Daldiniaeschsone A, a Rare Tricyclic Polyketide Having a Chromone Unit Fused to a δ-Lactone and Its Symmetrical Biphenyl Dimer, Daldiniaeschsone B, from an Endophytic Fungus Daldinia eschscholtzii SDBR-CMUNKC745.

Natnicha Wutthiwong,Tharakorn Maneerat,Rawiwan Charoensup,Stephen G Pyne,Jaturong Kumla,Aknarin Pintatum,Nakarin Suwannarach,Virayu Suthiphasilp,Sarot Cheenpracha,Surat Laphookhieo,Saisamorn Lumyong,Thunwadee Limtharakul

doi:10.3390/jof7050358

Abstract

Daldiniaeschsone A (1), a rare tricyclic polyketide having a chromone unit fused to a δ-lactone and its symmetrical 6,6′-biphenyl dimer, daldiniaeschsone B (2), together with three known compounds (3−5), were isolated from a plant-derived endophytic fungus, Daldinia eschscholtzii SDBR-CMUNKC745. Their structures were elucidated by extensive 1D and 2D NMR spectroscopic data and HRESIMS. All compounds showed α-glucosidase inhibitory activity with IC50 values ranging from 0.16−0.85 mM and compound 1 was the best α-glucosidase inhibitory activity (IC50 = 0.16 mM).

Highlights

Natural products from fungi have been observed to inhibit or kill a wide variety of harmful microorganisms, including, but not limited to, phytopathogens and bacteria, fungi, viruses, and protozoans that affect humans and animals [1,2,3]
Compound 1 was subjected to chiral HPLC analysis and the results showed that this compound was a scalemic mixture with an enantiomeric excess of 15.6% (Supplementary Materials, Figure S19)
Various types of compounds have been isolated and identified, but polyketides are found as the Previous chemical constituent investigations of D. eschscholtzii, using different fungal collections and different conditions of fermentation yielded different compounds

Summary

Introduction

Natural products from fungi have been observed to inhibit or kill a wide variety of harmful microorganisms, including, but not limited to, phytopathogens and bacteria, fungi, viruses, and protozoans that affect humans and animals [1,2,3]. The genus Daldinia belonging to the Xylariaceae is a genus of fungi that produces polyketide compounds with diverse structures and impressive biological activities, including immunosuppressive, cytotoxic, antiangiogenesis, anti-inflammatory, and antibacterial activities [1,2,5,6,7,8]. Previous chemical constituent investigation of D. eschscholtzii resulted in the discovery of various types of secondary metabolites, including chromones, lactones, phenolics, and alkaloids [1,12,13,14,15,16,17] Many of these isolated compounds have demonstrated a wide range of bioactivities, such as α-glucosidase inhibition [1], immunosuppression [12], antimicrobial [6,13,14,15], stem cell differentiation induction [16] and anti-inflammatory [17] activities. The α-glucosidase and NO production inhibition activities of all compounds are reported

Results

Discussion

Conclusion