Phytosynergy in some Hypoxis species and pharmacological properties of a Hypoxis-based phytopharmaceutical formula.

ETHNOPHARMACOLOGY RELEVANCE: Hypoxis species are used extensively in traditional medicine in southern Africa for several ailments including tuberculosis, chest infections, and nervous and urinary disorders. Several other claims have been made for extracts emanating from Hypoxis species and have led to the production of several commercial products used as immunostimulants mostly for people living with HIV/AIDS and cancer. This study was aimed at investigating the biological activity of four Hypoxis species and a commercial herbal product, 'African potato extract' (APE). MATERIALS AND METHODS: Antibacterial, antifungal, cyclooxygenase (COX) and acetylcholineasterase (AChE) inhibitory activities of four Hypoxis species (H. acuminata, H. colchicifolia, H. hemerocallidea and H. rigidula) and a popular Hypoxis-based herbal preparation, APE were tested. The phytoconstituents of the mixture were also profiled using TLC methods. Several combinations of the Hypoxis species were prepared and their synergism, additive, autonomic and antagonism effects investigated. As a quality control measure, batch to batch comparison in the phytoconstituents and biological activity of APE was carried out. RESULTS: The results confirmed H. colchicifolia and H. hemerocallidea as the phytoconstituents of APE. The extracts showed a broad spectrum of activities against the bacterial and fungal strains used. Of particular interest were the activities exhibited by the APE and combinations of H. colchicifolia and H. hemerocallidea. The APE mixture exhibited good antibacterial activity (MIC values of 0.78mg/ml each) in all the tested batches against the bacterial strains used. The water extracts of all four Hypoxis species, three batches of APE and the combination (water extracts) of H. colchicifolia and H. hemerocallidea exhibited high COX-1 and moderate COX-2 inhibitory activity except for H. acuminata which showed low activity against COX-2. All the extract, batches of APE and combinations showed low to moderate AChE inhibitory activity. These results provided some evidence of phytosynergy in some extracts of H. hemerocallidea and H. colchicifolia except for a few extracts which act as additive, autonomous and antagonistic when used to inhibit some bacterial and fungal strains. However, this was not the case for COX and AChE inhibition, as only acetone extracts acted in a synergistic way to reduce the activity of the enzyme. CONCLUSION: Even though the results give an indication of a positive interaction between some extracts of H. hemerocallidea and H. colchicifolia, the study was carried out on 1:1 v/v combinations only. It is therefore important to carry out isobologram studies, which considers more than one ratio of the combinations.

Antimicrobial, anti-inflammatory and mutagenic investigation of the South African tree aloe (Aloe barberae).

ETHNOPHARMACOLOGY RELEVANCE: In recent times, many products ranging from aloe drinks to aloe gels, powders, capsules, and creams have appeared on the commercial market prepared from different aloe species including Aloe barberae. These products are used in ethnomedicine to treat various conditions including gastrointestinal disorders, insect bites, skin burns and other skin injuries by traditional communities. AIM OF THE STUDY: This study was aimed at evaluating the antibacterial, antifungal and anti-inflammatory activities as well as genotoxic effects of different extracts of Aloe barberae. MATERIALS AND METHODS: Organic and water extracts of the upper stem, young bark, mature bark, leaves and roots of the South African tree aloe (Aloe barberae) were evaluated for their antimicrobial [gram-positive (Bacillus subtilis and Staphylococcus aureus), gram-negative (Escherichia coli and Klebsiella pneumoniae) bacteria as well as the fungus Candida albicans], anti-inflammatory (COX-1 and COX-2) and mutagenic properties (Ames test). Thin layer chromatography (TLC) was used to compare the phytochemical profiles of different extracts of Aloe barberae. RESULTS: The petroleum ether (PE) and dichloromethane (DCM) extracts of the mature bark, leaves and roots exhibited good activity against all the bacteria and fungus Candida albicans with minimum inhibitory concentrations (MIC) ranging from 0.195 to 1.56 mg/ml. All the PE extracts evaluated showed a high activity (>70%) in both COX-1 and COX-2 assays. Apart from the organic extracts of the root with consistently good activity (>70%), all the remaining extracts showed moderate activity (40-69%) in COX-1 assay. The PE extracts also showed a dose dependent increase in activity. Ultraviolet (UV) spectrum of the leaves and root EtOH extracts indicated the presence of compounds that could absorb UV light (wavelength: 190-820 nm). None of the extracts had a mutagenic effect in the Salmonella/microsome assay against a tester strain, TA98. CONCLUSION: Activity observed in the bark, leaves and roots of Aloe barberae validates its use in commercial herbal products, ethnobotany and ethnoveterinary medicine by South African communities and small scale farmers to treat various conditions.

