Momenteel is A. vulgaris het onderwerp van talrijke fytochemische en farmacologische onderzoeken. Fytochemische studies hebben de rijke samenstelling van de bovengrondse delen van deze plant bewezen, die bestaat uit sesquiterpenoïde lactonen, flavonoïden en coumarines, en een essentiële olie gemaakt van kwalitatief variabele componenten. Op hun beurt hebben farmacologische onderzoeken het bewijs geleverd van zeer waardevolle, voorheen onbekende biologische activiteiten van A. vulgaris, waaronder antioxiderende, hypolipemische, hepatoprotectieve, krampstillende, pijnstillende, bloeddrukverlagende, oestrogene, cytotoxische, antibacteriële en antischimmeleffecten. Vanwege de grote variabiliteit in de chemische samenstelling is deze soort ook onderworpen aan biotechnologisch onderzoek.
Een groot deel van dit onderzoek wordt uitgevoerd door niet-Europese onderzoekscentra. Dit komt omdat de soort wijd verspreid is over maar liefst vier continenten – Europa, Azië, Noord-Amerika en Zuid-Amerika – en er buiten Europa een grotere belangstelling voor deze soort bestaat. In Oost-Aziatische landen, voornamelijk China en Japan, maar ook in Europa staat deze soort bekend als specerij. In Europa is de huidige belangstelling voor de soort als specerij beslist niet zo groot als in Azië; het wordt echter steeds vaker gebruikt in de cosmetica-industrie. De tot nu toe bewezen biologische activiteiten van de A. vulgaris hebben de hoop doen rijzen op een heropleving voor deze middeleeuwse ‘kruidenmoeder’.
Antioxidant Effect
In 2008, scientists from Cairo (Egypt) evaluated for the first time the antioxidant activity of A. vulgaris. They found that the aqueous extract of the herb was able to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals at IC50 = 11.4 μg/mL and nitric oxide (NO) radicals at IC50 = 125 mg/mL in the first part of the experiment. They also estimated total phenols, flavonoids, and flavonols as 19 ± 0.16 mg/g gallic acid equivalents and 7.96 ± 0.76 and 3.4 ± 0.0 mg/g rutoside equivalents, respectively. In the second part of the experiment, they observed a significant increase in the levels of ascorbic acid and glutathione, and an increase in the activity of superoxide dismutase in the blood of rats administered with the extract at a dose of 100 mg/kg body weight (BW). The results of the study showed that A. vulgaris exhibits antioxidant activity and can thus be helpful to treat oxidative stress-related diseases [8].
Some newer investigations documented the antioxidant activity of the whole plant [101], its aerial parts [102] and leaf extracts [59], and its essential oil [120].
Various modern techniques have been applied in the above studies. Oyedemi and Coopoosamy proved the strong antioxidant potential of the extracts of A. vulgaris obtained from South Africa based on lipid peroxidation, protein glycation, xanthine oxidase, and the sTable DPPH radical scavenging assays [101]. Ben Nasr et al. investigated the antioxidant potential of the aqueous extracts of Tunisian A. vulgaris using the following in vitro techniques: ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid assay), DPPH, hydroxyl, superoxide, and NO scavenging assays, ferric reducing power activity assay (for determining total antioxidant capacity), and thiobarbituric acid reactive species assay (for determining the inhibition of lipid peroxidation) [103].
Hypolipemic Effect
An extract obtained from the root of A. vulgaris was tested by a Hindu team. They analyzed the rats in which hyperlipidemia had been caused by the administration of a high-fat diet for a period of 30 days. In the following month, the rodents received a standard diet. The team found that the A. vulgaris root extract showed a significant lipid profile-normalizing activity. Total cholesterol (TC) was reduced to 180 mg/dL, triglycerides (TG) to 147.2 mg/dL, low-density lipoprotein (LDL) cholesterol to 126.3 mg/dL, and very low-density lipoprotein (VLDL) cholesterol to 28.2 mg/dL, while the level of high-density lipoprotein (HDL) cholesterol and atherogenicity indicator (AI) increased to 68 and 2.63 mg/dL, respectively, compared to the control group (TC = 282.23 mg/dL, TG = 243.2 mg/dL, LDL cholesterol = 209.16 mg/dL, VLDL cholesterol = 47.56 mg/dL, HDL cholesterol = 34.17 mg/dL, and AI = 8.2 mg/dL) [9].
