Presence Of Double Bond Research Articles

ISOLASI SENYAWA TRITERPENOID DAN UJI ANTIBAKTERI EKSTRAK n-HEKSAN DAUN KAYU ARA (Ficus aurata (Miq.) Miq)

Triterpenoid isolation from n-hexane extract of kayu ara leaves (Ficus aurata (Miq.) Miq) has been performed. The Isolation has been done by column chromatography method using silica gel as a stationary phase and n-hexane and ethyl acetate as mobile phase with isocratic method and it is continued by trituration method. Isolated compound has white amorphous shape, decomposed at 86-87ºC and gives single spot with reddish brown violet in LB reagent and in H2SO4 reagent on TLC test. UV spectra indicate the presence of double bonds in the isolated compound at 204 nm λmax and IR spectra showed -OH functional group at 3290 cm-1, -CH stretching at 2912,90 cm-1, C=C at 1676 cm-1, C-O stretching at 1054,93 cm-1, and at 1374 cm-1 is spectra of geminal dimethyl compound that are characteristic of triterpenoids which supports ultraviolet spectroscopic data. Antibacterial activity test showed that isolated compound is active in inhibiting the growth of gram-positive bacteria Staphyloccocus aureus and gram-negative bacteria Escherichia coli.

Correlation between the hydration of acyl chains and phosphate groups in lipid bilayers: Effect of phase state, head group, chain length, double bonds and carbonyl groups

This paper demonstrates by means of FTIR/ATR analysis that water molecules intercalate at different extents in the acyl chain region of lipid membranes in correlation with the hydration of the phosphate groups.This correlation is sensible to the chain length, the presence of double bonds and the phase state of the lipid membrane.The presence of carbonyl groups CO modifies the profile of hydration of the two regions as observed from the comparison of DMPC and 14:0 Diether PC.The different water populations in lipid interphases would give arrangements with different free energy states that could drive the interaction of biological effectors with membranes.

Characterization of Ceramides with Phytosphingosine Backbone by Hydrogen-deuterium Exchange Mass Spectrometry

Ceramides are a lipid subclass of the sphingolipids that show large structural diversity. Structural characterization of the ceramides (CERs) can lead to better understanding of their role and function in the biological system. Here we investigated representatives of NP (CER III, CER IIIB) and AP ceramide classes (CER VI) that contain phytosphingosine (P) backbone. Ceramides were characterized in positive ionization mode by hydrogen-deuterium exchange mass spectrometry (HDX-MS). Fragmentation in positive ionization mode of the CER III and CER VI resulted in abundant ions assigned to phytosphingosine moiety at m/z 282, 300 and 318. HDX-MS of fragments showed increase in m/z of corresponding ions confirming the exchange of deuterium. In negative ionisation spectra multiple fragment ions were assigned to fatty acyl (RCOO–) moiety. Presence of RCOO– allowed unambiguous identification of CER III and CER IIIB which were distinguished by the presence of double bond on fatty acyl chain.

Carotenoid Stereochemistry Affects Antioxidative Activity of Liposomes Co-encapsulating Astaxanthin and Tocotrienol.

We previously found that antioxidative activity of liposomes co-encapsulating astaxanthin (Asx) and tocotrienols (T3s) was higher than the calculated additive activity, which results from intermolecular interactions between both antioxidants (J. Clin. Biochem. Nutr., 59, 2016, Kamezaki et al.). Herein, we conducted experiments to optimize Asx/α-T3 ratio for high antioxidative activity, and tried to elucidate details of intermolecular interaction of Asx with α-T3. Higher activity than calculated additive value was clearly observed at an Asx/α-T3 ratio of 2 : 1, despite two α-T3 would potentially interact with two terminal rings of one Asx. The synthetic Asx used in this study was a mixture of three stereoisomers, 3R,3'R-form (Asx-R), 3S,3'S-form (Asx-S) and 3R,3'S-meso form (Asx-meso). The calculated binding energy of the Asx-S/α-T3 complex was higher than those of Asx-R/α-T3 and Asx-meso/α-T3, suggesting that Asx-S and α-T3 is the most preferable combination for the intermolecular interaction. The optimal Asx-S/α-T3 ratio for antioxidation was shown to be 1 : 2. These results suggest that the Asx stereochemistry affects the intermolecular interaction of Asx/α-T3. Moreover, the absorption spectrum changes of Asx-S upon co-encapsulation with α-T3 in liposomes indicate that the electronic state of Asx-S is affected by intermolecular interactions with α-T3. Further, intermolecular interactions with α-T3 affected the electronic charges on the C9, C10 and C15 atoms in the polyene moiety of Asx-S. In conclusion, the intermolecular interaction of Asx/T3 depends on the Asx stereochemistry, and caused a change in the electronic state of the Asx polyene moiety by the presence of double bond in the T3 triene moiety.

