ANTIBACTERIAL POTENTIALS OF ENDOPHYTIC FUNGAL METABOLITESFROM MEDICINAL HERBS; Caricapapaya, Mangiferaindica And Gossypiumhirsutum ON PERIODONTAL ISOLATES.

Abstract

ABSTRACT The increasing level of multidrug resistance among bacterial pathogens is a major concern in public health sector. This necessitates for more research in search of newer potential drug components. This study aimed at determining the antibacterial potential of endophytic fungal metabolites. The medicinal plants, Carica papaya, Mangifera indica and Gossypium hirsutum were collected and identified at Botany Department, Federal University of Agriculture, Abeokuta. Fungal isolates were obtained from the plant parts (leaves, roots and stems) by surface sterilization to remove debris and epiphytes present in the plant parts, and were cultured on Potato Dextrose Agar plates. Fungal isolates were characterized using a combination of morphological and molecular techniques. The submerged fermentation was done by sub-culturing the isolates of the filamentous fungi on Potato Dextrose Broth, incubated on a rotary shaker for 18 days for the purpose of the release of their metabolites and finally macerated to obtain the extracts. The obtained extracts were tested by agar well diffusion, Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) for antimicrobial activity against bacteria implicated in periodontal isolates. These include Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, Streptococcus pyogenes, Proteus mirabilis and Enterococcusfaecalis. The crude extracts were analyzed with Gas Chromatography-Mass Spectrometry while pharmacokinetic properties of metabolites were evaluated using in silico methods. Data obtained were statistically analysed using one-way ANOVA and values were recorded as mean ±SEM. Four endophytic fungal isolates obtained from the plants were identified as Trichoderma harzianum, Penicillium notatum and two different strains of Aspergillus niger. The zones of inhibition of the fungal extracts ranged froml 8.0 ± 1.0 mm to 23.0 ± 1.0 mm where Aspergillus niger produced metabolites with the most potent inhibitory properties. However, no zone of inhibition was observed on E. coli showing that the E. coli strain was resistant to all the extracts used in this study. The MIC and MBC values ranged from (3.13 µg/mL - 12.50 µg/mL) and (6.25 µg/mL- 5.00 µg/mL) respectively. The GC-MS analysis of the extracts showed the presence of several compounds including acetic acid, oxoprophines, 6-heptenoic acid, ethyl ester, oleic acid, nonanoic acid. It was observed that A. niger extracts through GC-MS had the highest peak value of 36.79a.u. In silico studies revealed favorable binding interactions between the ligands and the target protein, indicating potential therapeutic applications. Pharmacokinetic studies revealed that all ligands examined in this study passed the Lipinski rule with no violation. The molecular characterization of the fungal isolates revealed Trichoderma harzianum NAS120-M44, Aspergillus niger AMUAN-1 and Aspergillus niger ASP-599. This study showed that the antibacterial activity exhibited by the endophytic fungi and the bioactive compounds of these plants possess a great potential for drug discovery.