Antischistosomal activity of Artemisia annua, Nigella sativa, and Allium sativum crude extracts: A comparative review

2.1 Artemisia annua: Antischistosomal activity and mechanisms

A. annua (Fig. 3) is famous for the sesquiterpene lactone artemisinin, which is an antimalarial chemical. But the water extracts from this plant also show strong antischistosomal activity (Table. 1). In 2022, Fadladdin conducted a study to evaluate the efficacy of A. annua aqueous extracts against Schistosoma mansoni in hamsters. The researcher tried doses between 31.25 and 500 μg/ml. The highest concentration, 500 μg/ml, killed all cells in vitro in six hours, showing that it was much better than lower doses. After 21 days of in vivo treatment with 300 mg/kg body weight, hamsters showed a 92% drop in worm burden and a 95% drop in egg load (Fadladdin, 2022). The integrity of the worm was damaged as a result of significant tegumental damage, which was discovered by scanning electron microscopy (SEM). This damage included spine peeling and tubercle erosion. The action of the extract can be attributed to artemisinin as well as co-metabolites such as flavonoids (quercetin, kaempferol) and phenolic acids (chlorogenic acid), which were identified by the LCT-MS technique. The endoperoxide bridge of artemisinin generates reactive oxygen species (ROS), resulting in damage to the worm’s tegument. Flavonoids, conversely, augment immunomodulatory effects, hence diminishing egg-induced inflammation in their presence (Hrckova and Velebny, 2012). The histological analysis of the treated hamsters demonstrated a moderate degree of hepatic inflammation, suggesting a well-regulated immune response. A. annua is a leading candidate for antischistosomal therapy due to its swift onset of action and remarkable efficacy.

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Fig. 3. Artemisia annua (sweet wormwood) (Septembre et al., 2020)

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2.2 Nigella sativa: Antischistosomal activity and mechanisms

The seeds of N. sativa (Fig. 4) are highly prized in traditional medicine due to the antiparasitic and immunomodulatory characteristics that they possess. These properties are attributed to thymoquinone, alkaloids, etc. (Table. 1). In the same study that Fadladdin did in 2022, N. sativa aqueous extracts were tested against S. mansoni at doses between 31.25 and 500 μg/ml. After 12 hours in vitro, the 500 μg/ml dose killed all of the worms, but it took longer than A. annua. In vivo, a dose of 300 mg/kg over 21 days reduced the worm burden by 85% and the egg load by 90%. The SEM study showed that the tegument was only slightly damaged, with the spine flattening and vesicle formation (Fadladdin, 2022). The damage was less severe than that seen with A. annua. LC-MS profiling showed that thymoquinone, nigellidine, and kaempferol glycosides were the most important bioactives. Thymoquinone’s antioxidant and anti-inflammatory properties are thought to be responsible for the damage to the tegument and the reduction of eggs, while saponins enhance the host’s immune system by stimulating cytokine production in the body (Shaterzadeh et al., 2018). Recent study showed that roasting diminishes thymoquinone levels, potentially leading to a decrease in the efficacy of antischistosomal preparations. This shows how important preparation procedures are. It works, but N. sativa is slower to work and less potent than A. annua, which suggests that it plays a secondary function in treatment rather than main one (Salem et al., 2023).

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Fig. 4. Nigella sativa (Black seed) plant, seed, and oil (Ahmad et al., 2021).

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2.3 Allium sativum: Antischistosomal activity and mechanisms

A notable feature of A. sativum (Fig. 5) is the presence of sulfur-containing chemicals, including allicin, which can suppress the proliferation of bacteria and parasites (Table. 1). Earlier a study was evaluated the aqueous extracts of A. sativum against S. mansoni (Bhatwalkar et al., 2021). The results showed that 500 μg/ml was the most effective against S. mansoni, killing all of the worms after 24 hours in vitro. This was the slowest of the three plants. Over the course of 21 days, a dosage of 300 mg/kg lowered the worm burden by 80% and the egg load by 85% in vivo. SEM showed severe tegumental changes, like spine shortening and surface blebbing. This meant that there was less structural damage than with A. annua or N. sativa. LC-MS and GC-MS studies showed that allicin, diallyl disulphide, and phenolic acids (ferulic and sinapic) are the most important metabolites. Allicin’s thiol-reactive properties break down the membranes of parasites, while phenolic acids’ antioxidant properties help lower oxidative stress caused by eggs in the body. In a recent study that was conducted confirmed that A. sativum possesses antioxidant activity in cellular models, which lends evidence to its role in reducing inflammation that is associated with schistosomiasis (Ghali et al., 2025; Nguepi et al., 2024). Therefore, the effectiveness of A. sativum is likely to be limited due to the decreased solubility of sulfur compounds in aqueous extracts, which makes it the least effective of the three medicinal plants.

