*3.3.1* C. spinarum *in human ethnomedicine: plant parts used*

A summary of *C. spinarum* plant part used in medicinal preparations for human use across all regions is seen in **Figure 7**. It illustrates that, for *C. spinarum*, the primary plant part used is the root followed by leaf, fruit, rootbark, stem and bark while 9% of reports do not state what plant part is used (N/S).

The data was analysed across 5 key geographical regions: Eastern Africa, Western Africa, Southern Africa, South Asia and Australia. The summary of key plant parts used is illustrated in **Figure 8** and shows that, at regional level, the root is still the most commonly used plant part. However, in Eastern Africa, the predominance is more marked where the root and rootbark together account for three quarters of all URs. Fruit and leaf use are minimal by comparison. In Western Africa, the root and rootbark together account for most usage with leaf, fruit and stem used infrequently. In Southern Africa the root accounts for over half of usage with stem and other parts lower. In South Asia,

Carissa spinarum *L.: A Case Study in Ethnobotany and Bioprospecting Research DOI: http://dx.doi.org/10.5772/intechopen.104665*

#### **Figure 8.**

C. spinarum *and variation in plant part usage across global regions (UR > 3, 85% of all URs; N/S = not stated; chart areas approximately reflect relative nos. of URs).*

root use is less dominant and followed by leaf and fruit. In Australia, the different plant parts are more evenly divided between root, stem and leaf. In most areas a proportion do not state what plant part is used, particularly so in Southern Africa.

More broadly in EM research, there are a number of reasons hypothesised for differences in the choice of plant and plant part such as availability and related cultural norms, the presence of bioactive metabolites, organoleptic qualities, appearance, time of year and location of a species.

A study of the most commonly used plant parts in East Africa stated that with trees and shrubs, the bark and root are more commonly used [91]. A study in a semi-arid region of Kenya found that most medicinal plants are trees and shrubs, and their bark and roots are the most commonly used parts [89]. Research in the Caatinga (semi-arid) region in North-eastern Brazil found that the species and plant parts that are available throughout the year are the most important medicinal species. Stembark was the most commonly used plant part [92]. The authors reported that herbaceous plants and leaves, which are only available for a few months of the year, are less commonly used in the same study. The authors examined tannin concentration in two medicinal species, assuming tannins to be responsible for much of the medicinal activity though they acknowledge that this may not be wholly correct. They found that both leaf and stem-bark contained significant quantities of tannins although the stem-bark is the part used medicinally. They postulated that the community develops a stronger relationship with the perennial woody plant parts regardless of the fact that the leaf may be as effective as the stem.

Organoleptic qualities of taste, smell, colour and texture are reported to be important to decision making around medicinal plants as described by Etkin [36] and are linked to explanatory models of illness. A study in Peru illustrated how sensation is at the centre of medicinal plant selection connecting culture and the environment [93]. A study in Brazil found that taste and smell are associated with therapeutic indications [94]. Studies in Mexico indicated a similar connection between taste, smell and therapeutic indication where, for instance, bitter and aromatic plants are valued in the treatment of gastrointestinal disorders [95]. Bitterness is a characteristic of aphrodisiac tonics in West Africa and the Caribbean [96]. Among the Pokot people in Kenya, bitter medicines were considered to be more effective at treating all illness [80]. Sensory attributes of plants were, likewise, seen, as an important indicator of healing power among the Suiei Dorobo of Northern Kenya [85]. The "doctrine of signatures" may be a contributor to the choice of plant or plant part such that, for instance, a root with a red extract may be considered to be useful in blood disorders [36, 97].

The choice of plant part in EM may be directly related to the presence of bioactive ingredients in different plant parts, an assumption often made in ethnodirected bioprospecting studies [98]. Secondary metabolites may benefit plants through action as pollinator attractants, as simple feeding repellents or as toxicants to prevent herbivory [99]. Voeks [99] states that this phenomenon, referencing a study on the presence of alkaloids, is more pronounced in low-latitude countries and is more likely in herbs and shrubs. Further studies in the Caatinga of Brazil reported that, in such semi-arid areas, plants invest more heavily in secondary metabolites based on phenolic compounds (such as tannins) providing quantitative defences against herbivory [98]. In comparison, in humid forest regions, plants are more likely to produce qualitative defences in the form of highly bioactive compounds such as alkaloids. Another consideration is that phenotypic plasticity is known to occur within a species across different habitats in response to different environmental stressors [98]. Plant defences are determined by the availability of resources such as light, water and nutrients in an ecosystem. The lack of resources such as water and nutrients in semi-arid habitats may result in a "metabolic specialisation" in quantitative defences such as phenolics [98]. The authors add that woody species growing in semi-arid areas could have lower concentrations of bioactive ingredients in the leaf than in perennial plant parts due to the short growth-period of the leaf, thus favouring the perennial parts as medicinal ingredients.

