Anticancer Activity of Certain Herbs and Spices on the Cervical Epithelial Carcinoma (HeLa) Cell Line

Acetone extracts of selected plant species were evaluated for their in vitro cytotoxicity against a noncancerous African green monkey kidney (Vero) cell line and an adenocarcinoma cervical cancer (HeLa) cell line. The plants studied were Origanum vulgare L. (Oregano), Rosmarinus officinalis L. (Upright and ground cove rosemary), Lavandula spica L. (Lavender), Laurus nobilis L. (Bay leaf), Thymus vulgaris L. (Thyme), Lavandula x intermedia L. (Margaret Roberts Lavender), Petroselinum crispum Mill. (Curly leaved parsley), Foeniculum vulgare Mill. (Fennel), and Capsicum annuum L. (Paprika). Antioxidant activity was determined using a quantitative DPPH (1,1-diphenyl-2-picryl hydrazyl) assay. The rosemary species exhibited effective radical scavenging capacity with 50% inhibitory concentration (IC50) of 3.48 ± 0.218 μg/mL and 10.84 ± 0.125 μg/mL and vitamin C equivalents of 0.351 g and 1.09 g for McConnell's Blue and Tuscan Blue, respectively. Cytotoxicity was measured using XTT (Sodium 3′-[1-(phenyl amino-carbonyl)-3,4-tetrazolium]-bis-[4-methoxy-6-nitro] benzene sulfonic acid hydrate) colorimetric assay. Only L. nobilis and O. vulgare exhibited pronounced effects on the HeLa cell line. Dose-dependent studies revealed IC50 of 34.46 ± 0.48 μg/mL and 126.3 ± 1.00 μg/mL on the HeLa cells and on the Vero cells 124.1 μg/mL ± 18.26 and 163.8 μg/mL ± 2.95 for L. nobilis and O. vulgare, respectively. Light (eosin and haematoxylin staining) and confocal microscopy (Hoechst 33342, acridine orange, and propidium iodide staining) were used to evaluate the cytotoxic mechanism of action for L. nobilis and O. vulgare

Isolation and identification of Naphthoquinones from Euclea natalensis with activity against Mycobacterium tubercolosis, other pathogenic bacteria and Herpes simplex virus

The antimycobacterial activity of twenty South African medicinal plants were investigated using two methods commonly used; the conventional agar plate method and the BACTEC radiometric method. Fourteen of the twenty acetone extracts of medicinal plants used to treat pulmonary diseases showed inhibitory activity at a concentration of 0.5 mg/ml against a sensitive strain of Mycobacterium tuberculosis using the conventional agar plate method. These fourteen extracts were also tested against M tuberculosis by the BACTEC radiometric method against a sensitive as well as a strain resistant to the drugs isoniazid and rifampin. Eight plants showed activity against both the strains at a concentration of 1.0 mg/ml. Susceptibility testing of M tuberculosis by the agar plate method is reliable, economical, and reproducible whereas the BACTEC radiometric method is much faster and probably more accurate than the agar plate method. A cytotoxicity assay of the fourteen plants on primary vervet monkey kidney cells showed that the crude acetone extracts of E. natalensis was the least cytotoxic extract with significant antimycobacterial properties. It was therefore, chosen for the isolation of active compound(s). An antibacterial assay of the water and acetone extracts of the roots of E. natalensis showed that they inhibited the growth of Gram-positive bacteria at concentrations ranging between 0.1 and 6.0 mg/ml. The water extract did not exert any inhibitory action on Gram-negative bacteria while the acetone extract showed inhibitory activity at a concentration of 5.0 mg/ml. The MIC of diospyrin, isolated from E. natalensis, was found to be 100 µg/ml for a drug-sensitive and a number of drug-resistant strains of M. tuberculosis and Gram-positive bacterial species. An antiviral investigation of the crude extracts of E. natalensis showed that the water extract of the roots of the plant inhibited the replication of herpes simplex virus type 1 moderately at a concentration of 0.2 mg/ml whereas, acetone extract at concentrations ranging from 0.1 to 0.02 mg/ml. Diospyrin exhibited no inhibitory effect against the virus. The MIC of 7-methyljuglone, isolated from E. natalensis, was found to be 50 µg/ml for both drug-sensitive and drug-resistant strains of M. tuberculosis. The compound inhibited the growth of Gram-positive bacterial species at concentrations ranging from 50 to 100 µg/ml. No inhibitory effect of the compound was observed on any Gram-negative bacteria at the highest concentration tested. A significant synergistic effect of the two naphthoquinones was observed against M tuberculosis and some of the bacterial species. MICs obtained were 10 µg/ml and 50 µg/ml for M tuberculosis and the bacterial species respectively. No synergistic effect was observed on any Gram-negative bacterial species investigated. In view of the encouraging results obtained from this study on the biological activity of the two naphthoquinones; diospyrin and 7 -methyljuglone, it appears that the compounds deserve further investigation in order to explore its potential as antimycobacterial agents.Thesis (DPhil (Plant Physiology))--University of Pretoria, 2007.Plant Scienceunrestricte

