MALDI-TOF/MS fingerprinting of triacylglycerols (TAGs) in olive oils produced in the Israeli Negev desert

Triacylglycerols (TAGs), composed of three esterified fatty acids with an attached glycerol backbone, are the main component of vegetable oil (approximately 95%) and an important source of energy and nutrition for humans, so their compositional analysis merits extensive interest. Intact TAG composition of oil in native form is highly important, rather than the fatty acid profile itself. This paper reports the analysis of the TAG profile of olive oils produced from the six common olive cultivars grown in the Negev desert of Israel (Barnea, Souri, Arbequina, Picual, Leccino, and Koroneiki) together with the content of some additional common oil quality parameters closely associated with TAG composition and integrity. Matrix-assisted laser ionization-desorption time-of-flight/mass spectrometry (MALDI-TOF/MS) fingerprintings were employed for TAG profiling. With 2,5-dihydroxybenzoic acid (DHB), MALDI-TOF/MS was able to fingerprint the intact TAG profiles in olive oils in a fast and easy manner without any derivatization. Triolein (31.53%) was found to be the main intact TAG followed by dioleoyl-palmitoyl (23.06%) and dioleoyl-linoleoyl (14.31%). MALDI-TOF/MS also enabled calculation of the main fatty acids and their compositions in a simple manner from the TAG profiles; the results are found to be very similar to conventional methods determined by GC and HPLC. Average free fatty acids and peroxide value were found to be less than 0.8% and 10 mequiv of O(2)/kg of oil, respectively, in all of the tested oils. Relatively high levels of tocopherols (av = 325 microg/kg) and phytosterols (av = 2375 mg/kg) were found. This study demonstrates MALDI-TOF/MS technology as an easy and fast methodology for TAG and fatty acid profile analysis in olive oils. Additionally, this study also shows the high levels of tocopherols and phytosterols in the olive oils produced from the common cultivars grown in the Israeli Negev desert.

Desert date (Balanites aegyptiaca) as an arid lands sustainable bioresource for biodiesel

The aim of this study was to assess the suitability of Desert date (Balanites aegyptiaca L. Delile) as an oil crop in arid lands for large-scale sustainable industrial biodiesel production. Characterization of the Desert date plant material showed that using proper cultivation practices with emphasis on low quality irrigation water trees can be extremely well developed in hyper-arid conditions of the Israeli Arava desert and yield oil-rich fruits. Best selected trees can yield date fruits up to 52 kg/trees. Desert date kernels oil content may reach up to 46.7% (based on dry weight). The oil is consisted on four major fatty acids: palmitic (16:0), stearic (18:0), oleic (18:1), and linoleic (18:2), constituting 98-100% of the total fatty acids in the oil of all tested genotypes. Linoleic acid was the most prevalent fatty acid, ranging from 31% to 51% of the fatty acids profile, very similar to soybean oil profile. In situ biodiesel production directly from oil-enriched powder was successfully developed. Yield efficiency for both conventional and in situ biodiesel production was about 90%. The qualities of the produced biodiesel well meet the international biodiesel standards. The present study clearly demonstrated Desert date as a model for the utilization of bioresources in the Israeli Arava desert and potentially other similar areas for cost-effective biodiesel production.

Determination of fatty acid profiles and TAGs in vegetable oils by MALDI-TOF/MS fingerprinting

Vegetable oils are complex mixtures containing a wide range of major compounds. Triacylglycerols (TAGs; consisting of a glycerol moiety with each hydroxyl group esterified to a fatty acid) are the major components (95-98%) of vegetable oils. TAGs are an important source of energy and nutrition for humans, so their compositional analysis merits extensive interest. Analysis of TAGs has increased in recent years and the advancement has been driven by the development of analytical technologies. This chapter discusses techniques for determination of TAG and fatty acid profiles (FAPs) of vegetable oils using matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF/MS) and gas chromatography-mass spectrometry (GC/MS). Considering the importance of TAG in its native form, rather than FAPs, special emphasis has been given to the TAG fingerprinting analyses of intact oils. MALDI-TOF/MS also enabled calculation of the main fatty acids and their compositions in a simple manner from the TAG profiles; the results are found to be very similar to the prevailing methods of derivatization using GC/MS. This study depicts the potential of MALDI-TOF/MS as an easy, fast, and reliable technique to characterize the TAG and FAPs in vegetable oils.