Improving the ceramic yield of polycarbosilane by radiation cross‐linking in the presence of multifunctional monomers

AbstractAn interesting method for radiation cross‐linking polycarbosilane (PCS) at high efficiency and low cost was developed by adding multifunctional monomers (trimethylolpropane trimethacrylate (TMPTMA) or divinylbenzene (DVB)). The effect of multifunctional monomers on the radiation cross‐linking and ceramic yield of PCS was investigated. The results revealed that the addition of a small amount of multifunctional monomer can substantially improve the ceramic yield and reduce the absorbed dose by promoting cross‐linking. The ceramic yields of radiation cross‐linked “PCS/2%DVB (300 kGy)” and “PCS/2%TMPTMA (300 kGy)” were 74 wt% and 78 wt%, respectively, while that of the radiation cross‐linked “PCS (300 kGy)” was only 64 wt%. The presence of double bonds in multifunctional monomers stimulated the combination reactions of free radicals in PCS induced by γ‐ray irradiation and subsequently enhanced the efficiency of cross‐linking. Furthermore, it was found that the incorporation of a small amount of multifunctional monomer hardly affected the chemical composition and crystallization behavior of the final SiC ceramics.

Inhibition of Fatty Acid Amide Hydrolase (FAAH) by Macamides

PurposePentane extract of the Peruvian plant Lepidium meyenii (Maca) has been demonstrated to possess neuroprotective activity in previous studies. This extract contains several macamides that might act on the endocannabinoid system. The aim of this study is to characterize the inhibitory activity of four maccamides (N‐benzylstearamide, N‐benzyloleamide, N‐benzyloctadeca‐9Z,12Z‐dienamide, and N‐benzyloctadeca‐9Z,12Z,15Z‐trienamide) on fatty acid amide hydrolase (FAAH), an enzyme that is responsible for the endocannabinoid degradation in the nervous system. The enhancement of endocannabinoid activity by inhibition of FAAH enzyme results in analgesic, anxiolytic, anti‐depressant and neuroprotectant effects, avoiding unwanted side effects of cannabinoid receptor activation such as weight gain and motor cognitive impairments.MethodsThe four compounds at concentrations from 1 to 100 μM were tested using a FAAH inhibitor screening assay method. This assay is based on fluorescence produced upon the hydrolysis of a substrate, 7‐amino‐4‐methylcoumarin‐arachidonamide (AMC‐AA) by the FAAH enzyme to the 7‐amino‐4‐methylcoumarin (AMC) which is measured 60 min following substrate addition at 37ºC with excitation and emission of 360 and 460 nm, respectively. To study the time dependence effect on the FAAH enzyme inhibition, the previous assay was repeated using different pre‐incubation times (0, 60 and 120 min) before substrate addition at 37ºC. To evaluate whether macamides are purely inhibitors or might be substrates of FAAH, LC/MS/MS was used to analyze the 60 min incubation of N‐benzyloctadeca‐9Z,12Z‐dienamide with and without FAAH enzyme at 37ºC. The benzylamine was used as a standard to determine the possible degradation of N‐benzyloctadeca‐9Z,12Z‐dienamide by FAAH enzyme.ResultsThe four macamides studied demonstrated concentration‐dependent FAAH inhibitory activity. Double bonds appeared to have an important impact on FAAH inhibitory activity. The macamides containing oleic, linoleic and linolenic acids produced FAAH inhibition of 64, 73, and 54%, respectively, while the macamide containing stearic acid and lacking a double bond produced only 13% inhibition at 100 μM. N‐Benzyloctadeca‐9Z,12Z‐dienamide (two double bonds) demonstrated the greatest inhibitory activity, indicating that two double bonds significantly influence the inhibition of FAAH. Pre‐incubation studies showed significant differences in the FAAH inhibitory activity of N‐benzyloctadeca‐9Z,12Z‐dienamide, N‐benzyloleamide, and N‐benzylstearamide, indicating that the inhibitory mechanism of these compounds is time‐dependent. Incubation of N‐benzyloctadeca‐9Z,12Z‐dienamide with FAAH enzyme for 60 min resulted in a 44% degradation, when analyzed by LC/MS/MS. This result indicates that N‐benzyloctadeca‐9Z,12Z‐dienamide likely acts as a slow substrate for the FAAH enzyme.ConclusionN‐Benzyloctadeca‐9Z,12Z‐dienamide is the most active macamide. The presence of double bonds in macamides significantly increases FAAH inhibition, which could improve the potential neuroprotective and analgesic activities. These results will provide useful information regarding the development of new compounds with FAAH inhibitory activity.Support or Funding InformationKing Saud ben Abdulaziz University for Health Sciences (KSAU‐HS)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Phosphoric acid activation of sugarcane bagasse for removal of o-toluidine and benzidine

