Chemistry and Biodiversity of Rhizophora-Derived Endophytic Fungi

Abstract

Rhizophora are salt-tolerant mangrove flora located in tropical and subtropical inter tidal coastal regions. This review summarizes frequently occurring fungal endophytes in Rhizophora . In total, 41 families and 64 genera belonging to 23 taxonomic orders of Ascomycota have been reported. Among those discussed here, Pestalotiopsis , Penicillium , and Mucor are the most abundant fungal genera, and they are widely studied. In previ ous studies, 195 metabolites were encountered in Rhizophora -derived endophytic fungi, and their structures are reported within a biogenetic context. Bioassays showed antitu - mor, antimicrobial, as well as anti-H1N1 activities to be the most notable bioactivities of the secondary metabolites discussed. Some secondary metabolites with unusual structures were identified in Rhizophora endophytic fungi. Novel hybrid sesquiterpene-cyclopaldic acid metabolites with unusual carbon skele -tons, pestalotiopens A and B ( 83, 84 ), were obtained from the endophytic fungus Pestalotiopsis sp. JCM2A4 isolated from the leaves of the Chinese mangrove, R. mucronata . Bioassays revealed that antitumor, antimicrobial, and anti-H1N1 activities are the most notable bioactivities of the secondary metabolites from Rhizophora endophytic fungi. Some compounds had significant bioactivities, as exemplified by pestalpolyol 1 ( 119 ), a novel polyketone derivative isolated from P. clavispora . Compound 119 has a strong inhibitory effect on mouse lymphoma cell line L5178Y with an IC 50 value of 4.10 μM. The indole diterpene alkaloids, rhizovrin A, B, and F ( 46, 47, 50 ), isolated from endophytic fungi Mucor irregularis QEN-189, have strong inhibitory effects on lung cancer cells A549, with IC 50 values of 11.5, 6.3, and 9.2 μM, respectively, as well as inhibitory effects on leukemia myeloid cells HL-60, with IC 50 values of 9.6, 5.0, and 7.0 μM, respectively. These findings suggest that Rhizophora endophytic fungi offering numerous use ful products with medicinal and pathogenic significance have yet to be established.