NotesNudibranchs are colorful, slow-moving, and shell-less mollusks. Their aposematic coloration and possession of toxic substances are believed to function synergetically for their protection from predators and microorganisms. 1,2) In our survey for the metabolites of nudibranchs collected along the coast of Okinawa, we often isolate exactly the same molecules obtained from their prey sponges. Some examples are isocyanoterpenes, latrunculin A, a spongian diterpene, 3) and reticulidins 4) which have been isolated from both sponges and nudibranchs. However, when we examined the contents of Chromodoris willani, the extract appeared to be different from the metabolites of their prey sponge, which contained two sesterterpenes, manoalide (3) and secomanoalide (4). 5) Manoalide was first discovered as an antimicrobial constituent of the sponge Luffariella variabilis 5) and later shown to have anti-inflammatory activity against phospholipase A2 (PLA2) 6) in addition to cytotoxicity. 7) In this note, we report the structures and biological activities of two manoalide analogs isolated from C. willani.
Results and DiscussionFive specimens of C. willani and its prey sponge were collected at the same spot in Okinawa and were separately extracted. The lipophilic extract of C. willani was subjected to conventional chromatography to give two molecules 1 and 2 as major metabolites. The sponge extract was similarly treated to give manoalide (3) and secomanoalide (4) which have been identified by the same spectral data as those reported. 8) The results indicated negative Dd values for H-2 (Ϫ0.07) and H-4 (Ϫ0.09, Ϫ0.04) and positive values for H-5 (ϩ0.03), H-6 (ϩ0.11) and H-24 (ϩ0.09) concluding the 4R configuration. This is the first report on compounds 1 and 2 from a natural source, although 1 has been known as a synthetic entity.
6)Both compounds are believed to be biotransformed by the Two sesterterpenes, deoxymanoalide (1) and deoxysecomanoalide (2), were isolated from the nudibranch Chromodoris willani collected in Okinawa and their structures determined on the basis of spectroscopic data and chemical conversions. The mollusk feeds on a sponge containing manoalide (3) and secomanoalide (4) and is likely to biotransform them into 1 and 2. Both 1 and 2 showed moderate antimicrobial activity against Escherichia coli and Bacillus subtilis and inhibited snake venom phospholipase A2 at 0.2 to 0.5 m mM.
Deoxymanoalides from the Nudibranch Chromodoris willani
Halda River (HR), the lone natural carp breeding ground in Bangladesh as well as in Southeast Asia is an economically important river and its water quality is deteriorating due to unplanned industrialization and various anthropogenic activities. The present research work has been conducted to assess the characteristics of HR water. Eighteen water quality parameters were studied including pH, temperature, Dissolved Oxygen (DO), Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Dissolved Solids, Electrical Conductivity, Hardness, Turbidity, Total Alkalinity, SO42-, PO43-, NO3-, Cl-, NH4+, Cr (VI), Mn (II) and Arsenic. This study shows that water in HR is regularly alkaline and its pH lies between 7.08-7.65. The DO value varies from 5.9-8.4 mgL-1, BOD ranged from 0.3-2.8 mgL-1 and COD from 24-96 mgL-1. According to the Water Quality Index study, the river is being intensely polluted due to the unscrupulous industrial wastes discharge into the HR through various canals.
Four new polyoxygenated steroids (1-4) together with four known ones (5-8) have been isolated from the gorgonian Isis hippuris. The structures of the new compounds have been elucidated by spectroscopic analysis and chemical conversion. All of the new steroids showed moderate cytotoxicity against cultured NBT-T2 cells.
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