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Fig. 5. Allium sativum (garlic). (Liu et al., 2023).

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3.1 In vitro efficacy

Both the rate of activity and the potency of the in vitro antischistosomal actions of the three plants’ aqueous extracts are considerably different from one another. A. annua is the most effective, obtaining a death rate of one hundred percent at a concentration of 500 μg/ml within a span of six hours (Chukwurah et al., 2014). This is followed by N. sativa, which takes twelve hours, and A. sativum, which takes twenty-four hours. When considering lesser concentrations, this hierarchy remains consistent. For instance, A. annua exhibits dose-dependent effects beginning at 31.25 μg/ml, which results in 50% mortality after 24 hours. On the other hand, N. sativa and A. sativum require greater dosages in order to achieve comparable effects (Fig. 6). SEM demonstrates that the quick action of A. annua is most likely owing to the fact that artemisinin has the ability to generate ROS, which causes immediate damage to the tegument(Kam and Yap 2020). Both thymoquinone from N. sativa and allicin from A. sativum can disrupt the tegument, but at a slower rate. This may be because the quantities of these compounds in aqueous extracts are lower.

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Fig. 6. Antischisosomal activity.

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3.2 In vivo efficacy

In vivo investigations provide more evidence that A. annua is superior. Compared to 85% and 90% for N. sativa and 80% and 85% for A. sativum, the worm burden was reduced by 92% and the egg load was reduced by 95% when A. annua was administered at a dose of 300 mg/kg(Masamha, 2010). Based on the findings of earlier studies, it can be concluded that these differences are statistically significant (p < 0.05). It has been found that the ability of A. annua to lower egg production is correlated with its increased efficacy. Egg production is a significant aspect in decreasing the pathophysiology of schistosomiasis (Taljaard et al., 2022; Elliott 1996). N. sativa’s strong effects can be linked to its ability to change the immune system, which works with its direct antiparasitic effects. The reduced efficacy of A. sativum may be attributed to the diminished bioavailability of sulphur compounds in aqueous extracts, which constrains the systemic impact of these compounds (Taljaard et al., 2022). Histological analysis of the liver demonstrated that A. annua and N. sativa induced significant inflammation, indicative of effective immunological modulation. On the other hand, A. sativum showed less severe changes, which means that it didn’t work as well to boost the immune system.

3.3 Tegumental damage

Understanding the mechanisms of action can be gained through the use of SEM analysis. At a concentration of 500 μg/ml, A. annua brings about the most severe damage to the tegument, resulting in the full peeling of the spine and erosion of the tubercle (Danna, 2024). This breaks down the worm’s protective layer and makes it harder for it to take in nutrients. N. sativa causes some damage, such as making vesicles and flattening the spine. A. sativum, on the other hand, causes the least damage, with only surface blebbing and shortening of the spine. There is a relationship between how much the tegument is damaged and how many worms die in vitro, since more damage speeds up the death of worms (Bhuker et al., 2024). The superiority of A. annua can be ascribed to the ROS-mediated assault on the tegument facilitated by artemisinin. Conversely, thymoquinone and allicin have more gradual effects and may target different molecular pathways (Bhuker et al., 2024).

3.4 Metabolomic contributions

According to the results of LC-MS and GC-MS, the actions of antischistosomes are driven by unique metabolite profiles, which are determined as follows:

Artemisinin, flavonoids (which include quercetin and kaempferol), and phenolic acids (which include chlorogenic acid) are essential components of Artemisia annua. A ROS is produced by the endoperoxide bridge of artemisinin, while flavonoids improve immunomodulation. The synergistic impact of co-metabolites was confirmed by a study that was conducted by Liu and colleagues. The study discovered 1109 metabolites in Artemisia species (Negri et al., 2024).

