A Systematic Review of Curtisia dentata Endemic to South Africa: Phytochemistry, Pharmacology, and Toxicology

The use of traditional medicine in treating a variety of both human and animal infections is ancient and still relevant. This is due to the resistance exhibited by most pathogenic microbial stains to currently-used antibiotics. The current work reports the phytochemistry, ethno-medicinal uses, toxicology, and most important pharmacological activities that validate the use of the plant species in African traditional medicine. Curtisia dendata is used in the treatment of many human and animal infections, including diarrhea, skin and related conditions, sexually transmitted infections, cancer, and a variety of ethno-veterinary infections. Pharmacologically, the plant species exhibited potent antimicrobial activity against a variety of pathogens. Further, both extracts and compounds isolated from the plant species exhibited potent antioxidant, anticancer, anti-parasitic, anti-inflammatory, and other important biological activities. Phytochemically, the plant species possess a variety of compounds, particularly triterpenes, that may well explain the various pharmacological activities of the plant species. The toxicological parameters, antimicrobial activities against microorganisms related to sexually transmitted infections, anti-diabetic effects, and inflammatory properties of the plant species are not well studied and still need to be explored. The biological activities observed validate the use of the plant species in African traditional medicine, particularly in the treatment of pulmonary infections associated with Mycobacterium species, and may well be due to the presence of triterpenes prevalent in the leaves.

GC-ToF-MS Profiling and In Vitro Inhibitory Effects of Selected South African Plants against Important Mycotoxigenic Phytopathogens

The harmful effects following the ingestion of mycotoxin-contaminated food include the induction of cancers, mutagenicity, immune suppression, and toxicities that target organs of the digestive, cardiovascular, and central nervous systems. Synthetic fungicides are generally associated with a high toxic residue in food and the development of excessive fungal resistance. This study aimed to determine the antifungal activities against mycotoxigenic fungi of selected South African plant leaves and potentially develop plant-derived bio-fungicides, and, furthermore, to explore the in vitro antioxidant activity and the phytochemical spectra of the compounds of the selected medicinal plant extracts. The extracts were tested for antifungal activity against phytopathogenic strains using a microdilution broth assay. Bauhinia galpinii extracts exhibited the lowest minimum inhibitory concentration (MIC) against C. cladospoides and P. haloterans at 24 h incubation periods. C. caffrum had good antioxidant activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) with 50% inhibitory concentration (IC50) values of 0.013 mg/mL while B. galpini had IC50 values of 0.053 against free radicals of 2,2'-azinobis (3-ethylbenzthiazoline-6-suphonic acid (ABTS). The antimycotoxigenic and antioxidant activity exerted by both B. galpinii and C. caffrum may well be attributed to high TPC. In the GC-ToF-MS analysis, all the selected medicinal plants exhibited the presence of Hexadecanoic acid at varying % areas, while both B. galpinii and C. caffum exhibited the presence of lupeol at % area 2.99 and 3.96, respectively. The compounds identified, particularly the ones with higher % area, may well explain the biological activity observed. Although the selected medicinal plants exhibited a notable biological activity, there is a need to explore the safety profiles of these plants, both in vitro and in vivo.

Bioprospecting the Biological Effects of Cultivating Pleurotus ostreatus Mushrooms from Selected Agro-Wastes and Maize Flour Supplements

Pleurotus mushrooms are valuable food supplements with health and environmental restorative potential. In this paper, we sought to evaluate the biological activities and profile the bioactive compounds found in Pleurotus ostreatus cultivated from agro-waste supplemented with maize flour. We investigated carbon to nitrogen (C/N), antimicrobial, antioxidant, and antimalarial potential for the varying supplementation during mushroom cultivation. GCMS was utilized for screening bioactive compounds found in P. ostreatus. Changes in supplementation directly correlate with changes in compound profiling. Nonetheless, some compounds were found to be common amongst the tested mushrooms, including pentadecanoic acid; 9,12-octadecadienoic acid, methyl ester; pentadecanoic acid, methyl ester; octadecanoic acid; and diisooctyl phthalate. The highest antimicrobial potential against Gram-positive Staphylococcus aureus was observed when maize flour supplements were increased to 12% and 18%. Our data demonstrated that the observed antioxidant (DPPH, ABTS, and reducing power) and antimicrobial activity could emanate from various supplementation conditions. Furthermore, supplementation has an impact on the mushroom yield and phytochemical profiles of the produced mushroom.

In vitro antibacterial and cytotoxic activity of leaf extracts of Centella asiatica (L.) Urb, Warburgia salutaris (Bertol. F.) Chiov and Curtisia dentata (Burm. F.) C.A.Sm - medicinal plants used in South Africa

Background

Compounds having both anticancer and antimicrobial activity have promising therapeutic potential due to their selective cytotoxicity and their potential to reduce the occurrence of bacterial and fungal infections in immune-compromised cancer patients. In our quest to find new antimicrobial agents with potent anticancer activity, the biological potential of leaves from the three medicinal plants Centella asiatica, Warburgia salutaris and Curtisia dentata as used by Zulu traditional healers for the treatment of cancer is investigated.

