Croton Insularis Research Articles

EBC-232 and 323: A Structural Conundrum Necessitating Unification of Five In Silico Prediction and Elucidation Methods.

Structurally unique halimanes EBC-232 and EBC-323, isolated from the Australian rainforest plant Croton insularis, proved considerably difficult to elucidate. The two diastereomers, which consist an unusual oxo-6,7-spiro ring system fused to a dihydrofuran, were solved by unification and consultation of five in silico NMR elucidation and prediction methods [i.e., ACDLabs, olefin strain energy (OSE), DP4, DU8+ and TD DFT CD]. Structure elucidation challenges of this nature are prime test case examples for empowering future AI learning in structure elucidation.

EBC‐342: A Novel Tetrahydrofuran Moiety Containing Casbane from the Australian Rainforest

The Australian rainforest plant, Croton insularis, has provided a further casbane diterpene family member in the form of EBC‐342, which contains a novel tetrahydrofuran ring. A combination of DP4 and TD‐DFT CD methods were required to confirm both structure and absolute stereochemistry.

New Halimanes from the Australian Rainforest Plant Croton Insularis

Two novel (EBC‐204 and EBC‐205), together with three known, halimanes were isolated from the Australian rainforest plant Croton insularis. EBC‐203 strongly inhibited K562 leukemia cell growth.

New Casbanes and the First trans-Cyclopropane seco-Casbane from the Australian Rainforest Plant Croton insularis.

Investigation of the Australian rainforest plant Croton insularis revealed seven new cis-, two new trans-cyclopropane casbanes, and the first trans-cyclopropane seco-casbane. The relative configuration of the cyclopropane moiety for all compounds (EBC-182, 217, 218, 220, 343, 357, 358, 361, 365, 373; EBC=EcoBiotics Compound) was assigned using 13 C NMR data. Comparison of the experimental electronic circular dichroism (ECD) spectra with the theoretical curves, calculated by TD-DFT at the B3LYP/6-31+G**//B3LYP/6-31+G** level, in conjunction with NOE data afforded the absolute configuration. EBC-180, 181 and 220 displayed potent activity against cervical carcinoma (HeLa cells).

The First Casbane Hydroperoxides EBC-304 and EBC-320 from the Australian Rainforest.

Investigation of the Australian rainforest plant Croton insularis led to isolation of the first casbane hydroperoxide diterpenes EBC-304 and EBC-320. Extensive DFT and electronic circular dichroism (ECD) calculations in combination with 2D NMR spectroscopy determined the absolute configurations. EBC-304 and EBC-320 both display significant cytotoxicity.

ChemInform Abstract: seco‐Casbanes from the Australian Rainforest: ECD Predictions Key for Determining Remote Absolute Configuration.

AbstractTwo novel seco‐casbanes EBC‐328 (I) and EBC‐363 (II) from the australian rainforest plant Croton insularis.

Seco‐Casbanes from the Australian Rainforest: ECD Predictions Key for Determining Remote Absolute Configuration

AbstractThe seco‐casbane framework, first isolated from Croton insularis, is surprisingly rare. Further evaluation of this Australian rainforest plant unearthed two additional members, EBC‐328 and EBC‐363. TD DFT predicted electronic circular dichroism (ECD) spectra were critical for remote absolute stereochemical determination. EBC‐328 displayed cytotoxic activity towards leukemia cells (K562). Potential biosynthetic relationships are discussed.

EBC-318 and 339: bicyclo[10.2.1]alkanes from Croton insularis

EBC-318 and EBC-339 were isolated from Croton insularis, an Australian rain forest plant. EBC-318 is characterised by a bridgehead double bond.

EBC-316, 325–327, and 345: New Pimarane Diterpenes from Croton insularis Found in the Australian Rainforest

Five new pimarane and related-type diterpenes (i.e. EBC-316, 325–327, and 345 (10–15)), together with two known pimaranes (EBC-221 (8) and EBC-346 (9)), were isolated from the stems of Croton insularis, found in the Australian rainforest. All pimarane diterpenes disclosed herein are suggested to be biogenetically related to the same keto-Jacobs–Reynolds intermediate 2, via ring A and C oxidation. Anticancer activities of compounds 11–13 are reported.

ChemInform Abstract: EBC‐219: A New Diterpene Skeleton, Crotinsulidane, from the Australian Rainforest Containing a Bridgehead Double Bond.

EBC-219 (4), isolated from Croton insularis (Baill), was established by spectroscopic and DFT methods as the first member of a new diterpene skeletal class, uniquely defined by the presence of a bicyclo[10.2.1] bridgehead olefin. The proposed biogenetic pathway to 4 from the co-isolated natural products EBC-131 (1), EBC-180 (2) and EBC-181 (3) is highly likely. EBC-180 (2) and EBC-181 (3) showed moderate to strong cytotoxic activity against various cancer cell lines.

