Medicinal properties and growth of Merwilla natalensis.

Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 2003.Merwilla natalensis (Planchon) Speta is ranked as one of the most commonly sold medicinal plants at most of the informal medicinal plant markets found throughout South Africa. The increasing demand for medicinal plants has resulted in over-exploitation of many of the wild populations. Overharvesting has resulted in M. natalensis being declared vulnerable. Although this species is so popular, and reports state that the bulbs are used for a variety of ailments, very little is known about its pharmacological activity or phytochemical composition. Extracts were made from mature M. natalensis bulbs using hexane, dichloromethane, methanol and water. These extracts were screened for antibacterial, anticancer, anti-inflammatory, antischistosomal and anthelmintic activity. Antibacterial activity was evaluated using the minimal inhibitory concentration (MIC) assay. Methanol extracts displayed good antibacterial activity against both Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli and Klebsiella pneumoniae) bacteria. Anti-inflammatory activity was evaluated using the COX-1 and COX-2 bioassays. Dichloromethane extracts displayed the highest inhibitory activity against both COX-1 and -2 enzymes. (80% and 91% inhibition respectively) Very good activity was displayed against the free-living nematode Caenorhabditis elegans and the schistosomula worms of Schistosoma haematobium using microdilution techniques. Anticancer activity was evaluated using the biochemical induction assay (BIA) in which DNA-damaging properties are tested for. No activity was found using this assay, however, these results do not prove that M. natalensis does not have other anticancer properties. The phytochemical investigation of mature M. natalensis plants showed the bulbs to contain both saponins and bufadienolides. One of the bufadienolides had the same Rf value as proscillaridin A. Cytotoxicity tests reveal M. natalensis to be extremely cytotoxic, yet the bulbs are commonly sold at traditional medicine markets around South Africa. This cytotoxicity may be accredited to the presence of saponins within the bulbs. No alkaloids or tannins were detected in the bulbs. With the growing population in South Africa, there is an increasing demand for traditional medicines. This increasing demand is placing tremendous strain on natural populations growing in the wild. However, as the demand cannot continue to be met other sources are needed. Tissue cultured plants have been grown at two different regions of South Africa. These plants have been grown under different conditions to determine the optimal ones needed to grow M. natalensis as a commercial crop on small-scale farms. Plantlets taken directly from tissue culture were acclimatized successfully for cultivation by means of simple and cost effective methods. Cultivated plants were harvested on a six-monthly basis for a period of two years. Field cultivation produced bulbs of almost marketable size (±300g fresh weight) after 24 months. Bulb size was not dependent on additional fertilizer or irrigation. No significant differences (p<_0.05) were shown in the average dry weights of bulbs grown under different treatments (control, fertilizer without irrigation, fertilizer with irrigation). Leaf senescence and dormancy of young plants were prevented with irrigation. Flowering occurred after 24 months, with the irrigation and fertilizer plot having the most flowering plants. TLC fingerprinting revealed differences in the chemical composition of the bulbs harvested at different stages of growth. Noticeable differences were found between bulbs cultivated at the different growing sites. Pharmacological screenings were done of the harvested bulbs to investigate the effect of age (time of harvest) and growing conditions on antibacterial, anti-inflammatory and anthelmintic activity. Methanol extracts were screened against Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli and Klebsiella pneumoniae) bacteria. Variations in activity were found. The time of harvest had a significant effect (p<_0.05) on biological activity, with the younger plants being more active. Antibacterial activity decreased with an increase in plants age. Methanol extracts were also screened for anthelmintic activity against Caenorhabditis elegans. Activity was found to increase with plant maturity. Irrigation was found to increase activity at the low rainfall (Fort Hare) site. Bulbs harvested from the irrigation treatment had significantly higher anthelmintic activity (p<_0.05) than bulbs harvested from treatments without irrigation. Dichloromethane extracts from bulbs grown at both sites had high anti-inflammatory activity. There were no significant differences (p<_0.05) in the activity of bulbs harvested from the different treatment plots. The time of harvest had an effect on the inhibition of prostaglandin synthesis by COX-1 enzymes. This study provides not only scientific verification for the use of M. natalensis to some extent as a medicinal plant, but also important data needed to successfully cultivate this species as a crop for small-scale farming

