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Integrative & Complementary Medicine
Daucus carota L., a member of the Apiaceae family, comprises 13 subspecies, with one being cultivated (D. carota L. ssp. sativus (Hoffm.) Arcang.) and the remaining being wild. Traditionally, the wild carrot has been recognized for its antilithic, diuretic, carminative, antiseptic, and anti-inflammatory properties and has been employed in the treatment of urinary calculus, cystitis, gout, prostatitis, and cancer.
- Daucus carota
- wild carrot
- terpenes
- anticancer
- anti-inflammatory
- antimicrobial
1. Introduction
Daucus carota belongs to the family Apiaceae or Umbelliferae and is part of the Daucus genus, which is a polymorphic taxon of multiple species and subspecies [1]. This family is characterized by aromatic, flowering, and celery/parsley-like plants that include edible as well as toxic species. Daucus carota L., commonly known as carrot, is classified into twelve subspecies; D. carota ssp. sativus (Hoffm.) Arcang. (the most well-known variety) and D. carota ssp. boissieri (Schweinf.) H. A. Hosni (red carrot) are the cultivated and edible varieties [2]. The wild subtypes of the carrot include the subspecies carota, maritimus, major, maximus, gummiferi, hispanicus, commutatus, fontanesii, and bocconei [3]. Selective breeding of an ancestral wild form of carrots, D. carota ssp. carota, over the centuries led to the origination of a cultivated form of D. carota, later made to be known as D. carota ssp. sativus [4]. Most of the available literature focuses on this specific subspecies, and it has been a topic of interest for researchers since the day of its cultivation. Differentiation among D. carota L. subspecies is difficult as the carrot is an outcrossing species, and both cultivated and wild carrot samples coexist, thus presenting the possibility of hybrids’ formation. Nonetheless, Thellung classifies the subspecies into two groups, eucarota and gummiferi, each classified into five more subspecies. The eucarota group includes the subspecies sativus, carota, maritimus, major, and maximus; these plants are mostly annual or biennial. Plants of the gummiferi group, on the other hand, are perennials and include the subspecies commutatus, hispanicus, fontanesii, bocconei, and gummifer [3], among others.
The wild carrot, commonly known as Bird’s Nest, Bishop’s Lace, and Queen Anne’s lace [15], is generally a biennial plant (around 1 m height) with distinctive clusters of tiny white flowers that bloom during warm seasons. Unlike the cultivated carrot, the wild carrot has a thin tap root, hairy stems, two- to three-pinnate leaves, pinnate bracts below a concave umbel, when fruiting, and spiny fruits [1]. Its flowering period spans from May to September [16].
It is important to mention that due to the similarities in their appearances, incidences of confusion have been observed between D. carota and poison Hemlock (Conium maculatum), which is infamously linked to the death of the Greek philosopher Socrates [17,18]. Thus, providers and consumers should be able to identify and distinguish between the two plants. For example, D. carota stems and leaves are hairy, whereas Conium maculatum stems are smooth and display purple blotching. Regarding the aerial parts, D. carota has a purple/red flower at the center of the umbel, absent in Conium maculatum, and the umbels in D. carota appear flatter, resembling an umbrella in Conium maculatum. Finally, only D. carota demonstrates three-pronged bracts at the base of the flower/umbel. Despite their similar fern-like leaves, extreme caution should be exercised when identifying them [19].
2. Ethnopharmacological Use of Daucus carota
About 300,000 species of higher plants have been identified worldwide, of which 17,810 species have been documented by The Royal Botanic Gardens, Kew, as medicinal plants (State of the World’s Plants, 2016). According to the World Health Organization (WHO), eighty percent of Africans utilize different forms of herbal medicine [21,22]. The global annual market of these herbal products is estimated at USD 60 billion (WHO, 2002). In China, herbal medicine played a significant role in containing and treating the 2004 severe acute respiratory syndrome (SARS) epidemic [23].