The hypolipidemic and anti-inflammatory effects of the A. vulgaris extract were studied in hypercholesterolemic rats by a Chinese team. They induced hypercholesterolemia in rats by feeding them with a high-fat diet containing 3% cholesterol in olein oil, for 8 weeks. This led to a significant increase in the serum levels of triglycerides, TC, LDL cholesterol, malondialdehyde, NO, and tumor necrosis factor-α and a significant decrease in the serum level of HDL cholesterol, activity of hydroxymethylglutaryl-CoA reductase in the liver, and activity of paraoxonase-1 as compared to the normal control group. Treatment of rats with A. vulgaris extract at a dose of 100 mg/kg per day for 4 weeks normalized the serum lipid profile, significantly increased the paraoxonase-1 activity, and decreased the serum levels of malondialdehyde, NO, and tumor necrosis factor-α as compared to the high-fat diet-treated animals. Moreover, the extract caused a decrease in the activity of hydroxymethylglutaryl-CoA reductase as compared to both high-fat diet-treated animals and control ones [104].
Hepatoprotective Effect
In 2005, two teams from Pakistani universities in Karachi investigated the hepatoprotective properties of A. vulgaris herb extracts in in vivo studies on mice. They divided the test rodents into five groups and conducted an experiment. The first and second groups were administered with a saline solution; two hours later, the second group received an additional 700 mg/kg d-galactosamine and 1 μg/kg lipopolysaccharide, which caused liver inflammation as confirmed by elevated levels of hepatic function indicators—alanine aminotransferase (ALAT) and aspartate aminotransferase (ASPAT). The third, fourth, and fifth groups were given different, prophylactic, doses (from 150 to 600 mg/kg BW) of a crude hydromethanolic extract prepared from the aerial parts of A. vulgaris, and an hour later, received d-galactosamine and lipopolysaccharide. A significant reduction was noted in ASPAT and ALAT activities in plasma in all the three groups. The results observed in these groups were confirmed by a histopathological examination of the liver, which showed a decrease in cellular edema and apoptotic cell count, and no hyperemia of the hepatic parenchyma, relative to the second group [105].
Antispasmodic Effect
A group of researchers in Cardiff (UK) tested the extracts prepared from the herb of A. vulgaris for their activity toward biogenic amine receptors in the smooth muscles of the gastrointestinal tract and respiratory tract of guinea pigs. The antagonistic effects of chloroform and methanol extracts were determined using concentration–response curves for contractions of the trachea and the small intestine under the influence of 5-hydroxytryptamine, methacholine, histamine, and phenylethylamine. The team found that both extracts had an antagonistic effect on the H1 receptors and caused the relaxation of smooth muscles. Two main compounds were isolated from the chloroform fraction—yomogin and 1,2,3,4-diepoxy-11(13)-eudesmen-12,8-olide—of which the former showed significant antagonism toward the H1 receptor in the ileum [10].
Researchers in São Paulo (Brazil) studied the antinociceptive activity of A. vulgaris herb extracts and observed their antispasmodic effects. They demonstrated that in mice treated with 500 or 1000 mg/kg hydroethanolic extract, a 48% or 59% inhibition of abdominal contractions was caused by the acetic acid solution, respectively [11].