Thymoquinone, nigellidine, and saponins are the main components of N. sativa. Thymoquinone’s antioxidant properties disrupt the tegument, while saponins boost the host’s immune system (Al-Gabri et al., 2021). Processing affects thymoquinone levels, influencing efficacy (Salem et al., 2023). There are three essential components of A. sativum: allicin, diallyl disulfide, and phenolic acids (ferulic and sinapic). The thiol reactivity of allicin enables it to target parasite membranes; however, its poor solubility in water limits its effectiveness. Recent study provided evidence that these chemicals were present in extracts that were dissolved in water. A. sativum may have a comparative advantage over N. sativa in aqueous extracts due to its broader range of potent metabolites, although neither artemisinin (a noted antimalarial compound) nor potent non-aqueous metabolites were confirmed present (Salem et al., 2023). In contrast, N. sativa benefits from a focused set of active compounds, whose efficacy can be limited by processing or extraction methods.

3.5 Immunomodulatory effects

The pathogenesis of schistosomiasis is characterized by inflammation that is caused by eggs; hence, immunomodulation is an essential component of treatment. According to the findings of histological research, N. sativa is exceptional in this regard because it contains saponins and thymoquinone, both of which stimulate the production of cytokines and reduce the formation of granulomas Mahmoud et al., (2002). Flavonoids in A. annua reduce inflammation in the liver, however the effectiveness of this action is lower than that of N. sativa. A. annua also affects immunity. A. sativum has the least efficacious immunomodulatory effects, while phenolic acids offer only a moderate amount of assistance for antioxidant defense. The immunomodulatory capabilities of N. sativa have the potential to improve long-term results in chronic infections, despite the fact that A. annua is superior in terms of its direct antiparasitic efficacy (Tiwari, et al., 2018).

3.6 Determining the best antischistosomal agent

Among the three plants, A. annua is the one that demonstrates the highest level of antischistosomal activity, according to the comparison investigation. Among its most important benefits are:

At a concentration of 500 μg/ml, the Rapid In Vitro Action method achieves a death rate of one hundred percent in just six hours, whereas the N. sativa method takes twelve hours and the A. sativum method takes twenty-four hours. High In Vivo Efficacy (El wakil, 2007): Reduces worm burden by 92% and egg load by 95% at 300 mg/kg, surpassing the efficacy of N. sativa (85%, 90%) and A. sativum (80%, 85%).

Important metabolites: Artemisinin can make ROS when combined with flavonoids and phenolic acids that work together (Khan et al., 2025). This makes it a very effective antiparasitic agent. N. sativa is a good choice for combination therapy because it has immunomodulatory effects that could work well with A. annua. As a standalone treatment, its potential is constrained by its delayed onset and marginally reduced efficacy (Khan et al., 2025). A. sativum is the least effective, partly because of the decreased bioavailability of sulfur compounds in aqueous extracts; yet it continues to be an important supporting agent.

3.7 Mechanisms of Action: A Deeper Look

The antischistosomal mechanisms of these extracts involve multiple pathways (Fig. 7):

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Fig. 7. Reasons of inefficient treatment.

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Tegumental disruption: The tegument of the worm is targeted by artemisinin (A. annua), thymoquinone (N. sativa), and allicin (A. sativum). The tegument is an important barrier that allows the worm to absorb nutrients and avoid immunological response. Artemisinin creates ROS, which cause oxidative damage, while thymoquinone and allicin damage the membranes’ integrity (Kam and Yap, 2020; Bricker et al., 1983).

Reproductive inhibition: The vitelline gland’s has role in providing nutrients and eggshell precursors (phenols proteins) for egg production, each of the three extracts had a negative impact on egg production as they include a specific metabolic compounds, particularly polyphenols and artemisinin derivatives, interfere with vitelline cell maturation and deplete the phenolic clusters required for eggshell formation thereby inhibiting the parasite’s reproductive capacity, with A. annua having the most significant effect. This is most likely the result of interfering with the function of the vitelline gland, which is necessary for the development of eggs (Ibrahim and Ghoname, 2018).

