Using Traditional Medicinal Plants from Arid and Desert Rangelands as a Potential Treatment for Covid-19 in Southern Tunisia

Rangelands provide good services, including forage for livestock, aromatic and medicinal plants, wildlife habitat, fuel wood, and the watershed. In the arid and desert rangelands of Tunisia, several medicinal plants are used locally in traditional medicine. Many of them have been scientifically investigated and validated. This study aimed to document the different plants used recently to treat and prevent Covid-19 by the rural communities in southern Tunisia. One hundred persons that were ensured to be cured after their infection by Covid-19 were asked to indicate what plants were used to prevent or treat the pandemic disease. It is noteworthy that the selected respondents did not use any other medication than medicinal plants due to the high price of medicament. Additionally, they had not received any Covid-19 vaccinations to date. Five species were harvested from the range lands to be used by the rural population in south Tunisia to treat and prevent Covid-19. The plants included Rosmarinusofficinalis,Thymbracapitata,Peganumharmala,Artemisiaherba-alba and Astragalus armatus . These species are medicinally essential when it comes to treating several human diseases. Still, there are no new scientific findings on whether these conclusions are valid. These results can still be the subject of future scientific research.


INTRODUCTION
Native range lands are an important source of rare and environmentally, economically, nutritionally, and medically valued plants around the globe. In recent decades, increased attention has been paid to the potential of wild plants in terms of medicinal uses. In many regions of the world, most medicinal plants grow in natural range lands rather than being planted 1 . In China, for example, it is estimated that 80% of medicinal plants are provided by the natural resources 2, 3 . In addition, it is estimated that 80% of the world population uses herbal medicine as part of its primary health care, with about 12 % being from South Asia 4 . Given the importance of plants in medicine, the Sri Lankan Government established the Ministry of Indigenous Medicine in 1980 due to the high demand for the drugs based on plants 5 . The arid environment is also one of diversity in terms of medicinal herbs and it is home to a large number of unique species 6 . Despite being under threat from various biotic and abiotic stresses, many arid range lands still produce medicinal plants that are valued in both traditional and modern medicine. Their harvesting greatly contributes to the annual livelihood income of many populations 7-9 . The excessive and unsustainable collection of medicinal plants on a large scale from the range lands contributes to rangeland degradation and the extinction of some plant species 10 . Tunisia's rangelands occupy about 5.5 million ha, of which 87% of them are arid 11 . These lands form the largest part of the Tataouine governorate surface, making up about 27% of the total rangeland in Tunisia 12 . Despite these harsh environments, arid rangelands are blessed with a wide diversity of medicinal plants due to their diverse ecological habitats 13-15 . An ethnobotanical survey conducted of a local community in Tataouine reported that 70 plant species are used for therapeutic purposes 16 . Through the floristic surveys conducted by Gamoun and Louhaichi 12 , a total of 279 species were recorded in the rangelands of Tataouine, and 35 of them were found to be greatly used in both traditional and modern medicine. Given the spread of diseases, medicinal plants are gaining attention in the context of traditional use. Recently, more than 199 million infections with at least 4 million Covid-19 associated deaths were reported by July 2021 17 . Tunisia is among the countries most severely affected by the ongoing pandemic, with more than 560 thou- sand infections and at least 18 thousand deaths reported by July 2021 17 . In light of the Covid-19 pandemic, the fragile health care system, and the lack of infrastructure, the use of medicinal plants has acquired a renewed interest by the rural population of Tunisia. The present study has therefore attempted to reveal some of the medicinal plants used in the south of Tunisia to prevent or treat Covid-19 infection.

METHODOLOGY
Tataouine is located in the south of Tunisia, totaling 150 thousand inhabitants. It recorded close to 10,500 coronavirus cases and 410 deaths by the end of July 2021 18 . Due to this record of infection, the slow pace of vaccination in Tunisia, and the mistrust in the available Covid-19 vaccines held by some people, the community has become increasingly disappointed. This has led them to using native plants which may help them to address the current pandemic. In July 2021, 100 persons that were cured of Covid-19 were asked to indicate what plants were used to prevent or treat the disease. It is noteworthy that the selected respondents did not use any medication other than the medicinal plants due to the high price of medication and that they had not received any Covid-19 vaccinations to date.