In the effort to find alternatives for low cost adsorbent, activated carbon using sugarcane bagasse (SBAC) has been introduced in this study that has undergo chemical treatment using phosphoric acid to determine the effectiveness of adsorption process in removing o-toluidine and benzidine. Throughout this study, 92.9% of o-toluidine has been successfully removed by SBAC at optimum value of 1.1 g of dosage with contact time of 10 minutes and concentration of 10 mg/L. While benzidine was remove by 83.1% at optimum dosage of 1.1 g with 60 minutes of contact time and at 20 mg/L concentrations. Testing of SEM proves that SBAC has high porosity and comparable to CAC. In FTIR results, shows that CAC has high number of double bond while SBAC shows no double bond at all. Presence of double bond in CAC lead to increase in percentage of removal of adsorbate. After considering other factor such as cost, energy and environmental friendly, it shows that SBAC was considerable to replaced CAC.

The role of radical polymerization in the production of thermoregulating microcapsules or polymers from saturated and unsaturated fatty acids

ABSTRACTThe microencapsulation of linoleic (LinA), oleic, erucic, and palmitic acids (PAs) from styrene and divinylbenzene were studied by using the suspension‐like polymerization technique. All materials exhibited a spherical shape, with a particle size between 166 and 416 μm. The phase change material (PCM) content decreased with the presence of double bonds in the fatty acid molecule. The thermal energy storage (TES) capacity of the microcapsules (MC) containing saturated PA was the highest (123.30 J g−1). Whereas, the lowest TES capacity was observed for the LinA. TES capacity values from unsaturated fatty acid materials and the high particle yield indicated that these kinds of acids played two different roles, as PCM and also as monomers, in the radical polymerization processes. At high initiator concentrations, the unsaturated fatty acids were observed to react. This was confirmed by Fourier transform infrared where the peak assigned to the CC bond disappears in the spectrum of MC. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45970.

Effect of different polysorbates on development of self-microemulsifying drug delivery systems using medium chain lipids

The primary objective of this study was to develop lipid-based self-microemulsifying drug delivery systems (SMEDDS) without using any organic cosolvents that would spontaneously form microemulsions upon dilution with water. Cosolvents were avoided to prevent possible precipitation of drug upon dilution and other stability issues. Different polysorbates, namely, Tween 20, Tween 40, Tween 60, and Tween 80, were used as surfactants, and Captex 355 EP/NF (glycerol tricaprylate/caprate) or its 1:1 mixture with Capmul MCM NF (glycerol monocaprylocaprate) were used as lipids. Captex 355-Tween-water ternary phase diagrams showed that oil-in-water microemulsions were formed only when the surfactant content was high (80–90%) and the lipid content low (10–20%). Thus, mixtures of Tweens with Captex 355 alone were not suitable to prepare SMEDDS with substantial lipid contents. However, when Captex 355 was replaced with the 1:1 mixture of Captex 355 and Capmul MCM, clear isotropic microemulsion regions in phase diagrams with sizes in the increasing order of Tween 20 < Tween 40 < Tween 60 < Tween 80 were obtained. Tween 80 had the most profound effect among all surfactants as microemulsions were formed with lipid to surfactant ratios as high as 7:3, which may be attributed to the presence of double bond in its side chain that increased the curvature of surfactant layer. Thus, lipid-surfactant mixtures containing 1:1 mixture of medium chain triglyceride (Captex 355) and monoglyceride (Capmul MCM) and as low as 30% Tween 80 were identified as organic cosolvent-free systems for the preparation of SMEDDS. Formulations with a model drug, probucol, dispersed spontaneously and rapidly upon dilution with water to form microemulsions without any drug precipitation.