Immunomodulation: By modulating the immune system of the host, flavonoids and saponins found in A. annua and N. sativa reduce the number of egg-induced granulomas. The anti-inflammatory effects of phenolic acids derived from A. sativum are shown to be less severe (Joseph, 2016).

Oxidative stress: Even though they have antioxidant characteristics, N. sativa and A. sativum paradoxically increase oxidative stress in parasites, which complement the ROS-mediated attack that A. annua is responsible for (Khan et al., 2025). The broad metabolite profile of A. annua makes it possible to launch a multi-pronged assault, and these mechanisms work together in a synergistic manner within each extract.

4.1 Artemisia annua

The metabolomic composition and bioactivity of A. annua aqueous extracts have been the subject of recent research, which has shed light on the potential of these extracts to combat both malaria and microorganisms (Taljaard et al., 2022). In a earlier study conducted for evaluation to determine the effectiveness of extracts from A. annua against Schistosoma mansoni in hamsters. The concentrations tested ranged from 31.25 to 500 µg/mL. After six hours of exposure, the results showed that the activity was very strong, as the worms all died at a concentration of 500 µg/mL. Metabolomic profiling revealed numerous significant bioactive components (Fadladdin, 2022). Even though artemisinin and its derivatives were only found in very small amounts because they don’t dissolve well in water, they were found with dihydroartemisinic acid, which is a biosynthetic precursor. This discovery shows that these compounds help the extract fight malaria. Flavonoids, such as quercetin and kaempferol derivatives, were identified in elevated concentrations and exhibited significant antioxidant and antibacterial properties, as evidenced by LC-MS analysis. Additionally, phenolic acids, such as chlorogenic and caffeic acids, enhanced the overall antioxidant capacity of the extract (Fadladdin, 2022). There were fewer terpenoids, mostly sesquiterpenes and monoterpenes, but they still added to the bioactivity that was seen. SEM demonstrated that S. mansoni worms displayed notable tegumental alterations. These alterations were marked by the desquamation of spines and tubercles upon the elevation of extract concentration (Fadladdin, 2022). A supplementary histological analysis of the livers from treated hamsters demonstrated notable inflammatory changes, suggesting immunomodulatory effects linked to aqueous extracts of A. annua.

4.2 Nigella sativa

During metabolomic profiling, aqueous extracts of Nigella sativa exhibited a complex and diverse phytochemical composition, predominantly consisting of phenolic compounds and alkaloids. Salem et al., (2023) employed a methodology termed non-targeted metabolomics to compare the raw and roasted seeds of the N. sativa plant. The researchers identified 197 metabolites distributed across various chemical classes (Salem et al., 2023)

Thymoquinone and its derivatives, which are the primary bioactive ingredients, were found in aqueous extracts; however, after roasting, they showed a significant decrease, which was correlated with a decrease in immunomodulatory activity. Flavonoids such as kaempferol and quercetin, together with their glycosides, were also discovered, and they were found to contribute to the antioxidant activities of the extract. However, the abundance of these flavonoids was found to be lower than that of methanolic extracts (Salem et al., 2023). In addition, saponins were identified as important polar metabolites, which bolstered the seeds’ capacity to provide nutrients and to modulate the immune system. Furthermore, alkaloids, such as nigellidine and nigellicine, were found to boost antibacterial activity against Gram-positive and Gram-negative bacteria. In addition, the research showed that roasting had a substantial impact on the metabolic profile, namely reducing the amount of immunomodulatory chemicals such as thymoquinone (Kurnia et al., 2025). This was confirmed using molecular docking analysis against inducible nitric oxide synthase (iNOS). Furthermore, the aqueous extracts demonstrated a significantly high level of xanthine oxidase inhibition, which highlights the powerful antioxidant potential and therapeutic significance of these extracts.

4.3 Allium sativum

The well-documented antibacterial and antioxidant capabilities of A. sativum are supported by the presence of phenolic metabolites and sulfur-containing compounds in abundance in aqueous extracts of the plant. Recent study reveals that using LC-MS, GC-MS, and FT-IR spectroscopy can completely evaluate the metabolomic profile of these extracts (Pop et al., 2020). The analysis revealed the presence of sulfur compounds such as allicin and diallyl disulfide, in addition to other volatile sulfur metabolites. Similar studies accomplished by Kurnia et al., (2023) and Kumar et al., (2023) also support these findings.

