Evaluation of Antiviral, Antibacterial and Antiproliferative Activities of the Endophytic Fungus Curvularia papendorfii, and Isolation of a New Polyhydroxyacid.

Afra Khiralla,Sakina Mohamed Yagi,Philippe André,Sophie Slezack-Deschaumes,Pascal Lemiere,Ietidal Mohamed,Mihayl Varbanov,Rosella Spina,Stéphanie Philippot,Dominique Laurain-Mattar

doi:10.3390/microorganisms8091353

Abstract

An endophytic fungus isolated from Vernonia amygdalina, a medicinal plant from Sudan, was taxonomically characterized as Curvularia papendorfii. Ethyl acetate crude extract of C. papendorfii revealed an important antiviral effect against two viral pathogens, the human coronavirus HCoV 229E and a norovirus surrogate, the feline coronavirus FCV F9. For the last one, 40% of the reduction of the virus-induced cytopathogenic effect at lower multiplicity of infection (MOI) 0.0001 was observed. Selective antibacterial activity was obtained against Staphylococcus sp. (312 µg/mL), and interesting antiproliferative activity with half maximal inhibitory concentration (IC50) value of 21.5 ± 5.9 µg/mL was observed against human breast carcinoma MCF7 cell line. Therefore, C. papendorfii crude extract was further investigated and fractionated. Twenty-two metabolites were identified by gas chromatography coupled to mass spectrometry (GC–MS), and two pure compounds, mannitol and a new polyhydroxyacid, called kheiric acid, were characterized. A combination of spectroscopic methods was used to elucidate the structure of the new aliphatic carboxylic acid: kheiric acid (3,7,11,15-tetrahydroxy-18-hydroxymethyl-14,16,20,22,24-pentamethyl-hexacosa-4E,8E,12E,16,18-pentaenoic acid). Kheiric acid showed an interesting result with a minimum inhibitory concentration (MIC) value of 62.5 µg/mL against meticillin-resistant Staphylococcus aureus (MRSA). Hence, endophytes associated with medicinal plants from Sudan merit more attention, as they could be a treasure of new bioactive compounds.

Highlights

The priority in research is the discovery of alternative treatments for viral and bacterial infections and cancer diseases
Human coronaviruses (HCoVs) are a set of viruses that induce respiratory disease of varying severity, including common cold and pneumonia [1,2]. This wide-ranging family of viruses infects many species of mammals, including humans [3]. Their ability for interspecies transmission has led to the emergence of the Severe Acute Respiratory Syndrome (SARS) [4] and the Middle East Respiratory Syndrome (MERS) [5], both associated with high mortality and morbidity
Noroviruses frequently cause acute gastroenteritis outbreaks globally, which is associated with heavy economic burden [6], as norovirus-induced gastroenteritis is acute in the elderly and in young children

Summary

Introduction

The priority in research is the discovery of alternative treatments for viral and bacterial infections and cancer diseases. Human coronaviruses (HCoVs) are a set of viruses that induce respiratory disease of varying severity, including common cold and pneumonia [1,2]. This wide-ranging family of viruses infects many species of mammals, including humans [3]. Noroviruses frequently cause acute gastroenteritis outbreaks globally, which is associated with heavy economic burden [6], as norovirus-induced gastroenteritis is acute in the elderly and in young children. It is a highly resistant and infectious virus, with an infectious dose close to 20 virions and is transmitted through person-to-person contact [7]. The feline calicivirus strain F9 (FCV F9) is used to study the biology of norovirus [8], given the difficulties of growing human noroviruses in laboratory conditions

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