New Limonoids from the Seeds of Xylocarpus granatum

Three novel limonoids, 2,3‐dideacetylxyloccensin S ( 1 ), 30‐deacetylxyloccensin W ( 2 ), and 7‐hydroxy‐21β‐methoxy‐3‐oxo‐24,25,26,27‐tetranortirucalla‐1,14‐diene‐23(21)‐lactone ( 3 ), were isolated from the seeds of the Chinese mangrove, Xylocarpus granatum. The structures were elucidated on the basis of 1D‐ and 2D‐NMR (including ¹H‐ and ¹³C‐NMR, DEPT, ¹H,¹H‐COSY, HSQC, HMBC, and NOESY) data and confirmed by HR‐MS.     

Antimalarial activity in Xylocarpus granatum (Koen)

The antimalarial activity of Xylocarpus granatum fruits and their active constituents gedunin and xyloccensin-I were investigated using an in?vitro model in this study. The chloroform fraction of X. granatum fruits was found to show promising antimalarial activity using an in?vitro model of Plasmodium falciparum. On purification of the active fraction, four pure compounds were isolated and characterised, namely gedunin, photogedunin, xyloccensin-I and palmitic acid. Out of these only gedunin and xyloccensin-I were found to show activity equivalent to the parent active fraction in?vitro model.     

Andhraxylocarpins A–E: Structurally Intriguing Limonoids from the True Mangroves Xylocarpus granatum and Xylocarpus moluccensis

Five new limonoids, including andhraxylocarpins A and B ( 1 and 2 ) which contain a 9‐oxa‐tricyclo[3.3.2.1^{7, 10}]undecane‐2‐ene motif, andhraxylocarpins C and D ( 3 and 4 ), which contain a (Z)‐bicyclo[5.2.1]dec‐3‐en‐8‐one substructure, and andhraxylocarpin E ( 5 ), which contains a tricyclo[3.3.1.1^{3, 6}]decane‐9‐one scaffold, were isolated from the seeds of two true mangroves, Xylocarpus granatum and Xylocarpus moluccensis, that were collected in the estuaries of Andhra Pradesh, India. The absolute configurations of these compounds were determined by extensive NMR investigations, single‐crystal X‐ray diffraction analysis, and by circular dichroism and optical rotatory dispersion spectroscopy, in combination with quantum‐chemical calculations. The pronounced structural diversity of limonoids from these mangroves might originate from environmental factors.     

Xyloccensins O and P, unique 8,9,30-phragmalin ortho esters from Xylocarpus granatum

Two unique 8,9,30-phragmalin ortho esters, xyloccensins O (1) and P (2), were isolated from the mangrove plant Xylocarpus granatum. They are a new type of ortho ester of phragmalin. The structures were determined by spectroscopic and single-crystal X-ray diffraction techniques. The biogenetic pathway to these new phragmalins was also proposed. [structure: see text]     

Structure elucidation of an unprecedented alkaloid and a new limonoid from Xylocarpus granatum

An unprecedented new limonoid-based alkaloid, granatoine (1), and a new phragmalin, xylocarpin L (2), along with xyloccensin Y were isolated as minor components from the fruits of the Chinese mangrove plant Xylocarpus granatum. Their structures were elucidated by extensive spectroscopic data (1D and 2D NMR) analysis. A possible biogenetic pathway for granatoine was also depicted.     

Xylogranatins A-D, new mexicanolides from the fruit of a Chinese mangrove Xylocarpus granatum

Four new mexicanolides with a Delta(14,15) double bond, named xylogranatins A and D (1-4), were isolated from the fruit of a Chinese mangrove Xylocarpus granatum, together with two known 8,9,30-phragmalin ortho esters, xyloccensins P and Q. Their structures were elucidated on the basis of spectroscopic data, especially 2D NMR techniques including HSQC, HMBC and NOESY.     