Larvicidal activity of saponins from Balanites aegyptiaca callus against Aedes aegypti mosquito

Seeking an alternative approach for producing a larvicidal product from Balanites aegyptiaca plants, callus was produced from in vitro cultures of root explants and its larvicidal activity against Aedes aegypti mosquito larvae was evaluated. Concentrations of 0, 50, 100, 500, 1000, and 1500 ppm of saponins from the root-derived callus of B. aegyptiaca were used to determine larvicidal effects and consequent effect on adult emergence. A dose-dependent effect was observed. In a chronic mortality assessment (after 7 days of exposure), concentrations of 500 ppm or greater killed 100% of the test larvae population. Fifty parts per million showed no difference in larval mortality compared to the control (0 ppm); however, this concentration allowed one-fourth of the adult emergence of the control treatment. These results suggest that saponins from in vitro cultures of the root explant of B. aegyptiaca can be used as a larvicidal agent against A. aegypti larvae.

Larvicidal Properties of the Three Major Furostanol Saponins of Balanites aegyptiaca Fruit Mesocarp against Aedes agypti Mosquito Larvae

Among various biological activities, saponin-rich extracts have been found to be larvicidal against mosquito larvae; however, no study so far has reported using pure furostanol saponins. In this study, three major furostanol saponins: 26-( O-β-D-glucopyranosyl)-3β,22,26-trihydroxyfurost-5-ene 3- O-β-D-glucopyranosyl-(1→4)-[α-L-rhamnopyranosyl-(1→2)]-β-D-glucopyranoside (1), 26-( O-β-D-glucopyranosyl)-22- O-methylfurost-5-ene-3β,26-diol 3- O-β-D-xylopyranosyl-(1→3)-β-D-glucopyranosyl-(1→4)-[α-L-rhamnopyranosyl-(1→2)]-β-D-glucopyranoside (2), and 26-( O-β-D-glucopyranosyl)-22- O-methylfurost-5-ene.3β,26-diol 3- O-β-D-glucopyranosyl-(1→4)-[α-L-rhamnopyranosyl-(1→2)]-β-D-glucopyranoside (3) were isolated from methanol extracts of the fruit mesocarp of Balanites aegyptiaca (L.) Del. (desert date). Their identification was carried out by ESI-MSn and structures were elucidated by 800 MHz 1H NMR spectroscopy. The larvicidal properties of these saponins against the Aedes aegypti mosquito larvae were evaluated. Results suggest that all three saponins possess larvicidal activity, but the activity was found to be related to the structure of the saponins, basically in the C-22 position of the aglycone and in the oligosaccharide chain. A furostanol saponin that presents -OCH3 at the C-22 position compared to an -OH group, and the lack of a xylose molecule compared to its presence is found to be more larvicidal.

Determination of saponins in the kernel cake of Balanites aegyptiaca by HPLC-ESI/MS

The kernel cake produced from Balanites aegyptiaca fruit of Israeli origin was analysed for its saponin constituents using high-performance liquid chromatography-mass spectrometry (HPLC-MS). The HPLC was equipped with a reversed-phase C18 column and a refractive index detector (RID), and elution was isocratic with methanol and water (70:30). The MS system was equipped with electrospray ionisation (ESI). Nine compounds were chromatographically separated, their masses were determined in the negative ion mode and subsequent fragmentation of each component was carried out. From the nine components, six saponins with molecular masses of 1196, 1064, 1210, 1224, 1078 and 1046 Da were identified, with the compound of mass 1210 Da being the main saponin (ca. 36%). Saponins with masses of 1224 and 1046 Da have not been previously reported in B. aegyptiaca. In all saponins, diosgenin was found to be the sole aglycone. This study shows that HPLC-ESI/MS is a quick and reliable technique for characterizing the saponins from kernel cake of B. aegyptiaca.

