Purification, crystallization and anticancer activity evaluation of the compound alternariol methyl ether from endophytic fungi Alternaria alternata

AIMS

Medicinal plant-associated endophytic fungi are important sources of precious bioactive compounds, contributing more than 80% of the natural drugs for various ailments. The present study was aimed at evaluating the anticancer activity of the crystallized compound alternariol methyl ether (AME) against hepatocellular carcinoma (HCC) both in vitro and in vivo from an endophytic fungus residing in the medicinal plant Vitex negundo.

METHODS AND RESULTS

The secondary metabolites from the endophytic fungus Alternaria alternata MGTMMP031 were isolated. Purification and characterization of the compound was performed and the potential compound was identified as AME. The crystal structure of AME was unambiguously confirmed by X-ray analysis. AME has been checked for its antibacterial and anticancer properties which showed its effectiveness against various bacteria and demonstrated marked anti-proliferative activity against the human HCC cells (HUH-7) both in vitro and in vivo. Mode of actions included cell cycle arrest, reducing the level of markers enzymes of liver cancer and preventing tumour growth.

CONCLUSIONS

Alternariol methyl ether acts as a potential therapeutic target against HCC. The compound was isolated and the crystal structure was obtained for the first time from the endophytic fungus A. alternata MGTMMP031. In the present study, the crystallized structure of AME was obtained by slow evaporation technique. It can be concluded that AME acts as a potential therapeutic target against HCC.

SIGNIFICANCE AND IMPACT OF THE STUDY

Endophytic fungi residing in the medicinal plants have strong biological significance and bioactive compounds from these fungi provide better therapeutic targets against diseases.

Bioactive compound from Aspergillus terreusDMTMGK004 synergistically contributes towards potential anti-pathogenicity

This study focused on the evaluation of fungal compound for their anti-pathogenic potential against respiratory pathogens. Soil samples were collected from various geographical regions in Madurai, fungal strain was isolated and identified as Aspergillus terreusDMTMGK004 (MGK004). Secondary metabolites were extracted and evaluated for antioxidant potential. It exhibited significantly high anti-proliferative property against gastric adenocarcinoma (AGS) cell lines. Antimicrobial activity against Gram positive (Streptococcus pneumoniae) and Gram negative (Klebsiella pneumoniae and Haemophilus influenzae) respiratory pathogens were analysed and the minimum inhibitory concentration (MIC) values were determined. Furthermore, the time-killing assay illustrated that the metabolite eliminates 50% of the vegetative cells within few hours of the treatment. From the spectral data, the major functional groups present in the compound were determined as carbonyl group and phenolic hydroxyl group which contribute towards its bioactivity. The compound significantly depreciates the production of extracellular polysaccharides which results in the weakening of biofilm architecture and resistance towards serum killing and phagocytosis. It also induced cell membrane damage which leads to protein and nucleic acid leakage. Hence, the results of the present study could provide a better insinuation towards the formulation of new drug targeting respiratory pathogens. SIGNIFICANCE AND IMPACT OF THE STUDY: The ubiquitous fungi Aspergillus terreus is well known for its secondary metabolite production. The fungus was evaluated for production of antagonistic molecule to reduce the growth of infectious agents causing respiratory infections. It exhibited the biological means of antioxidant, anti-proliferative and anti-pathogenic compound production. The compound exhibits killing effect against respiratory pathogens within two hours. It induced cell membrane damage leading to protein and nucleic acid leakage. It significantly reduced the production of extracellular polysaccharides. The results provide needed information to design innovative strategies for targeting pathogenic factors of the respiratory pathogens instead of killing it precisely.