Bronchodilatory Effect
Khan and Gilani tested the antispasmodic, bronchodilatory, tracheorelaxant, and antidiarrheal activities of the crude extract of A. vulgaris in the isolated tissue preparations of rabbit jejunum and guinea pig trachea, and also analyzed the in vivo castor oil-induced bronchodilation. They found that the A. vulgaris extract exhibited a combination of anticholinergic and Ca2+ antagonist mechanisms, which seemed pharmacologically promising for the treatment of airways disorders. The authors supposed that alkaloids, coumarins, flavonoids, saponins, sterols, tannins, and terpenes are the compounds responsible for the concentration-dependent (0.03–10 mg/mL) broncholytic effect of the A. vulgaris extract [106].
Natividad et al. proved that the Philippines A. vulgaris medicinal plant exhibited antagonistic activity at selected biogenic amine receptors in the smooth muscles of the airways and gastrointestinal tract. The chloroform and methanol extracts of the plant showed histamine H1 antagonism in the ileum and trachea. The researchers indicated that yomogin (sesquiterpenoid lactone) was the compound responsible for these activities [10].
Analgesic Effect
The team from São Paulo (Brazil) also investigated the antinociceptive properties of a hydroalcoholic extract prepared from the aerial parts of A. vulgaris using a mice model. Two tests were performed by the researchers: a hot plate test to measure the central analgesic effect and a writhing test to measure the peripheral analgesic effect. In the hot plate test, the control group was given only water, while the test group received 500 or 1000 mg/kg of A. vulgaris extract. Mice given 20 mg/kg BW morphine were adopted as the positive control. The response time (response latency) was determined after placing the rodents on a plate heated to 55 °C. The time taken by the mice to respond was not found to decrease after the administration of the A. vulgaris extract. In the writhing test, the mice were divided into groups and were given water, 20 g/kg BW morphine, and the hydroalcoholic extract of A. vulgaris at doses of 100, 250, 500, and 1000 mg/kg BW. After 30 min, the rodents were administered with a 0.8% acetic acid solution and writhing episodes were determined for the next 10 min. No decrease in the number of episodes was observed with the extract administered at the doses of 100 and 250 mg/kg BW; however, a decrease was observed with the higher doses of the extract (i.e., 500 and 1000 mg/kg BW). The results proved that the tested extracts of the A. vulgaris herb had a moderate peripheral antinociceptive effect but not a central effect [11].
MAO Inhibitory Effect
Lee et al. (South Korea) isolated flavonoids (jaceosidine, eupafolin, luteolin, quercetin, apigenine) and coumarins (esculetin, esculetin-6-methylether, scopoletin) from 80% aqueous ethanol extracts of whole A. vulgaris plants, and indicated that these compounds are good inhibitors of mouse brain monoamine oxidase (MAO) enzyme. The compounds showed MAO inhibitory effects at the IC50 values of 19.0, 25.0, 18.5, 12.5, 1.0, 31.1, 32.2, and 45.0 µmol, respectively [107].
Antihypertensive Effect
The aqueous and chloroform extracts of the aerial parts of A. vulgaris were tested by two teams from the Philippines to determine the hemodynamic potential of the plant. They found that the administration of a 10% solution of the aqueous extract into the isolated perfused mesentery of rats effectively reversed the hypertensive effect induced by noradrenaline; however, the baseline blood pressure values and heart rate remained unaltered [12].
The Chinese team performed a systematic review of randomized controlled trials based on a review of articles published from 1980 to 2013 in databases (CENTRAL, Pubmed, CBM, CNKI, VIP, and online clinical trial registry websites). They exhibit that in randomized controlled trials, moxibustion (a traditional Chinese method that uses the heat generated by burning herbal preparations containing A. vulgaris to stimulate acupuncture points) showed lowering of the blood pressure compared to antihypertensive drugs by stimulation of acupoint KI 1. Meta-analysis showed superior effects of moxibustion plus antihypertensive drugs (like: Metoprolol, Nifedipine, Enalapril) on systolic blood pressure (WMD (weighted mean difference): −4.91 [−7.54, −2.28]) but no superior effects on diastolic blood pressure (WMD: −6.38 [−17.17, 4.41]) [108].
