Prenylbicyclogermacrane diterpenoids from the formosan soft coral Nephthea pacifica

A world tour in the name of natural products

BACKGROUND

Names of natural products (NP) are usually given depending on the species of origin, be it a plant, a marine organism or a microbial species. In some cases, names have been given with reference to people, animals, music, foods or places. Many NP refer to countries, cities or specific places such as mountains, deserts, seas and oceans.

PURPOSE

On the basis of NP names, a world tour has been imagined referring to more than one hundred NP with names evocative of over 50 countries and regions.

RESULTS

The world tour goes from UK (britannin) to Italy (vaticanol) in Europe, from Uganda (ugandoside) to Senegal (senegalene, senegalenines) in Africa, from Brazil (brasilin) to Chile (santiaguine) in South America, from Utah (utahin) to Florida (floridanolide) in the US. It includes Central America (mexicanin, panamine) and the Caribbean islands (jamaicin, bahamaolides). It also crosses Alaska (alaskene) and Canada (quebecol, canadaline). The tour continues throughout Asia, from Thailand (thailandine) to China (Chinaldine) and Pakistan (pakistanamine), to finally reaches Oceania with Australia (australigenin) and Vanuatu (vanuatine), among other countries. This virtual journey, without bordure or wall, brings us to the highest mountains (himalayamine), the deepest oceans (pacificins) and the largest deserts (desertomycin).

CONCLUSION

In the current period of COVID-19 pandemia, with restricted opportunities for international travels, this NP name-based virtual journey offers a world tour to learn more from nature and to inspire scientists to contribute to the field of NP discovery and drug design. There are also limitations associated with the use of trivial names for NP. NP names can be further exploited for teaching and learning.

Total syntheses of ent-hypocoprin A and ent-hypocoprin B

This study reports the stereoselective total syntheses of the antipodes of the unique 3/10 bicyclic skeletal sesquiterpenoids, namely, hypocoprin A and hypocoprin B. The synthesis involved conjugate addition accelerated by trimethylsilyl chloride, construction of the ten-membered ring via the intramolecular S_N2 reaction promoted by 1,8-diazabicyclo[5.4.0]undec-7-ene, and osmium-mediated π-facial selective dihydroxylation to functionalize the 1,1-disubstituted alkene.

This study reports the stereoselective total syntheses of the antipodes of the unique 3/10 bicyclic skeletal sesquiterpenoids, namely, hypocoprin A and hypocoprin B.

Hydroperoxides derived from marine sources: origin and biological activities

Hydroperoxides are a small and interesting group of biologically active natural marine compounds. All these metabolites contain a group (R-O-O-H). In this mini-review, studies of more than 80 hydroperoxides isolated from bacteria, fungi, algae, and marine invertebrates are described. Hydroperoxides from the red, brown, and green algae exhibit high antineoplastic, anti-inflammatory, and antiprotozoal activity with a confidence of 73 to 94%. Hydroperoxides produced by soft corals showed antineoplastic and antiprotozoal activity with confidence from 81 to 92%. Metabolites derived from sea sponges, mollusks, and other invertebrates showed antineoplastic and antiprotozoal (Plasmodium) activity with confidence from 80 to 90%.

New Cytotoxic Terpenoids from Soft Corals Nephthea chabroli and Paralemnalia thyrsoides

A novel cytotoxic diterpenoid, chabrolin A (1) (possessing an unprecedented terpenoid skeleton), as well as three new cytotoxic sesquiterpenoids, parathyrsoidins E-G (2-4), were isolated by cytotoxicity-guided fractionation from soft corals Nephtheachabroli and Paralemnalia thyrsoides. The structures of the new compounds were determined by extensive analysis of spectroscopic data.

A New Trinor-guaiane Sesquiterpene from an Indonesian Soft Coral Anthelia sp

A new trinor-guaiane sesquiterpene has been isolated from an Indonesian soft coral Anthelia sp. The planar structure, possessing an octahydroazulene skeleton, and relative stereochemistry were established by analyzing 1D and 2D NMR data, including NOE experiments. Its absolute stereochemistry was elucidated to be 1 S, 4 S, 7 R, and 10 R by comparing observed and calculated optical rotation values. The new compound showed weak cytotoxicity against NBT-T2 cells.

New cembranoid diterpenes from the cultured octocoral Nephthea columnaris

Two new 15-hydroxycembranoid diterpenes, 2β-hydroxy-7β,8α-epoxynephthenol (1) and 2β-hydroxy-11α,12β-epoxynephthenol (2), were isolated from extracts of the octocoral Nephthea columnaris along with a new natural cembrane, epoxynephthenol (3) and a known sterol, nephalsterol A (4). The structures of cembranes 1–3 were elucidated by spectroscopic methods and comparison of the spectroscopic data with those of related analogues. The cytotoxicity of metabolites 1–4 against a panel of tumor cells is also described.

