Ketosteroids from the far-east marine prosobranch mollusk <Emphasis Type="Italic">Onchidiopsis variegata</Emphasis>

The composition of the ketosteroid fraction from the Far-East marine prosobranch mollusk Onchidiopsis variegata was determined. The structure of a new steroidal ketone cholesta-4,24-dien-3-one (1e) was established by NMR, IR, UV, and mass spectroscopy. It was proposed that O. variegata feeds on ascidians of the genus Styela. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 72–74, January–February, 2007.     

Comparison of Extraction Techniques and Surfactants for the Isolation of Total Polyphenols and Phlorotannins from the Brown Algae Lobophora variegata

Abstract

Surfactant-mediated extraction (SME), pressurized liquid extraction (PLE), and enzyme-assisted extraction (EAE) have been compared to improve the isolation of phlorotannins from the brown algae Lobophora variegata. Enzymatic treatment with Alcalase 2.4?L FG, Carezyme 4500?L, protease from Streptomyces griseus, pectinase from Aspergillus niger, Celluclast 1.5?L, protease from Bacillus licheniformis; surfactant extraction with triacetin and guaiacol and PLE with ethanol:water as extracting solvent, have been studied in terms of total phenolic content by the Folin–Ciocalteu method and total phlorotannin content using the DMBA assay. The results showed that SME yields the highest amount of phenols and phlorotannins by using food grade guaiacol as the surfactant. An extraction protocol was developed to maximize the amount of extract obtained from L. variegata. The effects of various parameters such as the type of surfactant, efficacy of surfactant, and optimum pH, on the extraction efficiency of polyphenols were examined. The simultaneous use of the enzyme and surfactant was also investigated. However, a synergistic effect between the enzymes and the surfactant for the extraction of polyphenols has not been observed. Considering total phenols and total phlorotannins in the extract, the extraction yield were obtained for total phenols as SME?>?EAE?>?PLE and for total phlorotannins as SME?>?PLE?>?EAE.     

NMR Profiling of Ononis diffusa Identifies Cytotoxic Compounds against Cetuximab-Resistant Colon Cancer Cell Lines

In the search of new natural products to be explored as possible anticancer drugs, two plant species, namely Ononis diffusa and Ononis variegata, were screened against colorectal cancer cell lines. The cytotoxic activity of the crude extracts was tested on a panel of colon cancer cell models including cetuximab-sensitive (Caco-2, GEO, SW48), intrinsic (HT-29 and HCT-116), and acquired (GEO-CR, SW48-CR) cetuximab-resistant cell lines. Ononis diffusa showed remarkable cytotoxic activity, especially on the cetuximab-resistant cell lines. The active extract composition was determined by NMR analysis. Given its complexity, a partial purification was then carried out. The fractions obtained were again tested for their biological activity and their metabolite content was determined by 1D and 2D NMR analysis. The study led to the identification of a fraction enriched in oxylipins that showed a 92% growth inhibition of the HT-29 cell line at a concentration of 50 µg/mL.