibanum) Strategies for Finding Marker Substances... 

Olibanum (frankincense) is one of a group known as the oleogum resins (mono-, sesqui-, di-, and triterpenes and mucous substances) that exude from incisions in the bark of the Boswellia trees (fam Burseraceae), the most common species of which are B. carterii (Sudan, Somalia, and Ethiopia) and B. serrata (India), whereas B. frereana (Oman, Somalia) and B. sacra (Arabia) belong to the rare resins on the market. 

For pharmaceutical purposes, oue of the maiu problems will be to defiue the botanical origin of the different olibanum resins. Up to now, there are no scientifically current pharmaceutical monographs on olibanum, and pharmaceutical companies that want to develop new medicinal products have an urgent need of analytical methods for the botanical identihcation and quality assurance of the resins. Attempts had been made by Hahn-Deinstrop et al. [2]. 

To identify the volatile components, gas chromatography-mass spectrometry (GC-MS) is still the method of choice. A comparison of the GC fingerprints of B. carter a and B. serrata reveals the different composition of the volatile fractions (Figure 16.1). Common monoterpenes, aliphatic, and aromatic compounds of olibanum are, e g., pinene, limonene, 1,8-cineole, bomyl acetate, and methyleugenol (Figure 16.2). 

A perceptible marker of the olibanum fragrances coming from Somalia, Sudan, or Ethiopia is the aliphatic octyl acetate marked by a distinct acrid smell. Boswellia carterii contains up to 50% of the aliphatic octyl acetate, demonstrated by the strong stinging smell of the fume, whereas Boswellia serrata (its common name in India is salai guggul) contains none or only small amounts of it and, consequentiy, does not have such a harsh smell. 

Figure 16.4 displays the separation of the resins of B. carterii and B. serrata, their hydrodistillates, and three commercially available olibanum essential oils on a Merck LiChrospher plate in the mobile phase heptane-diethylether-formic acid (7 + 3 + 0.3 v/v/v) without chamber saturation after derivatization with anisaldehyde reagent. 

FIGURE 16.2 Common monoterpenic, aromatic, and aliphatic constituents of olibanum resins. 

The solutions of the olibanum resins reveal an unpleasant property of stickiness. This must be considered with all steps of analyzing and isolation. That is why a preceding column chromatography (CC) is recommended, to enrich the diterpenes of interest. The further purifieation of the supposed marker substances was carried out by PLC. 

The investigation of the pyrolysates of the olibanum resins was initiated by an article in a newspaper. The anthor of this article seemed to be apprehensive about the pharmacological and toxicological effects of the fume of the resins, which are used in religious ceremonies, on the health of people. The resins used in churches named as Pontifical or Olibanum Konig mainly consist of B. carterii, whereas those of inferior quality contain B. serrata resins. For this reason, the fumes of both resins were investigated by Basar [4]. 

FIGURE 16.12 Structures of triterpenic pyrolysis products of olibanum resins. 

Common pharmaceutical products of olibanum and salai guggul are tablets prepared from dried extracts of boswellic adds, which are obtained by processes involving treatment of the resins with alkali and acid. The stress involved in this treatment is expected to lead to alteration of some triterpenes as, e.g., the conversion of the unstable 3-(9-acetyl-ll-hydroxy-[3-boswellic acid (compound 12) to the stable compound 3-(9-acetyl-9,ll-dehydro-[3-boswellic acid (compound 13). Two-dimensional TLC is an excellent means of observing this conversion [5]. For verification of this process, the substances have to be isolated by PLC and identified by GC-MS. 

Heifer, W., Die Tranen der Gotter, Jemen, Oman, V.A. Emirate, Merian, 59, 1996. Hahn-Deinstrop, E., Koch, A., and Muller, M., Guidelines for the assessment of the traditional herbal medicine Olibanum by application of HPTLC and DESAGA ProViDoc video documentation J. Planar Chromatogr., 11, 404, 1998. 

Basar, S. and Koch, A., Test of the stability of Olibanum resins and extracts, J. Planar Chromatogr, 17, 479, 2004. 

Burseraceae Commiphora (myrrh) Boswellia (olibanum or frankincense) Canarium (elemi) a and (3 amyrin, euphanes, oleananes... 

Frankincense, also known as olibanum, is obtained from trees belonging to the genus Boswellia (Burseraceae family). It is one of the best-known ancient plant resins. The ancient Egyptians were the first to use it as incense in embalming practices and in the preparation of medicines, cosmetics and perfumes, and today it is still used therapeutically. It contains pentacyclic triterpenoids belonging to oleanane, ursane or lupane type molecules and in particular of a- and p-boswellic acids, and their O-acetates [104 111], 11 -Oxo-p-boswellic acid and its acetyl derivative, identified in several Boswellia species, are also diagnostic for frankincense [112]. 

