A bioactivity-guided investigation of the lichen Parmotrema cristiferum (Taylor) Hale (Parmeliaceae) led to the isolation of two new depsidones, cristifones A and B (1 and 2). The structures of the isolated compounds were identified by spectroscopic methods and comparison with the literature data. Compound 1 showed the initial combined structures of depsidone and depside cores. The two isolated compounds were then evaluated for αglucosidase inhibition. Compounds 1 and 2 were confirmed as potent, with IC 50 values of 21.5 and 18.4 μM, respectively. Compound 2 was a non-competitive inhibitor against α-glucosidase, as indicated by the intersect in the second quadrant of each respective plot.
A new hopan-type triterpenoic peracid, tinctoride A (1), together with three known compounds, zeorin (2), 6β,22-dihydroxyhopane (3), and ergosterol peroxide (4), was isolated from Parmotrema tinctorum (Despr. ex Nyl.) Hale. Their chemical structures were identified by extensive 1D and 2D NMR analysis and high-resolution mass spectroscopy and compared with those reported in the literature. The enzyme inhibitory potential of compounds 1–3 against α-glucosidase was investigated, exhibiting nil to weak inhibitory activity.
Banana endophytic bacteria have many plant growth promoting activities and the enhanced influences based on the capable of endophytic colonization. Previous studies have mainly focused on endophytic bacteria in banana leaves, roots and shoots. This study aimed to evaluate the potential application of endophytic bacteria isolated from pseudostem of Cavendish banana. Eighteen endophytic bacterial isolates were collected from eight pseudostem samples. The tests showed that the indigenous endophytic bacteria, depending on the isolate, could dissolve insoluble inorganic minerals, produce extracellular hydrolytic enzymes, produce indole-3-acetic acid, fix nitrogen and control Phyllosticta sp. and Fusarium sp. Preliminary safety tests showed that one isolate did not exhibit hemolytic activity. Many isolates were compatible with each other, especially four strains including TC4.1, TC5.1, TC6.2 and TD7.1 were compatible with all remaining isolate and suitable for developing multi-strain products. Growth curves indicated that two isolates, TD7.2 and LA7.4, peaked at 16 and 18 hours respectively. The results showed that these endophytic bacteria have many potential activities. However, other plant growth promoting activities should be assessed in order to have potential applications as well as to exploit these bacteria.
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