Natural Products as Therapeutic Agents for Schistosomiasis

Singab A. Botanicals against some important nematodal diseases: Ascariasis and hookworm infections

Ascariasis and intestinal parasitic nematodes are the leading cause of mass mortality infecting many people across the globe. In light of the various deleterious side effects of modern chemical-based allopathic drugs, our preferences have currently shifted towards the use of traditional plant-based drugs or botanicals for treating diseases. The defensive propensities in the botanicals against parasites have probably evolved during their co-habitation with parasites, humans and plants in nature and hence their combative interference in one another's defensive mechanisms has occurred naturally ultimately being very effective in treating diseases. This article broadly outlines the utility of plant-based compounds or botanicals prepared from various medicinal herbs that have the potential to be developed as effective therapies against the important parasites causing ascariasis and intestinal hookworm infections leading to ascariasis & infections and thereby human mortality, wherein allopathic treatments are less effective and causes enormous side-effects.

Antischistosomal effects of green and chemically synthesized silver nanoparticles: in vitro and in vivo murine model

Schistosomiasis is one of the most important neglected tropical diseases in Africa, caused by blood fluke, Schistosoma sp. The use of nanotechnology in the treatment of this type of disease is urgently important to avoid the unwanted side effects of chemotherapy. The present study aimed to evaluate the efficacy of green silver nanoparticles (G-AgNPs), fabricated by (Calotropis procera), comparing with both chemically prepared silver ones (C-AgNPs) and Praziquantel (PZQ) treatments. The study included in vitro and in vivo evaluations. In in vitro study, 4 groups of schistosome worms were exposed to treatments as follows: the first one with a dose of PZQ (0.2 µg/ml), the 2^nd and 3^rd groups with different concentrations of G-AgNPs and C-AgNPs, respectively and the last one act as a negative control group. In in vivo study, six groups of mice were infected and then treated as follows: the first one with a dose of PZQ, the second with G-AgNPs, the third with C-AgNPs, the fourth with G-AgNPs plus a half dose of PZQ, the fifth with C-AgNPs accompanied by a half dose of PZQ, and the last group acted as a positive control group. The parasitological (worm burden, egg count & oogram) and histopathological parameters (hepatic granuloma profile) were used to evaluate antischistosomal activities in experimental groups. Additionally, the subsequent ultrastructural alterations were observed in adult worms using scanning electron microscopy (SEM). Transmission electron microscopy analysis showed that G-AgNPs and C-AgNPs have 8-25 and 8-11 nm in diameter, respectively, besides, fourier transform infrared analysis (FTIR) revealed the presence of organic compounds (aromatic ring groups) which act as capping agents around the surfaces of biogenic silver nanoparticles. In in vitro experiment, adult worms incubated either with G-AgNPs or C-AgNPs at concentrations higher than 100 µg/ml or 80 µg/ml, respectively, showed full mortality of parasites after 24 h. In the infected treated groups (with G-AgNPs plus PZQ & C-AgNPs plus PZQ) showed the most significant reduction in the total worm burdens (92.17% & 90.52%, respectively). Combined treatment with C-AgNPs and PZQ showed the highest value of dead eggs (93,6%), followed by G-AgNPs plus PZQ-treated one (91%). This study showed that mice treated with G-AgNPs plus PZQ significantly has the highest percentage of reduction in granuloma size and count (64.59%, 70.14%, respectively). Both G-AgNPs plus PZQ-treated & C-AgNPs plus PZQ treated groups showed the highest similar values of reduction percentage of total ova count in tissues (98.90% & 98.62%, respectively). Concerning SEM, G-AgNPs-treated worms showed more variability in ultrastructural alterations than G-AgNPs plus PZQ-treated one, besides, worms treated with C-AgNPs plus PZQ exhibited the maximum level of contractions or (shrinkage) as a major impact.

[Acute and subacute toxicity of Garcinia huillensis Baker, a plant used against urogenital schistosomiasis in Haut-Katanga, DR Congo]

This research evaluated acute and subacute toxicity of aqueous and methanolic extract from stem bark of Garcinia huillensis Baker, a plant used in Congolese traditional medicine against urogenital schistosomiasis. The acute toxicity is evaluated on guinea pigs by single oral administration of 1500, 2000, 2500, 3000 and 3500mg/kg of body weight of extracts based on the method described by protocol 423 of the Organization for Cooperation and Economic Development. Subacute toxicity is assessed after 28 days after daily administration of 4.5, 45, 450 and 1500mg/kg of body weight of extracts. Weight evolution, hematological and biochemical parameters of the guinea pigs that survived were analyzed and compared with those of the controls. Acute oral toxicity data were used to calculate the LD₅₀ of 2717.39 and 2625.00mg/kg bw for the aqueous and methanolic extract, respectively. Some signs of intoxication were noted, and certain haematological and biochemical parameters analyzed in the treated guinea pigs sometimes presented statistically significant differences compared to those of the controls. The minimum tolerated dose (1652.17mg/kg bw) found for the aqueous extract is far greater than the therapeutic dose administered by traditional therapists (4.5mg). Thus, the study shows that the stem bark of G. huillensis would be moderately toxic and would present a good margin of safety under the conditions of our experimentation, which would justify the non-toxic use of the plant under the traditional conditions of preparation and oral administration.

