Chemical Constituents and Antioxidant and Antibacterial Activity of a Fungal Endophyte Isolated from Plantago asiatica
- PDF / 146,723 Bytes
- 2 Pages / 594 x 792 pts Page_size
- 86 Downloads / 364 Views
CHEMICAL CONSTITUENTS AND ANTIOXIDANT AND ANTIBACTERIAL ACTIVITY OF A FUNGAL ENDOPHYTE ISOLATED FROM Plantago asiatica
Na Han,1,2 Aimei Yang,1,2* Songyao Ma,3 Huilan Shang,1,2 Long Chen,3 Fulu Zhang,1,2 and Zhihui Wang1,2
As a class of microorganism groups coexisting with host plants, endophytes synthesize chemical compounds that are similar or the same as what the host plants contain [1]. Plantago asiatica L., a well-known traditional China medicine plant, has diuresis [2] and anticancer effects [3]. It has been used as a diuretic, anti-inflammatory [4], and anti-asthmatic drug [5] in China. To the best of our knowledge, there are few works that have been reported on the chemical constituents of fungal endophyte metabolites from P. asiatica. In this paper, we describe the isolation and identification of seven compounds (1–7) from the fermentation production of the endophytic fungus (identified as Aspergillus terreus strain GKF2) of P. asiatica. In this study, 37 species of endophytes were isolated from the stems and leaves of fresh P. asiatica based on both morphologies on PDA. The strain cqc-23 was chosen as the test strain for its antioxidant and antimicrobial activities of the metabolites. The antioxidant activity of endophyte metabolites was evaluated by Yuanfeng Wang et al. [6]. The antimicrobial activity of endophytes metabolites was evaluated as Santos et al. [7]. The IC50 for hydroxyl radical scavenging of strain cqc-23’s metabolites was 91 μg/mL, and the MIC for Escherichia coli inhibition of strain cqc-23’s metabolites was 625 μg/mL, showing good potential application value. The fungal strain (cqc-23) was identified as Aspergillus terreus strain GKF2 based on DNA sequences of the18s rDNA gene region. A GenBank search for DNA sequence similarity revealed that the18s rDNA of cqc-23 was 99.65% homologous to that of Aspergillus terreus. Strain GKF25 reference strains (GenBank No. MK 713427.1). A large-scale culture (100 L) was grown in PDA liquid medium at 28°C for 21 days on a 50 L fermentation tank (50 L × 2). The crude fermentation broth was filtered. Then the broth was extracted with EtOAc (50 L × 2) to afford the crude extract (52.7 g). The extract was subjected to a series of chromatographic techniques using silica gel, a C18 column, MCI resin, and HPLC. A total of seven compounds was isolated and identified based on MS and NMR spectra. To the best of our knowledge, this is the first report on the isolation of terrein (1), alboatrin (2), (3R)-6-hydroxymellein (3), orcinol (4), and 2-hydroxybenzothiazole (5) from Aspergillus terreus. Terrein (1), white crystals, C8H10O3. ESI-MS m/z 155 [M + H]+. 1H NMR (400 MHz, DMSO-d6, δ, ppm, J/Hz): 6.77 (1H, dq, J = 16.0, 6.4, H-7), 6.39 (1H, d, J = 16.0, H-6), 5.70 (1H, s, H-5), 4.62 (1H, d, J = 2.4, H-2), 3.89 (1H, d, J = 2.4, H-3), 1.89 (3H, d, J = 6.4, CH3-8) [8]. Alboatrin (2), pale yellow gum, C14H18O3, mp 112–115°C. 1H NMR (400 MHz, DMSO-d6, δ, ppm, J/Hz): 6.29 (1H, J = 2.2, H-8), 6.27 (1H, d, J = 2.2, H-6), 4.91 (1H, s, OH), 4.16 (1H, m, H-4β), 3.51 (2H, m
Data Loading...
