Ethnobotanical investigation on medicinal plants used by local populations in Tlemcen National Park (extreme North West Algeria)

Medicinal plants are currently used by local populations to treat different diseases around the world. In the present study, the local knowledge of medicinal plants used by indigenous populations living in the Park of Tlemcen (North-West Algeria) has been documented. A total of 254 informants with a strong ethnomedicinal knowledge living in the national park of Tlemcen were interviewed by using a questionnaire. Data collected was analyzed using quantitative indices such as the ethnobotanicity index (EI), use value (UV), and Informant Consensus Factor (FIC). 109 species belonging to 54 families were identified and used by indigenous populations to treat different diseases. The most frequent families were lamiaceae (15.5%), asteraceae (11.9%), and rosaceae (5.5%).  Roots, rhizomes or tubers were the most used part for medical care (37.6%), followed by leaves (33.6%), other aerial parts (16%), fruits (8%), flowers (1.6%), and seeds (3.2%). Regarding modes of preparation, we noticed that decoction (40.4%) and infusion (28.5%) were the most predominant. Moreover, Thymus lanceolatus (UV=0.96), Origon glandulosum (UV=0.96) and Ammoides verticillata (UV=0.94) were the most frequently used species. FIC values ranged from 0.65 to 0.98. The highest FIC were recorded for reproductive and sexual disorders (0.98), respiratory tract diseases (0.98), cardiovascular system disease and blood disorders (0.94), digestive disorders (0.93), and general health (0.93). A variety of species are used to treat several ailments. Recorded species with high UV should be prioritized for conservation and subjected to further phytochemical and pharmacological studies.


Introduction
For centuries, man used medicinal plants to treat several health problems, and still uses this ancestral knowledge despite the enormous progress made by modern medicine. According to the World Health Organization (WHO), more than 80% of the world's population uses medicinal plants as a source for primary health care (Agisho et al., 2014). In recent years, an important increase has been observed regarding the use of medicinal plants owing to their abundance, cultural importance and low prices (Thomford et al., 2015). It has been found that about 28% of higher plant species are used for a therapeutic purpose while 74% of pharmacological principles are derived from plants, as a result of ethnomedicinal studies (Ncube et al., 2008). Even though the clinical use of a drug based on active principles derived from plants involves several disciplines such as botany, chemistry and pharmacology, so-called traditional medicine relating to the use of plants according to ancestral tradition and the ethnobotanical investigations among ethnic groups facilitate the search for these active principles (Rates, 2001;Radford et al., 2011). Owing to its diversified climate allowing an important development of medicinal plants, in coastal, mountainous and also Saharan regions, Algeria is considered one of the richest countries in flora. In fact, the Algerian flora consists of 4000 taxa with 131 families and 917 genera. The national endemic flora counts 464 Taxa (387 species, 53 subspecies and 24 varieties) (Radford et al., 2011). In spite of several ethnobotanical studies carried out to document the popular knowledge related to the use of medicinal plants in Algeria (Benarba et al., 2015a;Benarba et al., 2015b;Benarba, 2016;Benarba et al., Boudjelal et al., 2013, Ramdane et al., 2015, Azzi et al., 2012, The present study is the first comprehensive ethnobotanical investigation among indigenous populations living in the Park of Tlemcen (North-West Algeria).

Study area
The Tlemcen National Park is located in northwestern Algeria, with an area of 8225.04 hectares (Figure 1). The climate is characterized by a summer drought as early as June (only 7.2 mm in summer, with an annual rainfall of 483 mm). The mean maximum temperature for the hottest month is 32.35 ° C, the coldest month is 3.2 ° C. Emberger's precipitation index is 51.1. The altitude varies from 800 to 1418 m with a diversified relief.

Data collection
The ethnobotanical investigation was carried out using a stratified sampling plan to establish an overview of traditional local uses and floristic diversity of the pharmacopoeia of this area. On the other hand, 254 informants with a strong ethnomedicinal knowledge living in the national park of Tlemcen were interviewed by using a questionnaire. Demographic characteristics of the informants are shown in table 1. The ethnobotanical survey was realized in two phases. The first phase consisted of open interviews with the local population, trying to reach all categories with ethnomedicinal knowledge (old, men, women, and young people). During the second phase, more specific information was requested from the traditional therapists through semi-structured interviews by using a questionnaire, to obtain more specific information on medicinal plants (the vernacular name including the nominations in Arabic and/or Amazigh of the plant, diseases treated, parts used, mode of preparation, etc.). Besides, a herbarium was established for all the plants harvested in the park. The plants were identified by the Botanical laboratory (University of Tlemcen, Algeria) and the Botanical Department of the National Higher School of Agronomy (ENSA, El-Harrach, Algeria). Plants collection and ethnobotanical investigations were carried out between 2017 and 2018.

