Medicinal Plants from the Ankaratra Mountain In Madagascar: Diversity and Uses

Background The Ankaratra Mountain, the third summit of Madagascar, is covered in a large part by herbaceous vegetations. It is among regions where ethnobotanical works have not been done yet. Besides, there have not been so far any surveys of medicinal plants conducted in savannah vegetation from Madagascar. The objective of the present communication was to study the diversity of medicinal species encountered in this mountain, the most used species in traditional medicine and the most important species used to treat diseases with medicinal plants. Methods The voucher specimens of surveyed species in the Ankaratra Mountain were shown individually to 26 local traditional healers. Semi-structured interview was employed and dealt with the main questions such as: do you know this plan? Do you know the uses of this species in traditional medicine? Do you know the method of preparation?


Introduction
The Ankaratra Mountain is the third highest point of Madagascar that emerges in the median part of the island and reaches 2643m in Tsiafajavona [1]. Figuring among the key biodiversity areas in Madagascar [2], the east slope of the Mountain is largely composed by the New Protected Area of Ankaratra Manjakatompo, as referred to the enactment n° 2015-711 in April 21, 2015. No structure of protection exists in the west slope. This work is related to the ethnobotanical study of the herbaceous and remaining forestry vegetations of the Ankaratra Mountain.
It is of great importance for a number of reasons. Medicinal plants sold on the market in the city of Antananarivo are well-documented [3] [4], while the Ankaratra massif belongs to the regions in which no ethnobotanical work has been carried out [5], and where healers and crowds from other regions practicing annual cults collect medicinal plants [6] [7]. In addition, the island has 3,245 medicinal species [8] the majority of which are inventoried in unprotected areas [5].  This mountain is composed of is made up of trachytic, ordanchitic, basanitic and ultra-vulcanian eruptions. The soil is of volcanic nature, more or less deep, clayey to clayey-silty, black color and not very crumbly; the elements shrink by drying and become very hard [9] [10].
Two climatic seasons occur in the massif, the hot and humid season, from November to April and the cool and dry season, from May to October. The two slopes receive a climatic dissymmetry mainly concerning the rainfall regimes [10]. Indeed, during the hot and humid season, the western part is much more interested in the NW monsoon than the eastern part. Conversely, the latter are more marked by ne rains coming from the humid east trade wind, while the western slopes are warmed and cleared of any cloudiness by the descent of this trade wind, during the cool and dry season.
The annual rainfall ranges between 800mm and 1000mm during the rainy season. The dry season takes place from April to October where the mean monthly height of rainfall is 40mm. The temperature average is 7.1°C in August and 26.7°C in January [11].
These physical factors give rise to vegetation dominated by herbaceous vegetation which are hardly modi ed by the human activities since the 6th century [12], land for culture and reforestations [13]. The herbaceous vegetation is found in the rocky escarpments and the non cultivated areas. They are associated with numerous endemic species, such as those of the Asteraceae family: Helichrysum bracteiferum, H.gymnocephalum, H. benthamii, H. bojeri, Rochonea cinerarioides, Syncephalum arbutifolium; those of the Lamiaceae family: Tetradenia goudotii, Salvia cryptoclada; those of the Malvaceae family: Dombeya ankaratrensis, Kosteletzkya velutina; those of the Apiaceae family: Pimpinella perrieri, P. ebracteata, P. humbertii, Billburttia capensoides.
The forestry formations cover only few areas and are present in the foot of east slope. They consist of evergreen humid forest [14] inside of which remain ancestral tombs and waterfalls that attract many traditional pilgrims on the major dates of the Madagascan lunar calendar [6] [15], which is dominated by high trees of Dicoryphe stipulacea. The upper stratum is rich in epiphyte, mostly species belonging to the Orchidaceae family like Oberonia disticha,…The reforestations hold few areas and are generally composed of Acacia dealbata, Eucalyptus robusta, Cinnamomum camphora [6].
The populations, the Antankaratra, descendant of Andriampenitra [16] [17] [6] are of the Merina ethnic group. Being parts of the Itasy and Vakinankaratra regions, the studied area is among the most crowded zones in Madagascar. The density reaches up to 125.6 hab. /km 2 [11]. People in this area live on agriculture and farming. The cultivable surface is still wider by covering approximately 72% of the all surfaces. The main productions and speculations are food cultures such as potatoes, rice, manioc, maize, sweet potatoes… ( Figure 2)and the cash crop: tomatoes, pineapples, vegetables… the culture of fruit trees like Prunus persica is also practiced by populations in the suited area.  The most cited species are determined according to the value of their quotation frequency. It is the percent of informants citing the species (nu) with regard to the total number of informants (Ni) [19]. The more the quotation frequency is high, the more the species is well-known and is very employed in traditional medicine.