These sulphur compounds showed strong antimicrobial activity against Pseudomonas aeruginosa and Staphylococcus aureus, even though their concentrations were lower in water-based preparations. The LC-MS and FT-IR tests both showed that phenolic acids, like ferulic, coumaric, and sinapic acids, were present in high amounts and were strongly linked to the extract’s ability to act as an antioxidant (Sahidur et al., 2023). Flavonoid components, especially derivatives of kaempferol, were also found, but not as much as in A. annua and N. sativa. The extract contained several carbohydrates and amino acids, such as glucose and glutamic acid, which made the substance important for nutrition and metabolism. A. sativum aqueous extracts exhibited considerable antioxidant activity in H9c2 cell models of doxorubicin-induced cardiotoxicity, notwithstanding their diminished total phenolic content (TPC) relative to methanolic extracts. The extracts also effectively reduced ROS in both the cytosol and mitochondria, underscoring their potential cardioprotective and therapeutic benefits (Sahidur et al., 2023).

5.1 Metabolite classes

A comparative metabolomic analysis of A. annua, N. sativa, and A. sativum revealed that these three plants exhibit both shared and unique phytochemical characteristics, thereby delineating their individual traits. Even though all three plants have similar metabolite groups, such as flavonoids, phenolic acids, and terpenoids, there is a big difference in the dominance and concentration of some of these compounds (Khan et al., 2025). The plant A. annua has the most different kinds of flavonoids, especially quercetin and kaempferol derivatives. On the other hand, the species N. sativa contains monoterpenes like thymoquinone, and the species A. sativum does not have a significant amount of terpenoid content in its aqueous extracts. Distinctly, sulfur-containing compounds, notably allicin and diallyl disulfide, are peculiar to A. sativum and are principally responsible for its high antibacterial activity. When compared to the aqueous extracts of A. annua, the levels of saponins and alkaloids found in N. sativa are significantly higher (Khan et al., 2025). These compounds include nigellidine and nigellicine, which are either present in very little amounts or not present at all in A. sativum. Different therapeutic profiles have been observed across all three medicinal plants, and these metabolomic differences provide the basis for those differences.

5.2 Bioactivity

The metabolomic profiles of A. annua, N. sativa, and A. sativum are highly congruent with their respective biological activities. This is a reflection of the diversity and synergistic potential of the phytochemical constituents of these plants. Antimalarial and antischistosomal assays demonstrated that A. annua exhibited the most powerful parasiticidal action(Taljaard et al., 2022). This was attributed to the presence of artemisinin and flavonoids that were synergistic with artemisinin. Aqueous extracts of A. annua at a concentration of 500 µg/mL achieved a 100% mortality rate for Schistosoma mansoni worms within six hours. Conversely, a mortality rate of 12–24 hours was necessary for both N. sativa and A. sativum at comparable doses. A. sativum had the strongest effect on Pseudomonas aeruginosa and Staphylococcus aureus when it came to stopping the growth of bacteria (El wakil, 2007). The sulfur-containing metabolites it had were the main reason for this. Next came N. sativa, which had a lot of alkaloids and thymoquinone, and A. annua, which had moderate antibacterial effects from flavonoids and terpenoids. Taking into account their antioxidant properties, the water extracts of both N. sativa and A. sativum showed strong abilities to get rid of free radicals in cell models. A. sativum significantly diminished the levels of cytosolic and mitochondrial ROS in H9c2 cardiomyocytes, while N. sativa proficiently inhibited xanthine oxidase. The substantial flavonoid and phenolic acid content of A. annua contributed to the observed antioxidant activity that was equivalent to that of other plants. Finally, the immunomodulatory effects were strongest in N. sativa, which can be partly attributable to the presence of saponins and thymoquinone in the plant (Khan et al., 2025). However, the effectiveness of this impact was lowered by thermal processing methods such as roasting. There was a moderate immunomodulatory potential demonstrated by both A. annua and A. sativum, which was most likely mediated by the phenolic and sulfur-based chemicals that they contained.