Botanical Products in the Treatment and Control of Schistosomiasis: Recent Studies and Distribution of Active Plant Resources According to Affected Regions

Schistosomiasis, a parasitic disease caused by trematodes of the genus Schistosoma, is the second most prevalent parasitic disease in the world. It affects around 200 million people. Clinical treatment, prophylaxis, and prevention are performed in countries susceptible to schistosomiasis. In the pharmacological treatment for an acute form of schistosomiasis, the use of antiparasitics, mainly praziquantel, is more common. As an alternative way, prevention methods such as reducing the population of intermediate hosts (mollusks) with molluscicides are important in the control of this disease by interrupting the biological cycle of this etiological parasite. Despite the importance of pharmacological agents and molluscicides, they have side effects and environmental toxicity. In addition, they can lead to the development of resistance enhancing of parasites, and lead to the search for new and effective drugs, including resources of vegetal origin, which in turn, are abundant in the affected countries. Thus, the purpose of this review is to summarize recent studies on botanical products with potential for the control of schistosomiasis, including anti-Schistosoma and molluscicide activities. In addition, species and plant derivatives according to their origin or geographical importance indicating a possible utility of local resources for countries most affected by the disease are presented.

Essential oils from three Algerian medicinal plants (Artemisia campestris, Pulicaria arabica, and Saccocalyx satureioides) as new botanical insecticides?

Medicinal and aromatic plants represent an outstanding source of green active ingredients for a broad range of real-world applications. In the present study, we investigated the insecticidal potential of the essential oils obtained from three medicinal and aromatic plants of economic importance in Algeria, Artemisia campestris, Pulicaria arabica, and Saccocalyx satureioides. Gas chromatography coupled with mass spectrometry (GC-MS) was used to study the essential oil chemical compositions. The three essential oils were tested against a mosquito vectoring filariasis and arboviruses, i.e., Culex quinquefasciatus, a fly pest acting also as pathogens vector, Musca domestica, and an agricultural moth pest, i.e., Spodoptera littoralis, using WHO and topical application methods, respectively. The essential oil from A. campestris, containing β-pinene (15.2%), α-pinene (11.2%), myrcene (10.3%), germacrene D (9.0%) (Z)-β-ocimene (8.1%) and γ-curcumene (6.4%), showed remarkable toxicity against C. quinquefasciatus (LC₅₀ of 45.8 mg L^-1) and moderate effects (LD₅₀ of 99.8 μg adult^-1) against M. domestica. Those from P. arabica and S. satureioides, containing epi-α-cadinol (23.9%), δ-cadinene (21.1%), α-cadinol (19.8%) and germacrene D-4-ol (8.4%), and thymol (25.6%), α-terpineol (24.6%), borneol (17.4%) and p-cymene (11.4%), respectively, were more active on S. littoralis showing LD₅₀ values of 68.9 and 61.2 μg larva^-1, respectively. Based on our results, the essential oil from A. campestris may be further considered a candidate ingredient for developing botanical larvicides.

PZQ Therapy: How Close are we in the Development of Effective Alternative Anti-schistosomal Drugs?

Today schistosomiasis, caused mainly by the three major schistosome species (S. mansoni, S. haematobium and S. japonicum), has for many decades and still continues to be on a rapid and swift rise globally, claiming thousands of lives every year and leaving 800 million people at the risk of infection. Due to the high prevalence of this disease and the steady increase in the infection rates, praziquantel (PZQ) remains the only effective drug against this acute disease although it has no effect on the juvenile schistosome parasite. However, no significant approaches have been made in recent years in the discovery of new or alternative drugs and unfortunately, resistance to this drug has been reported in some parts of the world. Therefore, it is imperative to develop a new drug for this debilitating disease. In this review, a brief history of past, present, and new promising anti-schistosomal drugs is presented.

