Acanthamoebicidal activity of Fusarium sp. Tlau3, an endophytic fungus from Thunbergia laurifolia Lindl.

Abstract

A fungal endophyte identified as Fusarium sp. Tlau3 was isolated from fresh twig of Thunbergia laurifolia Lindl., a Thai medicinal plant collected from the forest of Chiang Mai Province, Northern Thailand. The fungus was grown on a medium containing yeast extracts and sucrose. The fungal metabolites were isolated from the culture broth by dichloromethane extraction, isooctane/methanol then n-butanol/water partitions, and fractionation with Sephadex LH 20 column chromatography. Acanthamoebicidal fractions were found to induce the formation of large contractile vacuole (LCV) in trophozoites of an Acanthamoeba clinical isolate, leading to cell lysis under isotonic and hypotonic conditions within 1 h. In hypertonic condition, LCV formation was also induced but without cell lysis. Acridine orange staining of the treated cells revealed increased intracellular acidity, implying an increased proton pumping or a vacuolar proton-ATPase (V-ATPase) stimulation. Scanning electron microscopy showed cell membrane damage with intact cytoplasmic organelles. Our finding has indicated that contractile vacuoles of Acanthamoeba trophozoites are the primary target of the amoebicidal substance(s) from this endophytic fungus.

Fungal endophytes and bioprospecting

“…Strobel and Daisy (2003) emphasize this in their review while stating that 'plants from unique environmental settings' and 'plants with an unconventional biology' as well as plants with established ethnobotanic values would be more promising sources of endophytes producing novel biochemicals. Endophytic fungi associated with traditionally used medicinal plants especially of the tropics could be a rich source of functional metabolites (Weber et al, 2004;Tejesvi et al, 2007;Aly et al, 2008;Boonman et al, 2008;Huang et al, 2008;Sappapan et al, 2008). In this regard, the endophyte-plant host association could also be exploited in enhancing the production of useful metabolites by the plant host (Wang et al, 2004).…”

In Vitro Acanthamoebicidal Activity of Fusaric Acid and Dehydrofusaric Acid from an Endophytic Fungus Fusarium sp. Tlau3

“…The untreated, PHMB-treated, and cFA-treated trophozoites were processed for observation under a scanning electron microscope using the same technique as previously described [21]. Details of the experiments are in Supporting Information.…”

“…Tlau3, an endophytic fungus isolated from the twigs of Thunbergia laurifolia Lindl. (Acanthaceae), produced the secondary metabolites that could kill pathogenic Acanthamoeba trophozoites in vitro [21]. The partially purified Fusarium metabolites interfered with the function of Acanthamoeba contractile vacuole, the essential osmoregulatory organelle of free-living protozoa, resulting in a large contractile vacuole (LCV) formation and trophozoite lysis [21].…”

“…(Acanthaceae), produced the secondary metabolites that could kill pathogenic Acanthamoeba trophozoites in vitro [21]. The partially purified Fusarium metabolites interfered with the function of Acanthamoeba contractile vacuole, the essential osmoregulatory organelle of free-living protozoa, resulting in a large contractile vacuole (LCV) formation and trophozoite lysis [21]. This preliminary result suggested that the Tlau3 metabolites might serve as a starting point for further development of therapeutic and environmental acanthamoebicides, and that the active principles should be identified.…”

Anticestodal Activity of EndophyticPestalotiopsissp. on Protoscoleces of Hydatid CystEchinococcus granulosus

“…Thus, it does require urgent steps to find out new natural, safe, and sustainable alternative to the chemical anthelmintics that can be designed as new therapeutic prodrug for parasitic infections. Scanty of reports are available about the potential of endophytes as antiparasitic agent; a few data too that have been reported very recently encourage us to explore the possibilities of new antiparasitic molecules from endophytes [11]. Hydatidosis or cystic echinococcosis (CE) is a chronic zoonosis affecting humans as well as domestic animals [12], caused by the larval stage of a cosmopolitan parasitic cestode Echinococcus granulosus [13, 14].…”