The lesser-known subspecies, wild carrots, are no less important subtypes and have been utilized for various indications. It was first described in the third century BCE by the ancient Roman Diphilus of Siphnos to possess diuretic properties and by Pliny the Elder for its aphrodisiac effects [27]. According to “The Encyclopedia of Medicinal Plants”, the wild carrot is a very beneficial plant that possesses hepatoprotective, diuretic, and detoxifying properties [28]. An infusion of its leaves prevents kidney-stone formation, treats existing stones, combats cystitis, promotes the pituitary gland release of gonadotrophins, and treats parasitic infections [12,28]. It presents itself as an effective remedy for numerous digestive, kidney, bladder, and menstrual ailments, as well as dropsy, flatulence, and edema [5,11,12,13,29,30,31,32]. The Romans were known to use the wild carrot as a component for contraception, a potent emmenagogue and an inhibitor of implantation [33]. Additionally, the plant was known as the traditional “morning after” contraception through the stimulation of the uterus [12,33,34]. Moreover, Duke et al. reported that the wild carrot exhibits carminative, diuretic, emmenagogue, and anthelmintic properties [35]. The seed oil has also been used in anti-wrinkle creams [36]. In European and Middle Eastern folk medicine, wild carrot oil is used as an antiseptic and anti-inflammatory therapy for prostatitis and cystitis [5,11,12,13], diabetes mellitus, and gastric ulcers, as well as for myorelaxation [37].
Wild carrot is consumed in salads as part of the Mediterranean diet and is used as a food additive in some recipes [38]. People eat its young taproot cooked, consume its flower umbels after French frying, and use its seed oil as a flavoring agent in beverages and food products [39]. In Lebanese folk medicine, the plant is used for protection against hepatic diseases and the treatment of diabetes, gastric ulcers, muscle pain, and cancer. Professor Nehme, in his book the ‘Wild Flowers of Lebanon’, mentioned that the aromatic seeds of the wild carrot were used as a vermifuge, a diuretic, an antidote for snake bites, and for sterility [40]. Traditional medicine presents D. carota, whether cultivated or wild, as a highly beneficial plant with promising potential for treating various ailments.
3. Phytochemistry and Bioactive Compounds/Chemical Composition
To better understand and characterize the medicinal benefits of the wild carrot, a phytochemical investigation is warranted. Numerous scholars have conducted extensive studies on the different D. carota subspecies to identify and characterize their bioactive constituents. As illustrated in Table 2, terpenoids and phenolics emerge as two significant chemical classes identified, with the terpenoids further classified into monoterpenes (e.g., α-pinene and geranyl acetate), sesquiterpenes (e.g., humulene and carotol), diterpenes (e.g., phytol), triterpenes (e.g., squalene), and tetraterpenes (e.g., α-carotene). Phenolics encompass phenylpropanoids, flavonoids, and tannins.
Table 2. Classification of different classes of chemical compounds.
| Class | Types | Examples |
|---|---|---|
| Terpenoids | Monoterpenes | Geraniol, Limonene, α-Pinene, β-Pinene, Sabinene, α-Terpinene, β-Myrcene, Geranyl acetate, Linalool, and α-Thujone |
| Sesquiterpenes | Bergamotene, Humulene, Nerolidol, Selinene, Farnesol, Germacrene, Carotol, Caryophyllene, β-Himachalene, and β-Bisabolene | |
| Diterpenes | Phytol, Vitamin A1, and Cembrene | |
| Triterpenes | Squaline, Saponins, and Ginsenoide | |
| Tetraterpenes | Carotenoids (e.g., α-carotene, β-carotene, lycopene) and Xanthophylls (lutein) | |
| Phenolics | Phenylpropanoids | Apigenin, Quercetin, Myristicin, and Methylisoeugenol |
| Flavonoids | Luteolin, Apigenin, Quercetin, Myristicin, and Kaempferol | |
| Tannins | Gallic acid and Ellagic acid |
As is evident in Table 3, D. carota subspecies have proven to be rich in various chemical components, with some being familiar and well-studied while others are new and worth further attention. In particular, the monoterpenes α-pinene, geranyl acetate, and sabinene, along with the sesquiterpene carotol, stand out as the most prominent constituents in different D. carota subspecies, exhibiting variable percentages. These compounds are noteworthy for their diverse pharmacological properties, including anti-inflammatory, antibacterial, and antifungal activities [51,52,53,54,55,56,57,58,59,60,61,62,63]. Although the country of origin and the plant organ differ, most of the components are shared among all subspecies, with some exceptions that are clearly evident.