Development of viscometric methods for studying the interaction of various porphyrins with DNA. Part III: Meso-tetra-(3N-alylpyridyl)porphyrin and its Cu-, Co- and Zn-containing derivatives

Present research continues the development of viscometry method for studying porphyrin–DNA interactions.Water soluble cationic meso-tetra-(3[Formula: see text]-alylpyridyl) porphyrin (H2TAlPyP3) and its Cu-, Co- and Zn-containing derivatives were studied using UV-vis absorption spectroscopy and viscometry in order to clarify the effect of chemical structure (presence of double bond in structure of a side radical) of porphyrins and ability to affect the DNA structure. Their binding constant ([Formula: see text] and stoichiometry ([Formula: see text] were determined based on the absorbance spectra for each DNA–porphyrin complex. The results were compared with results of previously conducted similar studies with meso-tetra-(3[Formula: see text]-hydroxyethylpyridyl) porphyrins. It was shown, that the planar porphyrins H2TAlPyP3 and CuTAlPyP3 interact with DNA predominantly by intercalation at low relative concentrations of [Formula: see text](([Formula: see text] [Formula: see text] [Porphyrin]/[DNA])) and by external binding mode at high values of [Formula: see text], whereas the change of chemical structure of peripheral radicals of porphyrins does not absolutely affect on the mechanism of interaction of outside binders CoTAlPyP3 and ZnTAlPyP3 with DNA.

Design of polymeric composite materials for coatings and sealants with increased weather resistance

In order to develop polymeric composite materials (PCM) for coatings and sealants with good weather resistance and physical and mechanical properties, the object of research is oligomeric composition based on hydrogenated oligobutadienedions with finite hydroxyl groups. The main disadvantage of oligobutadienedion-based compositions is unsatisfactory chemical resistance to air, due to the presence of double bonds in the polymer chain. In order to maximize eliminate the main disadvantage, it is decided to use oligomers that are subjected to partial hydrogenation. It is revealed that GI oligomers can be considered as binding bases of mortarless elastomeric compositions for coatings and sealants with good weather resistance due to the low viscosity and sufficiently small unsaturation values. Analysis of the kaolin effect as a filler on structural and mechanical properties of GI oligomers is determines that due to the low structural viscosity of GI oligomers for practical use as a binding PCM bases, it is necessary further inject the structuring additives into them, for example – Aerosil. The presence of hydroxyl groups makes it possible to perform composition structuring using diisocyanates at room temperature to obtain ozone resistant sealants and protective coatings. It is determined that the coatings, derived from kaolin-filled (20 % wt.) and aerosil (5 % wt.) GI oligomer, are characterized by high adhesion to steel Ст3, more than 5 MPa for separation, without the use of primers and adhesives.

Synthesis, physicochemical, and biological activities of novel N-acyl tyrosine monomeric and Gemini surfactants in single and SDS/CTAB-mixed micellar system

A series of single-chained N-acyl tyrosine surfactants with varying chain lengths (C10-C18) and degree of unsaturation, as well as an N-acyl Gemini tyrosine surfactant with chain length C12, were synthesized, and the structures were confirmed using spectral analysis. The effect of chain length and level of unsaturation on the physicochemical and antibacterial properties of the N-acyl tyrosine surfactants was evaluated. The C12 derivative displayed the optimum antibacterial activity among the single chain surfactants, and the presence of double bond in the oleoyl derivative enhanced the antibacterial activity over its saturated analogue. The N-acyl Gemini surfactant displayed the highest antibacterial activity among the series and also showed greater micelle forming ability than its single chain analogue. Mixed micellar behavior of the N-acyl Gemini surfactant with conventional cationic (CTAB) and anionic (SDS) surfactants in aqueous solution was studied. The negative value of the interaction parameter β12 observed for the N-acyl Gemini in binary mixture with CTAB surfactant indicated a synergistic interaction within the mixed micellar system. However, the binary mixture with SDS displayed antagonistic behavior. The binary mixture of N-acyl Gemini surfactant with CTAB displayed better antibacterial activity and foaming properties than with SDS mixtures. Optimum antibacterial activity was observed for N-acyl Gemini surfactant with mole ratio 0.4 to 0.6 in the CTAB binary mixture, at which the lowest ocular irritation index was observed. Overall, the study showed that the Gemini surfactant in combination with the conventional surfactant CTAB can be used as potential ingredients in detergent and pharmaceutical formulations.

