Molluscicidal saponins from Catunaregam nilotica

Erythrosaponins A-J, triterpene saponins from the roots and stem bark of Gardenia erythroclada

Ten undescribed triterpene saponins, named erythrosaponins A-J, along with one known analogue were isolated from the roots and stem bark of Gardenia erythroclada. Their structures were determined on the basis of extensive 1D and 2D NMR analyses. Absolute structure of erythrosaponin A was unequivocally affirmed by single-crystal X-ray crystallography. All isolated compounds were evaluated for their cytotoxicity against cancer cell lines (KB and HeLa S-3) and their anti-inflammatory activity based on the inhibition of NO production in RAW264.7 cells. Erythrosaponin D showed moderate cytotoxicity against KB and HeLa S-3 cells with IC₅₀ values of 25.8 and 29.5 μM, respectively. Erythrosaponins D, F, G, I and J showed moderate anti-inflammatory with IC₅₀ values in the range of 63.0-81.4 μM.

Secondary metabolites from Rubiaceae species

This study describes some characteristics of the Rubiaceae family pertaining to the occurrence and distribution of secondary metabolites in the main genera of this family. It reports the review of phytochemical studies addressing all species of Rubiaceae, published between 1990 and 2014. Iridoids, anthraquinones, triterpenes, indole alkaloids as well as other varying alkaloid subclasses, have shown to be the most common. These compounds have been mostly isolated from the genera Uncaria, Psychotria, Hedyotis, Ophiorrhiza and Morinda. The occurrence and distribution of iridoids, alkaloids and anthraquinones point out their chemotaxonomic correlation among tribes and subfamilies. From an evolutionary point of view, Rubioideae is the most ancient subfamily, followed by Ixoroideae and finally Cinchonoideae. The chemical biosynthetic pathway, which is not so specific in Rubioideae, can explain this and large amounts of both iridoids and indole alkaloids are produced. In Ixoroideae, the most active biosysthetic pathway is the one that produces iridoids; while in Cinchonoideae, it produces indole alkaloids together with other alkaloids. The chemical biosynthetic pathway now supports this botanical conclusion.

Evaluation of antinociceptive and anti-inflammatory activities of standardised rootbark extract of Xeromphis nilotica

ETHNOPHARMACOLOGICAL RELEVANCE

Xeromphis nilotica (Stapf) Keay (Rubiaceae), popularly known as 'barbaji' (in Nigeria), is a lowland shrub that grows wild in tropical areas of Africa and Asia. The plant׳s extract is used for the treatment of various diseases in folk medicine including pain related ailments. Important bioactive constituents have been isolated from the plant among them are coumarin, alkaloids, flavonoids, saponins, and terpenes. This study is aimed to evaluate the analgesic and anti-inflammatory efficacy of standardised aqueous extract of the plant using in vivo models of pain and inflammation in mice and rats.

MATERIALS AND METHODS

Aqueous extract of Xeromphis nilotica root bark was prepared and standardised using HPLC technique. Three dose levels (25, 100 and 400mg/kg) of the extract were used, administered orally to laboratory mice and rats. Acetylsalicylic acid (100mg/kg, p.o.) was used as the positive control. Nociception was induced in laboratory rodents: chemically using acetic acid and formalin, and mechanically using analgesy meter; while inflammation was induced using fresh raw egg albumin.

RESULTS

The extract showed 11 constituents peak profiles in the HPLC analysis. The extract alleviates mice response to acetic acid-induced writhing, analgesy-meter and formalin tests. It significantly decreased the oedema induced by egg albumin induced inflammation, but failed to show significant effect beyond 80min of the test.

CONCLUSION

The extract has antinociceptive effect and short acting anti-inflammatory activities. The results justify its usage in the treatment of pain and inflammatory conditions, and also provided evidence of its potential as source of new pain relief drug prototype.

Psychopharmacological properties of saponins from Randia nilotica stem bark

CONTEXT

Decoctions of Randia nilotica Stapf. (Rubiaceae) have been used in the Nigerian traditional medicine for the management of epilepsy, anxiety, depression and psychosis for many years and their efficacies are widely acclaimed among the rural communities of Northern Nigeria.

OBJECTIVE

The aim of this study is to establish whether the saponins present in R. nilotica are responsible for its acclaimed beneficial effects in Nigerian traditional medicine.

MATERIALS AND METHODS

The behavioural properties of the saponin-rich fraction (SFRN) of R. nilotica stem bark were studied on hole-board, diazepam-induced sleep, rota-rod and beam-walking in mice. The anticonvulsant properties of SFRN were also examined on maximal electroshock, pentylenetetrazole- and strychnine-induced seizures in mice.