Table 3. Summary of the main chemical components of different Daucus carota subspecies from different countries of origin (percentages > 3% were reported).
| Daucus carota ssp. | Plant Organ | Country | Main Components | References |
|---|---|---|---|---|
| carota | Umbels | Lebanon | β-2-himachalen-6-ol (33%), α-longipinene (3.22–15.87%), methyl linoleate (8.26%), (E)-methylisoeugenol (2.21–7.92%), 2-butanone (5.95%), α-Selinene (4.53–5.69%), Elemicin (4.03–4.93%), β-Asarone (4.07%), β Himachalene (2.24–4.63%), n-hexadecanoic acid (3.72%), humulene (3.27%), himachala-1,4-diene (3.09%), β-Bisabolene (1.76–3.78%) |
[37,64,65] |
| Flowering umbels | Portugal | α-Pinene (37.9%), geranyl acetate (15%), (E)-caryophyllene (4.9%), β-Pinene (3.5%), | [6] | |
| Umbels with ripe seeds | Geranyl acetate (65%), α-Pinene (13%) | |||
| Flowering umbels | Italy | Carotol (25.1%), 11αH-himachal-4-en-1-β-ol (21.6%), β-bisabolene (17.6%), elemicin (6.4%) | ||
| Umbels with ripe seeds | β-bisabolene (51%), (E)-methyl isoeugenol (10%), 11αH-himachal-4-en-1-β-ol (9%), elemicin (5.2%), α-longipinene (3.1%) | |||
| Ripe umbels | Portugal | Geranyl acetate (29%), α-Pinene (27.2%), Limonene (9%), 11αH-Himachal-4-en-1-β-ol (9.2%), Carotol (6.2%), β-Pinene (4.5%) | [66] | |
| Ripe umbels with mature seeds | Tunisia | Carotol (3.5–55.7%), Elemecin (1.4–35.3%), 11αH-Himachal-4-en-1-β-ol (12.7–17.4%), Sabinene (12–14.5%), α-Selinene (7.4–8.6%), Eudesm-7(11)-en-4-ol (8.2–8.5%), β-Bisabolene (5.5–7.6%), (Z)-β-Farnesene (1.6–5%), (E)-α-Bergamotene (0.2–3.8%) | [9] | |
| Herbs | Poland | Sabinene (30.1%), α-Pinene (30%), Terpinen-4-ol (6.1%), limonene (5.3%), myrcene (5.2%) | [8] | |
| Flowering Umbels | α-Pinene (42%), Sabinene (19.5%), limonene (3.7%), myrcene (3.1%) | |||
| Mature Umbels | Sabinene (40.5%), α-Pinene (17.2%), geranyl acetate (16.5%), Terpinen-4-ol (4.9%), | |||
| Aerial parts | France | (E)-methylisoeugenol (21.8–33%), β-Bisabolene (4.4–21.3%), Elemicin (11.4–16.3%), α-Pinene (15.9–24.9%), Sabinene (2.7–3.7%), Myrcene (2–3.5%), α-Terpinen-4-ol (0.5–3.5%) | [5,7] | |
| Flowers | Algeria | α-Pinene (10.9%), α-Asarone (9.8%), β-Bisabolene (7.6%), β-Caryophyllene (7.1%), Sabinene (7%), Daucol (3.2%), Limonene (3%) | [67] | |
| Leaves + Stems | α-Pinene (10.6%), α-Asarone (9.4%), β-Bisabolene (9.3%), Sabinene (7.2%), Carotol (6.8%), E-α-Bisabolene (6.3%), Daucol (5.3%), β-Caryophyllene (4.3%), Limonene (4%) | |||
| Aerial parts | α-Pinene (21.3%), α-Asarone (18.4%), β-Bisabolene (7.3%), Sabinene (6.5%), Limonene (6.4%), Carotol (3.5%), Terpinen-4-ol (3.5%), β-Caryophyllene (3.3%), E-α-Bisabolene (3.2%) | |||
| Leaves | α-Pinene (27.44%), sabinene (25.34%), Germacrene D (16.33%) |
[68] | ||
| Seeds | Geranyl acetate (52.45%), Cedrone S (14.04%), Asarone (11.39%), β-bisobolene (4.83%), Ar-himachalene (3.54%) | |||