Universal Stress Proteins as New Targets for Environmental and Therapeutic Interventions of Schistosomiasis

In spite of various control measures and eradication methods that have been in progress, schistosomiasis still prevails as one of the most prevalent debilitating parasitic diseases, typically affecting the poor and the underprivileged that are predominantly concentrated in sub-Saharan Africa. The parasitic schistosome blood fluke responsible for causing the disease completes its complex developmental cycle in two hosts: humans and freshwater snails, where they physically undergo gross modifications to endure the different conditions associated with each host. Just like any other organism, the worm possesses mechanisms that help them respond to environmental insults. It has been hypothesized that a special class of proteins known as Universal Stress Proteins (USPs) are up-regulated during sudden environmental changes, thus assisting the worm to tolerate the unfavourable conditions associated with its developmental cycle. The position of praziquantel as the drug of choice against all schistosome infections has been deemed vulnerable due to mounting concerns over drug pressure and so the need for alternative treatment is now a matter of urgency. Therefore, this review seeks to explore the associations and possible roles of USPs in schistosomiasis as well as the functioning of these proteins in the schistosomulae stage in order to develop new therapeutic interventions against this disease.

Antischistosomal Activity of Two Active Constituents Isolated from the Leaves of Egyptian Medicinal Plants

In this paper, we investigate the role of two active constituents isolated from the leaves of Egyptian medicinal plants. D-mannitol a naturally occurring sugar isolated from the leaves Ixora undulata Roxb., and the pectin a linear chain homogalacturonan (HG) polysaccharide isolated from the leaves of Linum grandiflorum Desf. (scarlet flax). Both are evaluated for their therapeutic effect against schistosomiasis with biochemical and histochemical evaluations and compared with praziquantel, a reference drug. Biochemical studies of hepatic glucose, the glycogen content, and total serum protein were carried out, and histochemical evaluations through serum protein fractions separated by polyacrylamide gel electrophoresis with different molecular weights (260-10 kDa) were made in all groups, in addition to liver and body weight. D-mannitol and pectin show a remarkable effect in enhancing liver and kidney functions through enhancing most protein fractions in the serum of mice infected with Schistosoma mansoni. Also, the glucose and glycogen content in injured liver tissues improved, in addition liver and body weight in the infected groups. Thus they may be of therapeutic potential in the treatment hepatoxicity and nephrotoxicity.

Analgesic, antipyretic, anti-inflammatory, hepatoprotective and nephritic effects of the aerial parts of Pulicaria arabica (Family: Compositae) on rats

OBJECTIVE

To explore the analgesic, antipyretic, anti-inflammatory, hepatic and nephritic effects of Pulicaria arabica (P. arabica) in several experimental models.

METHODS

For analgesic effect hot plate and writhing method were used, while for antipyretic and anti-inflammatory rectal temperature and carrageenan induced hind paw edema were used respectively. CCl4 intoxication method was used for hepatic and nephritic protective activity.

RESULTS

The results of the present studies revealed that P. arabica has potent analgesic, antipyretic and anti-inflammatory with the significant hepatic and nephritic protecting actions. The CCl4 intoxication changed the normal malondialdehyde and nonprotein sulfhydryls levels in both liver and kidney. These changes were normalized with P. arabica indicating the antioxidant nature of this plant.

CONCLUSIONS

The results of present study indicated that P. arabica can be used in analgesic, antipyretic and anti-inflammatory conditions even in hepatic and nephritic conditions. More supportive studies are required before clinical recommendation.

Idiotype/anti-idiotype immunoregulatory network correlates with an improved clinical outcome of schistosomiasis mansoni in humans

Anti-idiotypes (anti-Ids) have a potential role in the immune modulation of various diseases. To study the correlation of anti-Ids with schistosomiasis mansoni morbidity, ELISA using polyclonal idiotypes (Ids) was used to determine the presence of anti-Ids in sera of 69 patients susceptible and resistant to reinfection. Ids were purified against Soluble Worm Antigen (SWAP) from sera of New Zealand white rabbits immunized with SWAP. The results showed that anti-Ids were detected in 15 (40.5%) of susceptible and 21 (65.6%) of resistant patients. Correlation of intensity of infection with age revealed an inverse relationship in patients positive for anti-Ids (regression coefficient beta = -0.47, p < 0.05) and contrarily, a direct relationship in patients negative for anti-Ids (beta = 0.67, p < 0.001). In addition, there was a direct association between the presence of anti-Ids and the lack of schistosome-related symptoms (chi2 = 3.6, p < 0.05) and hepatomegaly (chi2 = 9.4, p < 0.01). Moreover, comparison of patients positive and negative for anti-Ids revealed that those negative for anti-Ids were more vulnerable to develop symptoms (3.7 times) and hepatomegaly (8.1 times). In conclusion, the study further confirms the role of Id/anti-Id regulatory network as an important participant in the assortment of an improved clinical outcome of schistosomiasis. This may help to formulate a better understanding of the mechanisms of protective immunity in humans and provide perspective for the development of a future vaccine.