RESULTS

The intraperitoneal LD₅₀ of SFRN in mice and rats were estimated to be 11.1 and 70.7 mg/kg, respectively. SFRN significantly prolonged the duration of diazepam-induced sleep; diminished head dip counts in the hole-board test and protected mice against maximal electroshock seizures. SFRN failed to protect mice against pentylenetetrazole- and strychnine-induced seizures; and had no effect on motor coordination on the rota-rod treadmill at the doses tested. SFRN significantly decreased the number of foot slips in the beam-walking assay in mice with no effect on time to reach the goal box.

DISCUSSION AND CONCLUSION

This study provides evidence of the psychopharmacological effects of SFRN, thus supporting further development of the psychoactive components as remedies for epilepsy.

Preliminary phytochemical screening and molluscicidal activity of the aqueous extract of Bidens pilosa Linné (Asteraceae) in Subulina octona (Mollusca, Subulinidade)

The aim of this study was to establish reference concentrations (LC50 e LC90) of aqueous extracts of Bidens pilosa on the land snail Subulina octona, in order to assess the changes caused by 24 and 48 h exposure to the sublethal concentration regarding species' fecundity, hatchability and in offspring produced after exposure to confirm the presence of tannins, saponins and flavonoids in this plant species. Eggs newly hatched and 30 day-old snails were exposed to sublethal concentration, calculated for adults. The phytochemical analysis confirmed the presence of flavonoids, condensed tannins and saponins in the aqueous extract of B. pilosa. The LC50 and LC90 obtained were 51.4mg/mL and 74.1mg/mL respectively. The exposure to sublethal concentration reduced significantly the hatchability and the survival of the offspring hatched from exposed eggs and also caused a reduction on survival and growth in snails exposed for both time period. The exposure time also caused a reduction at the evaluated parameters.

Triterpenoid saponins from the stem bark of Catunaregam spinosa

Four new triterpenoid saponins, Catunaroside E (1; 3-O-{β-D-glucopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→3)]-β-D-glucopyranosyl}-siaresinolic acid), Catunaroside F (2; 3-O-{α-L-rhamnopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→3)]-β-D-glucopyranosyl}-28-O-(β-D-glucopyranosyl)-oleanolic acid), Catunaroside G (3; 3-O-[α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranosyl]- 28-O-(β-D-glucopyranosyl)-siaresinolic acid), and Catunaroside H (4; 3-O-{β-D-glucopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→3)]-β-D-glucopyranosyl}-28-O-(β-D-glucopyranosyl)-siaresinolic acid), and the known triterpenoid saponin Mussaendoside J (5), were isolated from the stem bark of Catunaregam spinosa . Their structures were elucidated on the basis of their spectral data and chemical evidence.

Keeping leeches at bay: field evaluation of plant-derived extracts against terrestrial blood-sucking leeches (Haemadipsidae) in Lao PDR

Terrestrial blood-sucking leeches (Haemadipsidae) are common in the damp forests of the subtropical and tropical Indo-Pacific region. Members of the genus Haemadipsa are abundant in Laos and adjacent countries of Southeast Asia, and discomfort to people and livestock. Plant-derived repellents against arthropods and leeches are common in Lao PDR, and have been used by Lao ethnic groups for generations. Numerous studies have been conducted on the efficacy of traditional plant-derived repellents against mosquitoes but only a few on repellents against terrestrial blood-sucking leeches. Field experiments were conducted to evaluate the leech repellent activities of aqueous extracts of three traditionally used plant species, Sapindus rarak DC., Catunaregam spathulifolia Tirv. and Vernonia elaeagnifolia DC. Stockings impregnated with aqueous extracts exhibited moderate to high leech repellent activity, C. spathulifolia (62.6%), V. elaeagnifolia (63.0%), and S. rarak (82.6%). The corresponding repellencies of deltamethrin and DEET were 73.1% and 88.4%, respectively. An aqueous extract of S. rarak applied on cloth at a concentration of 1.9 mg/cm(2) is an effective and practical prevention method significantly reducing the number of blood-feeding leeches recorded on stockings worn by humans. This plant species is common in Southeast Asia and can be obtained at limited or no cost.