| Ripe fruits | Serbia | Sabinene (27.16%), α-pinene (21.3%), α-muurolene (8.23%), β-caryophyllene (6.82%), α-ylangene (5.21%), β-Pinene (3.9%) | [69] | |
| Unripe fruits | α-muurolene (10.97%), sabinene (10.67%), caryophyllene oxide (7.7%), α-amorphene (7.57%), α-pinene (7.05%), carotol (6.15%), dimenone (5.28%), α-ylangene (4.88%), | |||
| Flowers | α-Pinene (51.23%), Limonene (9.59%), Sabinene (8.62%), β-Myrcene (7.18%), Terpinen-4-ol (3.48%), β-Pinene (3.35%) | |||
| Roots | Sabinene (36.39%), α-Pinene (24.56%), Limonene (6.53%), β-Pinene (5.39%) | |||
| Leaves | α-Pinene (30.83%), Limonene (8.6%), β-Myrcene (5.6%), Germacrene D (4.56%) | |||
| Stems | α-Pinene (18.53%), α-Bisabolol (6.02%), Limonene (5.74%), β-Myrcene (3.4%), Sabinene (3.23%) | |||
| Fruits | Portugal | Geranyl acetate (28.7–65%), α-Pinene (13–27.1%), 11αH-Himachal-4-en-1-β-ol (0.5–9.4%), Limonene (1.2–9%), β-Pinene (2.3–4.5%) | [70] | |
| Roots | Vienna | α-Terpinolene (26.2–56.3%), β-Pinene (4.1–8.2%), p-Cymene (2.7–7.4%), Sabinene (5.6–5.9%), γ-terpinene (0.9–5.6%), Limonene (5.5%), Myristicin (4.9–5.1%) | [1] | |
| Leaves | α-Pinene (20.9–44.8%), Sabinene (11.3–19.5%), Germacrene D (4.9–14%), Limonene (3.9–12.7%), Myrcene (4–11.2%), β-Pinene (1.3–5.9%), Caryophyllene (1.2–3.7%) | |||
| Fruits | Sabinene (21.5–46.6%), α-Pinene (23.5–30.4%), Geranyl acetate (3.9–28.1%), β-Pinene (3–13.1%), α-Thujene (1–8.8%), γ-terpinene (0.3–4.1%), Myrcene (3.4–3.9%) | |||
| Seeds | Lithuania | Sabinene (28.2–37.5%), α-Pinene (16–24.5%), Terpinen-4-ol (5–6%), γ-terpinene (2.9–6%), Limonene (3–4.2%) | [61] | |
| Leaves | Uzbekistan | Carotol (68.3%), Daucene (5%), trans-β-Farnesene (3.7%), β-Bisabolene (3.3%), α-Pinene (3.1%) | [71] | |
| Flowers | Carotol (68.8%), Daucene (4.7%), Daucol (3.4%), trans-β-Farnesene (3.3%) | |||
| Petals | Carotol (78.3%) | |||
| Fruits | Carotol (69.8%), Daucene (9%), trans-α-Bergamotene (4.7%), trans-β-Farnesene (3.7%) | |||
| Umbels | United States | α-Pinene (33.02%), β-Pinene (25.77%), Borneol (10.4%), Myrcene (6.41%), Limonene (5.34%), γ-terpinene (4.97%) | [72] | |
| maximus | Ripe and mature fruits | Egypt | (E)-methylisoeugenol (37.22%), β-bisabolene (34.7%), β-Asarone (17.65%) | [2] |
| Leaf | Preisocalamendiol (17.95%), Shyobunone (16.84%), β-Cubebene (12.72%), Tridecane (3.411%), Linalool (3.34%), (E)-2-Nonenal (3.22%) | |||
| Stem | Preisocalamendiol (32.69%), Shyobunone (24.33%), α-Pinene (4.37%), β-Cubebene (3.55%) | |||
| Fruits | Portugal | α-Pinene (10–25.9%), α-Asarone (5.8–25.8%), Geranyl acetate (3.4–16%), β-bisabolene (8.3–15.1%), (E)-methylisoeugenol (8.2–15.7%), Elemicin (4.9–13.6%), β-Pinene (4–6.8%), Limonene (1.8–3.3%) [73] | [70] | |
| Ripe umbels | Portugal | α-Pinene (22.2%), Geranyl acetate (16%), β-bisabolene (11.5%), α-asarone (9.8%), (E)-methylisoeugenol (8%), Elemicin (6%), β-Pinene (5.8%) | [74] | |
