Chemistry and Bioactivity of Boswellic Acids and Other Terpenoids of the Genus Boswellia

Ahmed Al-Harrasi, Hidayat Hussain, René Csuk, Husain Yar Khan

• Éditeur: Elsevier
• Année: 2018
• ISBN:
  9780081024485
• Sujet: Naturwissenschaften
• Sous-sujet: Organische Chemie

Exhibiting a wealth of interesting activities and novel structures, Boswellic acid and the other terpenoids of the genus Boswellia (from which frankincense is derived) are a growing source of interest for the natural product drug discovery community. Chemistry and Bioactivity of Boswellic Acids and Other Terpenoids of the Genus Boswellia presents, in a single volume for the first time, key research into their structures, synthesis and potential as starting points for the development of medicinal agents.

Drawing on the authors' expert knowledge, this volume is an interesting insight into the identification of novel compounds from endemic plant sources, and is a useful tool for all researchers involved in the discovery and development of bioactive structures from natural products.

• Collates key information on the underlying chemistry and activities of bioactive agents from the Boswellia species
• Highlights techniques applicable to the study of natural products across the globe
• Provides insights into the assessment of medicinal natural products with high economic potential

Chapter 1

Taxonomy of Boswellia Tree, Traditional Medicinal Uses of Frankincense and Historical Aspects of Boswellic Acids

Ahmed Al-Harrasi¹, Hidayat Hussain¹, Rene Csuk² and Husain Y. Khan¹, ¹UoN Chair of Oman’s Medicinal Plants and Marine Natural Products, University of Nizwa, Birkat Al Mauz, Nizwa, Oman, ²Martin-Luther Universität Halle-Wittenberg, Organische Chemie, Halle, Germany

Abstract

The genus Boswellia belongs to the Burseraceae family, with approximately 700 species originating from 18 genera. The genus Boswellia, with 21 species, has its principal center of endemism in eastern Africa (Sudan, Eritrea, Ethiopia, Somalia, and Kenya), southern Arabia (Oman and Yemen), and India. Boswellic acid contents vary remarkably from one species to another. They are reported in significantly large amounts in Boswellia sacra, Boswellia serrata, Boswellia carterii, and Boswellia papyrifera. Parts of the Boswellia tree, in particular the resins, have been used in the traditional medicines of Arabia, India, Africa, and China for millennia. Interestingly, most of these traditional uses are strongly supported by recent findings. The known antiinflammatory activity of frankincense is likely due to Boswellic acids, as supported by several recent reports. Boswellic acids have received remarkable attention due to their potential therapeutic power. Since 1892, when Alexander Tschirch and Oscar Halbey performed the first extraction of the frankincense resin to separate it into neutral and basic fractions, this interest has continued to date.

Keywords

Burseraceae; Boswellia; frankincense; Boswellic acids; Luban; taxonomy

Contents

• 1.1 Taxonomy of Boswellia Tree 2
• 1.2 Traditional Medicinal Uses 3
• 1.3 Historical Aspects of Boswellic Acids 5
• References 6

1.1 Taxonomy of Boswellia Tree

The genus Boswellia belongs to the Burseraceae family holding both trees and shrubs of tropical and sub-tropical geographical distribution, with approximately 700 species originating from 18 genera.^1,2 The genus Boswellia was named in an honor of Johann Boswell (1719–80) who has described 25 species of Boswellia; some of them, however, appear now as synonyms of the 21 known species. The genus Boswellia has its principal center of endemism in Africa (Sudan, Eritrea, Ethiopia, Somalia, and Kenya), southern Arabia (Oman and Yemen), and India.

There are 21 species known in genus Boswellia (Table 1.1). These include Boswellia sacra (Oman, Yemen), Boswellia serrata/Boswellia thurifera (India), Boswellia ovalifoliolata (India), Boswellia pirottae (Ethiopia), Boswellia carterii (Somalia), Boswellia frereana (Somalia), Boswellia globosa (Somalia), Boswellia ogadensis (Ethiopia), Boswellia neglecta/Boswellia elegans/Boswellia hildebrandtii/Boswellia microphylla/Boswellia campestris/Boswellia holstii/Boswellia multifoliolata (Ethiopia, Somalia, Kenya), Boswellia rivae/Boswellia boranensis/Boswellia ruspoliana (Ethiopia, Somalia. Kenya), Boswellia papyrifera/Boswellia chariensis/Boswellia occidentalis (Ethiopia, Eritrea, Sudan), Boswellia odorata (Niger, northern Nigeria, and eastern Cameroun), Boswellia dalzielii (northern Nigeria), Boswellia madagascariensis (Madagascar), Boswellia popoviana, Boswellia nana, Boswellia bullata, Boswellia dioscorides, Boswellia ameero, Boswellia elongate, Boswellia socotrana (Socotra, Yemen).

Table 1.1

Boswellia species and their worldwide distribution

SN	Boswellia species	Geographical location
1	B. sacra	Oman, Yemen
2	B. serrata/B. thurifera/Boswellia glabra	India
3	B. ovalifoliolata	India
4	B. pirottae	Ethiopia
5	B. carterii	Somalia
6	B. frereana	Somalia
7	B. globosa	Somalia
8	B. ogadensis	Ethiopia
9	B. neglecta/B. elegans/B. hildebrandtii/B. microphylla/B. campestris/B. holstii/B. multifoliolata	Ethiopia, Somalia, Kenya
10	B. rivae/B. boranensis/B. ruspoliana	Ethiopia, Somalia. Kenya
11	B. papyrifera/B. chariensis/B. occidentalis	Ethiopia, Eritrea, Sudan
12	B. odorata	Niger, northern Nigeria, and eastern Cameroun
13	B. dalzielii	Northern Nigeria
14	B. madagascariensis	Madagascar
15	B. popoviana	Socotra
16	B. nana	Socotra
17	B. bullata	Socotra
18	B. dioscorides	Socotra
19	B. ameero	Socotra
20	Boswellia elongata	Socotra
21	B. socotrana	Socotra

Boswellic acid contents vary remarkably from one species to another. Accordingly, it is mandatory to highlight different Boswellia species and their geographical locations. Table 1.1 shows various species and their worldwide distribution. Synonyms for the same species are shown next to the original name to avoid confusion.

Boswellic acids are reported in significantly large amounts in B. sacra, B. serrata, B. carterii, and B. papyrifera.³

Boswellia trees possess an outer bark, often peeling in parchment like flakes, a green inner bark with a milky resin and wood with milky latex. The leaves of these species are generally congested at the end of the branches. Their flowers are bisexual, in panicles or racemes. They exist in rocky slopes and gullies, mostly on limestone boulders up to approximately 1000 m from sea level.⁴

1.2 Traditional Medicinal Uses

Parts of the Boswellia tree, in particular the resins, have been used in the traditional medicines of Arabia, India, Africa, and China for millennia.

The first reference of the use of frankincense for treatment goes back to the Ebers Papyrus, an Egyptian medical papyrus, dated to c. 1500 BC, and describing many herbal medicines.⁵ An ancient Egyptian myth described frankincense as the “tea...