Estrogenic Effect
The flavonoids present in the aerial parts of A. vulgaris were evaluated for estrogenic activity by three scientific institutions from USA and South Korea in cooperation. Saccharomyces cerevisiae fungi containing an expression plasmid with the cDNA of the human estrogen receptor and a reporter plasmid with the α-galactosidase gene was used in the experiment. The estrogenic effect, 5% relative to 17-β-estradiol, was observed in the polar extract (extraction with ethyl acetate), whereas the less polar ethanolic extract showed no activity. After testing the individual flavonoids of the plant, it was observed that the transcription of the reporter gene was significantly induced by eriodictyol and apigenin. The activity was also found to be concentration-dependent [12].
Shaik et al. (India) confirmed the strong anti-implantation and estrogenic activities of the leaf extracts from A. vulgaris on female Wistar rats [109].
Cytotoxic Effect
A methanolic extract prepared from the aerial parts of A. vulgaris was tested by Turkish teams to analyze its cytotoxic effects on human cancer cell lines (MCF7—estrogen-dependent breast adenocarcinoma cell line, A549—non-small cell lung cancer cell line, HeLa—cervical cancer cell line), and normal cell lines (A7R5—vascular smooth muscle cell line, 293T—human embryonic kidney cell line transformed with SV40 large T antigen). Cytotoxic activity was assessed by real-time electrical impedance measurements. A statistically significant inhibitory effect was observed against MCF7 (IC50 = 190 ng/mL), HeLa (IC50 = 284 ng/mL), A7R5 (IC50 = 382 ng/mL), and 293T (IC50 = 317 ng/mL), whereas a weak influence was found on A549 (IC50 = 778 ng/mL) cells [14]. Saleh et al. from Saudi Arabia evaluated the toxicity of the essential oil extracted from the buds and leaves of the A. vulgaris plant, and characterized its growth inhibitory effects on cancer cells. The results demonstrated that the essential oil-induced apoptosis in HL-60 leukemic cell line was mediated by caspase-dependent pathways, involving caspase-3, -9, and -8, which were initiated by Bcl-2/Bax/Bid-dependent loss of mitochondrial membrane potential, leading to the release of cytochrome c to the cytoplasm to activate the caspase cascade. The results showed that the studied essential oils were more efficient in inducing apoptosis in different cancer cell lines than noncancerous cells. Based on these observations, the authors suggested that A. vulgaris might be a promising source of new anticancer agents [111].
The latest study from 2020 was performed by a Serbian team on methanolic extracts of the A. vulgaris plant. The researchers proved the genotoxic and cytotoxic activities of the extracts, both separately and in co-treatment with a known mutagen (mitomycin C). They used the cytokinesis-block micronucleus assay for measuring the micronucleus frequency in human peripheral blood lymphocytes and MTT assay as the proliferation test in SW-480 human colon cancer cells and human periodontal ligament stem cells used as control. The results of the cytokinesis-block micronucleus assay showed that both extracts significantly increased the micronucleus frequency in the peripheral blood lymphocytes treated with the A. vulgaris extract at all the tested concentrations (10, 50, 100, and 250 μg/mL), except the lowest one (10 μg/mL). The extracts induced cytotoxic activity only in co-treatment with mitomycin C after long-term exposure and did not significantly affect the viability of the human periodontal ligament stem cells. The researchers indicated that these activities were induced by the flavonoids and other phenolic compounds present in the plant [110].
Antifungal and Antibacterial Activities
Researchers from Romania investigated the antifungal activity of a commercial preparation of the essential oil extracted from the A. vulgaris herb against Candida albicans. The disk-diffusion method was used in the in vitro experiment. The observed inhibition zone measured 12.5 mm. The zone of the positive control, carried out with nystatin, measured 15.0 mm, while that of the negative control, carried out with an empty paper disc, measured 6.0 mm. The results thus confirmed the antifungal activity of the essential oil of the herb against C. albicans [15].
