In silico screening of Moroccan medicinal plants with the ability to directly inhibit the novel coronavirus, SARS-CoV-2

Reda Ben Mrid (  rbenmrid@gmail.com ) Mohammed VI Polytechnic University https://orcid.org/0000-0001-6342-7405 Najat Bouchmaa Sultan Moulay Slimane University https://orcid.org/0000-0002-2757-6224 Imad Kabach Laboratory of Biochemistry and Molecular Genetics, Faculty of Sciences and Technologies of Tangier Mansour Sobeh Mohammed VI Polytechnic University https://orcid.org/0000-0002-2719-8534 Abdelmajid Zyad Sultan Moulay Slimane University https://orcid.org/0000-0002-3997-3649 Mohamed Nhiri Laboratory of Biochemistry and Molecular Genetics, Faculty of Sciences and Technologies of Tangier https://orcid.org/0000-0002-5612-7890 Abdelaziz Yasri Mohammed VI Polytechnic University https://orcid.org/0000-0002-7513-9037


Introduction
The current outbreak infection of a novel, highly pathogenic coronavirus SARS-COV-2 (formerly 2019-nCOV) emerged in December 2019 in Wuhan, Hubei Province, China, and which has spread rapidly across the ve continents . The SARS-COV-2 is a highly virulent human coronavirus with a high fatality rate . Human coronaviruses, including the SARS-COV-2 are associated with severe acute respiratory syndrome, and lead to global pandemics with high morbidity and mortality (Hoffmann et al., 2020). Unfortunately, until now, there is no e cient antiviral drug or vaccine for the treatment of COVID-19.
The molecular mechanisms of coronavirus invasion, depends rst on cell entry which depends on binding of the viral spike protein (protein S) to cellular receptors of the target cells (Xia et al., 2020). The alveolar epithelial cells, which highly express an angiotensin-converting enzyme 2 (ACE2), recognized by the protein S of the virus, represent an appropriate target for the coronavirus infection in the lung (Hoffmann et al., 2020). After the expression of coronavirus polyproteins, two viral enzymes, which are 3C-Like protease (3CL pro ) also known as main proteinase (M pro ) and the papain-like protease (PL pro ), were reported to be implicated in cleaving the expressed polyproteins into smaller compounds used to produce new viruses (Wrapp et al., 2020). In addition to their essential function for coronavirus replication, they were also reported to inhibit the innate immune responses of the host (Wrapp et al., 2020).
Unfortunately, there are currently no effective drugs targeting COVID-19. In this respect, Anti SARS-CoV-2 drug are urgently needed. Repurposing of existing antiviral drugs  or screening of available databases of natural molecules with antiviral properties is considered a near term strategy that could reduce the time and cost compared to the novo drug discovery.
The functional importance of 3CL pro and PL pro for replication of coronaviruses makes them attractive and promising targets for the development of broad-spectrum of anti-coronavirus drugs . As well, spike protein has been also extensively characterized to be a key target for development of antiviral medicines (Letko et al., 2020).
For centuries, medicinal plants have been an invaluable source for drug discovery and development. As a notable illustration, the discovery of artemisinin which was originally isolated from Artemisia annua L., is a milestone in the treatment of malaria (Su et al., 2020). As well, numerous medicinal plant compounds have demonstrated antiviral potent towards many viral diseases (Karagöz et al., 2018). Indeed, several naturals molecules including kaempferol (Park et al., 2017), gallocatechin gallate (Nguyen et al., 2012), procyanidin B1 (Zhuang et al., 2009) and Quercetin (Nguyen et al., 2012) among others, have already been tested in vitro to successfully treat SARS and MERS coronaviruses and these compounds could be a potential drug candidate towards SARS-COV-2. Moreover, currently, different computational studies are moving towards in-silico analyzes to nd potential candidates that might be effective for inhibiting the activity of SARS-COV-2 proteins.
In the present study, we conducted an in-silico drug repurposing by using natural compounds contained in Moroccan medicinal plants in order to identify appropriate natural inhibitors to SARS-COV-2. For that, molecular Docking was conducted and binding energy was determined against three key targets of the SARS-CoV-2, 3CL pro , PL pro and protein S. Therefore, we further conducted a performed literature analysis to select Moroccan plant species that contain at least three of the selected molecules.

