Antifungal Activities of Camellia Sinensis Crude Extract on Selected Pathogenic and Mycotoxic Fungi
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Date
2014-02-26
Authors
Sigei, Erolls Cheruiyot
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Abstract
Human fungal infections pose serious medical issues. Up to now, more than a hundred
thousand fungal species are considered as natural contaminants. During the last decade,
the incidence of superficial and deep mycotic infections has continued to increase
explosively. There is a general consensus among researchers, clinicians and
pharmaceutical companies that new, potent, effective and safe antifungal drugs are
needed. Majority of work has been conducted on Camellia sinensis extracts against
bacterial agent’s activity but little work for antifungal activity. In this study, in vitro
antifungal activities of Camellia sinensis crude extracts compared with azole group of
compounds on selected pathogenic and mycotoxic fungi were determined. That was done
by evaluating the difference in antifungal activities of green and black tea crude extracts
having a concentration of 100mg mL-1. Quantitative bioassay was done using disc
diffusion method and Minimum Inhibition Concentration was done using broth dilution
methods. The fungal isolates used for bioactivity testing were yeasts; Candida famata, C.
lusitaniae, C. tropicalis ATCC 750, C. parapsilosis ATCC 22019, C. glabrata ATCC
24433, C. krusei ATCC 6258 and Cryptococcus neoformans ATCC 66031; and moulds,
Trichophyton mentagrophytes, Microsporum gypseum, Fusarium monilliforme,
Aspergillus spp and Penicillium chrysogeneum. ATCC standard fungal strains and
clinical isolates were included. Green tea crude extract showed stronger inhibitory effect
against the fungal strains tested than black tea crude extract. There was a significant
difference in zone of inhibitions (T=4.09, P<0.05). Zone of inhibition exhibited by green
tea crude extracts (11.92±0.00mm) were higher than black tea crude extracts
(8.14±0.56mm). The pattern of activity by tea crude extracts against ATCC standard
fungal strains and clinical isolates strains were similar. C. famata, C. lusitaniae, C.
tropicalis ATCC 750 and dermatophyte, T. mentangrophyte were inhibited by green tea
crude extract (IZD≥15mm). Clinical isolates of Candida albicans (strain 4 and strain 5);
Cryptococcus neoformans (strain 3, 5 and 12), showed susceptibility to Camellia sinensis
green crude extracts. The MIC of Camellia sinensis crude extracts against fungal isolates
tested ranged from 50 mg mL-1 to 1.6 mg mL-1. Hot green tea crude extract (mean MIC
12.25mg mL-1) had a higher MIC on clinical fungal isolates than cold green tea crude
extract (Mean MIC 12.167 mg mL-1). The concentrates of aqueous Camellia sinensis
crude extracts showed synergistic activity with conventional antifungal drug. However,
level of synergism differed as observed in difference in inhibitory effect. The difference
in inhibitory effect was significant (P<0.05). The crude tea extract restored the activity of
lower concentration of antifungal, Fluconazole below MIC to susceptible breakpoints.
Generally, the MFC (Minimum Fungicidal Concentration) of Mixture crude extracts were
slightly higher as compared to that of green tea crude extract. These results are suggestive
that addition of milk to blend the crude extracts altered the bioactive ingredients resulting
to higher concentration for its MFC as compared to crude extracts alone. The studies on
Camellia sinensis crude extracts (green and black) have shown remarkable antifungal
activity against different strains of fungi and highlighted its significance to humans as
potential health products.
Description
Department of Medical Laboratory Sciences, 100p. 2013