Experimental and kinetic modeling study of 1-hexene combustion at various pressures

The pyrolysis of 1-hexene was studied in a flow reactor by synchrotron vacuum ultraviolet photoionization mass spectrometry and gas chromatography combined with mass spectrometry at 0.04, 0.2, and 1atm. Laminar flame speeds of 1-hexene/air mixtures at various pressures (1, 2, 5, and 10atm) were measured at an initial temperature of 373K and equivalence ratios from 0.7 to 1.5. A kinetic model of 1-hexene combustion with 122 species and 919 reactions was developed to investigate the key pathways in the decomposition of 1-hexene and the formation and consumption of products, as well as the chemical kinetic effects on the laminar flame propagation. The presence of double bond in 1-hexene molecule leads to the enhanced formation of resonantly stabilized radicals and unsaturated intermediates. The model was also validated against the experimental data of 1-hexene combustion from literature, including ignition delay times and species profiles in jet-stirred reactor oxidation and laminar premixed flames. The extensive validations demonstrate the applicability of the present model over a wide range of conditions, such as low to high pressures, intermediate to high temperatures, and pyrolysis to oxidation circumstances.

Degradation of enriched biodiesel under different storage conditions

ABSTRACTAlthough the commercial prospects for biodiesel have grown, some concern remains with respect to its resistance to oxidative degradation during storage. The presence of double bonds in the molecule induces a high level of reactivity with oxygen when it makes direct contact with air. Consequently, biodiesel storage over extended periods can lead to increased degradation of fuel properties, which can compromise fuel quality. This work used enriched biodiesel samples prepared by enriching palm oil methyl ester (PME) with methyl oleate (MO) at specified volumetric proportions (% v/v) PME80/MO20, PME70/MO30, PME60/MO40, and PME50/MO50 to determine the effects of long storage under two different conditions. The samples were stored either unexposed to air and daylight or exposed to air and daylight for 200 days. At regular intervals, the following physicochemical properties of the samples were measured: kinematic viscosity (KV), acid value (AV), higher heating value (HHV), and peroxide value (PV). Samples showed small differences under unexposed condition for KV, AV, HHV, and PV; however, samples showed significantly large differences under exposed condition. Biodiesel exposed to air and daylight tended to degrade at a faster rate than biodiesel under unexposed condition. The measured parameters of tested samples were not affected under unexposed condition but were affected under exposed condition.

Interactions of lauryl gallate with phospholipid components of biological membranes

The effect of different amounts of lauryl gallate (LG) on properties of the model membranes of phosphatidylcholines (PC), differing in the presence of double bonds in the hydrocarbon chains, and phosphatidylglycerol (PG) was described in terms of phase behaviour of mixtures, interactions between both components, monolayers stability and their organization. The Langmuir monolayer technique was used to monitor the surface thermodynamics (i.e. the excess area and excess Gibbs energy of mixing) on the basis of surface pressure–area per molecule (π–A) isotherms. Simultaneously, morphology of the studied monolayers was visualized by the Brewster angle microscopy (BAM). This allowed evaluating the kind and magnitude of interactions which influence on the phase behaviour and structural properties of the monolayers. The obtained results can be helpful to reveal the mechanism of phospholipid antioxidant protection and important pharmacological (antimicrobial) role of lauryl gallate for production of effective therapeutic substances.

Isolation of a new cytotoxic polyhydroxysterol from the South China Sea soft coral Sinularia sp.

A new polyhydroxysterol, (22E)-24-methylenecholestane-22-ene-3β,5α,6β-triol (1), together with four known analogues (2–5) were isolated from the South China Sea soft coral Sinularia sp. Their structures were elucidated by spectroscopic analyses and comparison with previously reported data. All these compounds exhibited cytotoxic effect against both HepG2 and HeLa cell lines with IC50 values ranging from 8.36 to 37.30 μM. Preliminary structure–activity relationship study identified that the presence of double bonds in the side chains of these polyhydroxysterols significantly reduced the biological effect obtained.

Solution Equilibrium Study of Divalent Metal Ions with Phenylpropanoid Derivatives and Acetylcysteine Ligands.