Materials And Methods
Compound selection and ADME screening Pubmed and Google Scholar papers related to natural inhibitors of SARS or MERS coronaviruses were selected. The query used for this search mode was: "coronavirus AND natural compound AND SARS" or "coronavirus AND natural compound AND MERS". After analysis of the articles generated by this search, we selected natural compounds biologically tested and con rmed to possess anti-coronavirus activity.
As the main objective of our study is to select natural compounds that could be orally administrated, we ran an in-silico analysis of absorption, distribution, metabolism and excretion (ADME) to select only molecules that could be orally bioactive. For this purpose, we used three indices that are, oral bioavailability (OB), Caco-2 (Caco-2) permeability, and human drug-likeness (DL), using the Traditional Chinese Medicine Systems Pharmacology database (TCMSP). Effectiveness of these three indices was validated by threshold values OB > 30%, Caco-2 > -0.4, and DL > 0.18, respectively (Hu et al., 2019).

Ligand and receptor preparation
Three-dimensional (3D) structures of PL pro , 3CL pro , and protein S of SARS-CoV-2 were retrieved from Protein Data Bank (http://www.rcsb.org//pdb) in pdb le formats, corresponding to the PBD ID 6w9c, 6lu7, and 6vyb, respectively. These proteins were served as receptors in docking process. Water molecules and ligands that were still attached to the receptors were removed. Using Autodock Tools (1.5.6), polar hydrogen atoms were added to the receptors. Subsequently, the les were saved in pdbqt le format. The ligands three-dimensional (3D) structures were obtained from the PubChem database (http://pubchem.ncbi.nlm.nih.gov). Each ligand's le was downloaded and saved in the sdf le format and converted to pdb using PyMol. Thereafter, AutoDock Tools was used to convert to pdbqt le format.

Molecular Docking
Molecular docking software AutoDock Vina (1.1.2) (Trott et al., 2010) was used to perform proteincompound docking analysis. Using this, the grid box size was set to a dimension (x, y, z) of 50 × 58 × 50, 60 × 70 × 60 and 82 × 98 × 126, and the coordinates (x, y, z) of -11.798, 10.956, 70.020, -26.626, 22.56, 33.809 and 232.215, 189.820, 263.862 for the 3CL pro , PL pro and for the protein S, respectively. Ligands and receptors that have been prepared with the pdbqt le format were copied into the Vina folder and the vina con guration le was typed into notepad, saved with the name 'conf.txt'. Then Vina program was run through command prompt. The results were shown in the output (notepad format) and nally analyzed. All the other vina parameters were kep at their default values.

Plant selection
The medicinal plants selection was conducted in two steps. Based on the results obtained from the ADME screening, only compounds that have been considered to be orally bioactive have been selected.
Thereafter, a search has been launched using Pubmed and Google Scholar to select Moroccan medicinal plants that contain at least 3 molecules from those natural compounds.
As an additional step and using the results obtained from above, plants that have been routinely used as either medicinal plants or used in daily diet in Morocco and also contain at least 5 anti-coronavirus compounds have been described for their medicinal value.