S. Hamm, J. Bleton, J. Connan, A. Tchapla, A chemical investigation by headspace SPME and GC MS of volatile and semi volatile terpenes in various olibanum samples, Phytochemistry, 66, 1499 1514(2005). 

The first results encouraged the authors to analyse, by headspace SPME, substances mentioned in ancient texts or hieroglyphics as components of embalming fluids [true resins such as mastic, labdanum and pine resin or pine pitch and gum resins such as olibanum, myrrh and galbanum] [27, 28] with the aim of finding characteristic chemical compounds for each type of resin or gum resin. 

For olibanum, six characteristic diterpenes were observed cembrene A (94), cembrene C (98), isoincensole acetate (104), a dimer of a-phellandrene (86) and two unidentified compounds (92) and (103). 

Peak no. Compound Rla Olibanum Myrrh Galba num Labda num Mastic Resin of Pinus pinea Pine pitch Pitch from Fayoum Sample 1485 Sample 1627 Sample 1625... 

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. 

SPME/GC MS in the Characterisation of Terpenic Resins 275 10.3.3 Application to Research on Olibanum [26]... 

As a first step, the authors built a database of the volatile terpenes for six olibanum samples with certified botanical origin and derived characteristic signatures associated with the botanical origin. In the second step they used these signatures to define the species of samples of different origin (commercial societies or markets from various countries of the Middle East) and to recognise the markers of olibanum in a mixture with other plants substances. 

The main compounds detected by headspace SPME in six olibanum samples are given in Table 10.3. Qualitative results obtained by headspace SPME were identical to those obtained by classical extraction with dichloromethane, except for the tri terpenes. 

The first observation is the similarity between the chemical compositions of both the Boswellia carteri and Boswellia sacra. For these three olibanum samples, a-pinene (2), (3-myrcene (8) and limonene (14) are the predominant monoterpenes. p-Caryophyllene (73) is the major sesquiterpene besides a-copaene (65), a-humulene (also called a-caryophyllene) (78) and caryophyllene oxide (95). The characteristic olibanum compounds isoincensole and isoincensole acetate (128) together with cembrene A (120) are the main diterpenes. 

Boswellia serrata olibanum has a chemical composition close to that of both the B. carteri and of B. sacra, but contains compounds that are absent in those from other Boswellia and could be used as markers methylchavicol (38), p-anisaldehyde (47), methyleugenol (70), isocaryophyllene (82), sesquiterpene 91, elemicin (92) and an unidentified diterpene (124) eluting between cembrene C (123) and verticilla-4(20),7,ll-triene (125). It is devoid of (5-caryophyllene (73), a-humulene (78), caryophyllene oxide (95) and bornyl acetate (50). 

B. frereana and B. papyrifera olibanum have very different terpenic composition from the others. B. frereana olibanum contains the same monoterpenes as olibanum from B. carteri, B. sacra or B. serrata, but is very poor in sesquiterpenes and contains none of the diterpenic biomarkers cited before. Two unidentified compounds (55 and 56) seem to be specific and the main diterpenes, present in high level, are four dimers of a-phellandrene. Dimer 3 (113) is the major component. On account of its absence in the other olibanum samples, it can be considered as characteristic of B. frereana olibanum. 

The chemical composition of B. papyrifera olibanum is markedly different from that of other Boswellia, with small amounts of monoterpenes and sesquiterpenes, large amounts of w-octanol (18) and -octy I acetate (40), with the latter being the major compound, and the presence of particular diterpenes [incensole (127), incen-sole acetate (129), incensole oxide (130) and incensole oxide acetate (131)] and the absence of both isoincensole and isoincensole acetate (128). Linear carboxylic acids from hexanoic acid (10) to lauric acid (93) were also identified in B. papyrifera olibanum exclusively. 

Table 10.3 Main components detected by headspace SPME/GC MS in the six reference olibanum samples with certified botanical origin and in three olibanum samples without botanical origin... 

Eight olibanum samples of unknown botanical origin have been analysed [26]. The chemical compositions are summarized in Table 10.3 for three of them. Both the olibanum coming from Somalia and that from a market in Ta izz (Yemen) have been attributed to Boswellia carteri or sacra on the basis of the occurrence of the characteristic diterpenes isoincensole and isoincensole acetate (128) together with diterpene 126. The absence of methylchavicol (38), oxygenated sesquiterpene 91 and diterpene 124 and the presence in relatively large amount of (3-caryophyllene (73), ot-humulene (78) and caryophyllene oxide (95) excluded the hypothesis of a B. serrata sample. 

Samples purchased on markets in Sa da and San a in Yemen comprise no diterpenes from the incensole family but large amounts of dimers of ot-phellan-drene, in particular dimer 3 (113), and of both compounds 55 and 56. This pattern identifies them as B. frereana olibanum. 

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