5.3 Impact of extraction method

Aqueous extraction favors polar metabolites, resulting in lower yields of non-polar compounds like artemisinin (A. annua), thymoquinone (N. sativa), and allicin (A. sativum) compared to ethanolic or methanolic extracts. However, aqueous extracts are safer for human consumption and align with traditional preparations like teas and decoctions (Khan et al., 2025). The metabolomic profiles of aqueous extracts are thus distinct from organic solvent extracts, with higher proportions of flavonoids, phenolic acids, and polar secondary metabolites.

5.4 Recent advances

Recent research has greatly improved our understanding of the metabolomic profiles of medicinal plants such as A. annua, N. sativa, and A. sativum. Fadladdin (2022) found that aqueous extracts from these plants were effective against schistosomiasis. A. annua had the highest activity, which may be due to artemisinin and flavonoids. In recent study researcher performed a comprehensive metabolomics analysis of three Artemisia species indigenous to Tibet using LC-MS profiling. They found 1,109 metabolites, such as flavonoids and terpenoids. Recently some researcher examined the impact of roasting on the seeds of N. sativa. They discovered that roasting caused a decrease in the concentration of thymoquinone, subsequently diminishing its immunomodulatory activity (Salem et al., 2023; Fadladdin, 2022). Moreover, Suberu et al., (2013), who updated their methods, improved an LC-MS/MS protocol for quickly studying the co-metabolites made by A. annua. This protocol validated the association between artemisinin and its biosynthetic precursor, dihydroartemisinic acid. These findings collectively underscore the growing application of contemporary metabolomic techniques to elucidate the diversity of bioactive compounds and the therapeutic potential of these traditional medicinal plants (Suberu et al., 2013; Pop et al., 2020). These studies underscore the power of metabolomics in elucidating the chemical basis of plant bioactivity and guiding the development of new therapeutics.

5.5 Challenges and limitations

There are a lot of problems that make it hard to use aqueous extracts of A. annua, N. sativa, and A. sativum in clinical settings, even though these plants have a lot of medicinal potential. Differences in plant species, growing conditions, and extraction methods cause inconsistencies in the composition and bioactivity of metabolites, making it harder to estimate doses and repeat experiments. These differences make standardization a big problem that keeps happening. Suberu and colleagues conducted a study that emphasized the necessity of developing standardized LC-MS analytical methods to ensure precise profiling and quantification of significant metabolites. In general, aqueous extracts have less of the main bioactives, like artemisinin, thymoquinone, and allicin, than organic solvent extracts do. This makes the extracts less effective as drugs. Another important issue is bioavailability. Toxicological concerns have been recorded; elevated concentrations of extracts from A. annua and N. sativa have shown hepatotoxicity symptoms in histological analyses, highlighting the importance of dose optimization and safety evaluations (Suberu et al., 2013). Furthermore, the potential for developing resistance to parasites through prolonged use of plant-derived medicines, similar to the resistance observed with praziquantel, necessitates the exploration of synergistic combination strategies. To deal with these problems, it will be necessary to do strict standardization, full pharmacokinetic assessments, and well-planned preclinical and clinical research. This will make sure that these promising natural treatments are safe, work, and can be done again.

5.6 Future directions

It is recommended that future study prioritize several critical directions in order to fully leverage the antischistosomal potential of A. annua, N. sativa, and A. sativum. Combination therapies are a promising approach. These therapies focus on the synergistic interactions between these extracts, specifically the combination of the strong antiparasitic effects of A. annua with the immune-modulating effects of N. sativa and the antibacterial effects of A. sativum. To get more bioactive compounds back, it’s also important to improve the methods used to extract them. Recently it is suggested that using cutting-edge, eco-friendly technologies like ultrasound-assisted extraction. These technologies could greatly improve the yield and stability of important metabolites in water-based preparations (Salem et al., 2023). As we move beyond preclinical investigations, it is essential to conduct clinical trials in order to corroborate the data obtained from in vitro and animal studies. A. annua is now being considered as the key candidate for therapeutic evaluation. It is also recommended that resistance monitoring be carried out in order to evaluate the effectiveness of plant-based treatments over the long term and to reduce the possibility of Schistosoma adaptation, which is comparable to the phenomenon that was observed with praziquantel. Collectively, these approaches have the potential to pave the way for the development of plant-derived replacements or adjuncts to conventional antischistosomal medicines that are standardized, effective, and sustainable within the environment.