Tulbaghia violacea Harv. Extracts Affect Key Intermediates of the Cryptococcus neoformans Ergosterol Biosynthetic Pathway

Benesh Munilal Somai, Mitradev Pattoo


This study investigated the mechanism of inhibition of Cryptococcus neoformans by Tulbaghia violacea plant extract. C. neoformans cultures were treated with sub-inhibitory concentrations of T. violacea extract and the effect of the exposure on the production of various sterol intermediates was analyzed by high performance reverse phase liquid chromatography. Plant extract treated C. neoformans cultures exhibited reductions in ergosterol production after 48 hrs of exposure in a dose dependent manner. HPLC analysis overall revealed an accumulation in squalene, 2,3-oxidosqualene and lanosterol intermediates after extract treatment. It is therefore concluded that T. violacea extract reduced ergosterol production in C. neoformans by interfering with squalene epoxidase, 2,3-oxidosqualene lanosterol cyclase and lanosterol 14-a demethylase. The inhibitory effect of T. violacea plant extract on ergosterol production in C. neoformans unlocks the potential of this extract as a chemotherapeutic agent.


Cryptococcus neoformans; antifungal; plant extract; Tulbaghia violacea


. Lee W, Lee DG. An antifungal mechanism of curcumin lies in membrane-targeted action within Candida albicans. International Union of Biochemistry and Molecular Biology. 2014; 66:780-785.

. Sant DG, Tupe SG, Ramana CV, Deshpande MV. Fungal cell membrane-promising drug target for antifungal therapy. Journal of Applied Microbiology. 2016; 121:1498-1510.

. Ng KE, Lee Y. Management of an emerging multidrug-resistant fungus: Candida auris. US Pharmacist. 2020; 45:https://www.uspharmacist.com/article/management-of-an-emerging-multidrugresistant-fungus-candida-auris.

. Revie NM, Iyer KR, Robbins N, Cowen LE. Antifungal drug resistance: evolution, mechanisms and impact. Curr Opin Microbiol. 2018; 45:70-76.

. Cournia Z, Ullmann GM, Smith JC. Diferential effects of cholesterol, ergosterol and lanosterol on a dipalmitoyl phosphatidylcholine membrane: A molecular dynamics simulation study. J Phys Chem B. 2007; 111:1786-1801.

. Zhang YQ, Gamarra S, Garcia-Effron G, Park S, Perlin DS, Rao R. Requirement for ergosterol in V-ATPase function underlies antifungal activity of azole drugs. PLoS Pathog. 2010; 6:e1000939.

. Jorda T, Puig S. Regulation of ergosterol biosynthesis in Saccharomyces cerevisiae. Genes. 2020; 11:795; doi:710.3390/genes11070795.

. Cardoso N, Alviano C, Blank A, Arrigoni-Blank M, Romanos M, Cunha M, da Silva A, Alviano D. 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. Pharm Biol. 2017; 55:1380-1388.

. Cardoso N, Alviano C, Blank A, Romanos M, Fonseca B, Rozental S, Rodrigues I, Alviano D. Synergism effect of the essential oil from Ocimum basilicum var. Maria Bonita and its major components with fluconazole and its influence on ergosterol biosynthesis. Evid Based Complement Alternat Med. 2016; 2016:doi.org/10.1155/2016/5647182.

. Nobrega R, Teixeira A, Oliveira W, Lima E, Lima I. Investigation of the antifungal activity of carvacrol against strains of Cryptococcus neoformans. Pharm Biol. 2016; 54:2591-2596.

. Somai B, Belewa V. Aqueous extracts of Tulbaghia violacea inhibit germination of Aspergillus flavus and Aspergillus parasiticus conidia. J Food Prot. 2011; 74:1007-1011.

. Pattoo M, Belewa V, Somai BM. Phytochemical constituents of Tulbaghia violacea Harv extract and its antifungal potential against Cryptococcus neoformans and Cryptococcus gattii. The Natural Products Journal. 2019; 9:330-340.

. Arthington-Skaggs B, Jradi H, Desai T, Morrison C. Quantitation of ergosterol content: Novel method for determination of fluconazole susceptibility of Candida albicans. J Clin Microbiol. 1999; 37:3332–3337.

. Alcazar-Fuoli L, Mellado E, Garcia-Effron G, Buitrago MJ, Lopez JF, Grimalt JO, Cuenca-Estrella JM, Rodriguez-Tudela JL. Aspergillus fumigatus C-5 sterol desaturases Erg3A and Erg3B: role in sterol biosynthesis and antifungal drug susceptibility. Antimicrob Agents Chemother. 2006; 50:453-460.

. Chiocchio V, Matković L. Determination of ergosterol in cellular fungi by HPLC. A modified technique. J Arg Chem Soc. 2011; 98:10-15.