Results And Discussion
Natural compounds reported to be anti-SARS or anti-MERS coronavirus and contained in Moroccan medicinal plants The coronavirus codes for several proteins, some of which are vital for viral entry and replication. The spike protein of coronaviruses facilitates viral entry into the target cells (Hoffmann et al., 2020). In fact, coronavirus cell entry is dependent on the binding of protein S, to a cellular receptor known as ACE2. Two other viral proteins were reported to have essential roles in the replication of the coronavirus. These proteins correspond to the papain type protease (PL pro ) and the 3CL type protease (3CL pro ) (Hoffmann et al., 2020). Therefore, these proteins constitute interesting targets for the development of drugs against Sars-Cov-2.
In the present study, we have carried out a multistep screening process to select Moroccan medicinal plants supposed to contain potent natural inhibitors to the SARS-CoV-2, and which could be used as a strategy for the prevention and the treatment of the COVID-19 while, around the world, the virus is still spreading and cause hundreds of deaths every day worldwide (Scheme 1).
Our study was based on two criteria to select the nal medicinal plants. First, the selected molecules contained in the screened plants should be orally bioavailable. On the other hand, the selected medicinal plants should contain natural compounds susceptible to act as anti-SARS-CoV-2 possessing ideal oral bioavailability and drug-likeness. To do this, natural compounds proved in previous scienti c publications as inhibitors for SARS or MERS coronaviruses have been extracted from PubMed and Google Scholar databases. Subsequently, the obtained molecules have been cross-checked for their existence in Moroccan medicinal plants using a new research on PubMed and Google Scholar. We selected 41 molecules that have been reportedly tested for their antiviral activities with either cell-based experimental systems or enzyme-based system (Table 1).
These molecules were then divided into two groups, one of them contains anti-coronavirus molecules that have been analyzed for their orally absorbable ability using an ADME screening or based on literature. In fact, the anti-viral effects of most of the selected natural molecules have been validated in vitro only. Therefore, to meet the requirement that we have installed as rst criterion for our study, the molecules should be active through oral preparation. For this, we ran an ADME ltration using three indices, oral bioavailability (OB), Caco-2 (Caco-2) permeability, and human drug-likeness (DL), using the TCMSP database. Among the 41 molecules, only 13 compounds have successfully passed this ltering step ( Table 2). The second group is composed of natural compounds that were active against coronavirus but for which the characteristics of oral bioavailability was not available or not appropriate (28 natural compounds). The method developed here is a rapid way to identify natural compounds both contained in Moroccan medicinal plants and also reported to have a high anti-coronavirus activity. The advantage of this approach is that the selected molecules were biologically tested and con rmed for their effectiveness against coronavirus. Furthermore, because of the genetic similarities that exist between SARS or MERS and the new SARS-CoV-2 Park et al., 2016), the selected molecules could have the same e cacy against the novel coronavirus.
We recall here that the selected molecules have been biologically tested against targets from the SARS and MERS coronaviruses, however, the mutations that have been noted between these two viruses and the SARS-CoV-2 could not guarantee the e ciency of the selected natural compounds against the new virus. To overcome this situation, we used molecular docking to determine whether the selected molecules could bind to the 3D structures of the three targets selected for this study (PL pro , 3CL pro , and protein S). In fact, High-resolution crystal structure of the SARS-CoV-2 PL pro , 3CL pro , and protein S have been recently published Osipiuk et al., 2020;Walls et al., 2020). The corresponding les of these structures have been downloaded from the RCSB PDB database. Then, the molecular docking was performed between all the 41 selected molecules and the three targets. Indeed, even if a molecule was reported in the literature to inhibit a speci c target of the MERS or SARS coronaviruses, in our study, all selected molecules were docked against the three targets (PL pro , 3CL pro , and protein S). The results obtained here are summarized in table 1.
The different molecules were divided into several families of secondary metabolites. From the different classes of molecules, avonoids were the most reported natural compounds that were tested positive for their anti-coronavirus activities (24/41 molecules). The molecular docking showed that the binding energies of the different molecules ranged between -4.7 and -8.9 Kcal/mol for the PL pro protein, -5.8 and -9.8 Kcal/mol for the 3CL pro protein, and -5.3 and -10.4 Kcal/mol for the spike protein. Furthermore, while avonoids gave the highest vina scores, furocoumarins showed the lowest vina scores for the three targets (Table 1).
Hopefully, from the molecular docking results, our 13 screened compounds showed abilities to bind to the selected proteins of the novel coronavirus as it was predicted. Moreover, most of these molecules showed high binding abilities to more than one protein and suggest a more pronounced effect for those molecules against the SARS-CoV-2 (Molecules in bold Table 1).