Structural analysis of complex saponins of Balanites aegyptiaca by 800 MHz 1H NMR spectroscopy

The main saponin (1) present in the mesocarp of Balanites aegyptiaca fruit is a mixture of 22R and 22S epimers of 26-(O-beta-D-glucopyranosyl)-3-beta-[4-O-(beta-D-glucopyranosyl)-2-O-(alpha-L-rhamnopyranosyl)-beta-D-glucopyranosyloxy]-22,26-dihydroxyfurost-5-ene. This structure differs from a previously reported saponin isolated from this source by the site of attachment of the rhamnosyl residue, and presumably represents a structural revision of the latter. The main saponin (2) present in the kernel is a xylopyranosyl derivative of 1. The use of high-field NMR enabled the practically complete assignment of 1H and 13C chemical shifts of these complex saponins, existing as a mixture of C-22 epimers. Moreover, the work represents a new approach to structural elucidation of saponins: direct preparative-scale HPLC-RID of crude extracts followed by high-field NMR investigations supported by ESI-MSn.

Phyto-saponins as a natural adjuvant for delivery of agromaterials through plant cuticle membranes

With growing use of synthetic adjuvants in modern agriculture, their impacts on the environment are being questioned. In a search for an environmentally safe phyto-adjuvant, we have investigated natural glycosidic saponin for delivery of agromaterials through plant cuticle membranes. Four saponin preparations from Quillaja saponaria bark (QE), obtained from Sigma-Aldrich, and Balanites aegyptiaca fruit mesocarp (ME), kernel (KE), and root (RE), isolated and characterized in our laboratory, were used for testing the delivery of [14C]-2,4-dichlorophenoxyacetic acid (2,4-D) across isolated intact astomatous adaxial Citrus grandis leaf cuticle membranes (CMs). The results showed that both Q. saponaria and B. aegyptiaca saponin preparations enhanced delivery of 2,4-D through CMs. Among the saponin preparations, ME exhibited a significantly higher level of delivery of 2,4-D with a concentration effect (2% being the highest). Transmission electron microscope (TEM) and dynamic light scattering (DLS) characterization of these saponin preparations in aqueous solution clearly demonstrated the formation of nanoscale vesicles. Various possibilities for a natural amphiphatic phyto-saponin as a delivery adjuvant through CMs are discussed.

Larvicidal activity of saponin containing extracts and fractions of fruit mesocarp of Balanites aegyptiaca

Chloroform, ethyl acetate, butanol and methanol extracts of fruit mesocarp of Balanites aegyptiaca and five fractions from the methanol extract were tested against the Aedes aegypti mosquito larvae. All extracts showed larvicidal effects however the highest larval mortality was found in methanol extract. One fraction obtained from the silica gel column chromatography of the latter was found most effective for larval mortality. This fraction also interfered with adult emergence. A concentration of 0.0014% (w/v) of this active fraction showed inhibition of the 50% of the test larval population from emerging adults (EC(50)). The analysis of total saponin content of these tested extracts and fractions revealed a strong correlation between saponin content and larval mortality.

Bioproduction of Diosgenin in Callus Cultures of Balanites aegyptiaca: Effect of Growth Regulators, Explants and Somatic Embryogenesis

This study describes the effects of plant growth regulators, explants, and somatic embryogenesis on in vitro production of the steroidal sapogenin, diosgenin, in callus cultures of the Balanites aegyptiaca (L.) Del.(desert date). Root, shoot, hypocotyl, and epicotyl callus culture of B. aegyptiaca, were raised on MS basal media supplemented with various combinations of either 2,4-D and NAA alone, or with BAP. The diosgenin content (on a dry weight basis) was found to be highest when calli were cultured in MS basal medium supplemented with 1.0 mg l−1 2,4-D alone and/or in combination with 0.5 mg l−1 BAP. However, the callus growth was highest in media supplemented with 2.5 or 3.0 mg l−1 2,4-D. MS basal media supplemented with 2,4-D 2.5 mg l−1 alone and in combination with 0.5 mg l−1 BAP induced pre-embryogenic callus formation on root cultures. When these pre-embryogenic callus cultures were used to establish cell suspension cultures, two growth densities were obtained in embryogenic suspension cultures, inducing clusters of somatic embryos at various stages of development. The maximum number of somatic embryos were obtained at the fifth week on the medium supplemented with 1.0 mg l−1 2,4-D. However, the diosgenin content in these somatic cells was found to be lower compared to the explant calluses. This study revealed that production of diosgenin in callus cultures of B. aegyptiaca is possible, but the amount is significantly affected by the growth regulators, type of explants, and somatic embryogenesis.