The potential of South African medicinal plants for the treatment of COVID-19

Severe acute respiratory syndrome coronavirus (SARS-CoV-2), currently the cause of coronavirus disease of 2019 (COVID-19), has been declared a pandemic. Currently, not many antiviral treatments are available to effectively treat COVID-19 and therefore ongoing waves of increasing infection numbers and deaths have been reported globally. The current repurposing of drugs has been investigated as possible treatment by researchers and includes remdesivir and ivermectin. Many natural products have been selected and investigated for their potential inhibitory activity against SARSCoV- 2, especially those that have previously been identified to have inhibitory activity against SARS-CoV. There are several genetic similarities between SARS-CoV-2 and SARS-CoV, such as their similarities in the genome, the main protease crystal structure and the primary host receptor (Kaur et al., 2021).http://www.ukaazpublications.com/publicationsam2022Plant Production and Soil Scienc

Are plants used for skin care in South Africa fully explored?

No AbstractUniversity of Pretoria, and National Research Foundation, South Africahttp://www.elsevier.com/locate/jethpharmhb201

Antibacterial, antioxidant activities and cytotoxicity of plants against Propionibacterium acnes

The use of plants to treat skin ailments has strong support in the current trend of drug discovery. Propionibacterium acnes, an anaerobic pathogen, plays an important role in the occurrence of acne. The present study was conducted to evaluate the antimicrobial and antioxidant activities against P. acnes and cytotoxic effects of 48 medicinal plants grown in South Africa. The broth dilution and DPPH radical scavenging methods were used to determine antibacterial and antioxidant activities, respectively. Cytotoxicity was determined on mouse melanocytes (B16-F10). The ethanolic bark extract of Acacia galpinii Burtt Davy. (Leguminosae) exhibited the lowest minimum inhibitory concentration of 62.5 μg/mL. Excellent antioxidant activity was shown by Aspalathus linearis (Burm.f.) R.Dahlgren (Leguminosae), Combretum apiculatum Sond. (Combretaceae), Harpephyllum caffrum Bernh. ex Krauss (Anacardiaceae) and Sclerocarya birrea Hochst. (Anacardiaceae), with 50% radical scavenging activity (EC50) at concentrations ranging from 1.6 μg/mL to 3.5 μg/mL. Greyia sutherlandii Hook. & Harv. (Greyiaceae) also exhibited good antioxidant activity with an EC50 value of 7.9±0.23 μg/mL. A. linearis, G. sutherlandii and S. birrea showed low toxicity with 50% viability of cells (EC50) at concentrations of 125.09±0.71 μg/mL, 107.85±1.53 μg/mL and 92.07±0.09 μg/mL, respectively. The extracts of A. linearis, G. sutherlandii and S. birrea showed good antibacterial and antioxidant activities and low toxicity. Therefore, these plants can be considered as possible anti-acne agents and warrant further investigation.University of Pretoria and the National Research Foundation (South Africa).http://www.sajs.co.zahb201

