Efficiency of vanillin in impeding metabolic adaptability and virulence of Candida albicans by inhibiting glyoxylate cycle, morphogenesis, and biofilm formation

Document Type : Original Articles


1 Amity Institute of Biotechnology, Amity University Haryana, Gurugram, India

2 Department of Biosciences, Jamia Millia Islamia, New Delhi, India

3 Department of Pharmaceutical Chemistry, Jamia Hamdard, New Delhi, India

4 DDepartment of Biosciences, Jamia Millia Islamia, New Delhi, India


Background and Purpose: Candida albicans is the fourth most common cause of nosocomial fungal infections across the world. The current drug regimens are suffering from such drawbacks as drug resistance, toxicity, and costliness; accordingly, they highlight the need for the discovery of novel drug agents. The metabolic adaptability under low-carbon conditions and expression of functional virulence traits mark the success of pathogens to cause infection. The metabolic pathways, such as glyoxylate cycle (GC), enable C. albicans to survive under glucose-deficient conditions prevalent in the hostile niche. Therefore, the key enzymes, namely isocitrate lyase (ICL) and malate synthase (MLS), represent attractive agents against C. albicans. Similarly, virulence traits, such as morphogenesis and biofilm formation, are the crucial determinants of C. albicans pathogenicity. Regarding this, the present study was conducted to uncover the role of vanillin (Van), a natural food flavoring agent, in inhibiting GC, yeast-to-hyphal transition, and biofilm formation in human fungal pathogen C. albicans.
Materials and Methods: For the determination of hypersensitivity under low-glucose conditions, phenotypic susceptibility assay was utilized. In addition, enzyme activities were estimated based on crude extracts while in-silico binding was confirmed by molecular docking. The assessment of morphogenesis was accomplished using hyphalinducing media, and biofilm formation was estimated using calcofluor staining, MTT assay, and biomass measurement. Additionally, the in vivo efficacy of Van was demonstrated using Caenorhabditis elegans nematode model.
Results: Based on the results, Van was found to be a potent GC inhibitor that phenocopied ICL1 deletion mutant and displayed hypersensitivity under low-carbon conditions. Accordingly, Van facilitated the inhibition of ICL and MLS activities in vitro. Molecular docking analyses revealed the in-silico binding affinity of Van with Icl1p and Mls1p. Those analyses were also confirmative of the binding of Van to the active sites of both proteins with better binding energy in comparison to their known inhibitors. Furthermore, Van led to the attenuation of such virulence traits as morphogenesis, biofilm formation, and cell adherence. Finally, the antifungal efficacy of Van was demonstrated by the enhanced survival of C. elegans with Candida infection. The results also confirmed negligible hemolytic activity on erythrocytes.
Conclusion: As the findings of the present study indicated, Van is a persuasive natural compound that warrants further attention to exploit its anticandidal potential


1. Pfaller MA, Diekema DJ. Epidemiology of invasive candidiasis: a persistent public health problem. Clin Microbiol Rev. 2007; 20(1):133-63.
2. Prasad R, Kapoor K. Multidrug resistance in yeast Candida. Int Rev Cytol. 2005; 242:215-48.
3. Saibabu V, Fatima Z, Khan LA, Hameed S. Therapeutic potential of dietary phenolic acids. Adv Pharmacol Sci. 2015; 2015:1-10.
4. World Health Organization. Summary of evaluations performed by the joint FAO/WHO expert committee on food additives. Hamilton, Ontario, CN: Canadian Centre for Occupational Health and Safety; 2004.
5. Fleck CB, Schöbel F, Brock M. Nutrient acquisition by pathogenic fungi: nutrient availability, pathway regulation, and differences in substrate utilization. Int J Med Microbiol. 2011; 301(5):400-7.
6. Van Schaik EJ, Tom M, Woods DE. Burkholderia pseudomallei isocitrate lyase is a persistence factor in pulmonary melioidosis: implications for the development of isocitrate lyase inhibitors as novel antimicrobials. Infect Immun. 2009; 77(10):4275-83.
7. Ebel F, Schwienbacher M, Beyer J, Heesemann J, Brakhage AA, Brock M. Analysis of the regulation, expression, and localisation of the isocitrate lyase from Aspergillus fumigatus, a potential target for antifungal drug development. Fungal Genet Biol. 2006; 43(7):476-89.
8. Krátký M, Vinšová J. Advances in mycobacterial isocitrate lyase targeting and inhibitors. Curr Med Chem. 2013; 19(36):6126-37.
9. Lorenz MC, Fink GR. Life and death in a macrophage: role of the glyoxylate cycle in virulence. Eukaryotic Cell. 2002; 1(5):57-62.
10. Lorenz MC, Fink GR. The glyoxylate cycle is required for fungal virulence. Nature. 2001; 412(6842):83-6.
11. Ansari MA, Fatima Z, Ahmad K, Hameed S. Monoterpenoid perillyl alcohol impairs metabolic flexibility of Candida albicans by inhibiting glyoxylate cycle. Biochem Biophys Res Commun. 2018; 495(1):560-6.
12. Webb W, Sali A. Protein structure modeling with MODELLER. Methods Mol Biol. 2017; 1654:39-54.
13. Wu S, Skolnick J, Zhang Y. Ab initio modeling of small proteins by iterative TASSER simulations. BMC Biol. 2007; 5:17.
14. Ahmad K, Bhat AR, Athar F. Pharmacokinetic evaluation of callistemon viminalis derived natural compounds as targeted inhibitors against δ-opioid receptor and farnesyl transferase. Lett Drug Design Discovery. 2017; 14(4):488-99.
15. Saibabu V, Fatima Z, Ahmad K, Khan LA, Hameed S. Octyl gallate triggers dysfunctional mitochondria leading to ROS driven membrane damage and metabolic inflexibility along with attenuated virulence in Candida albicans. Med Mycol. 2019; 28:54.
16. Ebel F, Schwienbacher M, Beyer J, Heesemann J, Brakhage AA, Brock M. Analysis of the regulation, expression, and localisation of the isocitrate lyase from Aspergillus fumigatus, a potential target for antifungal drug development. Fungal Genet Biol. 2006; 43(7):476-89.
17. Berman J, Sudbery PE. Candida albicans: a molecular revolution built on lessons from budding yeast. Nat Rev Genet. 2002; 3(12):918-30. 
18. Singulani JL, Scorzoni L, Gomes PC, Nazaré AC, Polaquini CR, Regasini LO, Fusco-Almeida AMMendes-Giannini MJSet al. Activity of gallic acid and its ester derivatives in Caenorhabditis elegans and zebrafish (Danio rerio) models. Future Med Chem. 2017; 9(16):1863-72.
19. Okoli I, Coleman JJ, Tampakakis E, An WF, Holson E, Wagner F, et al. Identification of antifungal compounds active against Candida albicans using an improved high-throughput Caenorhabditis elegans assay. PLoS One. 2009; 4(9):e7025.
20. Manoharan RK, Lee JH, Kim YG, Kim SI, Lee J. Inhibitory effects of the essential oils alphalongipinene and linalool on biofilm formation and hyphal growth of Candida albicans. Biofouling. 2017; 33(2):143-55.