Ailment categories
The ailments treated by the medicinal plants were grouped into 13 categories according to the use-reports reported by the informants (Table 2). Each citation of a particular part of a particular species was recorded as one use report. When a species was mentioned to be used to treat or manage different ailments in the same category, it was considered as a single use-report (Benarba et al., 2015).

Data analysis
Data analysis was carried out by calculating different indices as follows: Use-value (UV): The UV of each species was calculated by using the following formula: UV= ΣU/n, where U is the number of uses reported by each informant for a given species and n is the total number of informants (Prance et al., 1987;Rossato et al., 1999).
Informant consensus factor (F IC ): The F IC was calculated according to the formula: F IC = (Nur-Nt)/ (Nur-1) where Nur is the number of use citations in each category and Nt is the number of species reported in each category (Tardío & Pardo de Santayana, 2008).
Ethnobotanicity index (EI): The EI expressed as a percentage, was calculated as follows: EI= n/N where n is the number of useful medicinal species and N is the number of all the species of the total flora in the area according to Porterès (1970). The EI reflects the importance of medicinal plants in an area (Sreekeesoon & Mahomoodally, 2014).

Botanical data
The total flora of the national park of Tlemcen consists of 917 inventoried species, representing 31.6% of the national flora, with 22 protected species (9.7% of the total national protected species) (Radford et al., 2011). The flora is also rich and diverse with 31 endemic species, 38 rare species and 27 very rare species. Our results (Table 3) showed that 109 species belonging to 54 families are used by local populations to treat different health problems. Moreover, the most frequent families were lamiaceae with 18 species (15.5%), asteraceae with 13 species (11.9%), and rosaceae with 6 species (5.5%) ( Figure 2). Our findings are consistent with most of the previous ethnobotanical investigations carried out in Algeria and neighboring countries. Indeed, in a previous study realized in North-West Algeria (Mascara), we found that traditional healers used 141 medicinal plant species belonging to 54 families and 125 genera, with dominance of lamiaceae, asteracea and apiaceae (Benarba et al., 2015b). In line with our results, lamiaceae and asteraceae were found to be the most predominant botanical families in different Mediterranean countries such as Algeria Benarba et al., 2015c;Sarri et al., 2015), Morocco (Bachar et al., 2016;Hamsas EL Youbi et al., 2016), and Spain (Parada et al., 2009). The same predominant families lamiaceae and asteraceae were reported in other regions of the world such as Bolivia (Cussy-Poma et al., 2017), Iran (Mosaddegh et al., 2012), or South America (Molares & Ladio, 2009). In most of the ethnobotanical studies around the world, lamiaceae, asteraceae, and rosaceae are the most predominant families (Quave et al., 2012). This predominance could be explained by the important occurrence of species belonging to these families which may result in large use and enhanced ethnomedicinal knowledge by local populations (Benarba et al., 2015b).

Parts used
According to our results, roots, rhizomes or tubers represented the most used part for medical care (37.6%). Leaves occupied the second position (33.6%), followed by other aerial parts such as stem and bourgeons (16%), fruits (8%), flowers (1.6%), and seeds (3.2%). Although a majority of recent ethnobotanical studies reported that aerial parts (leaves) are the most used part of the medicinal species (Tugume et al., 2016;Benarba et al., 2015a,b;Salhi et al., 2010), our findings are in consistence with those reporting that roots, rhizomes and tubers are the most commonly used plant part (Jin et al., 2018;Bisht & Adhikari, 2018;Kumar & Pandey, 2015). The frequent use of underground parts of the plants that are responsible for their multiplication and regeneration would be responsible for their disappearance. Indeed, during our collection of medicinal plants in Tlemcen Park, we found that these species are becoming increasingly rare.
According to our results, oral administration (82.7%) was the most frequent route prescribed by local populations in the national park of Tlemcen. Moreover, 14.5% of plant species are used via topical application. Our findings are in perfect consistency with those we previously reported in North-West (Benarba et al., 2015b) and South-West Algeria (Benarba et al., 2016). Similar findings were reported in most of the ethnobotanical investigations carried out in Algeria and its neighboring countries (Skalli et al., 2019;Boudjelal et al., 2013;Teixidor-Toneu et al., 2016;Telli et al., 2016). A high incidence of internal disorders, as well as cultural factors, may explain the predominance of the oral route as preferred administration mode as revealed in the present study (Benarba et al., 2016).
Moreover, our results showed that 46% of the cited species are administered with other plants. Out of them, 8 species are mixed with one plant, 12 species with two or three plants and 20 species are administered with more than three plants. The use of herbal mixtures in popular therapy may be explained by the search of a synergistic effect or the reduction of toxic effects of certain species (Bruschi et al., 2011). On the other hand, our results revealed that 64 species (59% of total cited plants) are mixed with honey, milk, olive oil or sugar. Bees honey was found to be the most added adjuvant (Figure 3).
Our findings are in line with those previously reported in Algeria. Benarba et al., 2016 reported that more than 50% of the cited medicinal plants used by traditional healers in South-West Algeria were administered with other plant species or non-plant-adjuvant. They found that honey was the adjuvant most added (53%) to medicinal plants used to treat several diseases. Similar findings were reported in different regions in Algeria (Bouasla & Bouasla, 2017;Ouelbani et al., 2016), and other parts of the world (Appiah et al., 2019;Bhatia et al., 2015), probably to soften the unpleasant taste of plants (Benarba et al., 2015b).