Melanogenesis and Antityrosinase Activity of Selected South African Plants

Melanin is the pigment that is responsible for the colour of eyes, hair, and skin in humans. Tyrosinase is known to be the key enzyme in melanin biosynthesis. Overactivity of this enzyme leads to dermatological disorders such as age spots, melanoma and sites of actinic damage. Ten plants belonging to four families (Asphodelaceae, Anacardiaceae, Oleaceae, and Rutaceae) were investigated for their effect on tyrosinase using both L-tyrosine and L-DOPA as substrates. Ethanol leaf extracts (500 μg/mL) of Aloe ferox, Aloe aculeata, Aloe pretoriensis, and Aloe sessiliflora showed 60%, 31%, 17%, and 13% inhibition of tyrosinase activity respectively, when L-tyrosine was used as a substrate. Harpephyllum caffrum (leaves) at a concentration of 500 μg/mL had an inhibitory effect of 70% on tyrosinase when L-DOPA was used as a substrate. The IC50 of Harpephyllum caffrum (leaves and bark) were found to be 51 ± 0.002 and 40 ± 0.035 μg/mL, respectively. Following the results obtained from the tyrosinase assay, extracts from Harpephyllum caffrum were selected for further testing on their effect on melanin production and their cytotoxicity on melanocytes in vitro. The IC50 of both extracts was found to be 6.25 μg/mL for melanocyte cells. Bark extract of Harpephyllum caffrum showed 26% reduction in melanin content of melanocyte cells at a concentration of 6.25 μg/mL. The leaf extract of this plant showed some toxicity on melanocyte cells. Therefore, the bark extract of Harpephyllum caffrum could be considered as an antityrosinase agent for dermatological disorders such as age spots and melasoma

Antimicrobial Constituents of Artemisia afra Jacq. ex Willd. against Periodontal Pathogens

The phytochemical investigation of an ethanol extract of Artemisia afra led to the isolation of six known compounds, acacetin (1), 12α,4α-dihydroxybishopsolicepolide (2), scopoletin (3), α-amyrin (4), phytol (5), and a pentacyclic triterpenoid betulinic acid (6). The compounds were evaluated for antimicrobial activity against Gram positive (Actinomyces naeslundii, Actinomyces israelii, and Streptococcus mutans), Gram negative bacteria (Prevotella intermedia, Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans previously known as Actinobacillus actinomycetemcomitans), and Candida albicans. The crude extract of A. afra inhibited the growth of all tested microbial species at concentration range of 1.6 mg/mL to 25 mg/mL. The compounds 1–6 also showed activity range at 1.0 mg/mL to 0.25 mg/mL. Three best compounds (scopoletin, betulinic acid, and acacetin) which showed good antimicrobial activity were selected for further studies. Cytotoxicity of extract and compounds was determined using the XTT cell proliferation kit. The antioxidant activity of the extract and compounds was done using the DPPH scavenging method. The extract showed good antioxidant activity with an IC50 value of 22.2 μg/mL. Scopoletin had a strong transformation of the DPPH radical into its reduced form, with an IC50 value of 1.24 μg/mL which was significant to that of vitamin C (1.22 μg/mL). Acacetin and betulinic acid exhibited a decreased scavenging activity with the IC50 of 2.39 and 2.42 μg/mL, respectively. The extract and compounds showed moderate toxicity on McCoy fibroblast cell line and scopoletin was relatively nontoxic with an IC50 value of 132.5 μg/mL. Acacetin and betulinic acid also showed a smooth trend of non-toxic effects with IC50 values of 35.44 and 30.96 μg/mL. The obtained results in this study confirm the use of A. afra in the treatment of microbial infections

Synergistic Antimycobacterial Actions of Knowltonia vesicatoria (L.f) Sims

Euclea natalensis A.DC., Knowltonia vesicatoria (L.f) Sims, and Pelargonium sidoides DC. are South African plants traditionally used to treat tuberculosis. Extracts from these plants were used in combination with isoniazid (INH) to investigate the possibility of synergy with respect to antimycobacterial activity. The ethanol extract of K. vesicatoria was subjected to fractionation to identify the active compounds. The activity of the Knowltonia extract remained superior to the fractions with a minimum inhibitory concentration (MIC) of 625.0 μg/mL against Mycobacterium smegmatis and an MIC of 50.00 μg/mL against M. tuberculosis. The K. vesicatoria extract was tested against two different drug-resistant strains of M. tuberculosis, which resulted in an MIC of 50.00 μg/mL on both strains. The combination of K. vesicatoria with INH exhibited the best synergistic antimycobacterial activity with a fractional inhibitory concentration index of 0.25 (a combined concentration of 6.28 μg/mL). A fifty percent inhibitory concentration of this combination against U937 cells was 121.0 μg/mL. Two compounds, stigmasta-5,23-dien-3-ol (1) and 5-(hydroxymethyl)furan-2(5H)-one (2), were isolated from K. vesicatoria as the first report of isolation for both compounds from this plant and the first report of antimycobacterial activity. Compound (1) was active against drug-sensitive M. tuberculosis with an MIC of 50.00 μg/mL