Selection of anti-coronavirus herbal plants
The second criterion on which our study was based is the fact that the selected plants should contain 3 or more of the selected anti-coronavirus natural compounds. As explained before, there are just 13 molecules that have passed the test of the oral bioavailability and which were therefore selected for the next step of the study. Using these molecules and based on the data extracted from Pubmed and Google Scholar databases, we selected for this study 29 Moroccan medicinal plants because they meet this criterion (Table 3). However, in the present work, we chose 8 plants that are supposed to be very promising for the prevention and the treatment of the SARS-CoV-2 and we described them in more details. The selected plants have been chosen because they have been routinely used as either medicinal plants or used in daily diet in Morocco and also because they contain at least 5 potential anti-coronavirus compounds. Interestingly, 4 of these plants contain compounds that might inhibit the three targets of the coronavirus (PL pro , 3CL pro , and protein S) and which are Argania spinosa, Cydonia oblonga, Phoenix dactylifera and Punica granatum. The other plants contain potential inhibitors against either PL pro and/or 3CL pro , and which are Mentha longifolia, Salvia o cinalis, Rosmarinus o cinalis and Portulaca Oleracea (Table 3).
Potential Moroccan plants as Sars-CoV-2 PL pro , 3CL pro , and protein S inhibitors Among the 41 natural molecules screened, 13 compounds which possessed the high Oral bioavailability (Table 2), have been reported to exhibit potential anti-coronavirus activity as inhibitors of the proteins PL pro , 3CL pro , and protein S. Further, among the 29 Moroccan medicinal plants which were found to contain 3 to 6 of these molecules, 8 of them are described below as they might contain direct anti-SARS-CoV-2 molecules. These plants are: Argania spinosa L., Cydonia oblonga, Phoenix dactylifera, Punica granatum, Mentha longifolia, Salvia o cinalis, Rosmarinus o cinalis and Portulaca Oleracea.
Argania spinosa Argania spinosa L. or Argania spinosa L. Skeels, which contains ve potent anti-coroavirus molecules; procyanidin B1 , kaempferol, betulinic acid, quercetin and luteolin, is commonly known as argan tree (Table 3). It is an agroforestry species that belongs to the Sapotaceae family (Guillaume et al., 2019), and it is an endemic species from south-western Morocco (Hebi et al., 2018) where it covers an area of about 320 000 square miles (Charrouf et al., 2011). This species 'genus Argania', is the unique representative of the tropical family Sapotaceae growing in the subtropical zone 'Morocco' (Morton et al., 1987).
As a meaningful indigenous alimentary medicine, A. spinosa is a valuable potential for Moroccans (El Babili et al., 2010). All the different botanical parts of the Argania spinosa like the fruits, wood, leaves, and kernels are exploited for many folk medicine purposes (Khallouki et al., 2017). In fact, the Argan tree based preparations have been considerably used in Morocco for their biological properties for many purposes including among others: diabetes and colopathies (El Babili, et al., 2010), bactericidal and fungicidal remedies, anti-atherosclerotic, hepatoprotective properties, several dermatological indications, rheumatism disease and the treatment of lung infections (Moukal et al., 2004).

Cydonia oblonga
Cydonia oblonga chemical composition has been reported the presence of ve anti-coronavirus compounds including: procyanidin B1, β-sitosterol, kaempferol, betulinic acid and luteolin (Table 3). Cydonia oblonga (Rosaceae family) commonly known as quince, is a fruit of a deciduous tree (Silva et al., 2004). Quince is native to Mediterranean region and Central Asia having a long-term history of medicinal and ethnobotanical use. C. oblonga is considered as one of the most important medicinal plants throughout the world (Sabir et al., 2005). This is a medicinal plant known from ancient times by their health bene cial properties for curing several diseases such as cancer, hepatitis, diabetes and respiratory infections. Likewise, various parts of quince plant are used to cure respiratory disorders such as asthma, cough, and bronchitis (James et al., 2002).
A large number of studies conducted have reported that quince is a good, safe, low-cost and excellent natural source of different classes of phenolic compounds, such as avonols and avone heterosides and caffeoylquinic acids (Márcia et al., 2010). This species possesses various phytoconsitutents including quercetin, procyanidin B2, B3 procyanidin, and 9 kaempferol derivatives (Silva et al., 2001). In addition to this, the seed has been reported to be a rich source of fat soluble compounds that include tocopherol (α-β-γ), sitosterol, stigmastrol, vitamin C, organic acids, citric acid, oxalic acid, fumaric acid, free amino acids, and phenolic compounds (Silva et al., 2004). Therefore, C. oblonga parts used medicinally were leaves, fruits and seeds (Hegedűs et al., 2013).

