Meng Bai

Dihydroisocoumarins from the Mangrove-Derived Fungus Penicillium citrinum

Three new dihydroisocoumarin penicimarins G–I (1–3), together with one known dihydroisocoumarin (4) and three known meroterpenoids (5–7), were obtained from a fungus Penicillium citrinum isolated from the mangrove Bruguiera sexangula var. rhynchopetala collected in the South China Sea. Their structures were elucidated by the detailed analysis of spectroscopic data. The absolute configuration of 1 was determined by the X-ray diffraction analysis using Cu Kα radiation. The absolute configurations of 2 and 3 were determined by comparison of their circular dichroism (CD) spectra with the literature. All compounds were evaluated for their antibacterial activities and cytotoxic activities.

Penicilindoles A–C, Cytotoxic Indole Diterpenes from the Mangrove-Derived Fungus Eupenicillium sp. HJ002

Three new indole diterpenes, penicilindoles A-C (1-3), were isolated from the mangrove-derived fungus Eupenicillium sp. HJ002. Their planar structures and absolute configurations were determined by interpretation of NMR spectroscopic data, HR-ESIMS, and X-ray diffraction analysis using Cu Kα radiation. The cytotoxic and antibacterial activities were evaluated in vitro; penicilindole A (1) showed cytotoxic activity against human A549 and HepG2 cell lines with IC50 values of 5.5 and 1.5 μM, respectively.

Cytotoxic Constituents of the Twigs of Homalium stenophyllum

The family Flacourtiaceae consists of ca. 1000 species distributed between 93–100 genera. Homalium is one of the largest genera with 200 species. There is scant chemical information on the family and still less for the genus. In fact, less than 10 species of this genus have been reported in the chemical literature [1]. Homalium stenophyllum Merr. et Chun is an understorey tree about 40 m high and widely distributed in the rainforest of the temperate and subtropical regions [2]. H. stenophyllum is a unique local medicinal plant with its roots and leaves used as traditional folk medicine in Hainan [3]. The chemical constituents of the genus consist of alkaloids, glycosides, triterpenes, coumarin, etc. [4–8]. These constituents showed various biological activities, such as antivirus, antidiabetes, and other pharmacological activities [9, 10]. In the course of our previous investigation on bioactive chemical constituents from the crude extracts of medicinal plants growing in Hainan Province of China, it was found that the extract of H. paniculiflorum exhibited good biological activity [11]. The chemical constituents and biological activity of H. stenophyllum have not been studied. Investigation of the EtOAc extract led to the isolation of 11 compounds. The structures of these compounds were determined on the basis of their 1H NMR, 13C NMR, and ESI-MS spectroscopic data, and by comparison with those previously reported in the literature, as compounds (1–11): (+)-syringaresinol (1) [12], itosid P (2) [13], quercetin (3) [14], kaempferol (4) [15], rutin (5) [16], daidzein (6) [17], 2,3-dihydroxy-1-(4-hydroxy-3,5-dimethoxyphenyl)propan-1-one (7) [18], 3-(phenyl)isocoumarin (8) [19], 3-(3 -methylphenyl)isocoumarin (9) [19], trans-p-hydroxycinnamic acid (10) [20], and trans-ferulic acid (11) [21]. In this study, all the compounds were isolated from the H. stenophyllum for the first time. The cytotoxic activity of all the isolated compounds was also evaluated against two human cancer cell lines, including Hela and A549 cell lines (Table 1). The results indicated that phenolic acids 7, 10, and 11 showed strong cytotoxic activity against HeLa and A549 cell lines. The flavonoids 3–6, phenolic glycoside 2, and isocoumarins 8 and 9 did not show any cytotoxic activity against the two human cancer cell lines. General Experimental Procedures. 1D NMR spectra was obtained on a Bruker DRX-400 with TMS as the internal standard. HPLC was performed on an Agilent 1200LC. An Agilent C18 preparative HPLC column (XDB–C18, 5 m) was used. Silica gel (Qingdao Haiyang Chemical Group Co.; 300–400 mesh), octadecylsilyl silica gel (Unicorn; 45–60 m), and Sephadex LH-20 (Amersham Biosciences) were used for column chromatography. Precoated silica gel plates (Yan Tai Zi Fu Chemical Group Co.; G60, F-254) were used for thin-layer chromatography. Plant Material. The twigs of H. stenophyllum Merr. et Chun were collected from Bawangling National Forest of Changjiang County, Hainan Island, People s Republic of China, in May 2013 and authenticated by Prof. Qiong-xin Zhong (College of Life Science, Hainan Normal University). A voucher specimen (No. hsm201305) was deposited in the Key Laboratory of Tropical Medicinal Plant Chemistry of the Ministry of Education. Extraction and Isolation of Compounds. Air-dried powder of H. stenophyllum twigs (13.75 kg) was percolated three times with 80% EtOH to give a crude extract (1.12 kg). The extract was suspended in 2.0 L of water and then partitioned with petroleum ether and EtOAc successively. Then the EtOAc-soluble fraction was concentrated to give the EtOAc extract (116 g). It was further purified by column chromatography on silica gel and Sephadex LH-20, by precoated silica gel plates, and by preparative HPLC to yield compounds 1 (80.9 mg), 2 (64.2 mg), 3 (11.7 mg), 4 (9.1 mg), 5 (2.2 mg), 6 (8.1 mg), 7 (3.9 mg), 8 (4.0 mg), 9 (3.2 mg), 10 (6.0 mg), and 11 (11.9 mg).