| Green seeds | Italy | Carotol (44.68%), β-bisabolene (12.72%), Isoelemicin (11.51%), Geranyl acetate (4.36%) | [75] | |
| maritimus | Flowers | Tunisia | Sabinene (51.6%), Terpinen-4-ol (11%), p-Cymene (4.2%), Eudesm-6-en-4α-ol (3.6%) | [76] |
| Roots | Dillapiole (46.6%), Myristicin (29.7%), Limonene (3.6%) | |||
| major | Flowers | Italy | α-Pinene (24.4%), Sabinene (13.3%), Geranyl acetate (13%), epi-α-Cadinol (8.5%), Myrcene (4.8%), β-Oplopenone (4.3%) | [62] |
| Fruits | Geranyl acetate (34.2%), α-Pinene (12.9%), Geraniol (6.9%), Myrcene (4.7%), epi-α-Bisabolol (4.5%), Sabinene (3.3%) | |||
| halophilus | Flowering Umbels | Portugal | Sabinene (28.3–33.8%), α-Pinene (12.6–16%), Limonene (11–11.8%), (E)-methylisoeugenol (0.7–7.4%), Elemicin (5.9–6.2%), β-Bisabolene (0.4–5.3%), Terpinene-4-ol (4.1–4.8%), Myrcene (3.2–4.7%), β-Pinene (2.3–5.1%) | [73] |
| Ripe Umbels | Elemicin (26–31%), Sabinene (27.6–29%), α-Pinene (10.1–12.2%), Limonene (5.5–6.5%), (E)-methylisoeugenol (0.5–6.9%) | |||
| Fruits | Elemicin (15–31%), Sabinene (9–29%), α-Pinene (12.2–23%), Limonene (5.5–12%), (E)-methylisoeugenol (0.5–7.4%), Terpinen-4-ol (2–4.7%) | [70] | ||
| hispanicus | Roots | Algeria | Apiole (80.3%), Myristicin (16.6%) | [77] |
| Aerial parts | Myristicin (73.2%), Epiglobulol (5.1%), Germacrene D (3.1%) | |||
| Stems | Myristicin (66.9%), α-Thujene (4.3%) | |||
| Leaves | Myristicin (80.2%), Epiglobulol (3.1%) | |||
| Flowers | Myristicin (83.8%), Germacrene D (6.4%) | |||
| gummifer | Fruits | Spain | Geranyl acetate (51.74–76.95%), Sabinene (4.42–11.13%), Terpinen-4-ol (0.93–8.17%), Linalool (3.97–5.18%) [78] | [78] |
| Portugal | Geranyl acetate (18–55%), α-Pinene (11–31%), Carotol (5–15%), Sabinene (2.1–10%), Limonene (5.8–9%), Germacrene D (2–5.5%), β-Pinene (3.8–5.2%), Myrcene (2.1–3.7%) | [73] | ||
| Ripe umbels | Portugal | Geranyl acetate (37%), Limonene (5.8%), α-Pinene (30.9%), β-Pinene (3.8%) | [24] | |
| hispidus | Aerial parts | Tunisia | (4R)-1-p-menthen-6,8-diol, 1-p-menthen-4,7-diol, (1R,2R,4R)-p-menthane-1,2,4-triol, β-sitosterol 3-O-glucoside (abundance not specified) [79] | [79] |
6. Pharmacological Activities
6.1. Anticancer Activity
With the increasing need for optimizing cancer therapy, extensive studies were conducted to assess the potential benefit of herbal options in oncology. Regarding the anticancer potential of wild D. carota, only D. carota ssp. carota was studied and demonstrated to possess these properties.
Moreover, recent findings revealed that D. carota oil extract (DCOE) demonstrated substantial preventive and therapeutic effects against DMBA-induced breast cancer in rats. Animals pre-treated with DCOE exhibited prolonged survival and reduced tumor incidence. Also, DCOE treatment post-tumor induction resulted in a significant inhibition of tumor volume [80].
