Enzymatic production of modified 2‐dodecyl‐sophorosides (biosurfactants) and their characterization

Abstract

Alkyl sophorosides, a special type of sophorolipids, can be produced using Candida bombicola cultures with glucose as main carbon source and 2-dodecanol as co-substrate. The dominating component, 2-dodecylsophoroside SL-E 2-12 , was purified via medium pressure liquid chromatography (MPLC) and used as substrate for further enzymatic modifications. Using b-glucuronidase in aqueous media the first modification gave a glycosidic cleavage of the acetyl glucose unit leading to 2-dodecyl-glucoside GL-A 2-12 . In a subsequent lipase-catalyzed acylation with sebacic acid in toluene this compound was functionalized regioselectively at the primary C-6 0 position of glucose. Similar lipase-catalyzed reactions in toluene, but now using SL-E 2-12 as acyl acceptor and unusual hydroxyl fatty acids -3-hydroxy decanoic acid and 17-hydroxy stearic acid -as acyl donors, resulted in mono-and diacylations of primary hydroxyl positions of the sophorose unit (C-6 0 and C-6 00 ) as shown by NMR and MS studies. In physicochemical characterization experiments the new glycoconjugates lowered the surface tension of water from 72 to 27-32 mN/m. Moreover it was observed that the new products inhibit the growth of particular Gram-positive bacteria. Additionally they indicate potential for anti-tumor promoting activity.Practical applications: According to literature data 2-alkyl-sophorosides can be produced using Candida bombicola cultures with yields of more than 20 g/L. Based on this starting material, 2-dodecyl-sophoroside, several regioselective enzymatic modifications were performed. Initially, b-glucuronidase catalysis in aqueous buffer solution gave 2-dodecyl-glucoside which was then successfully acylated at the C-6 position of glucose by lipase catalysis using a common dicarboxylic acid, sebacic acid. The resulting free carboxylic function of the acidic derivative opens up the possibility of achieving additional chemo-enzymatic reactions at this position for conversion, for instance, into polyesters. In addition lipase catalysis in organic solvents of 2-dodecyl-sophoroside allows acylation with unusual hydroxyl fatty acids of microbial origin. Physicochemical studies showed that these new glycoconjugates may be of interest for the cosmetic industry due to moisture conservation of the skin. For practical applications the conditions of the above biocatalytic reactions have been improved and scaled up.

Chemical and enzymatic modification of sophorolipids

“…The modification of 2-dodecyl sophorolipid 99, prepared by fermentation with 2-dodecanol as substrate, was performed by Recke et al (Scheme 15). 56 The 2-dodecyl sophorolipid 99 was transformed into the 2-dodecyl glucolipid 100 via the selective removal of a glucose unit with the β-glucuronidase enzyme. Subsequently, this glucolipid was acylated at the 6′-position with sebacic acid towards glucolipid 101.…”

“…These hydroxyalkyl-etherified sophorolipid esters were incorporated in cosmetic compositions to prepare powdered compressed cosmetic materials such as face powder, cheek rouge, highlight or eye shadow or stick-shaped cosmetic materials such as stick- Scheme 15 Acylations at the 6'-and 6''-position of sophorolipid 99 and glucolipid 100. 56 shaped rouge, lip cream, stick-shaped eye shadow or cosmetic pencil. 61 They were also applied in cosmetics as moistureretaining and moisturizing agents, giving a less sticky and better moisturizing feeling than conventional moisturizers such as glycerine, sorbitol and ethylene glycol.…”

Enzymatic synthesis and modification of surface‐active glycolipids

“…Sophorolipids are very promising biosurfactants and have been object to several studies aiming to modify and to improve their properties. Recke et al (2013) recently reported the enzymatic modification of alkyl sophorolipids, a special sophorolipid produced by Candida bombicola , resulting in the formation of a new and unexplored glycolipids . These glycolipids have been acylated with fatty acids originating from other glycolipids, namely 3‐hydroxydecanoic acid from rhamnolipids and 17‐hydroxyoctadecanoic acid obtained from sophorolipids employing Novozyme 435 in toluene.…”

“…Being odor‐ and tasteless and non‐irritant, they might furthermore be very interesting for applications as emulsifier in food or cosmetic formulations . Additionally, antimicrobial , antiviral and antifungal properties of glycolipids, as well as their possible application as anti‐tumor agent are described in literature. This versatility and the physico‐chemical properties of glycolipids thus might allow their use in many different applications, e.g., in cleaning products or in food and pharmaceutical formulations.…”

Structure Elucidation and Characterization of Microbial 2-Tridecyl Sophorosides (Biosurfactants)

“…The infl uence of the purifi ed glycolipids on the surface tension (σ) of aqueous solutions and on the interfacial tension (γ) of water/n-hexadecane systems was determined at 25 °C with a tensiomat (TE1C MGW; Lauda, Lauda-Königshofen, Germany) using the ring method (Recke et al, 2013).…”