In vitro pharmacological effects of manufactured herbal concoctions used in KwaZulu-Natal South Africa.

ETHNOPHARMACOLOGY RELEVANCE: Manufactured and packaged herbal mixtures, known locally as muthi concoctions, have become a new feature of traditional medicine in South Africa. These herbal concoctions are often claimed to cure several diseases ranging from minor illness to life threatening conditions. AIM OF THE STUDY: To document the prevalence, variety and evaluate the efficacy of selected herbal concoctions sold in KwaZulu-Natal. MATERIALS AND METHODS: Nine herbal concoctions were evaluated for their effects as antibacterial and antifungal agents as well as their ability to inhibit the cyclooxygenase (COX-1 and COX-2) enzymes using standard in vitro methods. RESULTS: Imbiza ephuzwato and Ibhubezi, both multipurpose mixtures showed high abilities to inhibit bacterial and fungal growth as well as inhibit the COX-1 and COX-2 enzymes. Umzimba omubi and Umuthi wekukhwehlela ne zilonda, both remedies for wounds, boils and chest infections were not active against the two Gram-positive and two Gram-negative bacterial strains tested. Vusa umzimba and Supreme one hundred were active against Candida albicans. CONCLUSIONS: Four of the herbal concoctions showed no activity in all of the assays tested while only two showed good activity. Activity cannot be ruled out as there are many mechanisms upon which natural products can act.

Antimicrobial activity of South African Podocarpus species.

ETHNOPHARMACOLOGICAL RELEVANCE: Several species of Podocarpus (Podocarpaceae) are utilized in treating ailments across the world. In Africa, four species are used traditionally in both animal and human health. AIM OF THE STUDY: To investigate the antimicrobial activity of Podocarpus species against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Candida albicans. MATERIALS AND METHODS: Six solvents of varying polarity were used for extraction. Antibacterial activity was assessed using the microdilution bioassay and for antifungal activity, the microdilution bioassay and (M27-P) broth dilution were used. RESULTS: All species exhibited antimicrobial activity with MIC values of less than 1mg/ml. Inhibition against Gram-positive bacteria was stronger with an MIC value of 98 microg/ml while for Gram-negative bacteria, the highest inhibition was against Klebsiella pneumoniae with an MIC value of 0.33 mg/ml. All species exhibited strong antifungal activity with the best MIC being 30 microg/ml after 48 h. CONCLUSIONS: All four species exhibited strong inhibition against all tested microbials, based on Aligiannis et al. [Aligiannis, N., Kalpotzakis, E., Mitaku, S., Chinou, I.B., 2001. Composition and antimicrobial activity of the essential oils of two Origanum species. Journal of Agricultural and Food Chemistry 40, 4168-4170] classification they can be classified as strong inhibitors.

Riding the wave: South Africa's contribution to ethnopharmacological research over the last 25 years.

South Africa is a country with both rich floral biodiversity and cultural diversity. Traditional herbal medicines form an important part of the healthcare of most South Africans, and relies heavily on the use of indigenous plants. This article briefly describes the role South Africa has played in recent years, in contributing to the worldwide increase in research in the field of ethnopharmacology.

Effect of storage on the chemical composition and biological activity of several popular South African medicinal plants.

The in vitro biological activity of nine frequently used medicinal plants in South Africa was assessed and re-assessed after various lengths of storage. The plants investigated were Alepidea amatymbica, Leonotis leonurus, Drimia robusta, Vernonia colorata, Merwilla natalensis, Eucomis autumnalis, Bowiea volubilis, Helichrysum cymosum and Siphonochilus aethiopicus. Water, ethanol and hexane extracts of fresh, 90-day-old and 1-year-old material were assayed for antibacterial activity against four strains of bacteria and for COX-1 inhibition activity. TLC-fingerprints of the fresh and stored extracts were produce to document chemical changes. Alepidea amatymbica, Eucomis autumnalis, Helichrysum cymosum, Leonotis leonurus, Siphonochilus aethiopicus and Vernonia colorata were investigated further as to the effect of 1 year's storage. Elevated temperature and humidity (55 degrees C and 100% relative humidity) were used to accelerate the ageing process of Alepidea amatymbica, Leonotis leonurus and Vernonia colorata plant material for further investigation. The TLC-fingerprints indicated that there was chemical breakdown during storage in certain species. The degree of changes in biological activity and chemistry due to storage were species-specific. In general, antibacterial activity was retained in most species while COX-1 inhibition activity was lost rapidly.