RESULTS AND DISCUSSION
Botanical studies conducted in the arid and desert rangeland of Tataouine have identified a rich collection of over 270 plants from 58  Five species were harvested from the rangelands and used by the local community to treat and prevent Covid-19 ( Table 1). These included Rosmarinus officinalis, Thymbra capitata, Peganum harmala, Artemisia herba-alba and Astragalus armatus. The most important species in terms of the number of users was R. officinalis, used by 47 people. In addition, T. capitata was used by 25 people, followed by P. harmala by 19 people, A. herba-alba by 16 and A. armatus by 12 people. Some of the respondents used pairs of species at a time. Of the 100 interviewed, 12 people used R. officinalis and T. capitata, 5 people used P. harmala and A. herba-alba and 2 people used A. armatus and A. herba alba. Rosmarinus officinalis L.is a perennial shrub native to the Mediterranean basin belonging to Lamiaceae family (Figure 1). It is more commonly known as rosemary and "Iklil" in classical Arabic. It has multiple uses including medicinal, aromatic, and ornamental 19 . R. officinalis as an essential oil has important inflammatory 20-23 , antimutagenic 24,25 , cytotoxic 26-28 , antiphlogistic 24,29 , analgesic 30-32 , antiobesity 33 and hepatoprotective applications 34, 35 , as well as being used in the prevention and treatment of diabetic and cardiovascular diseases 36 . It is also well known for its biological active essential oils that are antioxidants 37-39 , anticancer 28,40,41 , antibacterial 42,43 , and antifungal 44-46 . Moreover, R. officinalis is a pulmonary antiseptic, as well as stomachic, hypertensive, and antidiarrheal due to its diuretic and sudorific qualities 15 . The leaves of R. officinalis were the most used plant part by the local people in the treatment of Covid-19. They boiled the dried rosemary leaves in water and drank it once it had cooled. Thymbra capitata (L.) Cav., is a perennial herbaceous shrub native to the Mediterranean area, belonging to Lamiaceae family (Figure 2). It is commonly known as thyme and it is locally known as "Zaâtar horr". In southern Tunisia, it is represented by scattered populations on sandy and often rocky soils. T. capitata is known for the effectiveness of its essential oil as part of a local utilization for traditional medicinal purposes. It is widely used for folk medicinal purposes to treat arterial hypertension, ulcers, colic, digestive and respiratory system disorders, and diarrhea 47, 48 . Nowadays, the essential oil of T. capitata is gaining interest due its potential biological properties 49,50 . It is mainly known for being an antioxidant 51 , anti-inflammatory 52,53 , antimicrobial 54-56 , cytotoxic 57,58 , antimycotic 59,60 , anticancer 61 , antiproliferative 62 , and antifungal 63 . These main biological activities were reported to be Putting the leaves of A. herba-alba on hot coals, and breathes the smoke through the nose, and it will cause all rheum to go away.