Ethnobotanicity index (E.I.)
Among the 917 plant species of the total flora, we identified 102 species used for medicinal purpose. Therefore, the calculated ethnobotanicity index was found to be 11.8%. This means that around 12.0% of the plant species are known to be useful as medicinal plants by local populations of the national park of Tlemcen. This finding is similar to those previously reported in the Mediterranean basin such as in Italy (Tuttolomondo et al., 2014), Spain (Menendez-Baceta et al., 2014), and Portugal (Novais et al., 2004). Nonetheless, when compared to EI estimated for Mediterranean regions with the same total flora (approximately 1000 species), the EI of the national park of Tlemcen is significantly lower than the reported in Spain (Martínez-Lirola et al., 1996) or Portugal (Camejo-Rodrigues et al., 2003).

Use value
Ranging from 0.01 to 0.96, the UV values allowed ranking the plant species according to the importance of their use by the local population of the Tlemcen national park. Our results (  (Table 3).
Species belonging to the genus Thymus were found to be the most frequently used medicinal plants in several ethnobotanical investigations in both Algeria (Bouredja et al., 2017;Benarba et al., 2016;Benarba et al., 2015b) and other countries (Axiotis et al., 2018;Rajaei & Mohamadin, 2012). In the present study, T. lanceolatus is used to treat respiratory diseases (flu, allergy, …) and several gastrointestinal problems (food poisonings, stomachache). The use of Thymus species to treat the respiratory diseases in the Mediterranean basin is well documented (Benarba et al., 2015b;Benarba et al., 2016;Leto et al., 2013;Teixidor-Toneu et al., 2016). Similarly, different Thymus species were reported to be used to treat several gastrointestinal disorders (Pant & Samant, 2010;Singh, 2012).
Recently, Nouasri et al. (2018) demonstrated that T. lanceolatus native of North-West Algeria was rich in phenolic acids, and had important antioxidant activity besides its antimicrobial effects against Staphylococcus aureus and Umpelopsis ramaniana. Furthermore, rosmarinic acid was the major compound of the fourteen identified. The ethanolic extract of T. lanceolatus exhibited a protective effect of human cells against oxidative damage (Caprioli et al., 2018). The use of Thymus species in the treatment of respiratory diseases could be attributed to their anti-inflammatory potential by targeting the NF-κB p65 and NF-κB p52 pathways resulting in a significant reduction pro-inflammatory cytokines (IL-1 beta and IL-8), and Muc5ac secretion (Oliviero et al., 2016).
In line with our results, Origanum sipyleum L. and Thymus sipyleus Boiss. were found to be the most frequently used species in Greek islands in North Aegean Region. These two species were mainly used to treat respiratory and gastrointestinal disorders (Axiotis et al., 2018).

Informant consensus factor (F IC )
As shown in Table 4, F IC values ranged from 0.65 to 0.98. The highest F IC were recorded for the reproductive and sexual disorders (0.98) with 10 species and 644 use reports, respiratory tract diseases (0.98), cardiovascular system disease and blood disorders (0.94), digestive disorders (0.93), and general health (0.93). Our findings are in agreement with those reported in nomadic populations in Algerian steppe revealing that reproductive and sexual disorders were the ailment category with the highest F IC of 0.92 . Similar to our results, it has been found that cardiovascular diseases had the 3rd F IC in two ethnobotanical studies carried out in two regions located in North-East Algeria (Miara et al., 2019;Bousala & Bousala, 2017). Likewise, Boughrara & Belgacem (2016) found that these ailments were ranked 3rd in the extreme east of Algeria. Moreover, in most of ethnobotanical investigations in Algeria and neighboring countries, digestive disorders were found to be associated with the highest F IC (Eddouks et al., 2017;Menale et al., 2016;Benarba et al., 2015b;El-Hilaly et al., 2003).

Conclusions
The present study reports an important ethnobotanical knowledge possessed by local populations living in the living in the Park of Tlemcen (North-West Algeria). Indeed, 109 species from 54 families are traditionally used to treat different diseases and health problems. Among them, Thymus lanceolatus, Origon glandulosum, Ammoides verticillata, Echinops spinosus, Mentha pulegium, Anacyclus pyrethrum, Daucus critinus, Arenaria aggregata, and Junipenus oxycedrus had the highest UV and therefore should be considered for further phytochemical and preclinical studies to evaluate their biological activities and identify the lead bioactive compounds. Moreover, high consensus has been found regarding the treatment of reproductive and sexual disorders, respiratory tract diseases, cardiovascular system disease and blood disorders, digestive disorders, and general health.