Ethnopharmacological Documentation of Medicinal Plants Used in the Traditional Treatment of Hypertension in Tarfaya Province, Morocco

The use of plants to treat chronic diseases is part of an ancient Moroccan tradition. This study will present the first relevant documentation on medicinal plants used in the treatment of hypertension in Tarfaya province. This study aimed to collect and document information on medicinal plants traditionally used by the local population of Tarfaya province for the treatment of hypertension. Ethnobotanical surveys were conducted using 150 questionnaires in the study area. Documented data were evaluated using the quantitative ethno-botanical indices of frequency citation (FC) and Relative Frequency of Citation (RFC). The results obtained allowed to inventory 52 species of medicinal plants belonging to 29 families traditionally used against hypertension. The species were rich in diverse chemical constituents. The most cited families are Lamiaceae (9 species), Apiaceae (5 species), Compositae (3 species), Leguminosae (3 species) and Myrtaceae (3 species). Ten plants are reported for the first time as used in the treatment of hypertension. The most cited plant species are Allium sativum (RFC = 0.28), Allium cepa (RFC = 0.2), Olea europaea (RFC = 0.18), Searsia tripartita (RFC = 0.16), Ammodaucus leucotrichus (RFC = 0.15) and Myrtus communis (RFC = 0.15). Leaves were the most used organs. The decoction was the dominant method of preparation. This study showed that the inhabitants of Tarfaya use a wide variety of plants for the treatment of hypertension. This work is a source of information that can serve as a basis for phytochemists and pharmacologists interested in research on plants with antihypertensive effect.


Introduction
Cardiovascular diseases are the largest cause of mortality worldwide, in both developed and developing countries. The number of adults with increased blood pressure from 594 million in 1975 to 1.13 billion in 2015, with the increase in low-and-middle income countries [1]. Many people in developing countries do not seek treatment for hypertension that could significantly reduce the risk of death or disability due to heart disease or stroke [2]. In these countries, social factors such as low level of education, lack of housing and unemployment with other risk factors have led to an increased prevalence of hypertension [3]. Population growth, the harmful use of alcohol, the increase in saturated fat consumption, the reduction of fiber consumption, obesity, reduced physical activity, the stress of modern life, have a negative impact on behavioral risk factors, which could influence the development of hypertension [3,4].
A person with a pressure equal to or more than 140/90 mm Hg suffers from high blood pressure [5,6]. Its frequency increases with age, but nowadays it affects younger population too. When not properly controlled, its consequences can be very serious such as stroke, and other cardiovascular complications [7].
In fact, one of three people in the world suffers from hypertension [6]. Hypertension in Morocco affects more than 34% of adults over the age of 20 and 53.8% of people over 40 and 72.2% of those aged 65 and over [4].
Currently, there are several types of antihypertensive drugs with various mechanisms of action. Although they are effective, some of them have side effects and in some cases they are unavailable to people in rural areas who have difficulty accessing medications [7]. Therefore, the use of traditional medicine for the treatment of hypertension is a very common practice in African countries and several investigations have targeted the discovery of new hypotensive agents from plants [2]. The best use of medicinal plants is through ethnobotanical surveys which make it possible to draw up a list of plant species used in traditional medicine by the population [8]. This type of knowledge has a real cultural value and may eventually allow the development of new pharmaceutical drugs. Ethnobotanical surveys conducted in different regions of Morocco have shown that several plant species are used in the traditional treatment of hypertension [4,[9][10][11][12]. Therefore, an ethnobotanical survey was carried out in the province of Tarfaya to collect as much information as possible about how to use and exploit plants in the traditional treatment of hypertension in order to valorize them, to keep and use them in a rational way.

Study area
The province of Tarfaya is located in southern Morocco. It is bounded on the north by the province of Tan-Tan, on the south by the province of Laayoune, on the east by the province of Smara, on the west by the Atlantic Ocean. This region covers an area of 15450 km2 with a population of 13082 inhabitants (Fig. 1).
The province is characterized by a semi-arid climate marked by the scarcity of rainfall. Rainfall amounts are generally low and unevenly distributed over the province. This rainfall is generally less than 60 mm / year. In the province, temperatures are moderate and influenced by the proximity of the Atlantic Ocean, generally around 30 ° C in summer and 20 ° C in winter, and there are not large annual variations.

Fig. 1. Location of study area
In terms of vegetation, the province is characterized by some isolated tufts or solitary trees; The appearance is that of a landscape left bare, covered only by some herbs that grow after the occasional rainfall.
The province of Tarfaya has significant economic potential, particularly in the sectors of sea fishing, livestock, tourism and renewable energy. While its potential in agriculture is very limited because of the unfavorable weather conditions. On the other hand, Overgrazing is practiced in the province because of the nomadic life that has marked the lives of the local population. The herd consists mainly of goats, sheep and camels.

Ethnobotanical survey
This work was carried out on the basis of ethnobotanical surveys to gather as much information as possible on the floristic diversity and therapeutic uses of medicinal plants used in the treatment of hypertension in the province of Tarfaya.
In a random sample of 150 people, the population of Tarfaya province was surveyed between August 2018 and December 2018. Using a questionnaire, the surveys collected information on the profile of the people surveyed (age, sex, level of education, family situation, and origin of the information) and to collect precise information on the therapeutic practices used by the population of this province in the treatment of hypertension, in particular the vernacular name of each species, the parts of the plant used and the method of preparation. The time spent on each interview was approximately one hour and all interviewees were informed about the purpose of this study.
In addition, medicinal plants have been identified by the bootanists of the Laboratory of Biotechnology and Valorization of Natural Resources (LBVRN), Faculty of Sciences, Ibn Zohr University, Agadir, with the help of the standard floras of the area and the online database (www.theplantlist.org). Voucher specimens were prepared for all plants and deposited at the herbarium of our laboratory.
The information on the ethnobotany records was transferred to a database, processed and analyzed to obtain standardized data. The phytotherapeutic importance of each species was assessed by calculating the Relative Frequency of Citation (RFC = number of citations of a species / total number of respondents).

