Antifungal Effects of Terminalia arjuna Fruit Extract on Multidrug-Resistant Candida auris: An In Vitro Study

Candida auris (C. auris) is a multidrug-resistant (MDR) fungal pathogen associated with high global mortality and rapidly increasing infection rates, particularly among immunocompromised patients. This growing resistance highlights the urgent need for new antifungal agents. The bark of Terminalia arjuna (T. arjuna) is widely used for treating skin ailments such as ringworm (Tinea infection) and cutaneous candidiasis. The traditional uses of T. arjuna strongly suggest that it may have antifungal activity.

Fresh fruits of T. arjuna were collected from the vicinity of Lucknow. The dried fruits (250 g) were subjected to dry distillation to obtain 50 mL of extract, as this method facilitates the recovery of volatile and thermally stable bioactive compounds. The extract was then concentrated to yield 10 mL of a concentrated fraction, which was subsequently dried and used to prepare different concentrations for further analysis. The antifungal efficacy of the extract was tested against clinical isolates of MDR C. auris. The antifungal activity of the T. arjuna extract was assessed using the disk diffusion susceptibility method for initial screening. Additionally, the minimum inhibitory concentration (MIC) of the extract was determined using a 96-well broth microdilution method. After overnight incubation at 37°C, the diameters of the zones of inhibition were measured and interpreted in accordance with CLSI guidelines. The effect of the extract of T. arjuna was compared with fluconazole, amphotericin B, and caspofungin.

The antifungal efficacy of T. arjuna extract was evaluated against three MDR clinical isolates of C. auris (KGMU-CA-01 to 03) using the disc diffusion method and broth microdilution assay. Baseline resistance profiling confirmed that all isolates were highly resistant (0 mm zone) to both fluconazole (25 ug/disc) and Amphotericin B (20 ug/disc), while the plant extract demonstrated a significant, dose-dependent inhibitory effect. At a concentration of 2000 ug/disc, the extract produced a mean zone of 16.33 mm, which increased to a maximum of 20.33 ± 0.58 mm at 4000 ug/disc in isolate KGMU-CA-03. Statistical analysis via one-way ANOVA confirmed a highly significant dose-response relationship (p = 0.0006), and a comparative analysis showed that the 4000 ug/disc concentration was statistically superior to the active control, caspofungin (5 ug/disc; 15.56 mm average, p = 0.0028). The MIC was 3.12 mg/ml. These comparisons between the crude botanical extract and purified standard drugs were observational and did not imply equivalent pharmacological potency.

The T. arjuna fruit extract demonstrated dose-dependent antifungal activity against MDR C. auris isolates. The observed inhibitory effects and MIC value indicated promising in vitro antifungal potential of the crude extract. However, these findings were preliminary, based on a crude preparation, and did not imply equivalence to standard antifungal agents. Further studies involving bioassay-guided fractionation and testing on a larger number of isolates were required to validate its therapeutic potential.