Phoenix dactylifera
Phoenix dactylifera L. (Family of Arecaceae) is one of the oldest plants cultivated in the Arabian region and in other parts of the world . In Morocco, 4.8 million trees of date palm groves occupy a surface area of more than 48,000 ha (Sedra et al., 2011). Due to their health promoting properties, the fruits of date palm were used as food and as remedy in folk medicine. The phytochemical screening of leaf, fruit, seeds and bark of date palm contains high quantity of secondary metabolites like avonoids, steroids, saponins and tannins (Al-daihan et al., 2012). Date fruit is characterized by a high energy content, carbohydrates (Myhara et al., 2000), lipids, proteins, and are an excellent source of dietary ber and certain essential vitamins and minerals (Khalid et al., 2017).
This richness leads to many in-vitro and in-vivo pharmacological studies as well as the identi cation and quanti cation of different classes of bioactive compounds (Chao et al., 2007) . In our investigation we found that P. dactylifera has been reported to contain ve potent anti-coronavirus molecules which are procyanidin B1 , kaempferol, β-sitosterol, quercetin, and luteolin (Table 3). In the study conducted by Hong et al. (HongYun et al., 2006), the authors reported the presence of thirteen glycosylated avonoids of luteolin, quercetin along with procyanidins at different stages of maturity.
The bioactive compounds of P. dactylifera have gained increased interest among several investigators due to their antioxidant (Biglari et al., 2004), antimutagenic (Vayalil et al., 2002), anti-diabetic (Mard et al., 2010), and anti-in ammatory (Zhang et al., 2013), anti-tumor (Ishurd et al., 2005), as well as cholesterollowering properties and other potential health bene ts such as prevention of cardiovascular diseases and chemoprevention of cancer (Chao et al., 2007) . Moreover, the study conducted by Jassim and Naji, (Jassim et al., 2010) revealed antiviral activity of date pits extract against lytic Pseudomonas phage ATCC 14209-B1, with minimum inhibitory concentration of 10 µg/ml. In light of the above, antiviral studies of Phoenix dactylifera phytochemicals should be extended to other viruses that threaten human health.