Furthermore, in 2015, Tawil et al. [25] reported that DCOE induced caspase-dependent apoptotic cell death in human Acute Myeloid Leukemia (AML) cells, partially through the Mitogen-Activated Protein Kinase (MAPK)-dependent mechanism. These kinases regulate important cellular mechanisms such as proliferation, stress responses, immune defense, and apoptosis [88]. DCOE was eluted into four fractions (pentane:diethyl ether, 50:50 (F2), diethyl ether, 100%) and F4 (chloroform:methanol, 93:7) and tested against various human cell lines [89]. The pentane (100%) and pentane/diethyl ether (50:50) fractions displayed the highest anticancer activity against MDA-MB-231, MCF-7, HT-29, and Caco-2 cells. Inhibition of cell proliferation in MDA-MB-231 and HT-29 cells was attributed to cell cycle arrest and apoptosis. The latter was mediated via the suppression of the MAPK/Erk pathway in MDA-MB-231 cells and the PI3K/Akt and MAPK/Erk pathways in HT-29 cells [89,90].
6.2. Antibacterial Activity
With the increasing resistance to antibacterial agents and the need for alternatives to the current options, few studies have assessed the role of D. carota in eradicating bacterial infections. Only D. carota ssp. carota, hispanicus, maritimus, and maximus have been investigated and have been shown to possess antibacterial properties against various bacterial species. In 2005, Staniszewska et al. [8] tested the essential oil of D. carota ssp. carota umbels from Poland against four different species of bacteria, revealing a greater efficacy against Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) than Gram-negative bacteria (Pseudomonas aeruginosa and Escherichia coli). Moreover, C. jejuni (reference strain and clinical isolates F38O11, LV7, and LV9) as well as other bacterial strains of the Campylobacter genus (C. coli and C. lari) were found to be equally susceptible to the antibacterial effect of the aerial parts of D. carota ssp. carota harvested in France [5].
Asilbekova et al. [71] reported that essential oils of different parts (leaves, flowers, petals, fruits) of Daucus carota ssp. carota from Uzbekistan demonstrated modest activity against Staphylococcus aureus and Bacillus subtilis. Furthermore, in 2009, Wehbe et al. [97] showed that the aqueous and methanolic extracts of Lebanese D. carota ssp. carota umbels exhibited a minimal inhibition of Staphylococcus aureus meti S and meti R (MIC20 and 10 mg/mL, respectively), while no effect was observed against Gram-negative bacteria. Essential oils extracted from flowers and roots of Tunisian D. carota ssp. maritimus were also tested, showing broad-spectrum antibacterial activity against P. aeruginosa, E. coli, E. faecalis, K. pneumoniae, and S. typhimurium [76]. The flower-derived oil was more effective against E. coli (ESLβ), while the root-derived oil demonstrated greater efficacy against S. aureus, S. pneumonia, Shigella spp., and E. faecalis. The authors attributed these pharmacological activities to the significant presence of sabinene and terpinen-4-ol, as well as phenolic compounds like dillapiole and myristicin.
Sabinene has been reported to possess antibacterial activities against several Gram-positive and Gram-negative bacteria. The sabinene-type of the essential oil obtained from berries and leaves of Juniperus excelsa from Macedonia exhibited moderate activity against Streptococcus pyogenes, Haemopilus influenzae, Campylobacter jejuni, and Escherichia coli [98].
Algerian D. carota ssp. hispanicus roots’ and aerial parts’ essential oils were shown to exhibit varied growth-inhibitory effects against Gram-positive and Gram-negative bacteria. The authors suggest that the antibacterial activity could be attributed to phenolic compounds such as myristicin and apiole [77].
6.3. Antifungal Activity
The antifungal properties of D. carota subspecies were studied against different fungal strains. D. carota ssp. carota, gummifer, halophilus, hispanicus, and maximus were found to exhibit significant antifungal activities. Oil extract derived from different plant organs of D. carota ssp. carota demonstrated both fungistatic and fungicidal activities, with Fulvia fulvum being the most susceptible and Trichoderma viride and Aspergillus ochraceus being the most resistant. Among the plant organs, the oil from unripe fruits exhibited the strongest antifungal activity, followed by ripe fruit oil, root oil, stem oil, leaf oil, and flower oil [69]. In 2017, Asilbekova et al. [71] showed that fruit essential oil of D. carota ssp. carota from Uzbekistan showed antifungal activity against C. albicans. However, the essential oils of D. carota ssp. carota umbels from Poland displayed weak inhibitory activity against Candida albicans and Penicillium expansum [8].
