Antimicrobial surfactant
Lactonic sophorolipids have multiple targets and mechanisms of action. As antimicrobial surfactants, they disrupt microbial cell membranes. As anticancer agents, they induce apoptosis in cancer cells through the caspase-3 pathway. Lactonic sophorolipids have been shown to inhibit cell proliferation, induce apoptosis, and regulate the expression of genes and proteins associated with apoptosis (e.g., Bax, Bcl-2, Apaf-1, caspase-3, caspase-9). Their surface-active properties contribute to their antimicrobial activity.

Liver cancer, one of the most common types of cancer in the world, is the second leading cause of death for cancer patients. For liver cancer, there is an urgent need for an effective treatment with no or less toxic side effects. Lactonic sophorolipids (LSL), as a potential anticancer drug, has attracted wide attention of pharmaceutical researchers with its good biological activities. The effects of LSL and cell death inhibitors were measured by MTT test on HepG2 cells. Meanwhile, the morphology of the cells was observed under a microscope. The apoptosis rate was detected by flow cytometry, and the expression levels of enzyme activity of Caspase-3 and Caspase-9 were measured by detection kits. Meanwhile, mRNA levels of Apaf-1, Caspase-3, Bax, and Bcl-2 were measured by quantitative real-time RT-PCR; protein levels of Caspase-3, Cleaved Caspase-3, Bax, and Bcl-2 were measured by western blot. LSL can inhibit the proliferation of cells, and it is possible to induce apoptosis in cells. The HepG2 cells with LSL co-culture exhibited typical apoptotic morphology, and the expression levels of enzyme activity of Caspase-3 and Caspase-9 increased (P< 0.05). We also found that LSL increases cell apoptosis rate and regulates the expression of genes and proteins associated with apoptosis through the Caspase-3 pathway. These results indicate that LSL may be one of the potential drug candidates to inhibit the proliferation and induce apoptosis in HepG2 cells.Key points• LSL, which is of good biological activities such as anti-bacterium, virus elimination, and inflammatory response elimination, has been firstly used to intervene in vitro to investigate its effect on HepG2 cell proliferation.• LSL can inhibit the proliferation of cells, and it is possible to induce apoptosis in HepG2 cells through the Caspase-3 pathway.• The mechanism of LSL action on HepG2 cell proliferation was firstly also discussed, which provides a certain experimental reference for the clinical treatment of liver cancer[2].
In vitro, lactonic sophorolipids have been shown to inhibit the proliferation of HepG2 liver cancer cells. The compounds induce apoptosis in HepG2 cells through the caspase-3 pathway. Treatment with lactonic sophorolipids results in increased expression of caspase-3 and caspase-9 enzyme activity, increased apoptosis rate, and regulation of apoptosis-associated genes and proteins (Bax, Bcl-2, Apaf-1). The compounds exhibit typical apoptotic morphology in treated cells. These effects demonstrate the potential of lactonic sophorolipids as anticancer agents.

Aims: To assess the efficacy of rhamnolipid (mixture of monorhamnolipid and dirhamnolipid congeners), purified monorhamnolipid, dirhamnolipid and lactonic sophorolipid biosurfactants against pathogens important for oral hygiene.[1]
Methods and results: Acquired and produced biosurfactants were fully characterized to allow the antimicrobial activity to be assigned to the biosurfactant congeners. Antimicrobial activity was assessed using the resazurin-aided microdilution method. Mixed rhamnolipid JBR425 (MR) and lactonic sophorolipids (LSLs) demonstrated the lowest minimum inhibitory concentration (MIC) which ranged between 100 and 400 μg ml-1 against Streptococcus mutans, Streptococcus oralis, Actinomyces naeslundii, Neisseria mucosa and Streptococcus sanguinis. Combining these biosurfactants with standard antimicrobial agents namely chlorhexidine, sodium lauryl sulphate, tetracycline HCl and ciprofloxacin showed a dramatic drop in the MIC values. In addition, in vitro studies demonstrated the biosurfactants' ability to prevent and disrupt oral pathogens biofilms. The increased permeability of microorganisms treated with biosurfactant, as shown using bisbenzimide dye, in part explains the inhibition effect.[1]
Conclusion: The results demonstrate that rhamnolipids and LSLs have the ability to inhibit oral pathogens both in planktonic and oral biofilm states.[1]
Significance and impact of the study: The findings indicate the potential value of biosurfactants for both oral hygiene and the pharmaceutical industries since there is a serious need to reduce the reliance on synthetic antimicrobials and antibiotics.[1]
In vivo, lactonic sophorolipids have been studied for their potential as anticancer and antimicrobial agents. As biosurfactants, they are used in various industrial applications including cleaning products, cosmetics, and as biodegradable alternatives to synthetic surfactants. Their natural origin and biocompatibility make them attractive for biomedical and industrial applications.

Caspase-3 and Caspase-9 enzyme activity assay[2]
The HepG2 cells were treated with the LSL (25 μg/mL) for 24 h, and then collected. Next, the cells were assayed in strict accordance with the instructions of the corresponding activity assay kits. Finally, absorbance value at 405 nm was determined by using a micro-plate reader. The protein concentration was calculated according to the manufacturer’s instructions.
In vitro enzyme/receptor binding assays for lactonic sophorolipids are not typically performed as they are natural products with pleiotropic effects. However, assays for antimicrobial activity (e.g., minimum inhibitory concentration, MIC, against various pathogens) are conducted. Apoptosis assays are performed using flow cytometry, caspase activity assays, and Western blot for apoptosis-related proteins. MTT assays measure cell proliferation inhibition. These assays characterize the compound's biological activities and mechanisms.