Unprecedented 1,14-seco-crotofolanes from Croton insularis: oxidative cleavage of crotofolin C by a putative homo-Baeyer-Villiger rearrangement.

EBC-162 isolated from Croton insularis, obtained from the northern rainforest of Australia, was structurally affirmed as crotofolin C (4). Novel oxidative degradation products, EBC-233 and EBC-300, which are the first crotofolane endoperoxides, were also isolated. Both endoperoxides were found to be stable intermediates, which are proposed to undergo an unprecedented homo-Baeyer-Villiger biosynthetic rearrangement to give a new class of 1,14-seco-crotofolane diterpenes. Prolonged storage of all isolates assisted in authenticating their natural product status. Anticancer activities of reported compounds are presented.

Croton insularis introduces the seco-casbane class with EBC-329 and the first casbane endoperoxide EBC-324

Investigation of Croton insularis afforded the first in class seco-casbane diterpene, EBC-329. A highly oxidised casbane, EBC-324, was also isolated. The structural motif within EBC-324, which consists of an epoxidised hemi-acetal endoperoxide, is new to the casbane family.

EBC-219: a new diterpene skeleton, crotinsulidane, from the Australian rainforest containing a bridgehead double bond.

EBC-219 (4), isolated from Croton insularis (Baill), was established by spectroscopic and DFT methods as the first member of a new diterpene skeletal class, uniquely defined by the presence of a bicyclo[10.2.1] bridgehead olefin. The proposed biogenetic pathway to 4 from the co-isolated natural products EBC-131 (1), EBC-180 (2) and EBC-181 (3) is highly likely. EBC-180 (2) and EBC-181 (3) showed moderate to strong cytotoxic activity against various cancer cell lines.

EBC‐219: A New Diterpene Skeleton, Crotinsulidane, from the Australian Rainforest Containing a Bridgehead Double Bond

AbstractEBC‐219 (4), isolated from Croton insularis (Baill), was established by spectroscopic and DFT methods as the first member of a new diterpene skeletal class, uniquely defined by the presence of a bicyclo[10.2.1] bridgehead olefin. The proposed biogenetic pathway to 4 from the co‐isolated natural products EBC‐131 (1), EBC‐180 (2) and EBC‐181 (3) is highly likely. EBC‐180 (2) and EBC‐181 (3) showed moderate to strong cytotoxic activity against various cancer cell lines.

Isolation and Confirmation of the Proposed Cleistanthol Biogentic Link from Croton insularis

The proposed cleistanthol biosynthetic intermediate en route to spruceanol, and other related family members, was isolated for the first time from Croton insularis, confirming the Jacobs-Reynolds hypothesis. Anticancer evaluation of the new isolates and their aerial oxidation products is also reported.

Mode de colonisation de la savane arborée par des plantes de forêt tropicale sèche en Nouvelle-Calédonie

Modalities of colonization of woody savannah by dry forest plants in New Caledonia. — Dry forests are the most endangered tropical forests in the world. Fortunately, they sometimes show some ability to colonize abandoned lands. Such a colonization potential has been investigated in the south of New Caledonia (Pacific Ocean). We analyzed the composition of the vegetation from transects from dry forest to proximate woody savannah, where an extension of the forest had been observed from the analysis of old aerial pictures. Three transects were followed in each of the four studied sites. Among 52 observed species, six were observed in more than 50% of the plots belonging to colonized sites. Among these six species, four provided suckers : Croton insularis, Elattostachys apetala, Emmenosperma pancherianum and Halfordia kendac. Ornithochory and barochory represented the dominant modes of seed dispersal of the colonizing species. Consequently, we conclude that fire control and bird conservation are relevant components of the conservation strategy of dry forest in New Caledonia.

Chemical Constituents from Croton insularis.

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Chemical Constituents from Croton insularis

AbstractThree new clerodane‐type terpenoids, furocrotinsulolide A (1), furocrotinsulolide B (2), and crotinsulactone (3), as well as a new phenolic disaccharide (4) have been isolated from the aerial parts of Croton insularis, together with eight known compounds. Their structures were established by in‐depth 1D‐ and 2D‐NMR spectroscopy, mass spectroscopy, and quantum‐mechanical calculations.

New Diterpenes from Croton insularis

Two new diterpenes (1 and 2) have been isolated from the aerial parts of Croton insularis. Their structures have been established by NMR and mass spectral data, and the absolute configuration of 1 and related trachylobane diterpenes was determined through a series of chemical correlations.