Two new lanostane-type triterpenoids from the fungus Periconia sp. TJ403-rc01

Abstract The endophytic fungus Periconia sp. TJ403-rc01 (Dematiaceae) isolated from the leaves of Rosa chinensis Jacq. (Rosaceae) was cultivated on rice medium and chemically investigated, affording two new lanostane-type triterpenoids, namely pericinones A and B (1 and 2). Their structures were determined mainly by 1 D and 2 D NMR and HRESIMS data. Notably, it is the first report of lanostane-type triterpenoids from species of Periconia. Compounds 1 and 2 showed moderate anti-inflammatory activity against the NO production with IC50 values of 24.12 ± 0.73 and 11.38 ± 1.56 μM, respectively. Graphical Abstract


Introduction
Plant endophytic fungi are increasingly recognized as prolific sources of structurally unique and bioactive secondary metabolites (Helaly et al. 2018;Hu et al. 2021). The species of genus Periconia are capable of producing diverse classes of metabolites such as cytochalasans (Zhang et al. 2013Fan et al. 2019), sesquiterpenoids (Zhang et al. 2014), diterpenoids (Kim et al. 2004), diterpenoid alkaloids (Wu et al. 2015), meroterpenoids  etc., many of which showed significant antiinflammatory, cytotoxic, cell-adhesion inhibitory, and antimicrobial activities. In our previous chemical investigation on Periconia sp. TJ403-rc01 (Dematiaceae), an endophytic fungus isolated from the leaves of Rosa chinensis Jacq. (Rosaceae), an architecturally intricate ergosterol bearing an unprecedented pentacyclo[8.7.0.0 1,5 .0 2,14 .0 10,15 ]heptadecane system, namely periconiastone A (Gao et al. 2019), was characterized and found to show significant antibacterial activity against Grampositive S. aureus and E. faecalis with MIC values of 4 and 32 lg/mL, respectively. To search for more new bioactive secondary metabolites, a continuing chemical investigation on the title strain was carried out, which led to the isolation of two new lanostane-type triterpenoids, pericinones A and B (1 and 2). Despite lanostane-type triterpenoids have been widely discovered from fungi (Khalilov et al. 2019;Satria et al. 2019;Chen et al. 2020;Quang et al. 2020;Jiang et al. 2021), it is the first report of lanostane-type triterpenoids from species of Periconia in our current work. Herein, we report the isolation, structure elucidation, and anti-inflammatory activity of new compounds 1 and 2 ( Figure 1).
Pericinone B (2), obtained as a white amorphous powder, had a molecular formula of C 32 H 50 O 4 , based on the HRESIMS data which showed a pseudomolecular ion peak at m/z 521.3592 [M þ Na] þ (calcd for C 32 H 50 O 4 Na þ , 521.3601). The IR spectrum of 2 ( Figure S20) showed absorptions of hydroxyl (3427 cm À1 ), ester carbonyl (1732 cm À1 ), keto carbonyl (1708 cm À1 ), and double bond (1651 cm À1 ) functionalities. Analysis of its 1 D NMR data (Table S1 and Figures S12 À S14) suggested that compound 2 was an analogue of 1, except for the presence of an ester carbonyl (d C 172.7) and a singlet methyl (d H 2.02; d C 21.6). Detailed analysis of its HMBC spectrum (Figures S1 and S17) revealed the correlations from H-12 (d H 5.33) and H 3 -32 (d H 2.02) to C-31 (d C 172.7), which indicated that the hydroxy group at C-12 in 1 was replaced by an acetyl group in 2. The similar NOESY data ( Figure S1) and shared biogenesis of 1 and 2 suggested that 2 possessed the same configuration as that of 1. Accordingly, the structure of pericinone B (2) was defined as 12b-acetyl-15a-hydroxy-3-oxo-lanosta-8,24-diene.
Compounds 1 and 2 were evaluated for anti-inflammatory activity against the nitric oxide (NO) production in LPS-induced RAW264.7 macrophages Li et al. 2018), and were found to show moderate anti-inflammatory activity with IC 50 values of 24.12 ± 0.73 and 11.38 ± 1.56 lM, respectively (positive control MG132: IC 50 ¼ 0.21 lM). An MTT assay was carried out to determine whether the suppressive effect was related to cell viability ), but no cytotoxicity (>20 lM) was detected in RAW264.7 macrophages, suggesting that the inhibitory activity against NO production in LPS-stimulated RAW264.7 cells did not involve general cytotoxicity.

General experimental procedures
Optical rotations, UV, CD, and IR data were collected from a PerkinElmer 341 polarimeter, a Varian Cary 50 instrument, a JASCO-810 CD spectrometer, and a Bruker Vertex 70 instrument, respectively. NMR experiments including 1 D ( 1 H, 13 C, and DEPT) and 2 D (HSQC, COSY, HMBC, and NOESY) NMR spectra were run on a Bruker AM-400 spectrometer, and the chemical shifts were determined with reference to the residual solvent peaks for CD 3 OD (d H 3.31 and d C 49.0) and CDCl 3 (d H 7.24 and d C 77.2). HRESIMS data were measured from a Bruker micrOTOF II spectrometer (Bruker Daltonic Inc., Karlsruhe, Germany). Semi-preparative HPLC was undertaken with an Agilent 1200 with dual pump and a DAD detector by using an RP-C 18 column (5 lm, 10 Â 250 mm, Welch Ultimate XB-C 18 ). Column chromatography (CC) was undertaken with ODS (50 lm, YMC, Kyoto, Japan), Sephadex LH-20 (GE Healthcare Bio-Sciences AB, Sweden), and silica gel (200-300 mesh, Qingdao Marine Chemical Inc., Qingdao, China). Thinlayer chromatography (TLC) was conducted on silica gel 60 F 254 (Yantai Chemical Industry Research Institute, Yantai, China).

Fungal material
Strain Periconia sp. TJ403-rc01 (Dematiaceae) was isolated from the fresh leaves of Rosa chinensis Jacq. (Rosaceae) collected from Wuhan city, Hubei Province, P. R. China, in April of 2018, and authenticated by one of the authors (J. Wang) based on sequencing of the ITS region (GenBank accession number MN307490). The fungal strain (No. GH403011) was deposited at the culture collection of College of pharmacy, Tongji Medical College, Huazhong University of Science and Technology.

Conclusions
In conclusion, a chemical investigation on fermented rice medium of an endophytic fungus Periconia sp. TJ403-rc01 (Dematiaceae) afforded two new lanostane-type triterpenoids, namely pericinones A and B (1 and 2). Notably, it is the first report of lanostane-type triterpenoids from Periconia sp. fungi. Moreover, all new compounds showed moderate anti-inflammatory activity against the NO production. These new findings improve phytochemical and pharmacological knowledge on the fungi of Periconia species.