Apoptosis inhibitor[1]
HepG2 cells were seeded in a 96-well plate at a density of 1 × 104 cells/well. Each group was cultured in a DMEM medium containing LSL (25 μg/mL) except the control group. In the treatment group, apoptosis inhibitor (0, 5, 10, 20 μM) was added. Then the cells’ survival rate of each group was tested.

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Necrosis inhibitor[1]
HepG2 cells were seeded in a 96-well plate at a density of 1 × 104 cells/well. Each group was cultured in a DMEM medium containing LSL (25 μg/mL) except the control group. In the treatment group, necrosis inhibitor (0, 20, 40, 80 μM) was added respectively. Then the cells survival rate of each group was calculated.
In vitro cellular studies are conducted using various cancer cell lines, particularly HepG2 liver cancer cells. Cells are treated with lactonic sophorolipids at various concentrations (typically μg/mL to mg/mL ranges) for defined time periods. Cell viability is assessed using MTT assays. Apoptosis is measured by flow cytometry (Annexin V/PI staining). Caspase-3 and caspase-9 enzyme activity is measured using detection kits. Gene expression (Apaf-1, caspase-3, Bax, Bcl-2) is measured by RT-PCR. Protein levels are measured by Western blot.

In vivo animal experiments with lactonic sophorolipids are limited. The compounds are natural biosurfactants used in various applications including oral hygiene. Further in vivo studies are needed to evaluate their therapeutic potential. The compounds are for research use only and not intended for human therapeutic applications.

Pharmacokinetic properties of lactonic sophorolipids include solubility in various solvents. The compound has the molecular formula C34H56O14 and molecular weight of 688.8 g/mol. It appears as a solid or powder and should be stored under recommended conditions. The compound is a glycolipid with surface-active properties. Purity is typically ≥90%. Storage conditions should be optimized to maintain stability.

Toxicological data for lactonic sophorolipids are derived from their use as natural biosurfactants. They are generally considered to have low toxicity and are biocompatible. As natural products from fermentation, they are biodegradable and environmentally friendly. No significant toxicity has been reported at effective concentrations. The compounds are for research use only and not intended for human therapeutic applications. Standard safety precautions should be followed when handling the compounds.

[1].Rhamnolipids and lactonic sophorolipids: natural antimicrobial surfactants for oral hygiene. J Appl Microbiol. 2017 Nov;123(5):1111-1123.

[2].Lactonic sophorolipid-induced apoptosis in human HepG2 cells through the Caspase-3 pathway. Appl Microbiol Biotechnol. 2021 Mar;105(5):2033-2042.

Lactonic (di-acetylated) Sophorolipids are also known as Lactonic Sophorolipid, 1',4-Sophorolactone 6',6-diacetate from yeast, and 1',4'-Sophorolactone 6',6'-diacetate from yeast. They are naturally occurring glycolipids generated from fermentation of sugar by yeasts including C. bombicola. These compounds are used as biosurfactants, antimicrobial agents for oral hygiene, and potential anticancer agents. They induce apoptosis in human HepG2 cells through the caspase-3 pathway. Purity is ≥90%.

C34H56O14

688.8

688.367

148409-20-5

117065237

Typically exists as light yellow to yellow solids at room temperature

1.2±0.1 g/cm3

843.8±65.0 °C at 760 mmHg

256.9±27.8 °C

0.0±0.6 mmHg at 25°C

1.484

7.83

4

14

6

48

1010

11

C[C@H]1CCCCCCC=CCCCCCCCC(=O)O[C@@H]2[C@@H](COC(=O)C)O[C@H]([C@@H]([C@H]2O)O)O[C@@H]3[C@H]([C@@H]([C@@H](COC(=O)C)O[C@H]3O1)O)O

OGTXYHUVJIPSDT-GNUCGHNBSA-N

InChI=1S/C34H56O14/c1-21-17-15-13-11-9-7-5-4-6-8-10-12-14-16-18-26(37)47-31-25(20-43-23(3)36)46-33(30(41)29(31)40)48-32-28(39)27(38)24(19-42-22(2)35)45-34(32)44-21/h4-5,21,24-25,27-34,38-41H,6-20H2,1-3H3/b5-4-/t21-,24+,25+,27+,28-,29+,30+,31+,32+,33-,34+/m0/s1

[(1S,3R,4S,5S,6R,8R,10S,17Z,28S,29R,31R,32R)-29-(acetyloxymethyl)-4,5,31,32-tetrahydroxy-10-methyl-26-oxo-2,7,9,27,30-pentaoxatricyclo[26.2.2.03,8]dotriacont-17-en-6-yl]methyl acetate

Lactonic Sophorolipid; Lactonic Sophorolipid; 148409-20-5; [(1S,3R,4S,5S,6R,8R,10S,17Z,28S,29R,31R,32R)-29-(acetyloxymethyl)-4,5,31,32-tetrahydroxy-10-methyl-26-oxo-2,7,9,27,30-pentaoxatricyclo[26.2.2.03,8]dotriacont-17-en-6-yl]methyl acetate; Lactonic sophorolipid, tech. grade; 1',4-Sophorolactone 6',6-diacetate from yeast; 1',4'-Sophorolactone 6',6'-diacetate from yeast

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ~125 mg/mL (~181.48 mM)

Solubility in Formulation 1: ≥ 2.08 mg/mL (3.02 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.08 mg/mL (3.02 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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 (Please use freshly prepared in vivo formulations for optimal results.)