The antifungal properties of other D. carota subspecies were also investigated. In 2015, Valente et al. [24] revealed that an essential oil from aerial parts of D. carota ssp. gummifer was found to be more active against C. guillermondii, dermatophyte strains, and C. neoformans compared to other Candida strains. The authors attributed the antifungal properties to the high contents of geranyl acetate and α-pinene. The essential oil from aerial parts of Portuguese D. carota ssp. maximus, also tested for antifungal activity, demonstrated a broad antifungal spectrum against many fungal strains, especially Aspergillus, Candida, dermatophytes and Cryptococus neoformans [74]. The oil also exhibited a higher antifungal activity against Aspergillus and Candida strains compared to other Portuguese subspecies and various D. carota ssp. taxa from different countries [8,69].
6.4. Antioxidant Activity
Free radicals are known to contribute to several ailments, including cardiovascular, cancer, and degenerative diseases. Numerous antioxidant studies have been conducted on D. carota ssp. carota, with only one study on D. carota ssp. gummifer. Akgul et al. [108] reported that oil extracted from D. carota L. ssp. carota flowers from Turkey possesses significant DPPH radical scavenging properties, and this effect was stronger than that of individual compounds extracted from the oil. Similarly, Shebaby et al. [37] indicated antioxidant properties for the Lebanese D. carota ssp. carota umbel oil extract (DCOE) using the FRAP and DPPH assays. The results exhibited significant radical scavenging activity of DCOE in comparison to Trolox. The authors attributed the scavenging role of DCOE to the high levels of terpenes, phenols, and polyphenolic compounds.
The antioxidant properties of different fractions of DCOE were examined both in vitro and in living organisms in vivo [109]. The fractions made using diethyl ether and chloroform/methanol were found to have the strongest antioxidant activity when tested using the DPPH and FRAP assays. This activity is likely due to the presence of various phenolic compounds, including luteolin, kaempferol, apigenin, caffeic acid, and quercetin, which are known to have antioxidant properties [110,111,112,113,114]. On the other hand, the pentane fraction that is abundant in sesquiterpenes displayed moderate antioxidant activity when evaluated by DPPH assay. This can be linked to the presence of α-humelene and β-caryophyllene, which are known to have significant antioxidant effects [82,115,116,117].
6.5. Anti-Inflammatory Activity
Wild carrot has traditionally been used in folk medicine to treat various inflammatory conditions like cystitis and prostatitis. In light of this, researchers have conducted numerous studies to examine the anti-inflammatory properties of various D. carota ssp. including spp. carota, gummifer, and maximus. Both the aqueous (100, 200, and 400 mg/kg BW) and methanolic (70, 140, and 280 mg/kg BW) extracts of the Lebanese D. carota ssp. carota umbels displayed a significant reduction in acute and chronic inflammation in rats. The anti-inflammatory effects observed were similar to those of the non-steroidal anti-inflammatory drug (NSAID) diclofenac and were associated with the presence of terpenes and flavonoids in the plant extracts [97].
6.6. Miscellaneous
In a study by Wehbe et al. [97], the researchers examined the ability of aqueous and methanolic extracts of Lebanese D. carota ssp. carota umbels to protect against ethanol-induced gastric damage in rats. Both extracts demonstrated a protective effect, with the methanolic extract showing a higher curative ratio compared to the aqueous extract and the group treated with cimetidine. According to these authors, this gastro-protective effect is likely due to the presence of flavonoids and tannins in the plant. Additionally, the aqueous extract was found to decrease levels of HDL, without having any significant impact on total cholesterol, triglycerides, and LDL concentrations.
7. Safety/Toxicological Evaluation
In addition to the assessment of their efficacy, subspecies carota, gummifer, halophilus, and maximus were evaluated for their safety. The aqueous extract of Lebanese D. carota ssp. carota umbels showed no significant variations in liver enzyme concentrations (SGOT, SGPT, ALP, and LDH) in rats, suggesting that the extract can maintain the structural integrity of the hepatocellular membrane [97]. Tawil et al. [25] revealed an extremely low susceptibility of normal human peripheral blood mononuclear cells (PBMCs) to DCOE methanol:acetone (1:1) treatment. Additionally, according to Dixon’s up and down model, the LD50 of the major compound β-2-himachalen-6-ol (HC), obtained from Lebanese D. carota ssp. carota umbels, was 1000 folds higher than that of cisplatin, highlighting the low toxicity profile of DCOE in adult Balb/c mice [64]. In another study, chronic treatments with HC displayed mild hepatotoxicity with no adverse effects on the kidneys of the treated mice. The HC-treated groups showed the highest survival rate among all groups [95].
