Orchid Biotechnology, Wen-Huei Chen and Hong-Hwa Chen (Eds), 2007, World Scientific Publishing Co. (Pty) Ltd., 5 Toh Tuck Link, Singapore, Price: US$ 76.00, 258 pages, ISBN 978-981-270-619-5, Website: http://www.worldscibooks.com/lifesci

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Antimicrobial Activity, Phenolic Content, and Cytotoxicity of Medicinal Plant Extracts Used for Treating Dermatological Diseases and Wound Healing in KwaZulu-Natal, South Africa

Medicinal plants used for wound healing and skin diseases are the key to unlocking the doors to combating problematic skin diseases as resistance of pathogens to pharmaceuticals and allopathic management continues to increase. The study aimed at investigating the antimicrobial efficacies, phenolic content and cytotoxicity effects of eleven medicinal plant extracts commonly used for treating skin conditions and wound healing in traditional medicine within KwaZulu-Natal. Eleven plant species were separated into different plant parts (bulbs, roots, leaves) and extracted with different solvents. The extracts were assessed for antimicrobial activity against six Gram-positive and seven Gram-negative bacterial strains and four fungi commonly associated with skin conditions using disc diffusion and microdilution techniques. The aqueous methanolic extracts were screened for phenolic content while cytotoxicity tests were performed on all extracts using the brine shrimp lethality and tetrazolium–based colorimetric (MTT) assays. Extracts from Aloe ferox, A. arborescens and Hypericum aethiopicum were the most active against almost all of the tested bacterial and fungal strains. All plant species exhibited some degree of antimicrobial activity. Total phenolic levels, flavonoids and tannins were also higher for A. ferox, followed by A. arborescens and H. aethiopicum respectively. The cytotoxicity results of all plant extracts were in the range of 90-100% survival after 24 h in the Brine shrimp assay. Extracts considered lethal would demonstrate > 50% shrimp death. The MTT cytotoxicity test yielded LC50 values of > 1 mg/mL on all extracts indicating that they are not cytotoxic. The observed antimicrobial efficacy demonstrated by some plant species and the general lack of cytotoxic effects on all the tested extracts presents some promising and beneficial aspects of these medicinal plant extracts in the treatment of skin diseases and wound healing. The two Aloe species and H. aethiopicum were among the best extracts that exhibited consistently good antimicrobial activity and warrants further investigations and possible isolation of bioactive principles

Screening for adulticidal activity against Anopheles arabiensis in ten plants used as mosquito repellent in South Africa

BACKGROUND : Due to the development of resistance to synthetic insecticides, adverse effects to human health, non-target organisms and the environment, there is an urgent need to develop new insecticides, which are effective, safe, biodegrable and target-specific. This study was undertaken to evaluate the adulticidal activity of 10 plants used traditionally as mosquito repellents in South Africa. METHODS : The dried plant materials were extracted with dichloromethane (DCM) and ethanol (EtOH). The extracts were evaluated for adulticidal activity against Anopheles arabiensis mosquitoes, a potent malaria vector in South Africa. Adult mortality was observed after 24 hours of exposure. RESULTS : All the extracts showed adulticidal activity. The highest activity was observed in both DCM and EtOH extracts of Aloe ferox leaves with 98 and 86% mosquito mortality, respectively. The DCM extract of A. ferox leaves was then subjected to a dose-dependent bioassay to determine the EC50 value. The extract exhibited an EC50 value of 4.92 mg/ml. CONCLUSION : The results of the present study showed that the DCM extract of A. ferox leaves may have the potential to be used as an insecticide against An. arabiensis. Further studies to isolate and identify active compounds are in progress.The South African Medical Research Councilhttp://www.malariajournal.com/content/13/1/173am201

Antimicrobial activity, phenolic content, and cytotoxicity of medicinal plant extracts used for treating dermatological diseases and wound healing in KwaZulu-Natal, South Africa