In 2006, Blagojević et al. from Serbia and Montenegro also studied the effects of A. vulgaris essential oil on various microorganisms. The oil was isolated from the aerial and underground parts of the plant by steam distillation. After 10- and 30-fold dilutions, the zone of inhibition of pathogen growth on paper filters was examined. The oil extracted from the aerial parts exhibited inhibitory activity against various bacteria (Escherichia coli, Salmonella enteritidis, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Staphylococcus aureus) and fungi (C. albicans and Aspergillus niger), which was attributed to its high levels of 1,8-cineole and β-thujone. On the other hand, the oil extracted from the underground parts of the plant exhibited only a low activity against the listed pathogens, due to the low level of 1,8-cineole and the lack of β-thujone in the roots [16].
In another experiment, an aqueous leaf extract of A. vulgaris was found to exhibit antibacterial activity against the C and D serotypes of Streptococcus mutans [3].
Some recent studies also documented the antimicrobial activity of the whole plant and leaf extracts [102,113,121] as well as the essential oil of A. vulgaris [67,112].
Anti-Inflammatory Activity
El-Tantawy from Pakistan tested the anti-inflammatory and hypolipidemic effects of A. vulgaris extract in hypercholesterolemic rats. Hypercholesterolemia was induced in the rats by feeding them with a high-fat diet containing 3% cholesterol in olein oil, for 8 weeks. Treatment of these rats with A. vulgaris extract at a dose of 100 mg/kg per day for 4 weeks normalized the serum lipid profile, significantly increased the paraoxonase-1 activity, and decreased the serum levels of malondialdehyde, NO, and tumor necrosis factor-α as compared to the animals that received only high-fat diet. Moreover, the extract caused a significant decrease in the activity of hydroxymethylglutaryl-CoA reductase as compared to both high-fat diet-treated animals and control ones [104].
Afsar et al. from India studied the anti-inflammatory activity of a methanolic extract of A. vulgaris leaves using the cotton pellet granuloma method. The A. vulgaris extract was administered to rats (150–250 g BW) at doses of 200 and 400 mg/kg BW, respectively, after surgical insertion of cotton pellets into their groin region. The study was conducted following the guidelines of the “cotton pellet granuloma method.” The extract showed anti-inflammatory activity at both 200 and 400 mg/kg, whereas the results were more significant at 400 mg/kg compared with the control [115].
The latest study performed on the extracts of Tunisian A. vulgaris plants proved their moderate anti-inflammatory activity based on lipoxygenase inhibition assay [103].
Antiallergenic Effect
Olsen et al. from Denmark studied the specificity and efficacy of immunotherapy with A. vulgaris extracts on 25 patients having seasonal rhinoconjunctivitis for more than two years and only two clinically important allergies—either to A. vulgaris and Betula verrucosa or to A. vulgaris and Phleum pratense. Twenty patients completed two years of specific immunotherapy. Nine patients were treated with the extracts of A. vulgaris and 11 with the extracts of either B. verrucosa or P. pratense. Treatment with A. vulgaris was followed by a significant decrease in skin and eye sensitivity to A. vulgaris but not to B. verrucosa or P. pratense. No significant decrease was observed in medicine consumption or symptom scores. The patients treated with B. verrucosa or P. pratense experienced a significant decrease in skin and eye sensitivity to these organisms, but not to A. vulgaris, and showed a significant decrease in medicine consumption and symptom scores in the B. verrucosa or P. pratense season but not in the A. vulgaris season. The treatment was both effective and specific, with one unexplained exception that both patient groups (A. vulgaris and B. verrucosa or P. pratense) experienced decreased skin sensitivity to A. vulgaris [116].
