Ethnobotanical, Phytochemistry, and Pharmacological Activity of Onosma (Boraginaceae): An Updated Review

The genus Onosma belongs to the Boraginaceae family and contains over 230 species. The present review sheds light on the ethnopharmacology, phytoconstituents, bioactivity, and toxicology of the Onosma species from previous investigations. Furthermore, the paper also highlights the unresolved issues for the future investigations. The review included previous studies of the genus Onosma available from Google Scholar and Baidu Scholar, Science Direct, SciFinder, Wiley Online Library, and Web of Science. Until now, more than 200 chemical compounds have been detected from the genus Onosma, including naphthoquinone (33), flavonoids (30), hydrocarbon (23), phenolic (22), ester (17), alkaloids (20), aromatics (12), carboxylic acid (11), fatty acids (9), terpenoids (10), while the most important ones are rosmarinic, ferulic, protocatechuic, chlorogenic, caffeic, p-coumaric acids, and apigenin. The Onosma species are reported as traditional medicine for wound healing, heart disease, and kidney disorders, while the pharmacological investigations revealed that the extracts and the phytochemicals of Onosma species have different therapeutic properties including antioxidant, enzyme inhibitory, antitumor, hepatoprotective, antiviral, anti-inflammatory, and antimicrobial actions. The summarized knowledge in this review provides valuable ideas for the current and future drug discovery and a motivation for further investigation on the genus Onosma.


Introduction
The genus Onosma comprises more than 230 species across the globe. The Asian continent has the highest share in terms of Onosma species existence [1], most of which are represented in Turkey by 88 species [2] followed by countries such as Iran and China by 58 [3] and 29 species [4], respectively. Iraqi Kurdistan represents 32 species of the genus Onosma based on the latest botanical studies [5]. However, recent investigations have revealed seven new species of Onosma in Asian countries, particularly Iran [6]. Continuous exploration on the ethnobotanical and plant taxonomy studies led to the discovery of several new Onosma species across our continent [7,8]. Some Onosma species have been well studied pharmacologically than others, and the most common ones are shown in Figure 1. The ethnobotanical and in vitro studies have revealed that most of this Onosma species has many medicinal capabilities such as sedatives [9], antioxidant [10], antiinflammatory [11], gastric disorders [11], antithrombotic [12], wound healing [13], Alzheimer [14], enzyme inhibitory [15], anti-tumor [16], anti-viral [17], antifungal [18], and COVID-19 curatives [19] (Figure 2).
The past decades have showed numerous new records, phytochemical, and pharmacological studies of the new Onosma species, and the published two reviews were found lacking integrity as they contained incoherent data with skipping of some biological activities of the genus Onosma [23,24]. Therefore, in order to provide theoretical reference for further research and to comprehensively understand the medicinal applications of this genus, this article systematically reviewed traditional uses, chemical constituents, pharmacological activities, and clinical applications of the Onosma species based on the published literature. The ethnobotanical and in vitro studies have revealed that most of this Onosma species has many medicinal capabilities such as sedatives [9], antioxidant [10], anti-inflammatory [11], gastric disorders [11], antithrombotic [12], wound healing [13], Alzheimer [14], enzyme inhibitory [15], anti-tumor [16], anti-viral [17], antifungal [18], and COVID-19 curatives [19] ( Figure 2).

Methodology
The authors independently extracted systematic literature data search from seven electronic databases: Google Scholar, PubMed, Science Direct, Sci-Finder, Wiley Online Library, Web of Science, and Baidu Scholar. The scientific name "Onosma" was searched to cover all relevant information from April 1800-2022, including folkloric uses,

Traditional Use
The folkloric use of many Onosma species as medicinal plants for different health problems by local ethnic groups in several countries such as Iraq, Turkey, Iran, China, and India roots back to hundreds of years ago. Almost all plant parts, such as leaves, roots, underground parts, flowers, and the whole plant of this genus species are reported to have a broad range of therapeutic potentials (Table 2) [32,33]. Species such as Onosma alborosea have traditionally been utilized by Iraqi Kurdistan populations as a remedy for sedative, heart diseases, and kidney disorders through ingesting its aerial part extracts prepared by aqueous extraction methods [33]. The aerial parts of Onosma orientalis has been macerated with hot water for treating sedatives by Kurdish nations living in Iraqi Kurdistan [33]. Furthermore, the O. armeniacum K. has been used as Turkish folkloric medicine for healing wounds, peptic ulcers, burns, dyspnea, hoarseness, hemorrhoids, and abdominal pains through methods of cooking and filtration of its roots with butter [34]. The extracts (oil and aqueous extracts) of O. argentatum and O. chlorotricum has been traditionally utilized in Turkey and Iran (Lorestan province) for the treatment of wounds and cutaneous injures [35,36]. Furthermore, the root extracts of O. hispidum Wall. have been used traditionally by the Iranian nation as curatives for headache, wounds, insect stings, bits, and

