A comprehensive review on natural occurrence, synthesis and biological activities of glycolipids.

Glycolipids are ubiquitous and biologically important molecules and are involved in diverse biological functions and exhibit biosurfactant applications due to their surface-active and biodegradability properties. Despite showing a wide range of biological functions, not enough commercial exploitation has been taken place. Possible reasons for this could be the lack of focus or commercially viable processes for isolation/purification, as these glycolipids are found to be complex mixtures in their respective natural sources. Keeping these complexities in view, in this review, we focused on natural occurrences, including plants, marine micro algae, microorganisms, and salient features of various chemical methods, including glycosylation methods for the synthesis of different types of glycolipids. Further, this review significantly summarises the biological evaluation of a diverse class of glycolipids isolated and/or synthesized either by partial or total synthesis.

Synthesis and biological evaluation of 5-fatty-acylamido-1, 3, 4-thiadiazole-2-thioglycosides.

In the present study, the synthesis of 1, 3, 4-thiadiazole-based thioglycosides were accomplished in good yields with employing a convergent synthetic route. The starting material 5-amino-1, 3, 4-thiadiazole-2-thiol and followed by a series of 5-fatty-acylamido-1, 3, 4-thiadiazole-2-thiols (4a-4j) were synthesized with different fatty acid chlorides. The glycosylation of compounds 4a-4j were achieved with trichloroacetimidate methodology. Antimicrobial and cytotoxicity activities of title compounds were evaluated. Among the entire compounds lauric acid and myristic acid derivatives showed good and moderate antimicrobial activity. In case of cytotoxicity results of compounds 8a-8j and 9a-9j, the acetate protected short chain (C6:0, C8:0, C10:0) compounds and the free hydroxyl long chain saturated (C16:0, C18:0) and unsaturated (C18:1, C22:1) compounds exhibited good activity against different cancer cell lines. Further, the free hydroxyl compounds 9a, 9c-9j did not show any toxicity towards normal CHO-K1 cell line whereas acylated compounds 8a-8j exhibited toxicity.

Synthesis of dihydrosterculic acid-based monoglucosyl diacylglycerol and its analogues and their biological evaluation.

In the present study, Lactobacillus plantarum glycolipid (GL1) molecule in ß-configuration and its fatty acid analogues were synthesized using trichloroacetimidate methodology. The ß-configuration of the GL1 molecule was unambiguously assigned by NMR studies using 2D-ROESY (NOE) and J-coupling analysis. Dihydrosterculic acid was synthesized using Furukawa's reagent and the selective esterification of dihydrosterculic acid at C-3 position of glycerol was achieved with EDC-HCl at 0 °C. In vitro cytotoxicity of the GL1 molecule and its fatty acid analogues was evaluated against DU145, A549, SKOV3 and MCF7 cell lines. Among all the synthesized molecules, the GL1 molecule and compound 7d showed moderate activity, while the compound 7b showed promising activity against all the tested cell lines with IC50 values of 20.1, 18.2, 19.1 and 17.6 µM, respectively. In addition, all tested compounds showed poor cytotoxicity against normal HUVEC cells. The MCF7 cells when treated with compound 7b showed lower bromodeoxyuridine incorporation levels as compared to untreated cells, suggesting that the compound 7b was highly effective and inhibited the cell proliferation. In addition, the compounds showed significant increase in caspases 3 and 9 levels by inducing apoptosis in MCF 7 cells.

Synthesis of novel ethyl 1-ethyl-6-fluoro-7-(fatty amido)-1,4-dihydro-4-oxoquinoline-3-carboxylate derivatives and their biological evaluation.

A series of novel ethyl 1-ethyl-6-fluoro-7-(fatty amido)-1,4-dihydro-4-oxoquinoline-3-carboxylate derivatives were prepared through multistep synthesis. The key step in the synthesis was to obtain the C-7 fatty amide derivative. The azide was selectively formed at C-7 position using sodium azide at 60°C. Subsequently, the azide was reduced under mild conditions using zinc and ammonium chloride to form the corresponding amine. The synthesized derivatives were further subjected to biological evaluation studies like cytotoxicity against a panel of cancer cell lines such as DU145, A549, SKOV3, MCF7 and normal lung cells, IMR-90 as well as with antimicrobial and antioxidant activities. It was observed that the carboxylated quinolone derivatives with hexanoic (8a), octanoic (8b), lauric (8d) and myristic (8e) moieties exhibited promising cytotoxicity against all the tested cancer cell lines. The results also suggested that hexanoic acid-based fatty amide carboxylated quinolone derivative (8a) exhibited promising activity against both bacterial and fungal strains and significant antibacterial activity was observed against Staphylococcus aureus MTCC 96 (MIC value of 3.9µg/mL). The compound 8a also showed excellent anti-biofilm activity against Staphylococcus aureus MTCC 96 and Bacillus subtilis MTCC 121 with MIC values of 2.1 and 4.6µg/mL, respectively.

Enzymatic production of trans fatty acid free fat from partially hydrogenated soybean oil (PHSO)--theory, strategy and practicability.

Development of an advanced process/production technology for healthful fats constitutes a major interest of plant oil refinery industry. In this work, a strategy to produce trans fatty acid (TFA) free (or low TFA) products from partially hydrogenated soybean oil by lipase-catalysed selective hydrolysis was proposed, where a physically founded mathematic model to delineate the multi-responses of the reaction as a function of selectivity factor was defined for the first time. The practicability of this strategy was assessed with commercial trans-selective Candida antarctica lipase A (CAL-A) as a model biocatalyst based on a parameter study and fitting to the model. CAL-A was found to have a selectivity factor 4.26 and to maximally remove 73.3% of total TFAs at 46.5% hydrolysis degree.

Lipases as biocatalysts for the synthesis of structured lipids.

Structured lipids (SL) are broadly referred to as modified or synthetic oils and fats or lipids with functional or pharmaceutical applications. Some structured lipids, such as triglycerides that contain both long-chain (mainly essential) fatty acids and medium- or short-chain fatty acids and also artificial products that mimic the structure of natural materials, namely human milk fat substitutes and cocoa butter equivalents, have been discussed. Further, other modified or synthetic lipids, such as structured phospholipids and synthetic phenolic lipids are also included in this chapter. For all the products described in this chapter, enzymatic production in industry has been already conducted in one way or another. Cocoa butter equivalents, healthy oil containing medium-chain fatty acids, phosphatidyl serine, and phenol lipids from enzyme technology have been reported for commercial operation. As the demand for better quality functional lipids is increasing, the production of structured lipids becomes an interesting area. Thus, in this chapter we have discussed latest developments as well as present industrial situation of all commercially important structured lipids.