FC (%) = (nu / Ni) x 100
The delity level (FL) as described by Friedman et al., [20]. It is the percent of informants agreeing to say that a species is used in the most part to treat a de ned disease. The high level of delity of a species for a disease means that this species is the most preferred and is very known to treat such disease.
It is the ratio between the number of informants who cite a species for a given disease (Ip) and the total number of informants who cite the species for any disease (Iu).
The analyses of variances are realized to better understand the degree of signi cance of the species quotation frequency and the delity level in function of the endemism.

Diversity of medicinal plants
The  (Table 1). These species are encountered in four types of habitats, namely herbaceous savannah which house the highest number of species (35.5%), the rainy forest of the mountain holds 31.5% of species, the degraded forest with 17.2% of species, and the shrub savannah with 13.3% of the species ( Figure 5A). Consequently, the species with herbaceous habit are prevalent in Ankaratra, with a percentage of 53.2%. The trees and shrubs represent 29.1 and 10.8%, respectively. The lianas only accounted for 7.4% of the all species ( Figure 5B). The greater part of the medicinal species inventoried are endemic with a percentage of 73.9%. They largely have priority over the introduced species, which have a percentage of only 7.2% ( Figure 5C). At the genus level, the rst four most diversi ed genera in terms of medicinal species are composed of savannah and endemic species. The most diversi ed genera have a high percentage of species. Helichrysum is the most diversi ed with 14 species, which represent 8.8% of the all species inventoried. It is followed by Senecio and Salvia with 7 (3.9%) and 4 (2.3%) species respectively, and Pimpinella and Gerbera with 3 (1.7%) species each. The species of the genera Helichrysum, Salvia and Pimpinella are all endemic, which is not the case for Senecio and Gerbera.
Regarding the most diversi ed families in traditional medicine, the richest families in medicinal species are the most diversi ed ones inventoried on the oristic standpoint. The Asteraceae accounts for more than half of the families of medicinal plants inventoried during this work (63.4% or 52 species). It is followed by the Rubiaceae which represents 17% or 14 species, while the Poaceae is found at the rate of 14.6% or 12 species, and the Lamiaceae and the Apiaceae go for 13.4% (11 species) and 12.2% (10 species), respectively.

The most cited taxa in traditional medicine
The quotation frequencies of the species, as calculated using the Singh formula, vary between 4.2% and 100%. Among the rst ten most cited species, the rst eight such as Tetradenia goudotii, Clematis pimpinellifolia, Billburttia capensoides, Micromeria agellaris, Agauria polyphylla, Helichrysum benthamii, Hubertia faujasioides, Lycopodiella cernua, have each a quotation frequency of 100%. Those of Pimpinella perrieri and Inulanthera brownii reach 95.8% (Table 2, Figure 6). Among these species, nine belong exclusively to Madagascar and six are aromatic plants. Moreover, the rst twelve most cited genera have the maximal quotation frequency of 100%. Four of them belong to the most represented genera regarding the inventoried species. They are Helichrysum, Senecio, Pimpinella, Micromeria, Salvia, Vernonia, Hubertia, Agauria, Geranium, Indigofera, Vaccinium, Buddleja. All of the representatives speci c to these genera are endemic and all the species of the four genera (Helichrysum, Pimpinella, Micromeria, Salvia) are aromatic. Relation between the quotation frequency and the endemism, biological forms and ecology The variance analysis of the quotation frequency of the species in relation to the endemism, to the biological forms and to the ecology is presented in the gure 7. These results show that: The endemic autochthon species are more cited than non endemic autochthon and introduced ones with a highly signi cant difference (p<0,0001), The herbaceous species and the shrub species are more cited than the trees and the liana with a highly signi cant difference (p<0,0001), The species from herbaceous savannah are most cited than those from other kinds of vegetations.  The delity level of species used to treat some infectious and parasitical diseases, and Symptoms, signs and abnormal results of clinical and laboratory analysis not classi ed elsewhere, the inclassables diseases, the skin diseases and the sub-cutaneous cellular tissue and the digestive tract diseases exceed 50%. The informants have more knowledge on these diseases and most of them agreed the uses of these species.
The delity level of species used for caring pregnancy, childbirth and puerperium, the eye diseases and its appendices, the ear diseases and the mastoid apophysis do not reach 50%. The informants have few knowledge about these diseases and that the majority of them diversify the uses of these species. Relationship of the delity level to endemism, biological forms and ecology The results of the variance analysis of the delity level versus the endemism, biological forms and ecology are summarized in gure 9. It shows that: The endemic species are of great importance in the treatment of diseases. The variance analyses of the delity level versus the degree of endemism of medicinal plants display a signi cant difference (p=0.0001) ( Figure 9A). The endemic species have a high delity level, so they are very important for use to treat the diseases in comparison with autochthon but non-endemic species and those which are introduced. Among the 54 species having a delity level more than 50% and employed for the treatment of the rst six diseases, only ve species, namely Clematis mauritiana, Ranunculus multi dus, Equisetum ramosisimum, Osmonda regalis and Lycopodiella cernua are not endemic.
The informants give much importance to herbaceous species which have a very signi cant difference (p=0.0001) ( Figure 9B).
The species from herbaceous savannah are more important in their health care than that of others. Nevertheless, the difference with those from rainy forest is not signi cant ( Figure 9C). transmitted generation to generation [22]. The occurrence of these newly identi ed medicinal plants might have two origins. First, the variation of ecological conditions at local level leads to a local endemism of the ora which is able to elaborate speci c secondary metabolites. Secondly, the local inhabitants have knowledge dedicated to the use of these species because of their long contact with ecosystem.