Solution equilibrium of divalent metal ions (M=Mn2+, Co2+, Ni2+, Cu2+ and Zn2+) with caffeic acid (ligand C) or dihydrocaffeic acid (ligand D) in binary system, and with acetylcysteine (ligand N) in ternary system were investigated at condition similar to human physiological temperature of 310.15 K and ionic strength of 0.15 mol·dm-3 NaCl. Potentiometry technique was used for the determination of formation constant (log β) assisted by spectrophotometry technique. The results indicated the formation of [ML], [MLH], [ML2], [ML2H] in binary species and [MLN], [MNLH], [MNLH2] in ternary species, where L represents ligands C or D. It was found that ligand D formed more stable complexes than that of ligand C, which were affected by the presence of double bond in the carboxylate moiety of ligand C. The speciation diagrams were simulated by HySS and discussed briefly, additionally the tendency of ternary complexes was evaluated from parameters Δ log KM and log X.

Hydrophobic and superhydrophobic surfaces fabricated by plasma polymerization of perfluorohexane, perfluoro(2-methylpent-2-ene), and perfluoro(4-methylpent-2-ene)

Fluoropolymer films were deposited on silicon (1 0 0) wafers, glass, epoxy, and hierarchical dual-sized filler epoxy composite surfaces by plasma polymerization of perfluorohexane, perfluoro(2-methylpent-2-ene), and perfluoro(4-methylpent-2-ene). The procedure involved continuous wave plasma-enhanced deposition, followed by a discharge-off period, with the monomer gas feed maintained. Silanization of silicon wafers and glass surfaces with triethoxyvinylsilane was employed to improve plasma fluoropolymer bonding to these substrates. The presence of double bonds in perfluoro(2-methylpent-2-ene) and perfluoro(4-methylpent-2-ene) was found to influence fluoropolymer coating topography, thereby increasing surface roughness in modified glass and epoxy substrates. All fluorocarbons provided a similar level of hydrophobization of flat substrates, exhibited by water contact angles (WCA) of about 110°. Hydrophobization of nanocomposite hierarchical surfaces by plasma polymerization provided superhydrophobic surfaces, with WCA of 160° and contact angle hysteresis below 8°.

Functionalized PEG‐b‐PAGE‐b‐PLGA triblock terpolymers as materials for nanoparticle preparation

ABSTRACTA series of poly(ethylene glycol)‐block‐poly(allyl glycidyl ether) (PEG‐b‐PAGE) macroinitiators are prepared using the living anionic ring‐opening polymerization (AROP) technique, and applied for further copolymerization studies. To overcome the low reactivity of the secondary hydroxyl end‐group of the PAGE block, a primary hydroxyl group is introduced into the macroinitiators via trityl and tert‐butyl‐dimethylsilane protective groups. The modified macroinitiators are used for copolymerization by applying different amounts of PEG‐b‐PAGE (5, 10, and 15%) and different PLGA lengths. To study their properties, nanoparticles from selected polymers are prepared and characterized by dynamic light scattering and scanning electron microscopy showing spherical particles with diameters around 200 nm and low PDIparticle values of 0.03–0.1. An advantage of the obtained polymers is the presence of double bonds in the side chain, which enables the modification via, for example, thiol‐ene reactions. For this purpose tertiary 2‐(dimethylamino)ethanethiol), acetylated thiogalactose and thiomannose are attached onto the double bonds of the PAGE‐blocks. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2163–2174

9,11-Secosteroids with cytotoxic activity from the South China Sea gorgonian coral Subergorgia suberosa

Nine new 9,11-secosterols (1–9), containing the same 3β,6α,11-trihydroxy-9,11-seco-5α-cholest-7-en-9-one steroidal nucleus, whereas possessing an array of structurally diverse side chains, along with fourteen known 9,11-secosterol compounds (10–23), were isolated from the South China Sea gorgonian coral Subergorgia suberosa, of which 3/4, 5/6, 7/8, and the known compounds 11/12, 20/21 were five pairs of inseparable C-24 epimers. Their structures were established by the extensive analyses of 1D and 2D NMR spectra, high-resolution chemical ionization mass spectrometry (HRCIMS), and by the comparison with literature data. Cytotoxic effect of these metabolites against the growth of HeLa cell lines was evaluated. The result showed that the inhibitory effect of compounds 1–23 varied considerably depending on the nature of the side chain in spite of sharing the same steroidal nucleus. Compound 19, featuring both the absence of hydroxyl group and the presence of double bond in the stigmasterol side chain, exhibited the most potent cytotoxicity with IC50 being 15.1μM. The preliminary structure activity relationship studies identified some important structural features considerably influencing the biological effect deserved, providing valuable information for chemists and pharmacologists to design and synthesize more effective antitumor agents bearing the 9,11-secosteroid framework.