Stryphnodendron adstringens and purified tannin on Pythium insidiosum: in vitro and in vivo studies

Abstract

Background Pythium insidiosum is the etiological agent of pythiosis, an emerging life-threatening infectious disease in tropical and subtropical regions. The pathogen is a fungus-like organism resistant to antifungal therapy, for this reason, most cases need extensive surgical debridments as treatment, but depending on the size and anatomical region of the lesion, such approach is unfeasible. We investigate the fungicidal effect and toxicity of crude bark extract of Stryphnodendron adstringens and commercially available tannin on Pythium insidiosum both in vitro and in vivo.MethodsStandardized fragments of mycelia of fifteen isolates of P. insidiosum were tested with different concentrations of bark extract (10 to 30% v/v) and tannin (0.5, 1.0 and 1.5 mg/mL). For in vivo study, fifteen rabbits were experimentally infected with zoospores of P. insidiosum and treated by oral and intralesional applications of bark extract and tannin. Acute toxicity tests with both substances were also performed in rats.ResultsIn vitro studies showed fungicidal effect for both substances at different concentrations and the SEM showed alteration on the cell wall surface of the pathogen. All infected rabbits developed a firm nodular mass that reached around 90 mm2 ninety days after inoculation, but neither the intralesional inoculation of tannin, nor the oral administration of crude extract and tannin were able to promote remission of the lesions.ConclusionsLesions developed by rabbits presented an encapsulated abscess being quite different of naturally acquired pythiosis, which is characterized by ulcerated lesions. Since no toxicity was observed in rats or rabbits inoculated with these products, while in vitro experiments showed direct antifungal effect, therapeutic activity of S. adstringens and tannin should be clinically tested as an alternative for healing wounds in naturally acquired pythiosis.

Analysis of xanthyletin and secondary metabolites from Pseudomonas stutzeri ST1302 and Klebsiella pneumoniae ST2501 against Pythium insidiosum

“…To investigate the in vitro anti- P. insidiosum effect of the crude extract from the bacteria and xanthyletin, we used the method of Rodrigo Trolezi et al with some modifications [24]. Briefly, fragments of P. insidiosum mycelia (5 mm in diameter) from the SDA plates were inoculated by aseptic technique into 1.95 ml of Sabouraud Dextrose Broth (SDB) and incubated at 37 °C for 3 days.…”

Evaluation of antifungal effect and toxicity of xanthyletin and two bacterial metabolites against Thai isolates of Pythium insidiosum

“…It is well known that the therapy of pythiosis has posed a challenge in recent decades as the current treatment options are highly variable and often lead to failure 14 . Therefore, many studies have searched for antimicrobial agents, natural compounds or secondary metabolites from microorganisms against P. insidiosum and results of in vitro testing are quite promising 6,7,[15][16][17][18][19][20][21] . The present study evaluated antimicrobial effects against P. insidiosum of xanthyletin and two fractions of the crude extracts from P. stutzeri ST1302 and K. pneumoniae ST2501.…”

“…Broth dilution susceptibility testing. The method by Trolezi et al was used with some modifications 20 .…”

“…Scanning electron microscopy of the hyphal morphology. The protocols described by Trolezi et al 20 and Mendoza et al 3 were followed with some modifications. For SEM analysis, hyphae in blocks from each testing solution evaluated as MFCs were selected.…”

Stryphnodendron Species Known as “Barbatimão”: A Comprehensive Report

“…Those effects could reflect alterations in cell metabolism and it was observed that the extract impaired mitochondrial oxidative phosphorylation and liver metabolism by increasing oxygen consumption [ 155 ]. In opposition, a methanolic extract did not show acute toxicity or histological alterations in liver and kidney of treated rats, neither showed hepatic or renal dysfunctions in rabbits [ 117 ].…”