Medicinal plants used for wound healing and skin diseases are the key to unlocking the doors to combating problematic skin diseases as resistance of pathogens to pharmaceuticals and allopathic management continues to increase. The study aimed at investigating the antimicrobial efficacies, phenolic content, and cytotoxicity effects of 11 medicinal plant extracts commonly used for treating skin conditions and wound healing in traditional medicine within KwaZulu-Natal. Eleven plant species were separated into different plant parts (bulbs, roots, leaves) and extracted with different solvents. The extracts were assessed for antimicrobial activity against six Gram-positive and seven Gram-negative bacterial strains and four fungi commonly associated with skin conditions using disc diffusion and microdilution techniques. The aqueous methanolic extracts were screened for phenolic content while cytotoxicity tests were performed on all extracts using the brine shrimp lethality and tetrazolium-based colorimetric (MTT) assays. Extracts from Aloe ferox, A. arborescens, and Hypericum aethiopicum were the most active against almost all of the tested bacterial and fungal strains. All plant species exhibited some degree of antimicrobial activity. Total phenolic levels, flavonoids and tannins were also higher for A. ferox, followed by A. arborescens and H. aethiopicum, respectively. The cytotoxicity results of all plant extracts were in the range of 90-100% survival after 24 h in the brine shrimp assay. Extracts considered lethal would demonstrate >50% shrimp death. The MTT cytotoxicity test yielded LC50 values of >1 mg/mL on all extracts indicating that they are not cytotoxic. The observed antimicrobial efficacy demonstrated by some plant species and the general lack of cytotoxic effects on all the tested extracts presents some promising and beneficial aspects of these medicinal plant extracts in the treatment of skin diseases and wound healing. The two Aloe species and H. aethiopicum were among the best extracts that exhibited consistently good antimicrobial activity and warrants further investigations and possible isolation of bioactive principles.The University of KwaZulu-Natal and the National Research Foundation (NRF) of South Africa.http://www.frontiersin.orgam2016Paraclinical Science

In Vitro Antioxidant Properties, HIV-1 Reverse Transcriptase and Acetylcholinesterase Inhibitory Effects of Traditional Herbal Preparations Sold in South Africa

The antioxidant potentials for fourteen multipurpose traditional herbal preparations sold in South Africa were determined using the DPPH radical scavenging, ferric reducing power and β-carotene-linoleic acid model system, the anti-HIV-1 reverse transcriptase (RT) enzyme inhibitory effects using an ELISA kit and acetylcholinesterase (AChE) enzyme inhibition using the microtitre plate assay. Nine of the herbal mixtures (Umzimba omubi, Umuthi wekukhwehlela ne zilonda, Mvusa ukunzi, Umpatisa inkosi, Imbiza ephuzwato, Vusa umzimba, Supreme one hundred, Sejeso herbal mixture Ingwe® and Ingwe® special muti) exhibited higher antioxidant potentials, while only four (Imbiza ephuzwato, Ingwe® muthi mixture, Sejeso herbal mixture Ingwe® and African potato extractTM) showed potent activity against the RT enzyme. Nine mixtures (Imbiza ephuzwato, Umpatisa inkosi, African potato extractTM, Sejeso herbal mixture Ingwe®, Vusa umzimba; Ingwe® muthi mixture, Ibhubezi™, Lion izifozonke Ingwe® and Ingwe® special muti) showed AChE enzyme inhibitory activity greater than 50%. The observed activity exhibited by some of the herbal mixtures gives some credence to the manufacturers’ claims and goes part of the way towards validating their use against certain conditions such as oxidative stress, HIV/AIDS proliferation and some mental conditions. It is however, desirable to carry out further studies to determine the effects of mixing plant species/parts in one mixture on the antioxidant potency as well as isolating active constituents from the herbal mixtures

Isolation and characterization of antimicrobial and anti-inflammatory triterpenoids from the acetone extract of Grewia flava DC. (Malvaceae) roots

Grewia flava root acetone extracts were assessed for antimicrobial activity against a range of pathogenic microorganisms using the broth microdilution and bioautography assays. Cytotoxicity against human dermal fibroblast (HDF) and bovine dermis (BD) cell lines was also investigated. Solvent-solvent fractionation was carried out on the acetone extract to yield fractions of different polarities. Bioautograms from fractions showed four antimicrobial compounds in the carbon tetrachloride fraction, with activity against Escherichia coli. Two compounds from carbon tetrachloride, hexane and butanol fractions were active against Candida albicans, Bacillus cereus, Klebsiella pneumoniae and Escherichia coli. The aqueous fraction had the lowest minimum inhibitory concentration (MIC) values of 40 µg/ml against Cryptococcus neoformans, Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa. Two triterpenoid compounds, namely taraxerol and lupeol, were isolated and had potent antimicrobial activity. Lupeol had better antimicrobial activity than vancomycin (control drug) with MIC of 10 µg/ml against Mycobacterium smegmatis, Mycoplasma hominis and Escherichia coli. Both taraxerol and lupeol exhibited better anti-inflammatory activity than quercetin (positive control) in the soybean lipoxygenase (15-LOX) inhibition assay and by inhibiting nitric oxide release from RAW264.7 macrophages. Although fractions and isolated compounds exhibited potent antimicrobial, antioxidant and anti-inflammatory activity, there is a need to explore the modes of action thereof. The study supports the use of the plant species in the treatment and management of various microbial infections posing danger to human health.The Research Centre for Plant Growth and Development, University of KwaZulu-Natal.http://www.elsevier.com/locate/sajb2024-06-04hj2022Paraclinical Science