Scorpion antivenom effect of micropropagated Aristolochia elegans

Ethnomedicines for the treatment of scorpion stings: A perspective study

ETHNOPHARMACOLOGICAL RELEVANCE

Scorpion sting is a public health concern with limited clinical symptomatic treatment. The clinical treatment uses anti-scorpion antivenom and prazosin (α-adrenergic inhibitor), often in combination with insulin, to reduce scorpion venom-induced hyperglycemia and other complications. However, these therapies also possess some limitations, necessitating urgent exploration of ethnomedicines, mainly traditional medicinal plants, to treat scorpion stings. Unfortunately, several conventional treatments are not scientifically validated, thus raising questions about their quality and utility. Therefore, pharmacological re-assessment of such medicinal plants to alleviate scorpion stings' complications is essential.

AIM OF THE STUDY

The principal objectives of this study are to provide a brief overview of medically important scorpions of the world, outline the extant traditional practices, and comprehensively review plants used in conventional ethnic medicines to treat scorpion stings over time. Modern technological advances in identifying and characterizing plant bioactive molecules are also mentioned in this review.

MATERIALS AND METHODS

The traditionally used medicinal plants against scorpion stings were reviewed from the available literature in the database. The Plant List (http://www.theplantlist.org/) was used to validate the scientific names of the plants mentioned in this study. The search targeted literature on conventional treatments and crude plant extracts or their bioactive components with proven neutralization capacity against scorpion stings. Search words used were 'scorpion sting,' 'treatment for a scorpion sting,' 'antivenom and scorpion sting,' 'traditional treatment for scorpion stings, and 'natural compounds against scorpion stings'.

RESULTS

A list of more than 200 medicinal plants traditionally used in several countries for treating scorpion stings is presented in this review. Though some myth-based remedies are practiced to treat scorpion stings, no empirical evidence exists to validate this aspect of traditional knowledge. Only 38 traditional medicinal plant extracts have been tested under in-vivo and in-vitro conditions to determine their neutralization potency of scorpion envenomation. Although a few bioactive plant constituents showing scorpion venom neutralization potency have been characterized, they are not yet commercially available for clinical application.

CONCLUSIONS

There is tremendous potential locked in medicinal plants' traditional knowledge for scorpion envenomation treatment. Translating this knowledge into the clinical application will require pharmacological reassessment, in tandem with isolation and characterization of active compounds to prove their prophylactic prowess. Almost equally important would be the formulation of stringent strategies to conserve such medicinal plants from overexploitation.

Neolignans from Aristolochia elegans as antagonists of the neurotropic effect of scorpion venom

ETHNOPHARMACOLOGICAL RELEVANCE

The high frequency of poisoning by sting or bite from venomous animals has begun to be a serious public health problem in Mexico where scorpion sting is the most common. Because of this, there is the need to seek active substances in plant species with an antagonistic effect against neurotropic activity of scorpion venom. The aim of this work was to demonstrate which of the compounds contained in the n-hexane extract from Aristolochia elegans roots display activity against scorpion venom.

MATERIAL AND METHODS

Antagonist activity displayed by extract, fractions and isolated compounds obtained from Aristolochia elegans was guided by the inhibition of smooth muscle contraction induced by scorpion venom (Centruroides limpidus limpidus) in a model of isolated guinea pig ileum. The neolignans obtained from this extract were isolated and analyzed by chromatographic methods including HPLC. The chemical characterization of these compounds was performed by the analysis of (1)H and (13)C NMR spectra.

RESULTS

The bio-guided chromatographic fractionation allowed us to isolate 4 known neolignans: Eupomatenoid-7 (1), licarin A (2), licarin B (3), eupomatenoid-1 (4) and other new neolignan which was characterized as 2-(3'-hydroxy-4'-methoxyphenyl)-3-methyl-5-[(E)-α-propen-γ-al]-7-methoxy-benzo [b] furan (5). This compound was named as eleganal. Compounds 1 and 2 were purified from the most active fraction AeF3 (EC50 of 149.9μg/mL, Emax of 65.66%). A doses-response analysis of eupomatenoid-7(1) and licarin A(2) allowed us to establish EC50 values (65.96μg/mL and 51.96μg/mL) respectively.

CONCLUSIONS

The antagonistic effect against Centuroides limpidus limpidus scorpion venom displayed by the n-hexane extract from Aristolochia elegans roots is due to the presence of neolignans 1-2 contained in the fraction AeF3. Chemical analysis of fraction AeF2 allowed the isolation of a new compound which was identified as 2-(3'-hydroxy-4'-methoxyphenyl)-3-methyl-5-[(E)-α-propen-γ-al]-7-methoxy-benzo[b]furan (5), denominated as eleganal.

Chemical Constituents and Pharmacology of the Aristolochia ( mădōu ling) species

Aristolochia ( mădōu ling) is an important genus widely cultivated and had long been known for their extensive use in traditional Chinese medicine. The genus has attracted so much great interest because of their numerous biological activity reports and unique constituents, aristolochic acids (AAs). In 2004, we reviewed the metabolites of Aristolochia species which have appeared in the literature, concerning the isolation, structural elucidation, biological activity and literature references. In addition, the nephrotoxicity of aristolochic acids, biosynthetic studies, ecological adaptation, and chemotaxonomy researches were also covered in the past review. In the present manuscript, we wish to review the various physiologically active compounds of different classes reported from Aristolochia species in the period between 2004 and 2011. In regard to the chemical and biological aspects of the constituents from the Aristolochia genus, this review would address the continuous development in the phytochemistry and the therapeutic application of the Aristolochia species. Moreover, the recent nephrotoxicity studies related to aristolochic acids would be covered in this review and the structure-toxicity relationship would be discussed.

Plants used to treat malaria in Nyakayojo sub-county, western Uganda

AIM OF STUDY

We performed an ethnobotanical study of plants used to treat malaria in Nyakayojo sub-county in south western Uganda because malaria in this region, and in Uganda at large, is still the single most important reason for ill health and mortality. Two of the most vulnerable groups affected by malaria are young children and pregnant women and plants are commonly used in their treatment.

MATERIALS AND METHODS

Twenty-eight traditional birth attendants were interviewed about how they used plants to treat malaria. Review of the literature available on all species identified was undertaken.

RESULTS

Altogether 56 plant species were used by the informants, 48 of which have been identified to species level. Thirty-two (67%) of the species used by the respondents are documented for antimalarial use in other studies, and nearly half (44%) have documented anti-plasmodial activity. Fifty-five percent of the species were used by 2 or more of the respondents. The most commonly used species were Vernonia amygdalina, the indigenous Aloe species, Justicia betonica, Vernonia adoensis and Tithonia diversifolia. It was common to use more than one plant in a recipe (43%). The respondents had good knowledge of the symptom of malaria, and fairly good understanding of the causes.

CONCLUSION

The interviews show that the group of traditional birth attendants has an extensive and diverse knowledge on plants used in the treatment of malaria. The literature survey may indicate a possible explanation for the use of several plants.