Novel Zierane‐ and Guaiane‐Type Sesquiterpenes from the Root of Melicope denhamii

Two novel zierane‐type sesquiterpenes, named melicodenones A and B ( 1 and 2 , resp.), and three new guaiane‐type sesquiterpenes, named melicodenones C–E ( 3 – 5 ), were isolated from the root of Melicope denhamii (Seem. ) T. G. Hartley together with zierone ( 6 ). Their structures were established by extensive NMR‐spectroscopic analyses. Compounds 1 – 6 were tested for cytotoxicity using human colon cancer DLD‐1 cells, and melicodenone A ( 1 ) was found to exhibit moderate activity.     

Tirucallane Triterpenoids from the Stems of Brucea mollis

Three new tirucallane triterpenoids, brumollisols A–C ( 1 – 3 , resp.), together with five known analogues, (23R,24S)‐23,24,25‐trihydroxytirucall‐7‐ene‐3,6‐dione ( 4 ), piscidinol A ( 5 ), 24‐epipiscidinol A ( 6 ), 21α‐methylmelianodiol ( 7 ), and 21β‐methylmelianodiol ( 8 ), were isolated from an EtOH extract of the stems of Brucea mollis. Their structures were elucidated by means of spectroscopic methods including 1D‐ and 2D‐NMR techniques and mass spectrometry. In the in vitro assays, compound 6 exhibited significant cytotoxic activity against A549 and BGC‐823 cancer cells with IC₅₀ values of 1.16 and 3.01 μM , respectively. At a concentration of 10 μM , compounds 1 – 5, 7 , and 8 were found to inhibit NO production in mouse peritoneal macrophages with inhibitory ratios ranging from 39.8±7.7 to 68.2±4.5%.     

Novel Indole Alkaloids from Nauclea latifolia and Their Renin‐Inhibitory Activities

Chemical studies on the crude MeOH extract of stems and barks of Nauclea latifolia resulted in the isolation of five new indole alkaloids, latifoliamides A–E ( 1 – 5 , resp.), along with one known alkaloid, angustoline ( 6 ). The structures of these compounds were elucidated by means of extensive NMR spectral studies. Compound 1 has a 20‐ethylidenetetrahydrofuran ring incorporated in its structure and represents the first example of this class of indole alkaloids. All of the isolates exhibited moderate in vitro renin inhibitory activities.     

Antibacterial Δ1‐3‐Ketosteroids from the South China Sea Gorgonian Coral Subergorgia rubra

Three new Δ¹‐3‐ketosteroids characterized with a 9‐OH, subergosterones A–C ( 1 – 3 ), together with five known analogs 4 – 8 , were obtained from the gorgonian coral Subergorgia rubra collected from the South China Sea. The structures of 1 – 3 , including their absolute configurations, were determined by comprehensive spectroscopic methods and electronic circular dichroism (ECD) experiments. Compounds 2 and 3 exhibited inhibitory antibacterial activities against Bacillus cereus with MIC values of 1.56 μM .     

Three New Phenylpropanoids from the Roots of Piper taiwanense and Their Inhibitory Activities on Platelet Aggregation and Mycobacterium tuberculosis

Bioassay‐guided fractionation of the active AcOEt‐soluble fraction from the roots of Piper taiwanense has led to the isolation of two new phenylpropanoids, taiwanensols A and B ( 1 and 2 , resp.), a new natural product, taiwanensol C ( 3 ), and 3‐acetoxy‐4‐hydroxy‐1‐allylbenzene ( 4 ). The compounds were obtained as two isomer mixtures ( 1 / 2 and 3 / 4 , resp.). Their structures were elucidated by spectroscopic analyses, including 1D‐ and 2D‐NMR spectroscopy and mass spectrometry, and by the comparison of their NMR data with those of related compounds. Compounds 1 – 4 were evaluated for their antiplatelet and antitubercular activities. The mixtures 1 / 2 and 3 / 4 showed potent inhibitory activities against platelet aggregation induced by collagen, with IC₅₀ values of 35.2 and 8.8 μM , respectively. In addition, 1 / 2 and 3 / 4 showed antitubercular activities against Mycobacterium tuberculosis H37Rv, with MIC values of 30.0 and 48.0 μg/ml, respectively.     