Seed germination of valuable high-altitude medicinal plants of southern Africa

Germination of nine important medicinal plant species from the high altitudes of southern Africa was investigated in relation to different environmental parameters. The seeds were subjected to different constant and alternating temperatures, temperature shifts, light and dark conditions, and cold stratification periods. Temperature regimes of 17-23°C appear most suitable for optimal germination for all the species examined. In some species, a temperature shift from 10°C to 20°C and 30°C to 20°C improved the final percentage germination. In the majority of the species investigated, exposure of seeds to continuous or alternating light significantly promoted germination over continuous dark. However, no phytochrome effect was determined. Tulbaghia alliacea and Dianthus basuticus germinated equally well in light and dark, while Urginea capitata responded significantly to the continuous light treatment. In some species, cold stratification stimulated germination and reduced the mean germination time

Larvicidal, antimicrobial and brine shrimp activities of extracts from Cissampelos mucronata and Tephrosia villosa from coast region, Tanzania

<p>Abstract</p> <p>Background</p> <p>The leaves and roots of <it>Cissampelos mucronata </it>A. Rich (Menispermaceae) are widely used in the tropics and subtropics to manage various ailments such as gastro-intestinal complaints, menstrual problems, venereal diseases and malaria. In the Coast region, Tanzania, roots are used to treat wounds due to extraction of jigger. Leaves of <it>Tephrosia villosa </it>(L) Pers (Leguminosae) are reported to be used in the treatment of diabetes mellitus in India. In this study, extracts from the roots and aerial parts of <it>C. mucronata </it>and extracts from leaves, fruits, twigs and roots of <it>T. villosa </it>were evaluated for larvicidal activity, brine shrimps toxicity and antimicrobial activity.</p> <p>Methods</p> <p>Powdered materials from <it>C. mucronata </it>were extracted sequentially by dichloromethane followed by ethanol while materials from <it>T.villosa </it>were extracted by ethanol only. The extracts obtained were evaluated for larvicidal activity using <it>Culex quinquefasciatus </it>Say larvae, cytotoxicity using brine shrimp larvae and antimicrobial activity using bacteria and fungi.</p> <p>Results</p> <p>Extracts from aerial parts of <it>C. Mucronata </it>exhibited antibacterial activity against <it>Staphylococcus aureus</it>, <it>Escherichia coli</it>, <it>Pseudomonas aeruginosa</it>, <it>Salmonella typhi</it>, <it>Vibrio cholera</it>, <it>Bacillus anthracis</it>, <it>Streptococcus faecalis </it>and antifungal activity against <it>Candida albicans </it>and <it>Cryptococcus neoformans</it>. They exhibited very low toxicity to brine shrimps and had no larvicidal activity. The root extracts exhibited good larvicidal activity but weak antimicrobial activity. The root dichloromethane extracts from <it>C. mucronata </it>was found to be more toxic with an LC₅₀value of 59.608 μg/mL while ethanolic extracts from root were not toxic with LC₅₀>100 μg/mL). Ethanol extracts from fruits and roots of <it>T. villosa </it>were found to be very toxic with LC₅₀values of 9.690 μg/mL and 4.511 μg/mL, respectively, while, ethanol extracts from leaves and twigs of <it>T. villosa </it>were found to be non toxic (LC₅₀>100 μg/mL).</p> <p>Conclusion</p> <p>These results support the use of <it>C. mucronata </it>in traditional medicine for treatment of wounds. Extracts of <it>C. mucronata </it>have potential to yield active antimicrobial and larvicidal compounds. The high brine shrimp toxicity of <it>T. villosa </it>corroborates with literature reports that the plant is toxic to both livestock and fish. The results further suggest that <it>T. villosa </it>extracts have potential to yield larvicidal and possibly cytotoxic compounds. Further studies to investigate the bioactive compounds responsible for the observed biological effects are suggested.</p

The chemistry and biological activity of the Hyacinthaceae

Covering: 1914 to 2012The Hyacinthaceae (sensu APGII), with approximately 900 species in about 70 genera, can be divided into three main subfamilies, the Hyacinthoideae, the Urgineoideae and the Ornithogaloideae, with a small fourth subfamily the Oziroëoideae, restricted to South America. The plants included in this family have long been used in traditional medicine for a wide range of medicinal applications. This, together with some significant toxicity to livestock has led to the chemical composition of many of the species being investigated. The compounds found are, for the most part, subfamily-restricted, with homoisoflavanones and spirocyclic nortriterpenoids characterising the Hyacinthoideae, bufadienolides characterising the Urgineoideae, and cardenolides and steroidal glycosides characterising the Ornithogaloideae. The phytochemical profiles of 38 genera of the Hyacinthaceae will be discussed as well as any biological activity associated with both crude extracts and compounds isolated. The Hyacinthaceae of southern Africa were last reviewed in 2000 (T. S. Pohl, N. R. Crouch and D. A. Mulholland, Curr. Org. Chem., 2000, 4, 1287-1324; ); the current contribution considers the family at a global level