Botanical repellents and pesticides traditionally used against hematophagous invertebrates in Lao People's Democratic Republic: a comparative study of plants used in 66 villages

Hematophagous parasites such as leeches, ticks, mites, lice, bedbugs, mosquitoes, and myiasis-producing fly larvae are common health problems in Lao People's Democratic Republic. Several arthropod-borne infections, e.g., malaria, dengue fever, and Japanese encephalitis, are endemic there. Effective vector control methods including the use of pesticides, insecticide-treated bed nets, and synthetic and plant-based repellents are important means of control against such invertebrates and the pathogens they may transmit or directly cause. In this study, we documented traditional knowledge on plants that are used to repel or kill hematophagous arthropods, including mosquitoes, bedbugs, human lice, mites and ticks, fly larvae, and blood-sucking leeches. Structured interviews were carried out in 66 villages comprising 17 ethnic groups, covering a range of cultures, throughout Lao People's Democratic Republic. A total of 92 plant species was recorded as traditional repellents (including plants for pesticidal usages) in 123 different plant-ectoparasite combinations. The number and species of plants, and animal taxa repelled (or killed) per plant species differed per region, village, and ethnic group. Traditional use was confirmed in the scientific literature for 74 of these plant species, and for an additional 13 species using literature on closely related species. The use of botanical repellents and pesticides from many plant species is common and widespread in the Lao countryside. In the future, the identification of the active components in certain plants to develop more optimal, inexpensive repellents, insecticides, acaricides, or antileech compounds as alternatives to synthetic repellents/pesticides against blood-feeding insects, ticks, mites, and leeches is warranted.

Physiological changes and molluscicidal effects of crude latex and Milin on Biomphalaria glabrata

Euphorbian latex is commonly used as molluscicides and the Euphorbia milii latex was reported as most powerful molluscicidal agents. The physiological and lethal effects of the latex components of Euphorbia milii, on the intermediate host Biomphalaria spp., of the human liver parasite Schistosoma mansoni were described in this study. The standard methodologies for testing plant derived molluscicides formulated by World Health Organisation (WHO) were followed with some modifications. The young specimen of fresh water snails showed altered physiological and physical response towards latex components. The working concentration of non-proteinaceous fraction (up to 0.1%) of the latex reduced the active physiological behaviour but was non-lethal to young specimen of snails. However, proteinaceous fractions (0.1mg/l) of the latex were found lethal to snail population, and lethality was enhanced with small amount of the non-proteinaceous fraction (0.01%) of the latex. Milin, a serine protease(up to 0.1mg/l), isolated from the latex of Euphorbia milii significantly reduced the growth and feeding activity but was not lethal to young specimen of snails. With an addition of 0.01% of non-proteinaceous fractions to Milin, lethality result was similar to that of crude latex. Milin is likely to be responsible for alteration of normal physiological functions and lethality of snails, thus it may be used as a molluscicide to control transmission of the endemic disease schistosomiasis.

Saponins, classification and occurrence in the plant kingdom

Saponins are a structurally diverse class of compounds occurring in many plant species, which are characterized by a skeleton derived of the 30-carbon precursor oxidosqualene to which glycosyl residues are attached. Traditionally, they are subdivided into triterpenoid and steroid glycosides, or into triterpenoid, spirostanol, and furostanol saponins. In this study, the structures of saponins are reviewed and classified based on their carbon skeletons, the formation of which follows the main pathways for the biosynthesis of triterpenes and steroids. In this way, 11 main classes of saponins were distinguished: dammaranes, tirucallanes, lupanes, hopanes, oleananes, taraxasteranes, ursanes, cycloartanes, lanostanes, cucurbitanes, and steroids. The dammaranes, lupanes, hopanes, oleananes, ursanes, and steroids are further divided into 16 subclasses, because their carbon skeletons are subjected to fragmentation, homologation, and degradation reactions. With this systematic classification, the relationship between the type of skeleton and the plant origin was investigated. Up to five main classes of skeletons could exist within one plant order, but the distribution of skeletons in the plant kingdom did not seem to be order- or subclass-specific. The oleanane skeleton was the most common skeleton and is present in most orders of the plant kingdom. For oleanane type saponins, the kind of substituents (e.g. -OH, =O, monosaccharide residues, etc.) and their position of attachment to the skeleton were reviewed. Carbohydrate chains of 18 monosaccharide residues can be attached to the oleanane skeleton, most commonly at the C3 and/or C17 atom. The kind and positions of the substituents did not seem to be plant order-specific.

Molluscicidal activity of some Moroccan medicinal plants

Among 14 plants of Moroccan folk medicine tested for molluscicidal activity, ethyl acetate extract from Origanum compactum and hexane extracts from both Chenopodium ambrosioides and Ruta chalepensis were the most active (LC(90)=2.00, 2.23 and 2.23 mg l(-1), respectively) against the schistosomiasis-transmitting snail Bulinus truncatus.