Traditional Use
The folkloric use of many Onosma species as medicinal plants for different health problems by local ethnic groups in several countries such as Iraq, Turkey, Iran, China, and India roots back to hundreds of years ago. Almost all plant parts, such as leaves, roots, underground parts, flowers, and the whole plant of this genus species are reported to have a broad range of therapeutic potentials (Table 2) [32,33]. Species such as Onosma alborosea have traditionally been utilized by Iraqi Kurdistan populations as a remedy for sedative, heart diseases, and kidney disorders through ingesting its aerial part extracts prepared by aqueous extraction methods [33]. The aerial parts of Onosma orientalis has been macerated with hot water for treating sedatives by Kurdish nations living in Iraqi Kurdistan [33]. Furthermore, the O. armeniacum K. has been used as Turkish folkloric medicine for healing wounds, peptic ulcers, burns, dyspnea, hoarseness, hemorrhoids, and abdominal pains through methods of cooking and filtration of its roots with butter [34]. The extracts (oil and aqueous extracts) of O. argentatum and O. chlorotricum has been traditionally utilized in Turkey and Iran (Lorestan province) for the treatment of wounds and cutaneous injures [35,36]. Furthermore, the root extracts of O. hispidum Wall. have been used traditionally by the Iranian nation as curatives for headache, wounds, insect stings, bits, and inflammatory diseases, while its flowers have been ingested for cardiovascular problems [37]. Moreover, same species has been used as a dye and as a substitute for alkanet [38]. The O. bracteatum Wall. extracts have been reported as traditional herbal medicine as a tonic agent for improving the body's immune system with enhancing regulation of urine output [39]. The O. bracteatum Wall. also has been used as remedy for asthma, respiratory problems, tonic, alterative, demulcent, diuretic, spasmolytic, rheumatoid arthritis, diuretic, and antileprotic in India, Nepal, Kashmir, and northwestern Himalayas countries [40,41]. The root extracts of O. sericeum have been traditionally used in cream preparations for skin injuries and burn scar treatments in Adıyaman, Turkey [13].
The O. microcarpum has traditional medicine record for the healing of wounds and burn scars by rural residents of Il'yca district, Erzurum, Turkey [36,42]. The leaf aqueous extracts of O. echioides DC. are prepared for children suffering from constipation and metabolic disorders. Meanwhile, its flowers are reported as a cordial and as a stimulant for orthopedic and cardiac problems [43]. The dried roots of O. paniculata have a traditional medicinal record in Chinese herbal medicine for curing several human diseases including tumors [44]. The O. aucheriana is another species with traditional medicinal usage for itchiness, leucoderma, bronchitis, abdominal pain, strangury, fever, wounds, burns, and urinary calculi. Meanwhile, its flowers have been highlighted as stimulants and cardiotonics, and its leaf extracts have been ingested as laxatives, purgatives, and as wound curatives [45]. Out of more than 230 species of Onosma, only 12 species were reported in traditional medicines as herbal medicine until now. This could be due to the large geographical distribution of the Onosma species and lack of scientific interest in the past, but this number is expected to increase in upcoming years as the researchers extensively search and investigate for other Onosma species after discovering some interesting phytochemical and pharmacological potentials of this genus in recent years.  [45] The traditional names, country, ingested parts, and medicinal purposes of the genus Onosma are listed in Table 2.

