Antiplasmodial Properties and Cytotoxicity of Endophytic Fungi from Symphonia globulifera (Clusiaceae)

Abstract

There is continuing need for new and improved drugs to tackle malaria, which remains a major public health problem, especially in tropical and subtropical regions of the world. Natural products represent credible sources of new antiplasmodial agents for antimalarial drug development. Endophytes that widely colonize healthy tissues of plants have been shown to synthesize a great variety of secondary metabolites that might possess antiplasmodial benefits. The present study was carried out to evaluate the antiplasmodial potential of extracts from endophytic fungi isolated from Symphonia globulifera against a chloroquine-resistant strain of Plasmodium falciparum (PfINDO). Sixty-one fungal isolates with infection frequency of 67.77% were obtained from the bark of S. globulifera. Twelve selected isolates were classified into six different genera including Fusarium, Paecilomyces, Penicillium, Aspergillus, Mucor, and Bipolaris. Extracts from the 12 isolates were tested against PfINDO, and nine showed good activity (IC₅₀ < 10 &mu;g&middot;mL^&minus;1) with three fungi including Paecilomyces lilacinus (IC₅₀ = 0.44 &mu;g&middot;mL^&minus;1), Penicillium janthinellum (IC₅₀ = 0.2 &mu;g&middot;mL^&minus;1), and Paecilomyces sp. (IC₅₀ = 0.55 &mu;g&middot;mL^&minus;1) showing the highest promise. These three isolates were found to be less cytotoxic against the HEK293T cell line with selectivity indices ranging from 24.52 to 70.56. Results from this study indicate that endophytic fungi from Symphonia globulifera are promising sources of hit compounds that might be further investigated as novel drugs against malaria. The chemical investigation of active extracts is ongoing.

Keywords: Symphonia globulifera; antiplasmodial IC50; chloroquine-resistant Plasmodium falciparum; endophytic fungi; malaria; selectivity index.

Figure 1

Classification of fungal endophytes isolated from Symphonia globulifera based on a neighbor-joining phylogenetic tree made with ITS1-5.8S rDNA-ITS2 nucleotide sequences. Taxa with accession numbers correspond to reference strains. Numbers at branch nodes are bootstrap values based on 500 replications.