. Alcazar-Fuoli L, Mellado E, Garcia-Effron G, Lopez JF, Grimalt JO, Cuenca-Estrella JM, Rodriguez-Tudela JL. Ergosterol biosynthesis pathway in Aspergillus fumigatus. Steroids. 2008; 73:339-347.

. Spanggord RJ, Sun M, Lim P, Ellis WY. Enhancement of an analytical method for the determination of squalene in anthrax vaccine adsorbed formulations. J Pharm Biomed Anal. 2006; 42:494-499.

. Foresti O, Ruggiano A, Hannibal-Bach H, Ejsing C, Carvalho P. Sterol homeostasis requires regulated degradation of squalene monooxygenase by the ubiquitin ligase Doa10/Teb4. eLife. 2013; 2:doi: 10.7554/eLife.00953.

. Perfect J, Dismukes W, Dromer F, Goldman D, Graybill J, Hamill R, Harrison T, Larsen R, Lortholary O, Nguyen M, Pappas P, Powderly W, Singh N, Sobel J, Sorrell T. Clinical practice guidelines for the management of cryptococcal disease: 2010 update by the Infectious Diseases Society of America. Clin Infect Dis. 2010; 50:291-322.

. Neilson E, Goodger J, Woodrow I, Moller B. Plant chemical defense: at what cost? Trends Plant Sci. 2013; 18:250-258.

. Davis L, Shen J-K, Cai Y. Antifungal activity in human cerebrospinal fluid and plasma after intravenous administration of Allium sativum. Antimicrob Agents Chemother. 1990; 34:651-653.

. Singh U, Prilhiviraj B, Sarma B, Singh M, Rai A. Role of garlic (Allium sativum L.) in human and plant diseases. Indian J Exp Biol. 2001; 39:310-322.

. Dorsaz S, Snäkä T, Favre-Godal Q, Maudens P, Boulens N, Furrer P, Ebrahimi S, Hamburger M, Allémann E, Gindro K, Queiroz E, Riezman H, Wolfender J-L, Sanglard D. Identification and mode of action of a plant natural product targeting human fungal pathogens. Antimicrob Agents Chemother. 2017; 61:e00829-00817.

. Sandrock R, VanEtten H. Fungal sensitivity to and enzymatic degradation of the phytoanticipin α-tomatine. Phytopathology. 1998; 88:137-143.

. Avis T. Antifungal compounds that target fungal membranes: applications in plant disease control. Can J Plant Pathol. 2007; 29:323–329.

. Ahmad A, Khan A, Akhtar F, Yousuf S, Xess I, Khan L, Manzoor N. Fungicidal activity of thymol and carvacrol by disrupting ergosterol biosynthesis and membrane integrity against Candida. Eur J Clin Microbiol Infect Dis. 2011; 30:41-50.

. Tian J, Ban X, Zeng H, He J, Chen Y, Wang Y. The mechanism of antifungal action of essential oil from dill (Anethum graveolens L.) on Aspergillus flavus. PLoS One. 2012; 7:e30147.

. Tian J, Huang B, Luo X, Zeng H, Ban X, He J, Wang Y. The control of Aspergillus flavus with Cinnamomum jensenianum Hand.-Mazz essential oil and its potential use as a food preservative. Food Chem. 2012; 130:520-527.

. Ahmad A, Khan A, Kumar P, Bhatt R, Manzoor N. Antifungal activity of Coriaria nepalensis essential oil by disrupting ergosterol biosynthesis and membrane integrity against Candida. Yeast. 2011; 28:611-617.

. Garaiova M, Zambojova V, Simova Z, Griac P, Hapala I. Squalene epoxidase as a target for manipulation of squalene levels in the yeast Saccharomyces cerevisiae. FEMS Yeast Res. 2014; 14:310-323.

. Kim Y, Cho J, Park S, Han J, Back K, Choi Y. Gene regulation patterns in triterpene biosynthetic pathway driven by overexpression of squalene synthase and methyl jasmonate elicitation in Bupleurum falcatum. Planta. 2011; 233:343-355.

. Chang W, Zhang M, Li Y, Li X, Gao Y, Xie Z, Lou H. Lichen endophyte derived pyridoxatin inactivates Candida growth by interfering with ergosterol biosynthesis. Biochim Biophys Acta. 2015; 1850:1762-1771.

. Goldman R, Zakula D, Capobianco J, Sharpe B, Griffin J. Inhibition of 2,3-oxidosqualene-lanosterol cyclase in Candida albicans by pyridinium ion-based inhibitors. Antimicrob Agents Chemother. 1996; 40:1044-1047.

. Balliano G, Milla P, Ceruti M, Carrano L, Viola F, Brusa P, Cattell L. Inhibition of sterol biosynthesis in Saccharomyces cerevisiae and Candida albicans by 22,23-epoxy-2-aza-2,3-dihydrosqualene and the corresponding N-oxide. Antimicrob Agents Chemother. 1994; 38:1904-1908.


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