Antibacterial and cytotoxic secondary metabolites from endophytic fungi associated with Antidesma bunius leaves

Abstract

Endophytic fungi isolated from Antidesma bunius leaves were investigated in this study. Six fungal endophytes were identified as Penicillium steckii AAB-01, Nemania bipapillata AAB-02, Xylaria feejeensis AAB-03, Hypomontagnella monticulosa AAB-04, Daldinia eschscholtzii AAB-05, and Phyllosticta capitalensis AAB-06. All of the isolated endophytic fungi were subjected to fermentation on rice media, followed by extraction with ethyl acetate. When tested for antibacterial activity, P. steckii AAB-01 extract showed the most potent inhibition against Staphylococcus aureus ATCC 6538 and Staphylococcus epidermidis ATCC 12228. Toxicity screening employing brine shrimp lethality test (BSLT) revealed potential toxicity of P. steckii AAB-01 and X. feejeensis AAB-03 extracts. Further investigation showed P. steckii AAB-01 extract had the highest inhibition toward MCF-7 cells, while D. eschscholtzii AAB-05 extract revealed the strongest cytotoxicity against 4T1 cells. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis tentatively identified five compounds, where indole acetic acid, O-acetylharmol, and oxindole I were suggested as the major metabolites in P. steckii AAB-01 extract, while 6-hydroxymelatonin and 2-methyl-6pentadecylpyridine were suggested as the major metabolites in D. eschscholtzii AAB-05 extract. This is the first report on LC-MS/MS identification of the main metabolites from bioactive extracts of P. steckii AAB-01 and D. eschscholtzii AAB-05 isolated from the leaves of A. bunius, which might contribute to the antibacterial and cytotoxic properties of the extracts. Thus, a detailed investigation of antibacterial and cytotoxic metabolites from these endophytes merits further studies.

Evaluation of Antibacterial and Toxicity Properties of Marine Endophytic Fungi from Red Algae Gracilaria Salicornia and Chondrus sp.

“…Each fungal colony with a different morphological appearance was transferred to a new agar plate containing medium without chloramphenicol for the purpose of fungal purification. For long-term fungal maintenance, a medium containing malt extract, Bacto agar, yeast extract, and glycerol in demineralized water was utilized [1].…”

“…(5'-GGTCCGTGTTTCAAGACGG -3') primers. The PCR mixture and condition were prepared and performed according to the protocol previously described [1]. The PCR product was subsequently sent for sequencing analysis to the 1st BASE (Malaysia).…”

“…The methanol and n-hexane phases were then evaporated into dryness in vacuo using a rotary evaporator. The obtained methanolic extracts were subjected for further research [1].…”

“…Before the process of hatching shrimp eggs, artificial seawater salt was prepared by dissolving 9.5 g artificial seawater in 300 mL of distilled water. A total of 20 mg of Artemia salina shrimp eggs were incubated in a brine incubator containing 300 mL artificial seawater salt [1]. The eggs were illuminated and aerated for 36-48 hours until they hatched to be nauplii.…”

“…The development of new drugs is currently a major global challenge, especially due to the increasing phenomenon of drug resistance. Secondary metabolites derived from natural products are still considered favourable sources of new drugs, including antimicrobial and anticancer agents [1]. The discovery of active compounds derived from marine natural materials is one approach to the discovery of new drugs.…”