Xylogranatins A-D: novel tetranortriterpenoids with an unusual 9,10-seco scaffold from marine mangrove Xylocarpus granatum

[reaction: see text] Four novel tetranortriterpenoids, xylogranatins A-D (1-4), with an unusual 9,10-seco skeleton were isolated from the seeds of a Chinese marine mangrove Xylocarpus granatum. Their structures were determined by spectroscopic and chemical means. Xylogranatin A (1) featured by a unique 1,9-oxygen bridge was confirmed by single-crystal X-ray diffraction, and xylogranatin D (4) with an unprecedented skeleton of C-30-C-9 linkage was postulated biogenetically from 3 via an alpha-hydroxyl ketone rearrangement and was chemically mimicked.     

Two new diterpenoids from the endophytic fungus Trichoderma sp. Xy24 isolated from mangrove plant Xylocarpus granatum

Two new harziane diterpenoids, named(9R,10R)-dihydro-harzianone(1) and harzianelactone(2), were isolated from the endophytic fungus Trichoderma sp. Xy24 by using various column chromatography techniques. Their structures were determined on the basis of extensive spectroscopic(HR-ESI-MS, 1D NMR, 2D NMR and CD) analyses. Among them, 1 was the reductive product of harzianone and 2 was the Baeyer–Villiger monooxygenase catalyzed oxidation product of harzianone. Compound 1 exhibited cytotoxic activity against He La and MCF-7 cell lines with IC_(50) values of 30.1 μmol/L and 30.7 μmol/L,respectively.     

Xylogranatins F-R: antifeedants from the Chinese mangrove, Xylocarpus granatum, a new biogenetic pathway to tetranortriterpenoids

Thirteen limonoids with a new carbon skeleton, the xylogranatins F-R (1-13), have been isolated from the seeds of a Chinese mangrove, Xylocarpus granatum; two recently reported compounds, xylogranatins C and D were also isolated. Their structures were elucidated on the basis of spectroscopic data and chemical methods. The absolute configurations of these compounds were determined by using the modified Mosher MTPA ester method and by quantum chemical circular dichroism (CD) calculations. Xylogranatins F-Q are the first aromatic B-ring limonoids found in nature. They belong to two substructural classes, of which one (1-3) contains a pyridine ring while the other one (4-12) contains a central furan core. Xylogranatins C and R can be considered to be key biosynthetic intermediates, while xylogranatin D, the only limonoid found so far with a carbon skeleton that conatains a C(30)-C(9) linkage, is apparently an artifact. The structures of these compounds suggest a new biogenetic pathway to tetranortriterpenoids. Xylogranatins F, G and R were found to exhibit marked antifeedant activity against the third instar larvae of Mythimna separata (Walker) at a concentration of 1 mg mL(-1). The most potent compound tested was xylogranatin G. Its AFC(50) (concentration for 50 % antifeedant activity) values at the exposure times of 24 and 48 h were 0.31 and 0.30 mg mL(-1), respectively.     

Xylocarpins A and B, two new mexicanolides from the seeds of a Chinese mangrove Xylocarpus granatum: NMR investigation in mixture

Xylocarpins A and B, two new mexicanolides with a tiglate group at C-3, have been identified in the mixture using NMR spectroscopy. Both compounds were isolated in the mixture from the seeds of a Chinese mangrove Xylocarpus granatum. The first complete assignments of 1H and 13C NMR data for these mexicanolides were achieved by means of 2D NMR techniques, including 1H-1H COSY, HSQC, HMBC and NOESY spectra. In order to separate xylocarpins A (1) and B (2) by chemical method, the mixture of two compounds was reduced with sodium borohydride in anhydrous methanol. However, the reduction led to the opening of the delta-lactone ring in xylocarpin B and afforded compound 3 as the main product. The complete NMR assignments of compound 3 were also achieved by means of the above 2D NMR techniques. Moreover, xylocarpin A was easily transformed into xylocarpin B during our normal liquid column chromatography. From this point of view, xylocarpin A was deemed to be the genuine natural product and xylocarpin B might be an artifact.     

Chemical Constituents of Hylotelephium erythrostictum

Chemistry of Natural Compounds -