#### Carissa spinarum *L.: A Case Study in Ethnobotany and Bioprospecting Research DOI: http://dx.doi.org/10.5772/intechopen.104665*

How do these general hypotheses and findings in relation to the choice of plant parts in EM relate to *C. spinarum*? While *C. spinarum* has a wide ecological tolerance, it can be seen from the map of ethnobotanical usage in **Figure 4** that many of the areas in which *C. spinarum* is used are semi-arid. This lends credence to the use of the perennial parts of this shrub, as these are available throughout the year. Organoleptic qualities may be a factor with choice of *C. spinarum* root. It is somewhat bitter in taste which, as described above, may lead to its being considered medicinal [89, 100, 101]. The root has an oily, volatile sap with a pleasant smell which lends itself to use as a rub for chest and muscle conditions and as an inhalant. *C. spinarum* is a member of the Apocynaceae family, a family which is known to produce toxic and medicinal metabolites such as the Vinca alkaloids. The choice of plant part may be related to the avoidance of toxic components in other plant parts. A review of the ethnobotany of Apocynaceae species in Kenya (25 in all), found that the root is the most commonly used plant part for medicinal use (63%) [102]. In contrast, a review of some medicinally important Apocynaceae species found that there is no particular preponderance of root use [103]. Rather, EM use in different species was found to be generally distributed across plant parts. This correlates with the finding in India and Pakistan where the plant part usage of *C. spinarum* is much more evenly distributed across plant parts than in Eastern Africa. This difference could point to factors such as availability of plant material, cultural norms around medicinal preparations or ecological differences across its range leading to different secondary metabolite patterns.

### *3.3.2* C. spinarum *in human ethnomedicine: methods of preparation*

The predominant methods of preparation of *C. spinarum* globally are summarised in **Figure 9**. In the data as a whole, where a method is given, it may be simply written as a single word such as decoction, infusion, paste, juice or raw. There is relatively little detailed description of the preparation of *C. spinarum* in the studies analysed. In the reviewed studies, over one third do not to include a method of preparation. The preparation of medicinal products by decoction i.e., boiling of the plant part in water for a length of time, is by far the most common method reported followed by use of the untreated plant, burning for smoke, cold water mixture, infusion, powder, juice, decoction with soup and mixing with alcohol (4 citations).

#### **Figure 9.**

*Methods of preparation of human EM containing* C. spinarum *(UR > 4) ("Decoction, powder" where unclear which method used per ailment).*

#### **Figure 10.**

*Regional variation in method of preparation of* C. spinarum *expressed as % URs per region (UR > 2). Methods with low occurrence are excluded.*

Methods of preparation vary across the geographical range represented in **Figure 10**. A significant proportion in each geographical area, except Australia, does not state the method of preparation. In South Asia, Eastern Africa and West Africa, decoction is the most common method used. In Southern Africa, infusion is the most popular method of preparation. In Australian studies the most common method is burning followed by decoction and untreated. Burning as a method of preparation globally is relatively high. When we examine the data in relation to burning, it is apparent that this is greatest in Australia and in Ethiopia with the emic context described above in Section 3.2. In Australia, burning is used in the main as a treatment to protect children by "smoking" while in Ethiopia, the primary illness category where burning is used is *Buda* (Evil Eye) (see Sections 3.2.1 and 3.2.2).

#### *3.3.3* C. spinarum *in human ethnomedicine: methods of preparation x key plant parts*

It is useful to take a closer view of the methods of preparation that are used for each plant part. The chart in **Figure 11** presents an overview of the most common methods of preparation for each plant part. The chart shows that the fruit is most often used raw; the bark is most often prepared by infusion; the leaf, root and rootbark are each most commonly prepared by decoction and the stem by burning.

Where fruit is treated, the minimal treatment is illustrated as follows:

*Fruits are crushed, dried, pounded into powder and sprayed on wound ([104] p. 6 Ethiopia).*

Carissa spinarum *L.: A Case Study in Ethnobotany and Bioprospecting Research DOI: http://dx.doi.org/10.5772/intechopen.104665*

#### **Figure 11.**

*Salient methods of preparation for each plant part (top 3, excludes combinations; 54% of total URs) (BK = Bark; ST = Stem; RTB = Rootbark).*

#### and of leaf:

*Leaves are crushed, squeezed and liquid taken (orally) with coffee (to treat febrile illness) ([104] p. 6 Ethiopia).*

#### Simple decoctions are prepared as follows:

*Among the Mitakoodi, it [root] is scraped and soaked in water and then boiled. The resultant liquid is drunk as a tea to treat aches and pains and used as an eyewash ([64], p. 14, Australia).*

*Leaves are boiled in water and liquor is used to treat jaundice* [105] Pakistan. Some additional ingredients may be added as part of the treatment prescribed:

*Rootbark is crushed and mixed with black pepper and given (for typhoid fever). [106] India. Fresh root of C. spinarum pounded mixed with cold water. One cup of tella [beer] is used as a drink for three days [to treat gonorrhoea] [49] Ethiopia*

The method of preparation of medicinal plants can have a significant influence on the extraction of active constituents. This can be seen in Chinese Herbal Medicine (CHM) whereby a variety of processing methods may be used to improve efficacy

and/or to reduce toxic effects [107]. In a study on the preparation of CHM, a variety of extraction methods is described whereby special preparation instructions relate to different physical, chemical and pharmacological activities of active compounds [108]. The authors describe the preparation of the two-herb formula, Danggui Buxue Tang (DBT), illustrating the variability in yields of marker compounds with duration of boiling, the drug/solvent ratio, the number of extractions and co-extraction vs. individual extraction of each plant. In relation to *C. spinarum* preparation in the studies analysed, the level of detail seen in CHM research is not provided. However, the example of DBT illustrates the importance of accurate data recording in EM studies. The use of decoction or maceration for root preparation, as described with *C. spinarum*, can be seen to aid extraction of active compounds in harder plant materials such as roots, bark and stem [109]. It may also have a role in reducing the toxicity of phytochemicals or plant extracts given that *C. spinarum* belongs to the Apocynaceae family, known to produce toxic metabolites. In bioprospecting, detail on EM preparation can be a crucial guide for ethnopharmacologists in their investigations [108]. Detailed ethnographic descriptions on preparation give a clearer view of the elements of the healing process as a whole which has relevance across other research foci such as cultural record, health care provision and sustainable plant use [32].