A previous report indicated that an essential oil derived from the aerial parts of D. carota ssp. gummifer does not affect the cell viability of macrophages at concentrations below 1.25 μL/mL [24]. Comparable results were observed for liver cells (hepatocytes) and skin cells (keratinocytes). However, it was somewhat more toxic to microglia cells, leading to decreased cell viability when used at concentrations above 0.64 μL/mL [24].
When testing D. carota ssp. halophilus umbel essential oils at concentrations possessing significant antifungal activity, no cytotoxicity was detected in mouse skin dendritic cells [70]. Lastly, the safety of the essential oil from aerial parts of Portuguese D. carota ssp. maximus was assessed on human keratinocytes and hepatocytes as well as mouse macrophages and microglial cells [74]. The results showed that cell viability at concentrations lower than 1.25 μL/mL was not affected for all cell lines except microglial cells, where cytotoxicity was observed at a concentration as low as 0.64 μL/mL.
8. Conclusions
To better characterize the therapeutic potential of wild D. carota, it is essential to investigate the interplay between its traditional uses and pharmacological activities in relation to its chemical composition. D. carota ssp. carota has a longstanding traditional use in Lebanon to fight oncological ailments, a usage substantiated by numerous studies underscoring its significant anticancer properties, attributed mainly to the presence of the distinctive compound β-2-himachalen-6-ol [25,37,64,65,89,90,91,92,93,94,95,96]. The wild carrot has also been traditionally employed by the Lebanese and Persian communities in the treatment of gastric ulcers [40,43], as supported by a study indicating that both aqueous and methanolic extracts possess protective effects against ethanol-induced gastric damage in rats. The authors attribute this gastro-protective activity to the presence of flavonoids and tannins within the plant [97].
Regarding the antimicrobial activities, various subspecies, including carota, hispanicus, maritimus, and maximus, have exhibited mild to moderate antibacterial properties against various bacterial species, aligning with their historical use in folk medicine as antiseptics for treating bacterial infections, such as prostatitis and cystitis [5,11,12,13]. Notably, α-pinene and geranyl acetate emerged as key constituents contributing to this antibacterial efficacy, which is in line with other studies that emphasize the antibacterial potential of α-pinene [51,52,53,54,55,56,57,58,59,60]. While folk medicine does not explicitly mention the use of the wild carrot for fungal infections, multiple studies underscore its significant antifungal activities against diverse fungal strains, particularly within D. carota ssp. carota, gummifer, halophilus, hispanicus, and maximus [6,8,24,66,69,70,74,77]. The phytochemicals responsible for this antifungal activity, namely, α-pinene, geranyl acetate, and α-limonene, align with findings from related studies [54,100,101,102,103,104,105,106,107]. In addressing inflammatory conditions, D. carota ssp. carota, gummifer and maximus have demonstrated noteworthy anti-inflammatory properties [24,74,97] that were mainly attributed to the presence of α-pinene and geranyl acetate [107,122,123]. This aligns with the historical utilization of wild carrots in folk medicine for the treatment different inflammatory disorders like pain, prostatitis, and cystitis [5,11,12,13]. The observed anti-inflammatory effect of the wild carrot may also be attributed to the existence of antioxidant compounds in the plant extract [24,37,66,67,108,109]. Notably, various terpenes including α-pinene, β-Caryophyllene, β-bisabolene, sabinene, limonene, and α-longipinene along with polyphenols like luteolin, kaempferol, apigenin, caffeic acid, and quercetin are recognized for their radical scavenging activities [110,111,112,113,114,118,119,121]. An elevated production of reactive oxygen species (ROS) is linked to oxidative stress and the oxidation of proteins [128]. This, in turn, triggers inflammatory mediators and numerous inflammatory signals in response to protein oxidations [129]..
This entry is adapted from the peer-reviewed paper 10.3390/plants13010093
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