Hypocoprins A-C: new sesquiterpenoids from the coprophilous fungus Hypocopra rostrata

Studies of the coprophilous fungus Hypocopra rostrata (TTI-0009, NRRL 66178) isolated from a sample of horse dung collected in Texas led to the isolation of three new sesquiterpenoids that we named hypocoprins A-C (1-3), together with the known fungal metabolite helvolic acid. The new metabolites have a distinctive ring system consisting of fused cyclopropane and cyclodecene units not previously reported from a fungal source. Compounds 1 and 3 moderately inhibited growth of Staphylococcus aureus. The structures of these metabolites were assigned mainly by analysis of 2D NMR and HRESITOFMS data. Relative and absolute configurations were assigned by interpretation of NMR J-values and NOESY data and by application of Mosher's method. These results represent the first report of chemistry from any strain of the genus Hypocopra.

Peroxy natural products

This review covers the structures and biological activities of peroxy natural products from a wide variety of terrestrial fungi, higher plants, and marine organisms. Syntheses that confirm or revise structures or stereochemistries have also been included, and 406 references are cited.

New steroids from the soft coral Nephthea chabrolii

A new cytotoxic 19-oxygenated steroid, nebrosteroid Q (1) and two new cytotoxic 19-norergosterols, nebrosteroids R and S (2 and 3) were isolated from the soft coral Nephthea chabrolii collected at San-Hsian-Tai. The structures of nebrosteroids Q–S (1–3) were elucidated by spectral analysis, and their cytotoxicity against selected cancer cells as well as antiviral activity against human cytomegalovirus (HCMV) were measured in vitro.

New 19-oxygenated steroids from the soft coral Nephthea chabrolii

In order to search for novel bioactive substances from marine organisms, we investigated the acetone extract of the soft coral Nephthea chabrolii collected at San-Hsian-Tai, Taitong County, Taiwan. From this extract three new 19-oxygenated steroids, nebrosteroids N–P (1–3) were isolated. The structures of these compounds were elucidated by extensive spectroscopic analyses.

New 19-oxygenated and 4-methylated steroids from the Formosan soft coral Nephthea chabroli

Chemical investigation of the Formosan soft coral Nephthea chabroli resulted in the isolation of four new 19-oxygenated steroids, nebrosteroids I-L (1-4), together with a new 4alpha-methylated steroid, nebrosteroid M (5). The molecular structures of these isolated metabolites were elucidated on the basis of extensive spectroscopic analysis and by comparison of the data with those of related metabolites. Compounds 1-5 were evaluated for anti-inflammatory activity using RAW 264.7 macrophages.

New anti-inflammatory 4-methylated steroids from the Formosan soft coral Nephthea chabroli

Eight new 4-methylated steroids, nebrosteroids A-H (1-8) were isolated from the acetone solubles of the Formosan soft coral Nephthea chabroli. The structures were elucidated by extensive NMR spectroscopic analysis and their anti-inflammatory activity was measured in vitro.

New 4-methylated and 19-oxygenated steroids from the Formosan soft coral Nephthea erecta

Two new 4-methylated steroids, erectasteroids A and B (1 and 2), six new 19-oxygenated steroids, erectasteroids C-H (3-8) and two known 19-oxygenated steroids (9 and 10) were isolated from the acetone solubles of the Formosan soft coral Nephthea erecta. The structures were elucidated by extensive NMR spectroscopic analysis and their cytotoxicity against selected cancer cells was measured in vitro.

Marine natural products

This review covers the literature published in 2005 for marine natural products, with 704 citations (493 for the period January to December 2005) referring to compounds isolated from marine microorganisms and phytoplankton, green algae, brown algae, red algae, sponges, coelenterates, bryozoans, molluscs, tunicates and echinoderms. The emphasis is on new compounds (812 for 2005), together with their relevant biological activities, source organisms and country of origin. Biosynthetic studies, first syntheses, and syntheses that lead to the revision of structures or stereochemistries, have been included.

Nardosinane Sesquiterpenoids from the Formosan Soft Coral Nephthea elongata

Seven new nardosinane sesquiterpenoids, elongatols A-G (1-7) were isolated from the methylene chloride solubles of the Formosan soft coral Nephthea elongata. Their structures were elucidated by extensive spectroscopic analysis and their cytotoxicity against selected cancer cells was measured in vitro.

Prenylbicyclogermacrane Diterpenoids from the Formosan Soft Coral Nephthea elongata

Seven new prenylbicyclogermacrane diterpenoids, pacificins K--Q (1--7), were isolated from the methylene chloride solubles of the Formosan soft coral Nephthea elongata. Their structures were elucidated by extensive spectroscopic analysis and their cytotoxicity against selected cancer cells was measured in vitro.

Diterpenoids

This review covers the isolation and structures of diterpenoids, including labdanes, clerodanes,pimaranes, abietanes, kauranes, cembranolides, taxanes and marine diterpenoids. The literature from January to December 2005 is reviewed, and 195 references are cited.