A. armatus
Milkvetch Roots Decoction of roots of A. armatus is orally taken to treat and prevent Covid-19, because it can stimulate the immune system and act against viruses like the ones that cause colds.     due to its richness of phenolic compounds in the extracted essential oils 64-66 . The leaves of Thymbra capitata were found to be the plant part used the most by the local people in their treatment of Covid-19. They boiled the dried leaves of T. capitata in water and drank the mixture when it cooled. Likewise, the leaf powder was also mixed with honey and applied to the chest to treat coughs, a fever, and bronchitis. Peganum harmala L. is a herbaceous perennial flowering plant that is widely distributed in Central Asia, North Africa, and the Middle East (Figure 3). It is commonly known as African rue, Syrian rue, and wild rue. This plant, known as harmal in North Africa, belongs to the Nitrariaceae family. Peganum harmala is a noxious invasive species. It is toxic to livestock when fresh but medicinally important 67 . The seeds are known to possess hypothermic properties 68, 69 and it is effective in the treatment of dermatosis 70 . Furthermore, P. harmala was shown to possess lactogogue, antihelmitic, antispasmodic, abortifient, antipyretic, emetic, emmenagogue, cardiovascular, neurologic, antimicrobial, gastrointestinal, anticancer, and antidiabetic activities 71 . It has also been found that P. harmala has insecticidal and anti-tumor effects 72 , as well as being antileishmanial 73 , anti-spasmodic, anti-malaria 72 , vasorelaxant and anti-histaminic 74 . This is as well as promoting wound healing, antioxidant activity, immunomodulator properties, and leukemia healing 75 with analgesic and anti-inflammatory properties. Finally, it also has antinociceptive 76 , hepatoprotective 77 , hypoglycemic, antitumor 78 , cytotoxic, antifungal, antibacterial and antiviral effects 79 .
To treat and prevent Covid-19, the local community takes any part of P. harmala (leaves, seeds, stems, roots) and puts it on hot coals. They breathe in the smoke through the nose. This causes all of the rheum to go away. Artemisia herba-alba Asso., is a perennial shrub belonging to the Asteraceae family. It is commonly known as white wormwood and it is locally known as "Chih." (Figure 4). It is widespread in the arid and semi-arid steppes of North Africa, Southwestern Europe, and the Middle East. Since ancient times, A. herba-alba has been extensively used in traditional medicine to treat hypertension, scorpion/snake bites, diabetes, colds, parasitic infections, intestinal disturbances, bronchitis, diarrhea, neuralgias, stomach pains, and hemorrhoids 16,80-83 . It is known for its antioxidant, anticancer, antimicrobial, anti-inflammatory, genotoxic, cytotoxic, antiacetylcholinesterase, and fungicidal activities 84-88 .
To treat and prevent Covid-19, the local community takes the leaves of A. herba-alba and puts them on hot coals. They breathe in the smoke through the nose, and this causes all of the rheum to go away. Astragalus armatus Willd. is a perennial spiny shrub native to Algeria, Libya, Morocco, and Tunisia. It is commonly known as thorny milkvetch and it is locally known as "Guetet" (Figure 5). Astragalus armatus has been used in traditional medicine as an effective treatment for leishmaniasis and helminthiasis 89 . It also relieves odentonecrosis 16 . Nowadays, pods of Astragalus armatus are receiving interest due to their potential antioxidant, anticholinesterase, antibacterial and phagocytic activities 90 . They are also a source of the bioactive galactomannan 91

CONCLUSION
Today, the world faces an ongoing Covid-19 pandemic. This pandemic has become a significant challenge when it comes to human security. Tunisia, like every country in the world, is facing the Covid-19 pandemic and the many connected challenges that it has caused. Due to the increased price of the cost of medication and medical supplies and the projected increase in the incidence of Covid-19, the use of medicinal plants has grown rapidly among rural populations. The arid and desert range lands of Tunisia provide a habitat for several medicinal plants used in traditional medicine that are used to prevent and treat Covid-19 such as Rosmarinus officinalis, Thymbra capitata, Peganum harmala, Artemisia herba-alba, and Astragalus armatus. However, harvesting shrubs for fuel wood and overgrazing is threatening the flora biodiversity found in these range lands and the lives of the people who live there. This calls for urgent action.

ABBREVIATIONS
None.

ACKNOWLEDGMENTS
The author would like to thank all the participants who entirely voluntarily participated in this study for providing their detailed and thoughtful responses.

AVAILABILITY OF DATA AND MATERIALS
Data and materials used and/or analyzed during the current study are available from the corresponding author on reasonable request.

ETHICS APPROVAL AND CONSENT TO PARTICIPATE
Not applicable.

CONSENT FOR PUBLICATION
Not applicable.