New 3,4‐Secocycloartane and 3,4‐Secodammarane Triterpenes from the Ecuadorian Plant Coussarea macrophylla

Coussarea macrophylla (Mart .) Müll.Arg . (Rubiaceae) was collected in Ecuador, and the bark was extracted with AcOEt. Chromatographic separation afforded six novel 3,4‐secocycloartane and 3,4‐secodammarane triterpenes, named macrocoussaric acids A–F, together with the known metabolites secaubryenol and 3,4‐secodammara‐4(28),20,24‐triene‐3,26‐dioic acid. The structures of the new compounds were determined on the basis of their spectroscopic data. This is the first report of 3,4‐secocycloartane and 3,4‐secodammarane triterpenes occurring in a Coussarea species. Macrocoussaric acids A and B ( 2 and 3 , resp.) were found to be moderately cytotoxic against five different tumor cell lines.     

Variation of Epimedins A – C and Icariin in Ten Representative Populations of Epimedium brevicornu Maxim., and Implications for Utilization

The concentration variations of main flavonoids, epimedins A–C and icariin, among ten representative populations of Epimedium brevicornu Maxim . were assessed by HPLC. The populations were collected during the flowering stage and included 419 individual samples. Remarkable variations within and among populations were detected. SXXA Population (see Fig. 1) was an outlier due to its significant low concentrations (<1.00–4.46 mg/g). But even without SXXA, significant concentration differences among populations were still observed in epimedin A (2.31–8.42 mg/g), epimedin B (6.67–55.7 mg/g), epimedin C (5.39–23.0 mg/g), icariin (8.50–39.9 mg/g), and their total (29.1–123 mg/g). All populations except SXXA showed much higher concentrations than the recommended standards (i.e. 5 mg/g for icariin and 13 mg/g for the total). A high‐concentration‐population structure, estimated both by principal component analysis (PCA) and unweighted pair group method with averaging (UPGMA) cluster analysis, based on Euclidean distances, was observed. Both methods allowed separation of the populations in four groups defined by the concentrations of four main flavonoids. The populations (SXLC and SXQS) located in north of Yellow River were clustered together and characterized by highest concentrations of epimedin B, icariin, and their total. Considering of the high concentrations of main flavonoids and abundant resources, E. brevicornu could be exploited as a good medical resource for Herba Epimedii and would offer a tremendous potential for commercial development, but SXXA population should be paid special attention, and further study is needed.     

Pierisformotoxins A – D,Polyesterified Grayanane Diterpenoids from Pieris formosa and Their cAMP‐Decreasing Activities

Four highly acylated diterpenoids, designated as pierisformotoxins A–D ( 1 – 4 , resp.), along with 26 known compounds, were isolated from the flowers of Pieris formosa. Among them, pierisformotoxins A and B ( 1 and 2 , resp.) were new highly acylated grayanane diterpenoids, of which the five‐membered ring A has undergone an oxidative cleavage between C(3) and C(4), followed by lactonization, to give rise to a five‐membered lactone ring between C(3) and C(5), differing from the previously reported grayanane diterpenoids with a 5/7/6/5 ring system. Results of the cAMP‐regulation‐activity assay showed that pierisformotoxin C ( 3 ) at 10 μM (inhibitory ratio (IR): 10.1%) or 2 μM (9.8%), and pierisformotoxin B ( 2 ) at 50 μM (13.9%) significantly decreased the cAMP level in N1E‐115 neuroblastoma cells (p<0.05).     

A New Cytotoxic Carbazole Alkaloid and Two New Other Alkaloids from Clausena excavata

One new carbazole alkaloid, excavatine A ( 1 ), and two additional new alkaloids, excavatine B ( 2 ) and excavatine C ( 3 ), were isolated from the stems and leaves of Clausena excavata Burm .f. (Rutaceae). Their structures were determined on the basis of detailed spectroscopic analyses, especially 2D‐NMR and HR‐EI‐MS data. Compounds 1 – 3 were tested for their cytotoxic activities against A549, HeLa, and BGC‐823 cancer cell lines, and for their antimicrobial activities against Candida albicans and Staphylococcus aureus. Only 1 exhibited cytotoxicity against A549 and HeLa cell lines with the IC₅₀ values of 5.25 and 1.91 μg/ml, respectively.     