Antimalarial Activity
Kodippili et al. from Sri Lanka investigated the antimalarial (both antiparasitic and antidisease) activity of the A. vulgaris extract. They assessed the antiparasitic activity of the extract at three doses (250, 500, and 1000 mg/kg) in vivo in the Plasmodium yoelii rodent malaria model, using distilled water as the negative control and Coartem as the positive control. In the 4-day suppressive assay, the oral administration of the extract at 500 and 1000 mg/kg significantly inhibited parasitemia by 65.16% and 51.46%, respectively. The antinociceptive activity of the extract was analyzed using the hot plate test, which indicated a central, supraspinally mediated response in relieving pain. The antidisease activity of the extract was further corroborated by the increased survival of the infected mice treated with the 500 mg/kg dose. The A. vulgaris extract was well tolerated by the mice over a period of 14 days (assay of subchronic toxicity), with no overt signs of toxicity or stress. Hepatotoxicity (evaluated in terms of the serum levels of glutamic–oxaloacetic transaminase and serum glutamic–pyruvic transaminase), renotoxicity (in terms of serum urea and creatinine), and hematotoxicity (in terms of total RBC, WBC, and differential leukocyte counts) were also ruled out. Based on these findings, the authors concluded that A. vulgaris leaf extract is orally active and nontoxic, and that A. vulgaris is a weed with the potential to act as a cheap source of the antimalarial plant [117].
Another team from the same center from Sri Lanka studied the ethanolic leaf extract of A. vulgaris for antiparasitic activity in Plasmodium berghei ANKA murine malaria model that elicits similar pathogenesis as falciparum malaria. The extract at doses of 500, 750, and 1000 mg/kg significantly inhibited parasitemia by 79.3%, 79.6%, and 87.3% respectively, in the 4-day suppressive assay. Chronic administration of the extract at high dose ruled out the overt signs of toxicity and stress as well as hepatotoxicity, renotoxicity, and hematotoxicity. Therefore, the authors claimed that the oral administration of a crude extract of A. vulgaris is nontoxic and induces antimalarial (antiparasitic) effects [118].
Anthelmintic Activity
Caner et al. from Turkey proved that the extracts of A. vulgaris and A. absinthium induce anthelmintic effects against trichinellosis (Trichinella spiralis) in rats. The results of trichinoscopy and artificial digestion showed that during the enteral (adult) phase of the illness, 300 mg/kg of methanol extracts prepared from the aerial parts of A. vulgaris and A. absinthium reduced the larval rate by 75.6% and 63.5% in the tongue, 53.4% and 37.7% in the diaphragm, 67.8% and 46.2% in the quadriceps, and 66.7% and 60.5% in the biceps–triceps muscles of rats, respectively. Furthermore, during the parenteral (encapsulated larvae) phase, 600 mg/kg dose of both the plant extracts decreased the larval rate by 66.4% and 59.9% in the tongue, 57.4% and 50.0% in the diaphragm, 47.6% and 43.7% in the quadriceps, and 60.2% and 46.4% in the biceps–triceps muscles of rats, respectively. In addition, antibody analysis showed that A. vulgaris extract can significantly reduce the antibody response [119].
Insecticidal Activity
The insecticidal activity of A. vulgaris was studied by a Hindu team from Tiruchirappalli in India. They exposed the larvae of Aedes aegypti (Egyptian mosquito, dengue virus vector) to various concentrations of the essential oil extracted from the A. vulgaris herb. Even at a low concentration of 10 ppm, insecticidal activity was observed after 24 h, while the best results were seen at a concentration of 500 ppm, where after 8 h of exposure to the oil solution, the larvae mortality rate was 100%. Thus, the study showed that the essential oil of A. vulgaris might serve as a potential insecticide [17].
The activity of essential oil obtained from the leaves and nanoparticles prepared with leaf extracts was evaluated by Lavor et al. from Brazil and Balasubramani et al. from India [122,123].
Furthermore, other teams have documented the effect of different raw materials against another insect species—Culex quinquefasciatus [124] and some stored product insects [125]
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7583039/
