[Frankincense has been traded in the Middle East and North Africa for upwards of 5,000 years. It is believed that the Babylonians and Assyrians burned it during religious ceremonies. Frankincense was used in the Jewish temple as well as Christian churches. Multiple references to the incense exist in the Old Testament. Frankincense is known for its use in incense and ancient rituals. It has antiseptic and inflammatory properties and once considered effective remedy for everything from toothaches to leprosy. The International Union for Conservation of Nature (IUCN) publishes a Red List of Threatened Species, and lists B. sacra as “near threatened,” – Gideon]
Boswellia papyrifera grows fairly extensively in Ethiopia, Eritrea, Kenya, and Sudan. It is a deciduous species that is taller than B. frereana and B. sacra, reaching 12 meters, with a clear bole. The species grows on steep escarpments in locations where other species find it difficult to survive. It thus helps protect hillsides by providing much needed soil cover and could perhaps be used in soil stabilization.
The soft timber is suitable for plywood and matchwood and is used locally as small timber. The plant bears sweetly scented white to pink flowers and red capsular fruit. The bark is whitish to pale brown and flaking, similar to B. sacra and B. frereana. Like other Boswellia species that produce frankincense, the resin channels are located just below the inner bark. The tapping blaze is a square of 2.5 centimeters that is made only on the surface at a depth of 1 millimeter. The tree can be tapped 8–12 times during dry periods, and trees can yield resin for 50–60 years.
African Frankincense from Ethiopia is classified into five grades based on granule size, color, and purity. The first grade includes white granules that are 6 mm and larger in diameter and larger; the second includes 4–6 mm granules; the third includes 2–4 mm granules; the fourth includes brown and black granules of any size; and the fifth grade is powder mixed with bark.
B. papyrifera frankincense has a fruity and citrus aroma with a predominantly soft orange flavor. B. papyrifera comprises 90 percent of exported frankincense; B. neglecta and B. rivae comprise the rest. Most frankincense produced from the region is exported to China for use in traditional medicine. The distilled oil is exported to Europe for use in incense in Orthodox and Roman Catholic ceremonies, though sandalwood is a popular alternative.
B. papyrifera forms the bulk of the world supply of frankincense today, though overexploitation of the resin has led to its rapid depletion. Setting of seed and regeneration, which is already difficult given the preference of the species to inhabit steep escarpments, is further jeopardized by overgrazing and trampling by goats, sheep, and other fauna that hardens the forest floor. Additionally, inadequately trained harvesters damage the already threatened trees, indicating a lack of sound silvicultural practices for B. papyrifera.
Studies by Rijkers et al. (2006) have revealed that tapping for frankincense leads to reduction in seeding and regeneration of B. papyrifera. Reduced saplings and seedlings on the forest floor are an early sign of degradation and decline of a crop. Although Tadesse et al. (2007) estimate that 1.5 million hectares of B. papyrifera remains available, it has been estimated that more than 170,000 hectares of B. papyrifera have been destroyed by fire over the last 20 years. Forest fires, either caused by humans or weather, are one reason for this decline. Fires occur in dry months when tapping is in full swing. The resin is inflammable. Ground fires tend to rapidly escalate into crown fires, which are more destructive to the ecology and cause rapid depletion of the site.
In Eritrea, frankincense exports have dropped to just 25 percent of their levels in the 1970s. The situation has been aggravated by war, lack of governance, and poor forest and habitat management. Thus, TRAFFIC has put B. papyrifera in the endangered species category.
Medicinal uses of Boswellia papyrifera. A comparative phytochemical analysis of B. papyrifera, B. neglecta, and B. rivae has revealed that B. papyrifera contains diterpenes and nortriterpenes, and the other two are composed of triterpenes. Studies on rats exposed to B. papyrifera and B. carterii smoke indicate that prolonged exposure to frankincense smoke has a negative impact on the human reproductive system. B. papyrifera and B. carterii resins are effective against a range of pathogenic bacteria.
Sediqui et al. (2014) conducted a clinical trial on 80 multiple sclerosis patients in an Iranian hospital and found that the resin had a positive effect on the visual-cognitive faculties, although no impact on verbal cognition was noticed. Experiments on rats also indicate that the plant improved learning abilities of rats. These findings validate the traditional uses of frankincense for treating mental disorders.
The B. sacra (Omani luban) tree is native to Yemen, Oman, and Somalia. It yields the best and most prized frankincense gum. The tree rarely grows taller than 20 feet. It bears whitish yellow flowers. Phytochemical analysis of the essential oil from botanically certified oleogum resin of B. sacra show that E-β-cymene and limonene make up 97.3 percent of the oil, followed by sesquiterpene E caryophyllene at 2.7 percent (Al-Harrasi and Al-Saidi, 2008). This analysis further shows a complete absence of diterpenes.
The world’s finest B. sacra frankincense comes from the Dhofar region in Oman, which lies in the Nejd valley with steep slopes of the rich soil and dense limestone. The climate is dry, hot, and xerophytic. The local Beit Kathir and al Mahra tribes control the frankincense trade, and the best trees are restricted to a small geographic region. Thus, consumers have been forced to look for alternatives. Cheaper substitutes may smell like frankincense, but they do not yield the white smoke that is typical of the pure oleoresin.
B. sacra resin exudes from the stem when the bark is either naturally or artificially stripped. Tapping of the resin is done by blazing, or cutting, the tree at multiple points. The resin forms tears, which are left in situ (the place of exudation) to dry and then collected by gum collectors. The blazes must be refreshed twice annually in spring and fall to re-open the channel, similar to other resin–yielding trees. The best resin is clear white with a greenish tinge, and it is said to be reserved for the Sultan of Oman. Very little resin is exported.
The entire B. sacra frankincense production region is adversely impacted by increasing biotic pressure from increased cattle herds. A lack of forest management and protection has led to exploitation and deforestation of B. sacra trees. The International Union for Conservation of Nature has classified the species growing in Oman, Somalia, and Yemen as “near threatened” category and has declared that the trees in Oman are so heavily harvested that they no longer flower or produce seed. This has led to rapid depletion of tree stock.
Studies further indicate that the Oman stands suffer from endemism, which diminishes gene pool diversity and increases the threat of extinction. The absence of a scientific supply chain, inadequate habitat protection, and the geopolitical situation in Yemen and Somalia has further adversely impacted the habitat.
Medicinal Use of Boswellia Sacra. As previously stated, chewing frankincense gum is common in Arabian countries, especially Saudi Arabia. It is traditionally believed that gum chewing is good for oral hygiene. Studies conducted in five human females aged 25–35 found that chewing frankincense gum for five hours reduced bacterial activity.
The antibacterial, anti–inflammatory, and anticarcinogenic properties of the oleoresin have also been tested and validated in animal trials. Treatment with essential oil of frankincense enhanced cell death and decreased growth of human breast cancer and skin cancer cells, indicating possible pharmaceutical use.
Tests conducted on the fungi Aspergillus flavus and Aspergillus parasiticus reveal that the resin and oil of B. sacra reduces carcinogenic and other deleterious effects of the fungus, validating its traditional use as a food preservative. The essential oil, which is distilled from gum crystals, is used in aromatherapy and massage oils and sold under various trade formulations. It has a soothing effect on the nerves and takes four to six hours to evaporate, properties which make it a useful fixative in incense making.