Punica granatum
Punica granatum (Pomegranate) is a small tree belonging to the family of Punicaceae. This plant is largely distributed in parts of Asia, North Africa and in the Middle East (Hmid et al, 2017). In Morocco, the pomegranate is cultivated on an area of 5000 ha, which give rise to a yield of 58,000 tons of fruits per year (Oukabli et al., 2004). The fruit of P. granatum can be consumed fresh or after transformation to juices or beverages. P. granatum has been widely used as a traditional medicine for the treatment of microbial infections, respiratory pathologies, dysentery, hemorrhage, and diarrhea (EM et al., 2009). Moreover, the dried pericarp of P. granatum was also reported to cure colitis, headache, acne, and oral diseases (Ricci et al., 2006).
The different parts of the P. granatum contain various phytochemicals with various pharmacological activities. In fact, the chemicals reported in this medicinal plant possess antioxidant properties, antiin ammatory and anti-mutagenic effects, and antiviral, antibacterial, anti-angiogenesis, and anticancer activities (Rahimi et al., 2012;Mestry et al., 2017).
The juice of P. granatum is rich in avonoids including phenolic acids and anthocyanins, and the pericarps contain ellagitannins and tannins (Kim et al., 2002). It should be noted that the juice of P. granatum is obtained by pressing the whole fruits, which results in an enrichment of this juice by polyphenols from the pericarp.
Mentha longifolia HPLC analysis of Mentha longifolia L. highlights their importance as a promising source of ve anticoronavirus ingredients: β-sitosterol, kaempferol, quercetin, luteolin, and hesperetin (  (Elansary et al., 2020). The Mentha genus plants are very popular for humankind since antiquity and is one of the most widely used herbal medicines. Many parts of this genus, including leaves, owers and stems, are used in herbal teas and condiments due to their distinct avor and aroma (Gulluce et al., 2007). In Morocco, Mentha species are widely used as food, medicine, spice, and avoring agents. Contrary to its abundance, Mentha longifolia is less known and rarely used in Europe and was not industrialized (Patonay et al., 2019).
In herbal remedies, M. longifolia L. was reported as an important crop widely consumed due to its healthpromoting properties, for the treatment of many infectious and in ammatory diseases as well as for respiratory and gastrointestinal disorders (Farzaei et al., 2017). Therefore, many bioactive molecules present in M. longifolia are in part responsible for these consequent therapeutic bene ts. As well, the phytochemical characterization of this medicinal plant revealed a vast variety of natural components that have been suggested to be responsible for the pharmacological potent of M. longifolia. These molecules include avonoids, terpenoids, phenolic acids, sesquiterpenes cinnamates, and ceramides, (Farzaei et al., 2017). As a result, various pharmacological investigations for M. longifolia extracts have been con rmed their potential effects, as antioxidant (Bahadori et al., 2018), anti-in ammatory (Karimian et al., 2013), anti-parasitic (Farzaei et al., 2017), cytotoxic and antimicrobial (Elansary et al., 2020) agents. Moreover, is has been shown that avonoids from M. longifolia such luteolin-7-O-glycoside, luteolin-7,3'-O-diglycoside, quercetin-3-O-glycoside and kaempferol-3-O-glycoside are potent inhibitors of some microorganisms that may be causal agents of human urinary, intestinal and respiratory tract infections (Bendjeddou et al., 2009). This herb exhibited therapeutic bene ts as antiviral (El-badry et al., 2010) as well, with high HIV 1 inhibitory properties.

Salvia o cinalis
Sage (Salvia o cinalis L.) which is named in Morocco "Salmia", is a potent aromatic and medicinal plant used in folk medicine, phytopharmaceutical preparations and aromatherapy (Hamidpour et al., 2014). The sage is rich in various secondary metabolites such as phenolic and volatile compounds. Furthermore, S. o cinalis L. possesses different biological properties such as antioxidant (Ghorbani et al., 2017), antiin ammatory activities (Rodrigues et al., 2012), and reported to have antitumor (Garcia et al., 2016), antibacterial (Stagos et al., 2012), and antifungal effects (Badiee et al., 2012). As well, the aerial parts of S. o cinalis have been also provided to act as potent antiviral against vesicular stomatitis virus (Tada et al., 1994). Moreover, methanolic extract of sage showed antiviral activity against herpes simplex, Sindbis and polio viruses, with minimum inhibitory concentration of 50 µg/ml (Mouhajir et al., 2001).

Rosmarinus o cinalis
Rosmarinus o cinalis L. (Lamiaceae family), also known as rosemary, is an edible, evergreen, medicinal plant. Native species of this herb spread spontaneously in the Mediterranean area (Carrubba et al., 2020)]. This plant is exploited in traditional medicine for its antioxidant activity ascribable to bioactive compounds (Andrade et al., 2018). In fact, there are many studies on the usefulness of bioactive substances of rosemary plants on human health as it was used to treat arthritis, diabetes, memory loss and hair restoration (El Omri et al., 2010). Rosemary has a great potential due to secondary biomolecules which have been characterized as antidiabetic (Yen et al., 2015), antimicrobial (Almela et al., 2006), spasmolytic, carminative, hepatoprotective, antiviral and anticarcinogenic agents (Bozin et al., 2007), and reported also to have antihyperglycemic, anti-in ammatory and antiproliferative activities (Oliveira et al., 2019). Some rosemary extracts have been shown strong inhibitory effect against human respiratory syncytial virus infection (Shin et al., 2013). Furthermore, an in vitro antiviral effect, against herpes simplex virus types 1 and 2, have been proved by aqueous extract of this species (Nolkemper et al., 2006).
In our investigation, we found that Rosmarinus o cinalis could be a potent anti-SARS-CoV-2 as it contains molecules such as kaempferol, hesperetin, quercetin, luteolin and betulinic acid (Table 3).

