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

Oluwagbemiga Sewanu Soyingbe,Nkoana Ishmael Mongalo,Tshepiso Jan Makhafola

doi:10.1186/s12906-018-2378-3

Oluwagbemiga Sewanu Soyingbe, Nkoana Ishmael Mongalo + Show 1 more

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https://doi.org/10.1186/s12906-018-2378-3

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Abstract

BackgroundCompounds 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.MethodsExtracts 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.ResultsThe 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.ConclusionsOverall, 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.

Highlights

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
Different types of plants contain a variety of phytochemicals, which may well act as antioxidants, antimicrobial, anti-inflammatory and anti-cancer agents, making the use of plants more advantageous [6]
F.) C.A.Sm are African medicinal plants which are generally used by traditional healers for the treatment and management of cancer [11,12,13,14]

Summary

Introduction

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. Traditional African medicine is based on using botanical preparations to treat human and animal illness Such medicine is prepared by extracting roots, barks, leaves, flowers, seeds from, or the entire plant of, different plant species [5]. Different types of plants contain a variety of phytochemicals, which may well act as antioxidants, antimicrobial, anti-inflammatory and anti-cancer agents, making the use of plants more advantageous [6] These plants generally possess little or no side effects when compared to western medicine. C. dentata belongs to the Cornaceae family and its stem, bark and leaves are used in the treatment of cancer, stomach disorders, diarrhoea, sexually transmitted diseases and as a blood purifier [14, 18]

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