Bioactive compounds from endophytic fungi isolated from Kaempferia parviflora

Abstract

The purpose of this research was to isolate bioactive compounds from endophytic fungi isolated from Kaemperia parviflora leaves were collected from 3 provinces in Thailand. The endophytic fungi were isolated using surface-sterillization technique and obtained 36 isolates. All isolates were examined antimicrobial activity using dual culture agar diffusion technique. Endophytic fungus isolate KPCH007 cultured on malt extract agar had the best antimicrobial activity because it can inhibited the growth of test gram positive Bacillus subtilis, Staphylococcus aureus and negative bacteria Pseudomonas aeruginosa. Based on morphology and nucleotide sequencing analysis of ITS regions of rDNA, endophytic fungus isolate KPCH007 was identified as Alternaria tenuissima. Isolation of culture broth EtOAc crude extract of endophytic fungus isolate KPCH007 cultivated in malt extract broth gave compound 1, compound 2 and compound 3. Isolation of mycelia EtOAc crude extract gave mixture 4, mixture 5 and compound 6. The structure elucidation of these compounds was achieved by analysis of spectroscopic data and physical properties. Compound 1 was identified as 1-methyl-2-pyrrolidone. Compound 2 was identified as dehydroaltenusin. Compound 3 was identified as 1,6-dihydroxy-3-methoxy-8-methyl-9H-xanthen-9-one. From the mycelia ; Mixture 4 was obtained as yellow liquid and it was identified as a mixture of triglycerides. Mixture 5 was a mixture of macrosporin and alternariol-9-methyl ether and Compound 6 was identified as alternariol-9-methyl ether. Antimicrobial activities and cytotoxicity of the pure compound were tested. For antimicrobial activities, Compound 1 was found to exhibit activity against B. subtilis , S. aureus, P. aeruginosa and E. coli. with the MIC value of 31.25, 31.25, 62.50 and 62.50 microgram/ml. Mixture 5 was found to exhibit activity against all four bacteria with the MIC value of 125, 250, 250, and 250 microgram/ml. Compound 6 was found to exhibit activity against all four bacteria with the MIC value of 62.50, 62.50, 125, 125 microgram/ml and inhibited C. albicans at 250 microgram/ml., respectively. In addition, compound 1 can exhibited cytotoxic activities against SW620 (colon), BT474 (breast), KATO-3 (gastric), HEP-G2 (hepatoma) and CHAGO (lung) cell line with IC[subscript 50] >10, >10, >10, >10, 8.4 microgram/ml, Compound 3 with IC[subscript 50] >10, 7.4, >10, >10, >10 microgram/ml, Mixture 5 with IC[subscript 50] >10, 6.4, >10, 10, >10 microgram/ml and Compound 6 with IC[subscript 50] 10, 6.4, 8.8, 7.9 and 10 microgram/ml, respectively.