Study On The Structure And In-vitro Anti-cancer Effects Of Triacylglycerols From Seed Oil Of Momordica Charantia L. Var. Abbreviata Ser

Momordica charantia L. var. abbreviata Ser. (MCV) is identified as a species of Momordica charantia. (MC). Triacylglycerols (TG) are the major components (85.43%) of the seed oil of MCV (MCVO). Conjugated linolenic acids (CLn, 55.13%) are the characteristic fatty acids (FA) of MCVO andα-eleostearic acid is the major isomer in three isomers of CLn in MCVO (51.54%). MCVO is a mixture of TGs containing CLn.Many investigations have focused their attentions on the anti-colon carcinogenesis activities and mechanisms of the seed oil of MC andα-eleostearic acid in the world recently. However, there are almost no reports concerning the inhibitory effect of TGs in MC or MCV on tumor cells. It is generally accepted that FAs are basic units of lipids and the inhibitory effect of lipids on tumor cell lines is attributable to FAs. The inhibitory effect of TGs is completely neglected. Another common thought that prevents the investigation of active effect of TGs is that TGs must be degraded to free fatty acids (FFA) to pass into the mucosal cells and FA composition is commonly regarded as the key factor for active effects of lipids. The anticancer effects of MCVTG, which contain CLn, were compared with that of CLn, which is in FFA form, in this paper. The connections between structures of MCVTGs and their anti-carcinogenesis activities were also studied.In this paper, the chemical components of the seed of MCV were analyzed and the lipids content was tested to be 32.04%; the basic chemical characters and the FA compositions of MCVO were also analyzed; the major characteristic FA of MCVO was identified asα-eleostearic acid.It was found that the method of pancreatic lipase recommended by AOCS and its corrected method are not the appropriate methods for the distribution analysis of FAs in MCVO. The sn-2 position of glycerol backbone of TGs in MCVO was mainly occupied by CLn according to the ¹³C-NMR data. The ¹³C-NMR data of AAA type TG containingα-eleostearic acid, which was separated from tung oil, were supplemented.With TGs mixture of MCVO separated by NARP-HPLC and their structures identified by APCI-MS, twenty kinds of TGs with CLn mainly occupying sn-2 position were obtained. The FA distribution of two kinds of pure TGs was analyzed by ¹³C-NMR and the result was consistent with that of APCI-MS. A positional isomer of an individual TG in MCVO—namely SCLnS, was synthesized by transesterification, and then the new compond was identified as SSCLn by APCI-MS. This shows APCI-MS is the appropriate method for TGs structure identification.Withα-eleostearic acid as control, the cytotoxic effects of TGs mixture and TGs separated from MCVO on five cultured human tumor cell lines were investigated to illustrate the connections between the effect and the component and structure of TGs. Six groups of MCVTG displayed different intenseness of cytotoxic effect on five human tumor cell lines. MCVTG are more cytotoxic thanα-eleostearic acid on four cell lines except for LS-174-T, suggesting that the anti-cancer effect of CLn in its FFA form is weaker than its TG form. MCVTG andα-eleostearic acid displayed weak cytotoxic effect on normal cell line of L02. They inhibited cells growth in a dose-dependent manner, but the time-dependent is not significant. On the whole, an individual TG, whose structure was identified as SCLnS, displayed the most intense cytotoxic effect on several tumor cell lines, e.g. SGC-7901, KB, and Bel-7402, especially at low concentrations. The difference of anti-cancer effct between SSCLn and SCLnS is not significant to deduce the conclusion that the different positions of glycerol backbone occupied by CLn can affect the anti-cancer effct of TGs. The cytotoxic action of TGs containing CLn against human tumor cells might be attributable to conjugated trienoic structure of CLn, with mechanism of lipid peroxidation. But oxidation rate of CLn can be slowed by triacylglycerol esterification and the bioactive center of CLn can be protected before absorption.MCVTG was compared with TGs of tung oil from the FAs composition, the component and structure of TGs, and the cytotoxic effect of similar TGs groups on tumor cell lines. The work probably gives us hints to illustrate the structure factors of TGs for the anti-cancer effect of MCVTG and probably promotes the development ofα-eleostearic acid sources in tung oil.SCLnCLn is the major component of MCVTG (approximately 60% of total TGs). It displayed most intense cytotoxic effect on SGC-7901 cell line and is a pure material isolated by NARP-HPLC. It was enriched by method of fractionation with mixed solvent of anhydrous ethanol and hexane.SCLnS was minor conponent in MCVO. TGs in MCVO or tung oil were converted to SCLnS by transesterification catalyzed by sn-1,3 lipase.