Cytotoxic and Anti-Inflammatory Compounds from Red Sea Grass
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MEDICINAL Medicinal Chemistry Research CHEMISTRY https://doi.org/10.1007/s00044-018-2143-7 RESEARCH ORIGINAL RESEARCH Cytotoxic and anti-inflammatory compounds from Red Sea grass Thalassodendron ciliatum 1,2 2 1 2 Reda F. Abdelhameed ● Amany K. Ibrahim ● Koji Yamada ● Safwat A. Ahmed Received: 24 October 2017 / Accepted: 23 January 2018 © Springer Science+Business Media, LLC, part of Springer Nature 2018 Abstract Chemical investigation of the less polar fraction methylene dichloride–methanol extract of the Red Sea grass Thalassodendron ciliatum led to the isolation of a new phytoceramide molecular species TCC-1, along with four known compounds: 7β-hydroxy cholesterol (10), 7β-hydroxysitosterol (11), stigmasterol glucoside (12), and β-sitosterol glucoside (13). Phytosphingosines with 2-hydroxy fatty acid residues constituted the phytoceramide molecular species TCC-1. Further purification of TCC-1 afforded two new phytoceramides: TCC-1-5 (5) and TCC-1-7 (7) as well as the known ceramide TCC- 1-6 (6). All compounds are reported for the first time from this genus. The chemical structures of the isolated compounds were clarified on the basis of spectroscopic techniques including IR, NMR experiments, mass spectrometry, and chemical fi 1234567890();,: methods, in addition to comparison with literature data. All isolated compounds exhibited signi cant cytotoxicity against two human cell lines (Hep G2 and MCF-7). Moreover, compounds (10–13) have been found to possess significant anti- inflammatory activity in which compound (13) is the most potent. Keywords Thalassodendron ciliatum ● Ceramide ● Cytotoxic compounds ● anti-inflammatory compounds Introduction marine vascular flowering plants that are widely distributed along the coastal and estuarine regions of the world. They Ethnobotanical studies have continued to validate folkloric are unique in that they are often completely submerged in use of plants (marine and terrestrial) (Moghadamtousi et al. water. There are approximately 12 genera affording 2015) in phytomedicinal remedies (Rivera et al. 2005); 50 species of sea grasses. Seven genera are tropical, while (Sharma and Gupta 2015). Now, more than any time, in the the remaining five are almost confined to temperate waters history of phytochemistry research, the chemical basis of (Pollard and Greenway 1993). In many places, sea grasses most age-long folkloric cures is better understood. Drug cover extensive areas, which are usually known as sea grass development in contemporary times have benefitted from beds. The sea grass beds play a vital role in the marine these bodies of knowledge, accounting for more than 50% ecosystem since they act as shelter for a variety of other of drugs and other pharmaceutical preparations approved organisms and provide food for commercially important fish for human use today (Sharma and Gupta 2015) for the species (Howard et al. 1989). McMillan (McMillan et al. treatment and/or management of diseases. Sea grasses are 1980) reported that sea grass is a rich source of secondary metabolites, especially phenolics, which are known to have various biological activities. One such plant whose bioac- tive principles are under intensive research currently is Electronic supplementary material The online version of this article Thalassodendron ciliatum. T. ciliatum is a tropical sea grass (https://doi.org/10.1007/s00044-018-2143-7) contains supplementary fi material, which is available to authorized users. which can be classi ed as sub-tidal and not deep water bed- forming sea grass (Carruthers et al. 2002). It is widely * Safwat A. Ahmed distributed in the Red Sea, the tropical part of the [email protected] Indo–Pacific region, and the western Indian Ocean (Den and 1 Graduate School of Biomedical Sciences, Nagasaki University, Hartog 1970). Recently, its phenolic constituents (rutin, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan asebotin, 3-hydroxyasebotin, quercetin-3-O-beta-D-xylo- 2 Departments of Pharmacognosy, Faculty of Pharmacy, Suez Canal pyranoside, catechin, and caffeic acid) were isolated and University, Ismailia 41522, Egypt characterized (Hamdy et al. 2012) and assayed for cytotoxic Medicinal Chemistry Research response in HCT-116, HEPG, MCF-7, and HeLa human Plant material, collection, and identification cancer cell lines. Furthermore, three independent studies have established that the extract of the plant and its isolated The sea grass T. ciliatum (coll. no. SAA-41) was collected components (especially asebotin) have potent anti-viral from Sharm el sheikh at the Egyptian Red Sea, air-dried, activities (Mohammed et al. 2014); (Ibrahim et al. 2013). and stored at low temperature (−24 ˚C) until processed. The Anti-oxidant activities have also been