Toxicity In Vivo Experiment
The chloroform and ethanolic extracts of O. aucheranum, O. isauricum O. sericeum, O. tauricum, and O. tauricum were safe in the administered doses from 100 mg/kg to 200 mg/kg based on the assessment of acute toxicity in the carrageenan-induced paw edema experiment as no abnormality in the morbidity nor mortality was recorded after 24 hours post treatment [73]. Furthermore, the 100, 200, 300, and 600 mg/kg of the MeOH of O. mutabilis administration to rats showed no changes in the appearance, behavior, and feed intake of the rats in a 7-day experiment [16]. Moreover, by the tarsal toxicity test, researchers have shown the acaricidal activity of the root extracts of O. visianii experimented against Tetranychus urticae mites in bean plants (P. vulgaris var. Carmen) after 24 h (considered as acute toxicity), which caused significant mortality of T. urticae adults with lethal doses 83.2 and 112.6 µg·cm causing 50% (LD 50 ) and 90% (LD 90 ) inhibition of oviposition, respectively. However, at 5 days (considered as chronic toxicity) from the start of the test, the lethal dose LD 50 was more than 30 times lower (2.6 µg·cm −2 ) as a function of time used in the LD 50 calculation [60]. Over the last two decades, several Onosma species have been tested for their toxicity to laboratory animal models. A study on toxicity of the bark extracts of O. echioides roots to Sprague Dawley rats (140 ± 10 g body weight) was performed and reported significant improvement in the body weight, food consumption, water intake, serum glucose, hematology, and biochemistry of rats with no adverse effect at a fixed dose [74].

Genotoxicity and Mutagenicity
Through the Allium-test, significant genotoxic effect from aqueous extracts of O. stellulata roots and aerial parts were observed in mitosis at meristematic cells of onion. Although the aerial parts showed significant genotoxicity after 4-h treatment (mitotic index was 2, 79%, vs. 9, 18% for control), but the root aqueous extracts had higher genotoxic effects. Genotoxic effects included changes in the structure of chromosomes (conglutination, spirality), and cytotoxic reaction and certain differentiation in the cell cycle, which were found to be in correlation with duration of treatment and solution concentration [75]. A genotoxic study by Allium anaphasetelophase assay reported that the safety of the ethanolic extract of O. aucheriana aerial parts at lower dose (62.5 mg/mL) had no toxic or genotoxic effects, while the higher dose (500 mg/mL) showed significantly the highest genotoxic effect including chromosomal aberrations, cells with multipolarity, cell bridges, and vagrant chromosomes (24.4%), cell fragments, and mitosis entrance [76]. In vivo genotoxic study of methanolic extracts of O. sericea and O. stenoloba at different doses (25,50,100,200, and 400 µg/mL) against EMS-induced DNA damage in the flies and larvae of the wild-type strain of Drosophila melanogaster showed the absence of genotoxic effect of O. sericea and O. stenoloba at concentration 80 mg/mL. Furthermore, significant antigenotoxic effects reported after dual treatment with 80 mg/mL of both plant extracts plus EMS (ethyl methane sulfonate) caused significant decrease in DNA damage (with over 80% reduction) [15]. By using Ames assay, the antimutagenic potential of ethanolic extract of O. bracteatum has been reported against sodium azide and 2-aminofluorene mutagenicity in Salmonella typhimurium in TA100 strain (-S9 mix) as it displayed significant inhibition rate (82.30% at 250 mg/0.1 mL/plate), showing strong modulation of genotoxicity of base-pair substitution mutagen sodium azide when compared to NPD (frameshift mutagen) in TA98 tester strain. The O. bracteatum extracts showed significant antimutagenicity activity for preincubation mode than in co-incubation approach without -S9 in both TA100 and TA98 [77].