Assessing African medicinal plants for efficacy and safety: agricultural and storage practices.

The paper reviews an important but little researched area of ethnopharmacology, namely, the effect of cultivation and post-harvest storage practices on levels of biological activity in traditionally used medicinal plants. Changes in COX-1 inhibition and antibacterial activity, for example, occur at the onset of senescence and, in some species, are influenced by plant age. Plants in cultivation were also shown to have reduced anthelmintic and antibacterial activity while hypoxoside production was affected by nitrogen and phosphorous. Irrigation treatments, however, increased anthelmintic activity and, therefore, could be applied to medicinal plants cultivated in low rainfall areas. Pesticides have also been implicated in the regulation of plant growth and secondary metabolite production in cultivated medicinal plants, but residue levels have, so far, not been monitored. Post harvest storage of medicinal plants has been poorly researched in southern Africa. Available data indicates that antibacterial and anti-inflammatory activity changes following storage and is both species and temperature dependent. Similar trends were noted for materials that had been rapidly aged. Fatty acids with antibacterial activity are stable in dry specimens and, as such, may account for the fact that activity is unaffected by storage in certain instances.

Assessing African medicinal plants for efficacy and safety: pharmacological screening and toxicology.

This paper reviews progress in establishing the scientific rationale for and safety of traditional medicine use in Africa. Selected plants were screened for antibacterial, antifungal, anthelmintic, anti-amoebic, antischistosomal, antimalarial, anti-inflammatory and antioxidant activity, as well as psychotropic and neurotropic activity using appropriate in vitro tests. Isolation of active compounds, in almost all cases, provided scientific validation for the use of the plants in traditional medicine. Although plants used medicinally are widely assumed to be safe, many are potentially toxic. Where poisoning from traditional medicines has been reported, it is usually because the plants used have been misidentified in the form in which they are sold, or incorrectly prepared and administered by inadequately trained personnel. The issue of quality control may, in the interim, be addressed using chromatographic techniques.

Blockade of parathyroid hormone-related protein prevents joint destruction and granuloma formation in streptococcal cell wall-induced arthritis.

OBJECTIVE: To determine whether parathyroid hormone-related protein (PTHrP), an interleukin-1beta-inducible, bone-resorbing peptide that is produced in increasing amounts by the synovium in rheumatoid arthritis (RA), may play a role in the pathophysiology of joint destruction in RA. METHODS: PTHrP expression and the effect of PTHrP 1-34 neutralizing antibody on disease progression were tested in streptococcal cell wall (SCW)-induced arthritis, an animal model of RA. RESULTS: As has been reported in RA, while serum levels of PTHrP did not change during SCW-induced arthritis, PTHrP expression dramatically increased in the arthritic synovium. Treatment with PTHrP neutralizing antibody (versus control antibody) did not affect joint swelling in SCW-treated animals. However, PTHrP antibody significantly inhibited SCW-induced joint destruction, as measured by its ability to block increases in serum pyridinoline (a marker of cartilage and bone destruction), erosion of articular cartilage, decreases in femoral bone mineral density, and increases in the numbers of osteoclasts in eroded bone. Unexpectedly, granuloma formation at sites of SCW deposition in the liver and spleen was also inhibited by PTHrP antibody, an effect associated with significant decreases in the tissue influx of PTH/PTHrP receptor-positive neutrophils and in SCW-induced neutrophilia. In vitro, neutrophil chemotaxis was stimulated by PTHrP 1-34. CONCLUSION: These findings suggest that PTHrP, consistent with its previously described osteolytic effects in metastatic bone disease, can also be an important mediator of joint destruction in inflammatory bone disorders, such as RA. Moreover, this study reveals heretofore unknown effects of PTHrP peptides on neutrophil function that could have important implications in the pathogenesis of inflammatory granulomatous disorders.