Xiao-Bao Li

New clerodane diterpenoids from the roots of Polyalthia laui.

Five new clerodane diterpenoids, polylauiester A (1), (4→2)-abeo-2,13-diformyl-cleroda-2,12E-dien-14-oic acid (2) and polylauiamides B-D (3-5), together with 11 known clerodane diterpenoids (6-16), were isolated from the roots of Polyalthia laui. Among them, polylauiester A (1) represents the first example of a novel norclerodane diterpenoid only containing 17 carbon atoms on the carbon skeleton, and polylauiamide B (3) is an unusual diterpenoid with a p-substituted benzene ring as a substituent. Their structures were elucidated by extensive spectroscopic methods, and the relative configuration of polylauiamide B (3) was further confirmed by the single crystal X-ray diffraction method. Biological evaluation of new compounds against human Hela, MCF-7 and A549 human cancer cell lines showed that all compounds displayed weak cytotoxicities against various human cancer cell lines in the range of IC50 at 25.01-39.31μM.

Two New Lanostane Triterpenoids from the Branches and Leaves of Polyalthia oblique

Two new lanostane triterpenoids, 20-hydroxyeuphorbol-7-one (1) and 15α-hydroxyeuphorbol-7,11-dione (2), together with four known triterpenoids, euphorbol-7-one (3), friedelin (4), stigmast-4-ene-6α-ol-3-one (5), stigmasta-4-en-3,6-dione (6), were isolated from ethanol extract of the branches and leaves of Polyalthia obliqua. The structures of 1 and 2 were elucidated on the basis of extensive spectroscopic analysis and comparisons with related known compounds. Antibacterial activities of two new compounds and four known compounds were tested.

A new biphenyl derivative from the mangrove endophytic fungus Phomopsis longicolla HL-2232

Abstract A new biphenyl derivative 5,5′-dimethoxybiphenyl-2,2′-diol (1), together with five known compounds (2–5), was isolated from the mangrove endophytic fungus Phomopsis longicolla HL-2232. The structures of these compounds were elucidated using comprehensive spectroscopic methods. The absolute configuration of 4 was determined by single-crystal X-ray diffraction for the first time. The inhibitory activities of all compounds against two Vibrio bacteria were evaluated.

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).

New phenylpropanoid and 6H-dibenzo[ b , d ]pyran-6-one derivatives from the stems of Dasymaschalon rostratum

Three new phenylpropanoid derivatives, dasymaroacid A (1), dasymaroesters B and C (2 and 3), and one new polyoxygenated 6H-dibenzo[b,d]pyran-6-one derivative dasymarolactone D (4), together with seven known compounds (5-11), were isolated from the stems of Dasymaschalon rostratum Merr. Compounds 1 and 2 are unusual phenylpropanoid derivatives with a polymethyl substituted cyclopentene conjugated diketone as a substituent, and 3 is a unique cinnamic acid detective with a polymethyl substituted cyclohexene conjugated triketone as a substituent. Their structures were elucidated by extensive spectroscopic methods and chemical method, and 4 was further confirmed by the single crystal X-ray diffraction method. Compounds 1-4 and 7 showed weak anti-HIV-1 activities with EC50 values ranged from 16.44 to 25.91μM.

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.

A new12-membered lactone from the stems of Ficus auriculata

Abstract A new lactone ficusine D (1), together with six known compounds (2–7) were isolated from the stems of the Ficus auriculata. The new compound 1 was a rare 12-membered lactone containing a quinone ring skeleton. The structure of the 1 was elucidated by comprehensive spectroscopic data. The relative and absolute configurations of 1 were elucidated by the ROESY analysis and biogenesis pathway. All compounds were evaluated for their antibacterial activities against six pathogenic bacteria in vitro. Compounds 6 and 7 exhibited potent antibacterial activities against Bacillus cereus with the MIC values of 2.5 and 5 μM, respectively.

A new norsesquiterpene from the roots of Polyalthia laui

Abstract One new norsesquiterpene polyalone A (1), and one new natural product 9-keto-cyclocolorenone (2), along with three known analogues (3–5) were isolated from the roots of Polyalthia laui. Their structures were elucidated by the detailed analysis of comprehensive spectroscopic data. All compounds were evaluated for their cytotoxic activities and antibacterial activities.