An Anti-microbial Terpenoid Fraction from Gymnema sylvestre Induces Flip-flop of Fluorescent-Phospholipid Analogs in Model Membrane

Behuria, Himadri Gourav; Sahu, Santosh Kumar

doi:10.1007/s12010-020-03399-3

Cited by 9 publications

(13 citation statements)

References 34 publications

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“…ex Sm purified in an earlier study. 13 The prominent peaks at 1749–1716 cm –1 indicate the characteristic ester linkage in terpenoids 8 ( Figure 1 B). The broad and prominent peak between 3600 and 3400 cm –1 that results from heavily hydrogen bonded −OH groups with surrounding water molecules is absent from MEFGS.…”

Section: Resultsmentioning

confidence: 99%

“…Induction of lipid flip-flop by Gymnema terpenoids is one of the proposed mechanism of their membrano-lytic activity. 13 Lipid flip-flop across the lipid bilayer is a slow process due to the unfavorable energy barrier that a lipid has to overcome when its polar head group moves through the hydrophobic membrane core. 28 Amphiphilic phytochemicals in MEFGS exhibited lipid flippase activity across LUV membranes that was measured by %flipping of NBD-PE from the inner leaflet to the outer leaflet and subsequently quenched by the dithionite.…”

Section: Resultsmentioning

confidence: 99%

“…LUVs were prepared following the electroformation method. 13 Briefly, a mixture of 0.1 mg (∼130 nmol) egg-PC and 1.5 mol % NBD-PE in CHCl 3 was deposited on a copper electrode of the electroformation chamber and dried under a stream of nitrogen so as to remove any trace of CHCl 3 . The chamber was filled with low salt solution (LSS) (10 mM KCl and 100 mM sucrose), and LUVs were formed by passing alternating current of 10 Hz and 1.5 V for 2 h at 25 °C using a transformer.…”

Section: Methodsmentioning

confidence: 99%

“… 12 A recent investigation showed that antibacterial terpenoids from G. sylvestre induced rapid flip-flop of fluorescent phospholipid analogs in large unilamellar vesicles (LUVs). 13 Lipid flip-flop-inducing agents could perturb lipid organization, leading to their altered packing in the membrane, resulting in the increased permeability. 14 In this study, we identified the lipid flip-flop-inducing phytochemicals in the G. sylvestre leaf extract and investigated their effect on the bacterial membrane permeability.…”

Section: Introductionmentioning

confidence: 99%

“…A recent investigation showed that antibacterial terpenoids from G. sylvestre induced rapid flip-flop of fluorescent phospholipid analogs in large unilamellar vesicles (LUVs) . Lipid flip-flop-inducing agents could perturb lipid organization, leading to their altered packing in the membrane, resulting in the increased permeability .…”

Section: Introductionmentioning

confidence: 99%

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Lipid Flip-Flop-Inducing Antimicrobial Phytochemicals from Gymnema sylvestre are Bacterial Membrane Permeability Enhancers

et al. 2021

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An amphiphilic phytochemical fraction isolated from methanol extract of Gymnema sylvestre leaf powder contained six terpenoids, two flavonoids, and one alkaloid that induced rapid flip-flop of fluorescent phospholipid analog in the phosphatidyl choline bilayer. Lipid-flipping activity of the methanol-extracted fraction of G. sylvestre (MEFGS) was dose-dependent and time-dependent with a rate constant k = (12.09 ± 0.94) mg –1 min –1 that was saturable at (40 ± 1) % flipping of the fluorescent lipid analogue. Interactions of MEFGS phytochemicals with large unilamelar vesicles led to time-dependent change in their rounded morphology into irregular shapes, indicating their membrane-destabilizing activity. MEFGS exhibited antibacterial activity on Escherichia coli (MTCC-118), Staphylococcus aureus (MTCC-212), and Pseudomonas aeruginosa (MTCC-1035) with IC 50 values 0.5, 0.35, and 0.1 mg/mL, respectively. Phytochemicals in MEFGS increased membrane permeabilization in all three bacteria, as indicated by 23, 17, and 17% increase in the uptake of crystal violet, respectively. MEFGS enhanced membrane damage, resulting in a 3–5 fold increase in leakage of cytosolic ions, 0.5–2 fold increase in leakage of PO 4 – , and 15–20% increase in loss of cellular proteins. MEFGS synergistically increased the efficacy of curcumin, amoxillin, ampicillin, and cefotaxime on S. aureus probably by enhancing their permeability into the bacterium. For the first time, our study reveals that phytochemicals from G. sylvestre enhance the permeability of the bacterial plasma membrane by facilitating flip-flop of membrane lipids. Lipid-flipping phytochemicals from G. sylvestre can be used as adjuvant therapeutics to enhance the efficacy of antibacterials by increasing their bioavailability in the target bacteria.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%