Three New Polyoxygenated Steroids from Two Species of the South China Sea Gorgonian Muricella flexuosa and Menella verrucosa Brundin

Three new polyoxygenated steroids, muricesteroid ( 1 ), and menellsteroids A ( 2 ) and B ( 3 ), were isolated from two species of the South China Sea gorgonian Muricella flexuosa and Menella verrucosa Brundin , respectively. The structures of these new compounds were elucidated on the basis of extensive spectroscopic analysis, chemical methods and comparison with known related compounds.     

南海中华小尖柳珊瑚Muricella sinensis化学成分的研究

从采自中国南海的中华小尖柳珊瑚(Muricella sinensis)中分离得到了1个新的Eunicellane型二萜, 命名为sinensin (1), 和6个已知化合物: 13-去乙酰氧基calicophirin B (2), calicophirin B (3), calicophirin C (4), astrogorgin (5), calicoferol E (6)和calicoferol B (7), 这些化合物的结构是经波谱学实验(1H NMR, 13C NMR, HMQC, HMBC, COSY和NOESY)并与文献报道的数据对照而确定的.     

Flavonoid/Polyphenol Ratio in Mauritia flexuosa and Theobroma grandiflorum as an Indicator of Effective Antioxidant Action

Studies on polyphenols and flavonoids in natural products reveal benefits in the prevention of multiple diseases. Proper extraction, treatment of extracts, and quantification of polyphenols and flavonoids demand attention from the scientific community in order to report more specific biological action. Total polyphenol content (TPC) and total flavonoid content (TFC) (measured at three different times) of ethanol, methanol and acetone extracts of Mauritia flexuosa (aguaje) and Theobroma grandiflorum (copoazú) fresh pulp, from the Colombian Amazon region, were evaluated with the purpose of focusing in the polyphenol/flavonoid proportion and its effective antioxidant activity. This objective could help to explain specific flavonoid biological action based on higher flavonoid proportion rather than higher total polyphenol content. Differences in extracting solvents resulted in statistically significant different yields; the highest TPC was observed with acetone 70% in Mauritia flexuosa and ethanol 80% for T. grandiflorum. The best flavonoid/polyphenol ratio in M. flexuosa was about 1:2.4 and 1:12.8 in T. grandiflorum and the antioxidant efficacy was proportionally higher for flavonoids extracted from T. grandiflorum. HPLC analysis revealed 54 µg/g of the flavonoid kaempferol in M. Flexuosa and 29 µg/g in T. grandiflorum. Further studies evaluating this proportionality, in seeds or peel of fruits, as well as, other specific biological activities, could help to understand the detailed flavonoid action without focusing on the high total polyphenol content.     

Antioxidant Activity of Polyphenols,from Mauritia flexuosa (Aguaje), Based on Controlled Dehydration

Plant polyphenols offer several benefits for the prevention of diverse illnesses. Fruit’s edible and inedible parts (pulp, seeds, peels, stems, flowers) are important sources of polyphenols. Different industrial processes for fruit treatment and commercialization affect the total polyphenol content (TPC), and probably the biological activity. The purpose of the present work was to determine the TPC and antioxidant activity (by DPPH) of polyphenols extracted from the pulp and seeds of Mauritia flexuosa (aguaje), in fresh and dehydrated forms, in order to determine the possible connection with the quantity of polyphenols and their specific antioxidant activity. The highest phenolic content for M. flexuosa seeds in fresh form (non-dehydrated) was 270.75 mg GAE/100 g with a 96-h extraction. With respect to the dehydrated samples, the best yield was quantified in the 96-h dehydrated seed sample. For all pulp and seeds, dehydrated for 24, 48, and 96 h, TPC showed a slightly decreasing pattern. The DPPH results were the highest in the 96-h dehydrated samples and the differences among all dehydrated pulp and seed samples were minimal. More studies testing the presence of other antioxidant components could help in understanding the detailed antioxidant activity, and related more to the specific action, rather than only total polyphenol content.     

Two new eunicellin diterpenoids from the South China Sea gorgonian Muricella sibogae and their bioactivities

A systematic re-study on gorgonian Muricella sibogae from South China Sea yielded 10 eunicellin-based diterpenoids including two new ones, sibogins C and D (1 and 2). Their structures were elucidated by extensive spectroscopic analyses (1D and 2D NMR, IR and MS) and by comparison with data reported in literatures. All the isolates were tested for cytotoxic and antifouling activities. Compounds 3 and 5 showed significant antifouling activity against the green mussel Perna viridis, and especially 3 was suggested as a potent low-toxic antifouling agent with a large LC₅₀/EC₅₀ value of 18.6. This was the first report on the antifouling activity of the eunicellin-type diterpenoids against the green mussel.     

New Eunicellin Diterpenes and 9,10‐Secosteroids from the Gorgonian Muricella sibogae

Bioactivity‐guided isolation of the rare gorgonian Muricella sibogae (Nutting ) yielded the two new eunicellin diterpenes sibogin A and B ( 1 and 2 ), the three new 9,10‐secosteroids sibogol A–C ( 6 – 8 ), together with the three known eunicellin diterpenes 3 – 5 and the five known 9,10‐secosteroids 9 – 13 . Their structures were established by extensive spectral analysis (1D‐ and 2D‐NMR, IR, and MS). The cytotoxicity of the isolates 1 – 13 was evaluated in vitro against the selected tumor cell lines P388 and BEL‐7402. All the compounds showed only weak activity against P388 cell lines, with an inhibition rate ranging from 10 to 60% at a concentration of 50 μg/ml, whereas the were inactive against BEL‐7402 cell lines.     

中国南海裸鳃目软体动物美丽拟皮片鳃(Dermatobranchus orna-tus)及其可能的食源动物柳珊瑚Muricella sp.的化学成分研究

从中国南海的裸鳃目软体动物美丽拟皮片鳃(Dermatobranchus ornatus)中分离得到4个eunicellane型二萜: Ophirin (1), calicophirin B (2), 13-去乙酰氧基 calicophirin B (3)及3-去乙酰基-13-去乙酰氧基calicophirin B (4); 而由同时、同地采集到的柳珊瑚Muricella sp. 中则分离得到calicophirin B (2), 13-去乙酰氧基 calicophirin B (3), astrogorgin (5) 及类似物6. 这些化合物的结构经波谱学实验并与文献报道的数据相对照得以确定, 并首次对Ophirin (1) 的NMR数据进行了全归属. Ophirin (1) 的单晶X衍射实验不但进一步确证了化合物的结构, 而且使这一类化合物的立体结构表述得到修正. 本文是对Dermatobranchus属软体动物化学成分研究的首次报道; 研究提示, 美丽拟皮片鳃能通过选择适当的食物, 并将食物中有用的次生代谢产物转移、富集到身体的特定部位, 使之成为自身的化学防性物质. 美丽拟皮片鳃与Muricella 属柳珊瑚中共同出现的类似化合物支持二者间可能存在的捕食与被捕食的生态学关系.