A new dihydrochalcone glycoside from the stems of Homalium stenophyllum

Abstract A new dihydrochalcone glycoside, phloretin-4-O-β-D-glucopyranoside (1), together with seven known flavonoids (2–8), were isolated from the stems of Homalium stenophyllum. The structure of 1 was elucidated by extensive spectroscopic methods and the known compounds were identified by comparisons with data reported in the literature. The known compounds (2–8) were isolated from the genus Homalium for the first time. All compounds were evaluated for their antibacterial activities against six pathogenic bacteria in vitro.

Bioactive Phenolic and Isocoumarin Glycosides from the Stems of Homalium paniculiflorum

Two new phenolic glycosides (1 and 2) and two new isocoumarin glycosides (3 and 4), along with 14 known compounds (5–18), were isolated from the stems of Homalium paniculiflorum. Their structures were established on the basis of extensive spectroscopic analyses and chemical methods. All new compounds were evaluated for their anti-inflammatory activities via examining the inhibitory activity on nitric oxide (NO) production induced by lipopolysaccharide (LPS) in mouse macrophage RAW 264.7 cells in vitro. Compounds 1 and 4 exhibited inhibitory activities with IC50 values of 30.23 ± 1.23 μM and 19.36 ± 0.19 μM, respectively.

One new berberine from the branches and leaves of Polyalthia obliqua Hook.f. & Thomson

Abstract One new alkaloid consanguine B (1), together with 10 known alkaloids (2–11), were isolated from ethanol extract of the branches and leaves of Polyalthia obliqua Hook.f. & Thomson collected in the Hainan Province, China. Their structures were elucidated by the detailed analysis of comprehensive spectroscopic data. All compounds were evaluated for their cytotoxic activities. Compound 1 showed weak cytotoxic activities against Hela and MCF-7 human cancer cell lines.

Biologically active oligostilbenes from the stems of Vatica mangachapoi and chemotaxonomic significance

Abstract Phytochemical investigation of the stems of Vatica mangachapoi (Dipterocarpaceae) led to the isolation and structural elucidation of twenty-seven oligostilbenes (1–27), including a new natural compound 1. The structure of 1 was elucidated on the basis of spectroscopic analyses including NMR, MS and ECD data, and the known compounds were identified by comparisons with those reported in the literature. The absolute configuration of 1 was first time determined by a combination of NOESY spectrum and quantum chemical computation. Among of isolates were tested for their anti-osteoporosis and anti-HIV-1 activities in vitro by the MTT method. Moreover, the chemotaxonomic significance of these compounds was summarised.

A new norisoprenoid from the leaves of Ficus pumila

Abstract One new norisoprenoid 3,9-dihydroxy dihydro actinidiolide (1), together with eleven known compounds (2–12), were isolated from ethanol extract of the leaves of Ficus pumila collected in Hainan Province, China. Their structures were elucidated by the detailed analysis of comprehensive spectroscopic data. Compounds 1, 2, 4, 5, 8 and 10–12 were isolated from the F. pumila for the first time. All compounds were evaluated for their cytotoxic activity. Compounds 3 and 9 showed weak cytotoxic activity against Hela, MCF-7 and A549 cell lines.

