Antifungal and anti-mycotoxigenic activity of selected South African medicinal plants species.

Antifungal and anti-mycotoxigenic activity of 25 acetone leaf extracts of South African medicinal plants with potent antioxidant activity were investigated against three phytopathogenic fungal strains. The extracts exhibited varying degrees of in vitro anti-mycotoxigenic effect against Fusarium verticillioides, Aspergillus flavus and Aspergillus ochraceous. Markhamia obtusifolia (Baker) Sprague exhibited the lowest minimum inhibitory concentration (MIC) values as low as 0.08 mg/ml against Aspergillus flavus and Furasium verticilloides at both 24 and 48 hr incubation period, while Curtisia dentata exhibited similar MIC value against Aspergillus ochraceous. Curtisia dentata further yielded the highest total activity of 1583 ml/g against Aspergillus ochraceous at 24 and 48 hr incubation period. In the mycelial growth inhibition (MGI) evaluation, Fusarium verticilloides was more sensitive to plants extracts, while Kirkia wilmsii exhibited highest MGI of 50.08% against Fusarium verticilloides on the 6th day of incubation. Five acetone extracts from Acokanthora oppositifolia, Bauhinia galpinii, Combretum caffrum, Ricinus communis and Solanum aculeastrum exhibited lowest IC50 value of 0.01 mg/ml against (2,2'-azinobis-3-ethylbenzthiazoline-6-suphonic acid (ABTS). Curtisia dentata and Markhamia obtusifolia extracts were further subjected to gas chromatography mass-spectrophotometry (GC-MS) analysis. Curtisia dentata revealed the presence of triterpenoid compounds, ß-amyrin (53.30%) and α-amyrin (6.42%), while Markhamia obtusifolia yielded the presence of neophytadiene (4.38%) and palmitic acid (3.61%) The results suggest that natural products from plants may well be used as possible substitutes for synthetic fungicides. Given the antifungal and antioxidant potential of the selected plants, they may have potential as possible leads for the development of biofungicides that may well prevent oxidation related food spoilage.

Studies on antibacterial, anti-inflammatory and antioxidant activity of herbal remedies used in the treatment of benign prostatic hyperplasia and prostatitis.

Crude water and ethanolic extracts of five herbal remedies reported in the literature for traditional treatment of benign prostatic hyperplasia (BPH) and/or prostatitis were investigated for their effect on hydroxyl scavenging activity, antibacterial activity and their ability to inhibit cyclooxygenase-1 and -2 (COX-1 and COX-2) catalysed prostaglandin biosynthesis. Both the water and ethanol extracts of Hypoxis hemerocallidea and Epilobium parviflorum inhibited the growth of Escherichia coli. All 10 extracts scavenged the hydroxyl radical but with various potencies (32-93%). Ethanolic extracts were the most active in inhibiting COX-1 catalysed prostaglandin biosynthesis. The ethanolic extract of Epilobium parviflorum showed inhibitory effects on both the COX-1 and -2 catalysed prostaglandin biosynthesis, inhibited growth of Escherichia coli and exerted antioxidant activity. Although these results support the traditional use of Epilobium parviflorum for treatment of prostatitis and BPH, further investigation is required, for this promising plant.

Antibacterial, anti-inflammatory, anti-cholinesterase and mutagenic effects of extracts obtained from some trees used in South African traditional medicine.

Extracts obtained from 10 trees used in South African traditional medicine were screened for antibacterial, anti-inflammatory (COX-1 and COX-2) and anti-cholinesterase activities and investigated for potential mutagenic effects using the Ames test. Antibacterial activity was detected using the disc-diffusion and micro-dilution assays. The extracts were tested against Gram-positive bacteria: Bacillus subtilis, Staphylococcus aureus, Micrococcus luteus and Gram-negative bacteria: Escherichia coli and Klebsiella pneumoniae. Of the 78 different plant extracts investigated, 80% showed activity against both Gram-positive and Gram-negative bacteria in the disc-diffusion assay. In the micro-dilution assay, 60% of the plant extracts showed minimum inhibitory concentration (MIC) values < or =1.56 mg ml(-1). The lowest MIC value (0.092 mg ml(-1)) was recorded for an ethyl acetate root extract of Acacia sieberiana against Staphylococcus aureus and Escherichia coli. In the anti-inflammatory assay, 70% of the investigated plant extracts (0.25 mg ml(-1)) inhibited both COX-1 and COX-2 activity (>50% and 70% for water and organic solvent extracts, respectively). An ethyl acetate leaf extract of Trichilia dregeana showed selective inhibition of COX-2 (81%). In the acetylcholinesterase inhibitory test, 21% of the plant extracts were active at a concentration < or =1 mg ml(-1) using the micro-dilution assay. The lowest IC(50) value was 0.04 mg ml(-1) obtained with an ethanol bark extract of Combretum kraussii. None of the investigated plants showed any potential mutagenic effects.