Melanogenesis‐Inhibitory Saccharide Fatty Acid Esters and Other Constituents of the Fruits of Morinda citrifolia (Noni)

Five new saccharide fatty acid esters, named nonioside P ( 3 ), nonioside Q ( 4 ), nonioside R ( 8 ), nonioside S ( 10 ), and nonioside T ( 14 ), and one new succinic acid ester, butyl 2‐hydroxysuccinate (=4‐butoxy‐3‐hydroxy‐4‐oxobutanoic acid) ( 31 ), were isolated, along with 26 known compounds, including eight saccharide fatty acid esters, 1, 2, 5, 6, 7, 9, 12 , and 13 , three hemiterpene glycosides, 15, 17 , and 18 , six iridoid glycosides, 21 – 25 , and 27 , and nine other compounds, 20, 28, 29 , and 32 – 37 , from a MeOH extract of the fruit of Morinda citrifolia (noni). Upon evaluation of these and five other glycosidic compounds, 11, 16, 19, 26 , and 30 , from M. citrifolia fruit extract for their inhibitory activities against melanogenesis in B16 melanoma cells induced with α‐melanocyte‐stimulating hormone (α‐MSH), most of the saccharide fatty acid esters, hemiterpene glycosides, and iridoid glycosides showed inhibitory effects with no or almost no toxicity to the cells. These compounds were further evaluated with respect to their cytotoxic activities against two human cancer cell lines (HL‐60 and AZ521) and their inhibitory effects on Epstein? Barr virus early antigen (EBV‐EA) activation induced with 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA) in Raji cells.     

Four New Flavonoids with α‐Glucosidase Inhibitory Activities from Morus alba var. tatarica

Four new flavonoids, mortatarins A–D ( 1 – 4 , resp.), along with eight known flavonoids ( 5 – 12 ) were isolated from the root bark of Morus alba var. tatarica. Their structures were established on the basis of spectroscopic data analysis, and the absolute configuration of 4 was determined by analysis of its CD spectrum. All isolates were tested for inhibitory activities against α‐glucosidase. Compounds 4, 7 , and 8 exhibited a significant degree of inhibition with IC₅₀ values of 5.0±0.3, 7.5±0.5, and 5.9±0.2 μM , respectively.     

A New Long‐Chain Alkene and Antituberculosis Constituents from the Leaves of Pourthiaea lucida

A new long‐chain alkene, dotriacont‐1‐ene ( 1 ), was isolated from the leaves of Pourthiaea lucida, together with twelve known compounds. The structure of this new compound was determined by NMR and mass‐spectrometric analyses. Among the isolated compounds, α‐tocospiro A ( 2 ), α‐tocopheryl quinone ( 4 ), and (E)‐phytol ( 5 ) exhibited antituberculosis activities (MICs ≤30 μg/ml) against Mycobacterium tuberculosis H₃₇Rv in vitro.     

Triterpene Saponins from the Roots of Ilex asprella

Six new triterpene saponins, ilexasprellanosides A–F ( 1 – 6 , resp.), together with eleven known compounds were isolated from the roots of Ilex asprella. The new saponins were characterized as ursa‐12,18‐dien‐28‐oic acid 3‐O‐β‐D ‐xylopyranoside ( 1 ), 19α‐hydroxyursolic acid 3‐O‐β‐D ‐(2′‐O‐acetylxylopyranoside) ( 2 ), 19α‐hydroxyursolic acid 3‐O‐β‐D ‐glucuronopyranoside ( 3 ), 3β,19α‐dihydroxyolean‐12‐en‐23,28‐dioic acid 28‐O‐β‐D ‐glucopyranoside ( 4 ), 19α‐hydroxyoleanolic acid 3‐O‐β‐D ‐(2′‐O‐acetylxylopyranoside) ( 5 ), 19α‐hydroxyoleanolic acid 3‐O‐β‐D ‐glucuronopyranoside ( 6 ). The structures of the new compounds were elucidated by analysis of their spectroscopic data and chemical degradation. Compounds 2, 4 , oleanolic acid 3‐O‐β‐D ‐glucuronopyranoside, 3‐β‐acetoxy‐28‐hydroxyurs‐12‐ene, and pomolic acid showed significant cytotoxic activities against human tumor cell line A549 (IC₅₀ values of 1.87, 2.51, 1.41, 3.24, and 5.63 μM , resp.).     

