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Pharm Biol. 2017 Dec;55(1):1380-1388. doi: 10.1080/13880209.2017.1302483.

Anti-cryptococcal activity of ethanol crude extract and hexane fraction from Ocimum basilicum var. Maria bonita: mechanisms of action and synergism with amphotericin B and Ocimum basilicum essential oil.

Author information

1
a Department of General Microbiology , Institute of Microbiology Paulo de Góes, Federal University of Rio de Janeiro , Rio de Janeiro , Brazil.
2
b Postgraduate Program in Plant Biotechnology , Federal University of Rio de Janeiro , Rio de Janeiro , Brazil.
3
c Department of Agronomy , Federal University of Sergipe , São Cristóvão , Brazil.
4
d Research Institute of Natural Products , Federal University of Rio de Janeiro , Rio de Janeiro , Brazil.

Abstract

CONTEXT:

Ocimum basilicum L. (Lamiaceae) has been used in folk medicine to treat headaches, kidney disorders, and intestinal worms.

OBJECTIVE:

This study evaluates the anti-cryptococcal activity of ethanol crude extract and hexane fraction obtained from O. basilicum var. Maria Bonita leaves.

MATERIALS AND METHODS:

The MIC values for Cryptococcus sp. were obtained according to Clinical and Laboratory Standards Institute in a range of 0.3-2500 μg/mL. The checkerboard assay evaluated the association of the substances tested (in a range of 0.099-2500 μg/mL) with amphotericin B and O. basilicum essential oil for 48 h. The ethanol extract, hexane fraction and associations in a range of 0.3-2500 μg/mL were tested for pigmentation inhibition after 7 days of treatment. The inhibition of ergosterol synthesis and reduction of capsule size were evaluated after the treatment with ethanol extract (312 μg/mL), hexane fraction (78 μg/mL) and the combinations of essential oil + ethanol extract (78 μg/mL + 19.5 μg/mL, respectively) and essential oil + hexane fraction (39.36 μg/mL + 10 μg/mL, respectively) for 24 and 48 h, respectively.

RESULTS:

The hexane fraction presented better results than the ethanol extract, with a low MIC (156 μg/mL against C. neoformans T444 and 312 μg/mL against C. neoformans H99 serotype A and C. gattii WM779 serotype C). The combination of the ethanol extract and hexane fraction with amphotericin B and essential oil enhanced their antifungal activity, reducing the concentration of each substance needed to kill 100% of the inoculum. The substances tested were able to reduce the pigmentation, capsule size and ergosterol synthesis, which suggest they have important mechanisms of action.

CONCLUSIONS:

These results provide further support for the use of ethanol extracts of O. basilicum as a potential source of antifungal agents.

KEYWORDS:

Basil; Cryptococcus neoformans; antifungal activity; drug synergism; ergosterol

PMID:
28317465
PMCID:
PMC6130641
DOI:
10.1080/13880209.2017.1302483
[Indexed for MEDLINE]
Free PMC Article

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