Diversi ed and cited family and genera in traditional medicines
The most diversi ed genera are dominated by the genera which are the most proli c in endemic species.
The most diversi ed families are rst those among the large families of the Madagascar ora such as the Asteraceae and the Lamiaceae [25].These results give support to those obtained by Moerman and  [23], suggesting that the villages at high altitude have known and used more medicinal plants than the inhabitants from the villages at low altitude. Besides, the places far from houses, with di cult access, at high altitude and the areas without perturbation were frequently cited by the traditional healers as sanctuaries for products of good quality [24]. This is con rmed by the presence of two sacred sites in the Ankaratra massif where many traditional healers perform periodic worship services throughout the year [24]. Endemic species are then very important in traditional Malagasy medicine and the Ankaratra Mountain is considered as an important reservoir of medicinal plants and traditional knowledge.

Important species for a given disease and other uses in Madagascar
The species having the highest delity levels in Ankaratra are compared with those of Madagascar as ascertained by [8]. Two species among the rst 88 ones having the highest delity levels in Ankaratra are found in the list related to those of the whole Madagascar. These are Drosera madagascariensis and Hubertia faujasiodes.
The rst species has a high level of delity in the treatment of diseases of the respiratory system throughout Madagascar, but it is considered very effective in mental and behavioral disorders according to traditional healers at the study site. The second species is mainly used in the treatment of diseases of the genitourinary system throughout Madagascar, while it is of high importance in the treatment of Symptoms, signs and abnormal clinical and laboratory ndings, not elsewhere classi ed for Antankaratra. When considering species of maximum importance for a disease in the study site:  [39]. Thus, in many cases, the widely distributed plants (Chenopodium ambrosioides and Psidium guajava (in our case) have similar uses in several regions [40] and the same degree of importance.

Diseases treated with medicinal plants
For the traditional healers from Ankaratra, the most cited diseases are those which need particular knowledge (SYMP) and those frequent in Madagascar (MIP, MAR). This correlation between diseases treated with plants and the most morbid diseases is also observed in other regions of Madagascar [41] [33] [22][8] and in Africa [42]. However, some diseases require more knowledge that only the specialists can gain during their experiences or acquaintances, referring to an heavenly healer [43]. So, the majority of plant species in a given region, with their properties held by traditional healers, constitute one of the effective means of treating many diseases that are rife in this region.

Conclusion
The ethnobotanical survey conducted in the Ankaratra Mountain shows the richness of herbaceous formations in medicinal plants. Two hundred and three species out of the 235 species inventoried are used in traditional medicine. These species are encountered in 4 types of vegetations, namely the rainy forest, the degraded rainy forest, the shrub savannah and the herbaceous savannah. The herbaceous savannah and the rainy forest are very important since they host 35.5 and 31.5% of the total species, respectively. These species are also important in the treatment of diseases, although the species from the savannah are the mostly cited. The use of endemic species is very signi cant regarding the quotation frequency and the level of delity. Special measures at national level are essential to mitigate the threats to natural resources inventories and traditional knowledge linked to the cultural speci city of the site studied.
All these data constitute a useful tool to reinforce the conservation of the ora from the Ankaratra Mountain, not only the eastern slope, but also the western slope. The ecological studies of the most cited and the most important endemic species in the treatment of diseases as well as the chemical and pharmacological of these studies are in prospect.

Declarations
Ethics approval and consent to participate