Recent progress on anti-Candida natural products

Streptomyces: a natural source of anti-Candida agents

Introduction. There is an urgent need to source new compounds that can combat the current threat of serious infection caused by Candida spp. and contend with the problem of antimicrobial resistance.

Gap. A synthesis of the evidence available from the current literature is needed to identify promising antifungal chemotherapeutics.

Aim. To highlight anti-Candida compounds derived from Streptomyces spp. (a well-known source of antimicrobial compounds) that could translate to potential candidates for future clinical practice.

Methodology. A comprehensive review was conducted across three scientific literature databases spanning a 13-year period.

Results. We identified 151 compounds with anti-Candida activity. Amongst these, 40 were reported with very strong inhibitory activity, having minimum inhibitory concentrations (MICs) against Candida spp. of <3.5 µg ml−1, 66 compounds were considered strong inhibitors and 45 compounds exhibited moderate inhibitory potential. From an analysis of the MICs, we deduced that the actinomycin-like compounds RSP01 and RSP02 were probably the most promising anti-Candida compounds. Other antifungals of note included filipin-like compounds, which demonstrated superior inhibition to amphotericin B and activity against Candida glabrata and Candida krusei, and bafilomycin derivatives, which had substantial inhibition against Candida parapsilosis.

Conclusion. It is essential to recognize the limitations inherent in the quest for new antifungals, which encompass toxicity, in vivo effectiveness and constraints associated with limited data access. However, further investigation through in-depth study and emerging technologies is of paramount importance, given that there are still many more compounds to discover. This review highlights the importance of antifungal compounds derived from Streptomyces , which demonstrate robust inhibition, and, in many cases, low toxicity, making them promising candidates for the development of novel antifungal agents.

Phenyl Pentyl Ketone and m-isobutyl Methoxy Benzoate Produced by Streptomyces Chrestomyceticus ADP4 are Potent Antimicrobial Agents Displaying Broad Spectrum Activities

Isolation and identification of two antimicrobial compounds, a phenyl pentyl ketone (CP1) and m-isobutyl methoxy benzoate (CP2), from Streptomyces chrestomyceticus ADP4 have been reported. Structure of the compounds were elucidated from analyses of spectral data that included LCMS/MS, NMR, FTIR and UV spectroscopies. Both the compounds displayed significant inhibition of albicans and non-albicans species of Candida (NAC) pathogens including C. auris, which is currently a pathogen of global concern. Also, the compounds showed potent antagonistic activity against Staphylococcus aureus, another significant human pathogen. No in-vitro cytotoxicity against HePG2 cells was observed with either of the compounds. Both displayed favourable drug likeness properties as determined by in-silico ADME and toxicological studies. Also, this is the first report on production of these anti-microbial compounds by an actinobacterium.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-023-01068-7.

Biocontrol of Candida albicans by Antagonistic Microorganisms and Bioactive Compounds

Candida albicans is an endogenous opportunistic pathogenic fungus that is harmless when the host system remains stable. However, C. albicans could seriously threaten human life and health when the body’s immune function declines or the normal flora is out of balance. Due to the increasing resistance of candidiasis to existing drugs, it is important to find new strategies to help treat this type of systemic fungal disease. Biological control is considered as a promising strategy which is more friendly and safer. In this review, we compare the bacteriostatic behavior of different antagonistic microorganisms (bacteria and fungi) against C. albicans. In addition, natural products with unique structures have attracted researchers’ attention. Therefore, the bioactive nature products produced by different microorganisms and their possible inhibitory mechanisms are also reviewed. The application of biological control strategies and the discovery of new compounds with antifungal activity will reduce the resistance of C. albicans, thereby promoting the development of novel diverse antifungal drugs.

Boswellia&nbsp;serrata Extract as an Antibiofilm Agent against Candida spp

The use of antibiotics or antifungals to control infections caused by pathogenic microorganisms is currently insufficiently effective because of their emerging resistance. Thanks to the ability of microorganisms to form a biofilm and thus increase their resistance to administered drugs even more, modern medicine faces the task of finding novel substances to combat infections caused by them. In this regard, the effects of essential oils or plant extracts are often studied. Among the relatively neglected plants is Boswellia serrata, which has a high content of biologically active boswellic acids. In this study, we focused on one of the most common nosocomial infections, which are caused by Candida species. The most common representative is C. albicans, although the number of infections caused by non-albicans species has recently been increasing. We focused on the antifungal activity of Boswellia serrata extract Bioswellix against planktonic and adhering cells of Candida albicans, Candida parapsilosis and Candida krusei. The antifungal activity against adhering cells was further explored by determining the metabolic activity of cells (MTT) and determining the total amount of biofilm using crystal violet. Boswellic acid-containing plant extract was shown to suppress the growth of a suspension population of all tested Candida species. Boswellia serrata extract Bioswellix was most effective in inhibiting C. albicans biofilm formation.