Methods

Extracts were assayed for antibacterial activity using the agar well diffusion and micro plate dilution assay. In addition, minimum bactericidal concentrations (MBC), lactate dehydrogenase (LDH) release assay and rhodamine 6G intake assay were used to ascertain the antibacterial activity. The cytotoxic effects of the plant extracts were determined using tetrazolium-based colorimetric (MTT) cell proliferation assay against MCF-7, human colorectal carcinoma cells (Caco-2), A549 and HeLa cancerous cell lines.

Results

The acetone extracts from Waburgia salutaris revealed noteworthy anti-proliferative effect yielding IC₅₀ value of 34.15 μg/ml against MCF-7 cell line, while acetone extract from Curtisia dentata significantly (P ≤ 0.05) revealed promising IC₅₀ values of 41.55, 45.13, 57.35 and 43.24 μg/ml against A549, HeLa, CaCo-2 and MCF-7 cell lines. The extracts further revealed a broad-spectrum antibacterial activity against bacterial strains used in the study. An acetone extract from W. salutaris revealed the highest zone of inhibition and the lowest minimum inhibitory concentration (MIC) of 21.0 mm and 0.16 mg/ml respectively against Staphylococcus aureus. Methanol extract from W. salutaris and ethyl acetate extract from C. dentata revealed 53% inhibition of R6G inside the cell against Staphylococcus aureus and Escherichia coli respectively in a cytosolic lactate dehydrogenase assay, suggesting that the mode of action of such extracts may be through efflux pump.

Conclusions

Overall, the extracts had good antibacterial activity and anti-proliferative effects against selected cancerous cell lines. Given the good antibacterial activity of the extracts the plants may act as an immune booster and prevent infection in immunosuppressed cancer patients. This is further supported by the plants’ anti-proliferative potential, bacteriostatic, bactericidal properties and also their ability to block bacterial efflux pump systems.

Ethnobotanical knowledge of the lay people of Blouberg area (Pedi tribe), Limpopo Province, South Africa

BACKGROUND

Limpopo province, South Africa, has a rich plant diversity and is referred to as one of the hotspots areas within the country. The aim of the current work was to identify and document medicinal plant species used by the indigenous Pedi people of Blouberg area, Limpopo Province, South Africa.

METHODS

A total of 40 informants which includes both traditional healers and medicinal plant sellers were randomly selected and asked about the plant species used in treatment of variety of infections using a structured questionnaire. Follow-up visits and various field walks were also used to identify and document various plant species used in Traditional medicine (TM). The interviews were carried out from April 2008 to June 2016 using indigenous language (Sehananwa).

RESULTS

A total of 82 medicinal plants species belonging to 42 families have been collected, identified and documented. About 46.34% of the plant species were herbs, followed by trees (25.61%), shrubs (20.73%) and climbers (7.32%). The most used plant parts are roots and rhizomes (58.58%). Peltophorum africanum Sond revealed frequency index of greater than 70 and is used in combination with other plants species to treat various pathogenic infections. Most of the plant species reported are used in the treatment of sexually transmitted infections (24), management of HIV-AIDS (15) and stomach ache (14). Our informants indicated that the use of plant medicines in combinations is also applied to cure pathogenic infections.

CONCLUSION

The current study demonstrate that the indigenous people of Blouberg area, Limpopo Province harbours an important information about the vegetation around them. The plant species are used in the treatment of various pathogenic infections, offers fruits as additional source of food and form integral part of other medicinal products that may in turn produce income.

Ethnobotany, phytochemistry, toxicology and pharmacological properties of Terminalia sericea Burch. ex DC. (Combretaceae) - A review

ETHNOPHARMACOLOGICAL REFERENCE

The use of medicinal plants in the treatment of infections is ancient. A wide variety of ethnotherapeutic properties and pharmacological actions has been attributed to Terminalia sericea. Studies by various groups of investigators reveal that it is a multipurpose medicinal plant used mostly in the treatment of diarrhoea, sexually transmitted infections, skin rashes, tuberculosis and other infections. The current paper is aimed at providing an overview of the ethnomedicinal uses, toxicology, pharmacology and the phytochemistry of Terminalia sericea.

MATERIALS AND METHODS

Information was retrieved using various search engines, including Pubmed, Science Direct, Google Scholar, Scielo, SciFinder and Scopus. The key words used included Terminalia sericea, secondary metabolites, phytochemistry, biological activity, pharmacology, ethnobotanical survey, medicinal uses, safety, toxicology and other related words.

RESULTS

Terminalia sericea is an important medicinal plant which possesses anti-HIV, anti-fungal, anti-bacterial, anticancer, lipolytic, wound healing, antiparasitic, anti-inflammatory and anti-oxidant activity, as the most valuable biological activities, thus lending pharmacological support to the plant's folkloric uses in indigenous medicine. Toxicologically, the extracts and isolated compounds from the plant species may have mild toxic effects. Phytochemically, the plant species possesses valuable compounds including triterpenes, alkaloids and flavonoids which may well contribute to its biological activity.