New Labdane Diterpenes and Their Glycoside Derivatives from the Roots of Isodon adenantha

Two new labdane‐type diterpenes (adenanthic acids A and B; 1 and 2 , resp.) and three new labdane diterpene glycosides (adenanthosides A–C; 3 – 5 , resp.) were isolated from the roots of Isodon adenantha, together with 23 known constituents including seven diterpenoids ( 6 – 12 ), eight triterpenoids ( 13 – 20 ), one lignan glycoside ( 21 ), six steroids ( 22 – 27 ), and one ceramide ( 28 ). Their structures were elucidated by spectroscopic methods including extensive 2D‐NMR techniques. Cytotoxicity and antibacterial activities of the samples were measured by the MTT method and the filter paper disc agar diffusion method. But none of them showed significant activities.     

Sinuladiterpenes A–F,New Cembrane Diterpenes from Sinularia flexibilis

Chromatographic investigation of the octocoral Sinularia flexibilis afforded six new cembrane diterpenes, sinuladiterpenes A–F ( 1 – 6 , resp.), in addition to four known cembranolides, 11‐episinulariolide acetate, 11 ‐ dehydrosinulariolide, 11‐episinulariolide, and sinulariolide. Their structures were elucidated by spectroscopic analysis, especially 2D‐NMR and HR‐ESI‐MS. Compound 2 exhibited significant in vitro cytotoxic activity against human colon adenocarcinoma (WiDr) cell line.     

Cytotoxic ent‐Kaurane Diterpenoids from Isodon nervosus

Four new ent‐kaurane diterpenoids, rabdonervosins G–J ( 1 – 4 , resp.), were isolated from the leaves and stems of Isodon nervosus. Their structures were elucidated by extensive spectroscopic analyses, including 1D‐, 2D‐NMR and HR mass spectra. Compound 2 showed potent cytotoxicity against the HepG2 and PC‐9/ZD cell lines with IC₅₀ values of 2.36 and 6.07 μM , respectively, and compound 3 exhibited cytotoxicity against the HepG2 and CNE2 cell lines with IC₅₀ values of 8.64 and 9.77 μM , respectively.     

Identification and Antifeedant Activities of Limonoids from Azadirachta indica

Four new limonoids, azadiraindins A–D ( 1 – 4 , resp.), together with seven known analogs, were isolated from the MeOH extract of Azadirachta indica. The structures of 1 – 4 were elucidated by NMR and MS spectroscopic analyses, and the relative configuration of 1 was determined by single‐crystal X‐ray crystallography. The compounds isolated in comparatively large amount were evaluated for their antifeedant activities against Plutella xylostella; the antifeedant rate of 10 was 90.6% and the corrected mortality of 8 was 79.2%.     

Drimane Sesquiterpenoids from the Aspergillus oryzae QXPC‐4

Three new drimane sesquiterpenoids, astellolides C–E ( 1 – 3 , resp.), four new drimane sesquiterpenoid p‐hydroxybenzoates, astellolides F–I ( 4 – 7 , resp.), together with two known compounds astellolides A and B ( 8 and 9 , resp.), have been isolated from the liquid culture of Aspergillus oryzae (strain No. QXPC‐4). Their structures were established by comprehensive analysis of spectroscopic data. The relative and absolute configurations were determined on the basis of NOESY and CD data, together with single‐crystal X‐ray diffraction analyses of compounds 1 – 3 . The metabolites were evaluated for their cytotoxic activities, however, no compounds showed a significant cytotoxicity against the tested cell lines at a concentration of 20 μM .