One new cytochalasin metabolite isolated from a mangrove-derived fungus Daldinia eschscholtzii HJ001

Abstract One new cytochalasin metabolite [11]-cytochalasa-5(6),13-diene-1,21-dione-7,18-dihydroxy-16,18-dimethyl-10-phenyl-(7S*,13E,16S*,18R*) (1), together with three known compounds (2–4) were obtained from the EtOAc extract of the endophytic fungus Daldinia eschscholtzii HJ001 isolated from the mangrove Brguiera sexangula var. rhynchopetala collected in the South China Sea. Their structures were elucidated by the detailed analysis of comprehensive spectroscopic data. Compounds 1 and 2 were evaluated for their antibacterial and cytotoxic activities.

Bioactive Flavonoid Derivatives from Scutellaria luzonica

Scutellaria is one of the most widely used traditional Chinese herbal medicines, and the other name is “HuangQin” in Chinese [1]. Its root is the traditional medicinal part and has been listed in the Chinese Pharmacopoeia for a long time [2]. The aerial parts of Scutellaria also have diverse and strong therapeutic functions and potentially beneficial effects, such as cardiovascular [3], neuroprotective [4], antitubercular [5], memory improving [6], antitumor [7], and antibacterial activity [8]. There have been previous investigations on the chemical constituents of the roots of Scutellaria luzonica Rolfe, and 18 flavonoids, including 13 flavones, two flavanones, one chalcone, and one flavone glycoside, were isolated from this plant [9]. However, Scutellaria luzonica is a variant of Scutellaria luzonica, and the chemical constituents and bioactivities of S. luzonica have not been reported. In order to search for the bioactive chemical constituents of S. luzonica, 14 flavonoid derivatives were isolated from the EtOAc extract of S. luzonica. The isolated compounds were identified as 5-hydroxy-7-methoxyflavanone (1) [10], 6-methoxynaringenin (2) [11], 5,6,7,4 -tetrahydroxyflavanone (3) [12], 5,7,2 -trihydroxyflavone (4) [13], 5,7-dihydroxyflavone (5) [14], hispidulin (6) [15], 5,7,8-trihydroxyl-6-methoxyflavone (7) [16], wogonin (8) [17], 5,6-dihydroxy-7-methoxyflavone (9) [18], 5,7,3 ,4 -tetrahydroxyflavone (10) [19], baicalein (11) [20], oroxylin A (12) [21], 5,8-dihydroxy-7-methoxyflavone (13) [22], and 5,7,2 -trihydroxy-8-methoxyflavone (14) [23], on the basis of their spectroscopic data and by comparison with those previously reported in the literature. All compounds were isolated from S. luzonica for the first time. The biological activity of all the isolated compounds was evaluated against seven pathogenic bacteria, including Candida albicans, Staphylococcus aureus, Bacillus cereus, Bacillus subtilis, Escherichia coli, Vibrio parahaemolyticus and V. alginolyticus; Antimosquito larva activity was also tested. Compounds 8 and 11 showed significant antibacterial activity against C. albicans with the same MIC values of 4.17 g/mL. Compounds 8, 10, and 11 showed strong antibacterial activity against V. parahaemolyticus with the same MIC values of 3.12 g/mL. Compounds 8, 11, and 12 showed significant antibacterial activity against V. alginolyticus with the same MIC values of 6.25 g/mL. The other compounds showed weak or no antibacterial activity with MIC values greater than 10 g/mL (Table 1). Compounds 5, 12 and 14 showed Antimosquito larva activity with LC50 values of 50, 30, and 100 g/mL, respectively. General. 1D (1H, 13C, DEPT) and 2D (1H–1H COSY, NOESY, HMQC, HMBC) NMR spectra were recorded on a Bruker AV 400 NMR spectrometer. ESI-MS spectra were recorded on an Agilent 1200 series HPLC interfaced to a Bruker Esquire 6000 Ion Trap mass spectrometer equipped with an electrospray ionization source. HPLC separation was performed on an Agilent-HPLC column (Eclipse XDB-C18, 10 250 mm, 5 m). Silica gel and GF254 were obtained from the Qingdao Marine Chemical Factory. Sephadex LH-20 was manufactured by Pharmacia Co. Ltd. Plant Material. The dried whole plants of Scutellaria luzonica Rolfe were collected in Ledong County, Hainan Province, China, in September 2014 and were identified by Dr. Rongtao Li, Hainan Branch of the Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College. A voucher specimen has been deposited in the Key Laboratory of Tropical Medicinal Plant Chemistry of the Ministry of Education, Hainan Normal University. Extraction and Isolation. The dried whole plants of Scutellaria luzonica (2 kg) were powdered and refluxed with 85% EtOH three times. Evaporation of the solvent under reduced pressure gave the ethanolic extract (55 g), which was dissolved in water and then extracted with petroleum ether and ethyl acetate successively at room temperature.