CONCLUSIONS

Terminalia sericea contains secondary metabolites which are valuable in the treatment of a variety of human infections, including community acquired infections which may be prevalent in developing countries. The degree of toxicity reported in various extracts warrants further exploration of the cytotoxicity of the plant species, both against normal human cell lines and in vivo. Moreover, the acetylcholinesterase inhibitory and anti-inflammatory effects also need to be further investigated as there are only a few reports from the literature on these aspects. There is also a need to further understand the mode of action of the extracts against various enzymes relating to inflammation. Antioxidant activity of the plant extracts against various forms of free radicals needs to be investigated. Although T. sericea is reported to be used for ethnoveterinary infections, there are no scientific reports on the anti-parasitic activity of the plant species against common animal parasites.

In vitro evaluation of the comprehensive antimicrobial and antioxidant properties of Curtisia dentata (Burm.f) C.A. Sm: toxicological effect on the Human embryonic kidney (HEK293) and Human hepatocellular carcinoma (HepG2) cell lines

Curtisia dentata is used in African traditional medicine to treat variety of infections. C. dentata leaves were collected from Buffelskloof Nature Reserve, South Africa. The ethanol, chloroform, ethyl acetate and acetone extracts were evaluated for antimicrobial activity using micro dilution assay against Escherichia coli, Pseudomonas aeruginosa, Mycobacterium smegmatis, Mycoplasma hominis, Candida albicans and some clinical isolates of Moraxella catarrhalis, Proteus mirabilis and Staphylococcus aureus isolated from HIV patient. Acetone extract exhibited lowest MIC of 0.01 mg/ml against Candida albicans compared to other extracts. Besides lupeol, betulinic acid and ursolic acid, β-sitosterol was isolated for the first time from C. dentata leaves and exhibited antimicrobial activity with MIC values ranging from 0.20 to 6.25 mg/ml. Furthermore, the ethanol extract and the four isolated compounds revealed microbicidal effect, with MIC index of less than 4. Ethanol extract revealed the best total activity of 2400 ml/g against Mycoplasma hominis. Cytotoxicity of the isolated compounds was further investigated against the Human embryonic kidney (HEK293) and Human hepatocellular carcinoma (HepG2) cell lines using the MTT assay. Ursolic acid exhibited the lowest LD₅₀ of 122.4 µg/ml against HEK293 cell line while lupeol exhibited LD₅₀ of 278.8 and 289.4 µg/ml against HEK293 and HepG2 respectively. Lupeol exhibited low selectivity index. Ethyl acetate and acetone extracts were further investigated for antioxidant activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH). The acetone extract exhibited potent inhibition of DPPH compared to ethyl acetate extract. The findings of the current work validate the use of the plant species in the treatment of various human infections.

Securidaca longipedunculata Fresen (Polygalaceae): a review of its ethnomedicinal uses, phytochemistry, pharmacological properties and toxicology

ETHNOPHARMACOLOGICAL RELEVANCE

Securidaca longipedunculata Fresen (Polygalaceae) is a multi-purpose plant with a long history of use in African traditional medicine to treat various sexually transmitted infections, hernias, coughs, fever, ascariasis, constipation, headaches, rheumatism, stomach ache, malaria, tuberculosis, pain, epilepsy, pneumonia, skin infections, and it is also used as an aphrodisiac for men. The current paper provides an overview of the present phytochemistry, toxicology, ethnomedicinal uses and pharmacological properties of S. longipedunculata.

MATERIALS AND METHODS

The information reported in this paper was collected from a literature search using various computerised databases including ScienceDirect, Scopus, Scielo, PubMed and Google Scholar. The extra information was sourced from various academic dissertations, theses and botanical books.

RESULTS

Phytochemically, extracts from various parts of S. longipedunculata, especially the root bark, contain numerous valuable compounds including xanthones, some benzyl benzoates and triterpene saponins amongst others. Toxicity studies, both in vivo and in vitro, revealed that extracts are only toxic at relatively high concentrations. Furthermore, extracts have antimicrobial, antioxidant, antiparasitic, anti-diabetic, anti-inflammatory, antimalarial, insecticidal, pesticidal, and anticonvulsant properties.

CONCLUSIONS

S. longipedunculata is an important plant species with potential benefits in the treatment of transmissible and infectious diseases, including malaria, tuberculosis, and those caused by community acquired microorganisms. Although extracts from this species generally have little toxicity at low concentrations, further efforts are required to investigate the potential toxicity of S. longipedunculata. The antimicrobial properties of extracts and purified compounds against microorganisms causing sexually transmitted infections are also deserving of further research. Moreover, the pharmacokinetic properties of extracts and compounds of the species need to be explored as there is insufficient data available on these aspects.