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.

Pharmacological screening of six Amaryllidaceae species.

Dichloromethane and 90% methanol extracts of different parts of 6 Amaryllidaceae species were investigated for anti-inflammatory (COX-1 and COX-2), antibacterial and mutagenic (Salmonella/microsome test strain TA98) activities. Antibacterial activity was carried out using disc diffusion assay against three Gram-positive (Bacillus subtilis, Staphylococcus aureus and Microccus luteus) and two Gram-negative (Escherichia coli, Klebsiella pneumoniae) bacteria. With the exception of the leaf of Cyrtanthus mackenii, all CH(2)Cl(2) extracts of different parts of Cyrtanthus species inhibited the growth of at least one bacterium, with the CH(2)Cl(2) bulb/root extracts of Cyrtanthus suaveolens showing broad-spectrum antibacterial activity. In the anti-inflammatory assay, CH(2)Cl(2) extracts, resuspended at 500 microg/ml, from different parts of all species under investigation, inhibited activity of both COX-1 and COX-2 by at least 70%. The most active, 90% methanolic extracts (resuspended at 500 microg/ml) were from the leaves (78%) and roots (76%) of Cyrtanthus falcatus and the leaves of Gethyllis ciliaris (70%). Only CH(2)Cl(2) extracts of Cyrtanthus falcatus (leaf and root) and Cyrtanthus suaveolens (bulb/root and leaf) had a mutagenic effect in the Salmonella/microsome assay strain TA98.

Investigation of the antimutagenic effects of selected South African medicinal plant extracts.

Dichloromethane extracts from different parts of Rhamnus prinoides, Ornithogalum longibracteatum, Gardenia volkensii, Spirostachys africana, Diospyros whyteana, Syzigium cordatum and Prunus africana were investigated for mutagenic and antimutagenic effects in Salmonella/microsome and micronucleus tests. None of the extracts tested in the Ames test were found to induce mutations or to modify the effect of the mutagen 4-nitroquinoline-oxide (4NQO). In the micronucleus test, extracts from twigs/bark of R. prinoides, twigs of D. whyteana, P. africana and S. cordatum significantly lowered the effect of the mutagen mitomycin C (MMC). Extracts from twigs/bark of G. volkensii and S. africana were genotoxic in the micronucleus test, while extracts of O. longibracteatum leaves potentiated the genotoxicity of MMC. This preliminary investigation shows that plant extracts used in traditional medicine may have particular effects with regard to mutagenicity and antimutagenicity indicating careful use in some instances and the need to isolate their active principles for further research.

Alkaloid production in Crinum moorei cultures.

The alkaloids cherylline (1), crinamidine (2), crinine (3), epibuphanisine (4), lycorine (5), powelline (6), undulatine (7), 1-epideacetylbowdensine (8), and 3-O-acetylhamayne (9) were identified in the in vitro propagated bulblets of Crinum moorei. In addition, crinine, powelline, and undulatine were detected in the solidified Murashige and Skoog (MS) medium. The identity of the alkaloids was confirmed by comparing retention times and mass spectra with known samples. Light, as well as benzyladenine (BA) and charcoal supplementation of the tissue culture medium, influenced the levels of specific alkaloids in both the bulblets and media.

Alkaloids from Crinum moorei.

Thirteen alkaloids were isolated from Crinum moorei two of which are new. These are 3-[4'-(8'-aminoethyl)phenoxy] bulbispermine and mooreine. The structures of the new alkaloids were determined by spectroscopic methods.