Demographic features
Ethnobotanical surveys conducted in the field made it possible to interview 150 people (Table 1), 56.7 % of whom were female compared to 43.3% of men. Similarly, the results show that it is women who use medicinal plants much more than men. These results confirm the results of other ethnobotanical studies conducted nationally [9][10][11][12][13][14]. This is an indicator of women's attachment to traditional knowledge [9,11].
In this region, the majority of users of medicinal plants are illiterate with a rate of 53.3%. This reflects the low level of schooling of the local population. People with primary education level have a percentage of 32.6% while people with secondary and university level use very little medicinal plants with a rate of respectively 11.3% and 2.7%.
Most of the respondents, 69.3%, reported having acquired knowledge in a hereditary way. Herbalists are ranked as the second source of information (22.7%). These percentages reflect the image of the transmission of traditional practices from one generation to another.

Diversity of medicinal plants and their applications
The study of medicinal plants made it possible to identify 52 species belonging to 29 families ( Table 2). The most represented families are Lamiaceae (9 species) and Apiaceae (5 species), followed by Compositae, Leguminosae and Myrtaceae (3 species). The remaining families have only one or two species. The high representativeness of these families has also been noted in ethnobotanical surveys conducted in other regions of the country [4,10].

International Journal of Pharmacology, Phytochemistry and Ethnomedicine
Vol. 14 Single-species remedies are mostly represented in relation to multi-species remedies. This preponderance is to the advantage of the patients because the mixing of plants is sometimes toxic that 30% of the fatal accidents in Africa are due to intoxications due to plants [26]. Indeed, these intoxications are sometimes the result of confusion with another plant or a lack of knowledge of the side effects of the plant as well as ignorance of the methods of their use, including the methods of preparation and recommended doses. The use of medicinal plants must be rationalized to take advantage of them and avoid risks. Therefore, we need more studies to achieve these goals.
Through pharmacological and phytochemical assays, the activities claimed by the present ethnobotanical study were already confirmed for several species listed by our respondents ( Table 3). These results, which confirm the biological activity of these plants, explain the knowledge and practices in herbal medicine acquired by the inhabitants of the province. In fact, this research opens up new and interesting perspectives in the search for new therapeutic means, which can thus bring effective solutions by the manufacture of medicines sold in pharmacy for people suffering from hypertension International Journal of Pharmacology, Phytochemistry and Ethnomedicine Vol. 14  [27] Effective role in preventing weight gain, antiatherosclerotic and Cardioprotective [28,29] 2 Adansonia digitata Malvaceae Glutamic acid, aspartic acid, oleic acid, linoleic acid and palmitic acid [30] Analgesic, antioxidant, hepatoprotective [31][32][33] 3

Ziziphus lotus Rhamnaceae
Oleic acid, linoleic, palmitic, elaidic acid, threonine, glutamic acid, leucine, arginine and aspartic acid [203,204] Antiradical, antioxidant and antimicrobial [203,205] Plant parts used, mode of preparation and administration A total of 11 parts of plants are used including leaf, seed, aerial part, fruit, bulb, root, Stem, gum, clove, chalices of flowers and stigma. The percentage of use of these different parts shows that the most used part of the plant is the leaf, with a percentage of 32.7% (Fig. 2). Several previous ethnobotanical studies have shown the predominance of leaves in the preparation of various herbal remedies [206][207][208]. The high frequency of use of leaves can be explained by the ease of identification and the speed of harvest [209], but also by the fact that they are the site of photosynthesis and storage of plants bioactive phytochemicals [210,211]  The most common methods of use are classified as follows: decoction, infusion, powder and maceration with respectively 46.1%; 21.1%; 19.2%; 5.8% (Fig. 3). Our results are in agreement with other studies conducted throughout Morocco [212,213]. Herbal medicine is a rational use of medicinal plants. Rigorous selection of the most effective method of preparation to ensure the preservation of all properties while allowing the extraction and assimilation of active ingredients [214,215]

Conclusion
This study allowed us to inventory and identify 52 species of plants belonging to 29 families used in the province of Tarfaya to treat hypertension. Among the most commonly used species are Allium sativum, Allium cepa, Olea europaea, Searsia tripartita, Ammodaucus leucotrichus, Myrtus communis and Carum carvi. The results of the study also showed that the frequency of plant use is very much related to the profile of the people surveyed. The illiterates predominate with a rate of 53.3%. Women and men have knowledge and practices in herbal medicine with an advantage for women. The rate among young people aged 21 to 30 is 11.3%, while it is around 34% for people aged 41 to 50. This study also showed that the therapeutic remedies are mainly prepared by the decoction and that the leaf and the seed are the most used parts.
Ultimately, the results of this study could constitute a database for the valorization of medicinal plants in order to discover new natural active ingredients that can be used in pharmacology for the treatment of hypertension.

Conflict of Interest
The authors declare no conflict of interest.