Portulaca oleracea
Portulaca oleracea L. belongs to the family of Portulacaceae. This plant which is largely distributed in tropical and temperate regions worldwide, has been widely used in traditional medicine to treat different diseases including severe in ammations, respiratory problems, and headaches (Zhuet al., 2010;Iranshahy et al., 2017). Bioactive molecules could be of different nature as this plant is rich in avonoids, terpenoids, alkaloids, organic acids, and vitamins (Zhou et al., 2015). This annual succulent plant is used in several countries as soups and salads (Iranshahy et al., 2017 ;Miao et al., 2019).
While the aerial parts were used to cure in ammations of the urinary system, intestinal ulcers, high cholesterol level, cough and was also used for its anti-oxidant and anti-microbial properties (Dan et al., 2006). Oral administration of P. oleracea seeds was used for the treatment of respiratory problems, spermatorrhea and fevers in Spain as it was stated by Abulcasis (Al-Zahrawi, Arab-Andalusian physician (936-1013)) (Iranshahy et al., 2017). In a recent study conducted by Li et al. (Li et al., 2019), the authors reported an anti-IAV (in uenza A virus) of the water extract of P. oleracea and recommended the use of this extract as an herbal diet for the prevention and treatment of H1N1 infection at an early stage.
In Africa, P. oleracea is used to cure different diseases including gastric problems, diabetes, hypertension, spastic paralysis, etc (Iranshahy et al., 2017). It is also used for the preparation of salad In Morocco by mixing its shoots with garlic, green olives, olive oil and some spices (Benkhnigue et al., 2010). In Morocco, P. oleracea is also used as an energizing food (Bachar et al., 2016).
Studies of acute toxicity on mice have showed that P. oleracea is moderately toxic with LD 50 value of 1853 mg/kg (Iranshahy et al., 2017). Moreover, no adverse effects have been detected on most clinical trials.

Conclusion
Alternative Medicine has accumulated thousand-of-year's experiences to treat pandemic viral infections. The SARS-CoV-2 is spreading at a rate and scale much worse than previous emerging coronavirus SARS or MERS, and continue to become a global burden on human health. So, there is an urgent need to nd some e cacious treatments against SARS-CoV-2 infection. Providing complementary or alternative treatments are still urgently needed to manage COVID-19 disease.
In brief, this study offers a powerful, integrative network-based pharmacology methodology for rapid identi cation of potent naturals compounds against the SARS-CoV-2. As well, among 41 natural molecules screened, the molecular docking results showed 13 molecules to be orally bioactive and exhibiting potential abilities as inhibitors of the proteases PLpro, 3CLpro, and protein S targets of the novel coronavirus. Moreover, most of these molecules showed high binding abilities to more than one protein and suggest a more pronounced effect for those molecules against the SARS-CoV-2. Moreover, 29 Moroccan medicinal plants were found to contain 3 to 6 of these molecules including, kaempferol, quercetin, hesperetin, luteolin, procyanidin B1, aloe emodin, betulinic acid and β-sitosterol. From the 29 plants, 8 of them have been chosen as they might contain direct anti-SARS-CoV-2 molecules including: Argania spinosa L., Cydonia oblonga, Phoenix dactylifera, Punica granatum, Portulaca Oleracea, Mentha longifolia, Salvia o cinalis, and Rosmarinus o cinalis L.
Based on these results, our study reports for the rst time a selection of Moroccan Medicinal plants that could contain direct anti-SARS-CoV-2 compounds by targeting the 3CLPro, PLpro proteases and the protein S of this virus.

Declarations
Funding: Not applicable.
Competing interests: The authors declare no competing interests.
Ethics approval: Not applicable.
Availability of data and material (data transparency): Not applicable.
Code availability (software application or custom code): Not applicable.
Author  PL pro : papain-like protease; 3CL pro : 3C-like protease; protein S: Spike protein The 13 compounds that have been successfully passed the ADME screening are in bold