Boric Acid and Commercial Organoboron Products as Inhibitors of Drug-Resistant Candida albicans

Abstract

Clinical use of boric acid as a topical antifungal in women who have failed standard antifungal therapy with azole drugs has been used sporadically for decades. Our previous in vitro work showing inhibition of Candida albicans growth was conducted on clinical isolates without antifungal drug susceptibility profiling. Here, we report that boric acid restricts growth of drug-resistant Candida albicans and inhibits hyphal growth and diminishes cell volume. The availability of over-the-counter organoboron compounds intended for use as oral nutritional supplements led us to determine if these also were inhibitory toward resistant Candida and show here that they also possess antifungal activity. Candida glabrata was also found to be inhibited by boric acid and organoboron compounds. Further development of organoboron compounds as topical therapeutics is of potential value.

Effects of 3% Boric Acid Solution on Cutaneous Candida albicans Infection and Microecological Flora Mice

“…Fungal hyphae could be seen under a fluorescence microscope, smooth emerald green colonies were shown on the CA screening medium, and the colony culture count reached 10 5 -10 6 CFU/g. Boron exists in the form of boric acid at physiological pH (Larsen et al, 2018). Boric acid, a common antibacterial agent (Schmidt et al, 2010), is widely used to treat fungal infections.…”

“…Boron exists in the form of boric acid at physiological pH ( Larsen et al, 2018 ). Boric acid, a common antibacterial agent ( Schmidt et al, 2010 ), is widely used to treat fungal infections.…”

“…Nevertheless, its mechanisms of action are not clear. They may involve destroying the cytoskeleton and preventing actin recombination, resulting in abnormal mycelium development, thereby inhibiting mycelium growth ( Larsen et al, 2018 ). Some investigators found that boric acid inhibits glyceraldehyde 3-phosphate dehydrogenase (an NAD glycolysis-dependent enzyme) and ethanol dehydrogenase (an NADH-dependent fermentation enzyme) in CA, thereby inhibiting NAD/NADH-dependent reactions in carbohydrate metabolism, affecting energy metabolism, promoting ethanol production, and increasing the sensitivity of CA to ethanol toxicity ( Pointer and Schmidt, 2016 ).…”

Boron and Health

“…Larsen ve ark., oral yoldan kullanılan orgonabor komplekslerinin, ilaca direnç geliştiren C. albicans ve Candida glabrata üzerinde etkili olduğunu tespit etmişlerdir. 24 Yeni antibakteriyel bileşikler olarak kabul edilen, borik asit kinolin esterlerinden AN0128; atopik dermatitis tedavisinde kullanılır. 25 Yine, Sağlam ve ark.nın yaptığı bir derlemede de belirtildiği gibi Luan ve ark.…”

Synthetic Naphthofuranquinone Derivatives Are Effective in Eliminating Drug-Resistant Candida albicans in Hyphal, Biofilm, and Intracellular Forms: An Application for Skin-Infection Treatment

“…Cutaneous mycosis is also caused by the other dermatophytes, including Microsporum, Epidermophyton, and Trichophyton (Martinez-Rossi et al, 2017). In recent years, the increasing use of antifungal drugs for cutaneous mycosis treatment has led to the development of drug-resistant C. albicans (Larsen et al, 2018). This situation advocates the urgent need for novel antifungal agents.…”