Cytotoxicity Activity
For the past decades, several studies have confirmed the traditional usage of the Onosma species as cytotoxic agents, and mammalian cancer cell division was inhibited by its extracts and isolated compounds [45,55,60].
The  [84]. Furthermore, the hydrochloric root extracts of O. dichroanthum Boiss. roots have shown significant anticancer actions against gastric cancer cells [11]. Moreover, O. paniculata has shown notable cytotoxicity activity against a number of cancer lines and linked their action with its ability to accelerate apoptosis [60]. The 50 µg/mL ethanolic extract from aerial parts of O. sericeum exhibited significant cytotoxicity activity against the breast cancer cells (MCF-7) with significantly decreased cell viability (28.76 ± 11.31%) [13]. The petroleum ether and aqueous extracts of O. hispidum roots have shown significant anticancer actions against HepG2 liver cancer cell lines [85]. 9.5. Enzyme Inhibitory Activity 9.5.1. Antidiabetic Activity A literature search revealed multiple research works that confirmed the anti-diabetics properties of Onosma species as the in vitro antidiabetic activity of Onosma species was reported based on its inhibitory potentials on α-amylase and glucosidase enzymes. The ethyl acetate extraction of aerial parts of O. gigantea showed higher α-amylase and glucosidase inhibitory activity (15.98 and 1.07 µmol/g) than that (410.50 and 6.75 µmol/g) and (1320.53 and 5.16µmol/g) of methanol and water extracts, respectively [53]. The α-amylase inhibitory activity from MeOH extracts of O. aucheriana and O. sericea were reported higher (2.50 and 2.51 mg/mL, respectively) than that (3.15 mg/mL) of O. frutescens [49]. The ethyl acetate extraction of O. ambigens aerial parts showed stronger α-amylase inhibitory activity (IC 50 : 2.64 mg/mL) than that (2.98 and 16.34 mg/mL) for methanol and water extracts, respectively [30]. The methanol extracts of O. lycaonica and O. papillosa aerial parts exhibited significant α-amylase inhibitory concentration (IC 50 : 2.57 and 2.40 mg/mL) and glucosidase inhibition (IC 50 : 2.60 and 2.61 mg/mL), respectively [48]. The ethyl acetate extract of O. pulchra aerial parts showed higher α-amylase inhibitory activity (2.40 mg/mL) than that (5.47 and 19.23 mg/mL) of methanol and water extracts, respectively [14]. The aerial part extraction of O. rigidum showed higher glucosidase and lower α-amylase enzyme inhibitory activity than that of O. trapezuntea extracts [50]. The MeOH aerial extracts of O. stenoloba exhibited higher α-amylase and lower glucosidase inhibitory activity (0.89 and 43.47 mmol/g) than that (1.26 and 33.38 mmol/g) of O. sericea, respectively [15]. The hydroalcoholic extract of the aerial part of O. Dichroanthum was reported to have antidiabetic and anti-neuropathy properties based on its ability to down regulation of the MDA and Glutathione levels in homogenized tissues of brain and liver in a rat experiment [86]. The petroleum ether, chloroform, and methanol extracts of O. hispidum wall roots have shown significant anticancer actions with inhibitory percentages reported as 70, 58, and 50%, respectively. Meanwhile, the superiority of petroleum ether extracts has been linked with its higher polyphenolic contents [85].

Anti-Tyrosinase Activity
Tyrosinase enzymes are well-known for their participation in melanin biosynthesis, and hypersecretion accompanied by accumulation of melanin pigments may lead to hyperpigmentation disorders and photo carcinogenesis [87]. The ethyl acetate partition of aerial parts of O. gigantea showed higher tyrosinase inhibitory activity (0.15 µmol/g) than that (0.49 and 10.48µmol/g) of methanol and water extracts, respectively [53]. The tyrosinase inhibitory activity of methanol extracts of O. aucheriana aerial parts was higher (2.19 mg/mL) than that (2.23 and 2.40 mg/mL) of O. sericea and O. frutescence, respectively [49]. The methanol partition of aerial parts of O. ambigens showed higher tyrosinase inhibitory activity (2.81 mg/mL) than that (3.79 and 4.45 mg/mL) of water and ethyl acetate extracts, respectively [30]. Onosma lycaonica and O. papillosa aerial extracts have been reported as tyrosinase inhibitors with IC 50 values 2.20 and 2.05 mg/mL, respectively [48]. The methanol extracts of O. pulchra aerial parts showed higher tyrosinase inhibitory activity (2.47 mg/mL) than that (3.77 and 4.35 mg/mL) of ethyl acetate and water extracts, respectively [14]. The aerial part extracts of O. rigidum and O. trapezuntea showed comparable tyrosinase inhibitory potentials activity [50]. A previous study also reported modest tyrosinase inhibitory activity (136.35 and 135.68 mg/g) for methanol extracts of aerial parts of O. sericea and O. stenoloba, respectively [15]. The ethyl acetate extracts of O. isauricum showed higher tyrosinase inhibitory activity (19.96 mg/g kojic acid equivalents) than that (15.33 and 14.83 mg/g) of methanol and water extracts, respectively [83].