reported due to the plant was identified by Dr Tarek Temraz, Marine Science presence of flavonoids. Department, Faculty of Science, Suez Canal University, A limited number of phytochemical studies are found on Ismailia, Egypt, A voucher specimen was deposited in the the isolation and structure elucidation of the chemical herbarium section of Pharmacognosy Department, Faculty constituents from the polar fractions of the Red Sea grass of Pharmacy, Suez Canal University, Ismailia, Egypt under Thalassodendron ciliatum and to the best of our knowledge registration number SAA-41. there is no chemical investigation for the non polar fraction till now, except for the diglyceride ester isolated by our Extraction and isolation group (Ibrahim et al. 2013). Therefore, in this study we have further expanded the chemical landscape of the Red T. ciliatum was dried (250 g dry weight), grounded, and Sea grass T. ciliatum with the isolation and spectral char- repeatedly extracted with a mixture of CH2Cl2/MeOH (1:1) acterization of phytosphingosine type ceramides and ster- (3 × 2 L) at room temperature. The combined extracts were oidal scaffolds for the first time. concentrated under vacuum to afford a dark green residue TC (30 g). The residue was chromatographed over silica gel column using CHCl3: MeOH: H2O (100:0:0 ~ 60:40:10) Material and methods gradient elution to give 11 sub-fractions (TC-1–TC-11) based on TLC analysis. Fraction TC-6 (0.64 g), was sub- General experimental procedures jected to SiO2 column eluting with a gradient of increasing MeOH in CHCl3 to afford 6 fractions (TC-6-1 ~ TC-6-6). 1H-NMR chemical shifts are expressed in δ values refer- Fraction TC-6-4 (114 mg) was chromatographed over ring to the solvent peak δH 7.19, 7.55, and 8.71 for Pyr- Sephadex LH-20 column and eluted with CHCl3: MeOH idine-d5, 7.26 for CDCl3, and coupling constants are (1:1) to yield 4 fractions (TC-6-4-1 ~ TC-6-4-4). Fraction expressed in Hz. 13C NMR chemical shifts are expressed TC-6-4-3 (56 mg) was successively re-chromatographed in δ values referring to the solvent peak δC 123.5, 135.5, over silica gel column using CHCl3: MeOH (9.5:0.5) iso- 1 13 and 149.9 for Pyridine-d5, and 77 for CDCl3. Hand C cratic elution to give a pure phytoceramide molecular spe- NMR spectra were recorded with a Unity plus 400 spec- cies TCC-1 (28 mg). TCC-1 (23 mg) was finally purified on trometer (Varian Inc., U.S.A.) operating at 400 MHz for semi-preparative HPLC (cosmosil 5C18, 100% MeOH) to 1H, and 100 MHz for 13C. Optical rotations were mea- afford TCC-1-1 (1) (0.3 mg), TCC-1-2 (2) (0.9 mg), TCC-1- sured with a JASCO DIP-370 digital polarimeter. Positive 3(3) (0.6 mg), TCC-1-4 (4) (0.8 mg), TCC-1-5 (5) (2.1 mg), ion FAB-MS spectra were recorded on JMS DX-303 TCC-1-6 (6) (6.4 mg), TCC-1-7 (7) (2.4 mg), TCC-1-8 (8) spectrometer (JEOL Ltd., Japan), using m-nitrobenzyl (1.3 mg), and TCC-1-9 (9) (1.0 mg) as pure phytocer- alcohol or Magic bullet as a matrix. Sephadex LH-20 amides. Fraction TC-4 (1.4 g), was further chromatographed (Pharmacia Fine Chemical Co.Ltd) and Wakogel C-300 over SiO2 column using CHCl3: MeOH (100:0 ~ 80:20) (Wako Pure Chemical Industries, Ltd, Japan, 45 ~ 75 μm) gradient elution to afford 10 fractions (TC-4-1 ~ TC-4-10). were used for column chromatography. Precoated silica Fraction TC-4-5 (320 mg) was chromatographed over gel plates (Merck, Kieselgel 60 F254, 0.25 mm) and RP- Sephadex LH-20 column and eluted with CHCl3: MeOH 18 F254s plates (Merck) were used for thin-layer chro- (1:1) followed by silica gel column using n-hexane: EtOAc matography (TLC) analysis. IR spectra were obtained (70:30 ~ 50:50) to yield 6 fractions (TC-4-5-1 ~ TC-4-5-6). with JASCO FT/IR-410 spectrophotometers. The UV Fraction TC-4-5-3 (65 mg) was chromatographed over spectra were recorded on a double beam Shimadzu silica gel column using n-hexane: EtOAc (70:30) isocratic UV–visible spectrophotometer (model UV-1601 PC, elution followed by semi-preparative reversed-phase HPLC Kyoto City, Japan). Semi-preparative high-performance (cholester, 100% MeOH) to give 10 (2.5 mg) and 11 (2.2 liquid chromatography (HPLC) was performed on a cos- mg). Fraction TC-7 (0.6 g), was subjected to silica gel mosil 5C18–MS–II (150 × 4.6 mm) at a flow rate of 0.5 ml/ column using CHCl3: MeOH (100:0 ~ 90:10) gradient elu- min, and cholester column at a flow rate of 0.5 ml/min. tion to afford seven fractions (TC-7-1 ~ TC-7-7). Com- Both columns were equipped with a TOSOH RI-8020 pounds 12 (7.7 mg) and 13 (13.5 mg) were isolated after detector and a JASCO BIP-I HPLC pump. column chromatography over Sephadex LH-20 column and Medicinal Chemistry Research Table 1 1H and 13C-NMR spectral data of TCC-1 (δ values in C D N)a eluted with CHCl3: MeOH (1:1) followed by semi- 5 5 preparative reversed-phase HPLC (cholester, 90% MeOH) Position TCC-1 from fraction TC-7-5 (66 mg).