Anti-Lipoxygenases Activity
Lipoxygenases enzymes are known to catalyze oxidation of polyunsaturated fatty acids (linoleic, linolenic, and arachidonic acid) yielding hydroperoxides. Such reactions may be favorable, but also lipoxygenases may interact undesirably. Aromatic compounds are major yields of lipoxygenase reactions that can interfere with food properties, mainly during long-term storage. Lipoxygenase's impact on unsaturated fatty acids may lead to off-flavor/off-odor formation, leading to food spoilage. Furthermore, lipoxygenase is considered as an important enzyme in stimulation of inflammatory reactions in the human body by playing as a key factor in the biosynthesis of many bio-regulatory compounds such as hydroxyeicosatetraenoic acids (HETEs), leukotrienes, lipoxins, and hepoxylines that were linked to major diseases such as cancer, stroke, and heart and brain diseases [88]. Therefore, searching for natural products that could target this enzyme has become a continuous scientific mission to prevent such diseases. The onosmins A

Parasiticidal Activity
The antileishmanial activities of the crude methanol extract of O. griffithii and its fractions were statistically significant (p < 0.05) against the Leishmania promastigotes, Pakistani isolates in comparison with the standard drug called Pentamidine [17].

Anti-Inflammatory and Analgesic Activity
The chloroform extracts from roots of O. aucheranum, O. isauricum, and O. tauricum showed 28.0%, 34.3%, and 15.6% inhibitory action in p-benzoquinone-induced abdominal constriction experiment, while the ethanol extracts of O. isauricum and O. sericeum demonstrated inhibition action of 24.6% and 27.5%, respectively, in the same test. The chloroform and ethanol extracts of O. isauricum and ethanol extract of O. sericeum also showed significant inhibitory activity, ranging between 12.3-27.3%, 10.5-25.3%, 8.2-22.6%, respectively, in a carrageenan-induced hind paw edema model at 100 mg/kg dose without gastric damage, and the activity was very comparable to indomethacin (32.0-38.4% inhibition) as a standard sample [73]. The chloroform extracts of O. aucheranum and O. isauricum and ethanolic extracts of O. isauricum and O. sericeum exhibited notable antinociceptive activity; 28.0%, 34.3%, 24.6%, and 27.5% inhibition, respectively, against p-benzoquinoneinduced abdominal contractions, without induction of any sign of gastric lesion [73]. The methanol extraction of aerial parts of O. bracteatum showed potent analgesic activity by inducing significant increase in the latency period in a dose-dependent manner at different doses at 1, 2, and 3 h (with superiority of 500 mg/kg i.e., 258.9% (p < 0.05) at 3 h) post feeding, respectively, in a tail flick test. Furthermore, the methanol extract of O. bracteatum showed significant analgesic effect at 500 mg/kg body weight dose by inducing 54% inhibi-tion (p < 0.05) in comparison to 45.9% inhibition activity for standard Diclofenac sodium (5 mg/kg body weight) [89].

Gastric-Ulcerogenic Activity
The chloroform and ethanol extracts from O. aucheranum, O. isauricum, O. sericeum, and O. tauricum roots did not cause any gastric lesions or bleeding in the stomach of mice in a 48-h experiment [71].

Treatment and Prevention of COVID-19
The Onosma phytochemicals, deoxyshikonin, 3-hydroxy-isovaleryl shikonin, propionyl shikonin, and acetyl shikonin showed significant binding affinities for the Mpro enzyme based on the molecular docking studies using two distinct approaches, in which a SiteMap module of Maestro was used to detect the possible ligand binding sites for the Mpro enzyme. Docking simulations and molecular mechanics suggest that shikonin derivatives might be effective anti-SARS-CoV-2 compounds [19].

Conclusions
Application of natural products and their metabolites as chemically diverse starting building blocks has been a major driving force in drug discovery over the last century. However, the use of natural products is not linked only to the modern era, as most folkloric medicines have plant-derived extracts. Moreover, the technological advancement and new technical development for isolation and identification of the natural bioactive compounds in herbs have motivated scientists to investigate and use them as nutrients and nutraceuticals, as well as curatives.
Several biological activities were reported from Onosma compounds and extracts, including, Genotoxicity and Mutagenicity, antifungal, antibacterial, antioxidant, anticancer, antidiabetic, anti-Alzheimer, anti-tyrosinase, anti-lipoxygenases, parasiticidal, anti-inflammatory, and gastric-ulcerogenic activities. Finally, despite the fact that rosmarinic acid is reported as the most detectable compound in the Onosma species, it was not found in other species such as O. echioides, O. hookeri, O. heterophylla, and O. erecta, requiring further investigation for more confirmation by profiling many other species for comparison.

Conflicts of Interest:
The authors declare no conflict of interest.