Antimicrobial garlic-derived diallyl polysulfanes: Interactions with biological thiols in Bacillus subtilis

Abstract

Background: Diallylpolysulfanes are the key constituents of garlic oils, known to exhibit broad spectrum anticancer and antimicrobial activity. Studies in vitro, and in mammalian cells, have shown they react, via thiolpolysulfane exchange, with their major low molecular weight thiol, glutathione. However, there are no detailed reports of diallylpolysulfane effects on other common thiol metabolites (cysteine and coenzyme A) or major thiol cofactors (e.g. bacillithiol) that many Gram positive bacteria produce instead of glutathione. Methods: Diallylpolysulfanes were individually purified then screened for antimicrobial activity against Bacillus subtilis. Their impact on thiol metabolites (bacillithiol, cysteine, coenzyme A, protein thiols allyl thiols//persulfides) in B. subtilis cultures were analysed, by HPLC. Results: Diallylpolysulfane bioactivity increased with increasing chain length up to diallyltetrasulfane, but then plateaued. Within two minutes of treating B. subtilis with diallyltrisulfane or diallyltetrasulfane intracellular bacillithiol levels decreased by ~90%. Cysteine and CoA were also affected but to a lesser degree. This was accompanied by the accumulation of allyl thiol and allyl persulfide. A significant level of proteinS -allylation was also detected. Conclusions: In addition to the major low molecular weight thiol, diallylpolysulfanes can also have an impact on other thiol metabolites and protein thiols. General Significance: This study shows the rapid parallel impact of polysulfanes on different biological thiols inside Bacillus subtilis alongside the concomitant generation of allyl thiols and persulfides.

Antioxidant and antihypertensive effects of garlic protein and its hydrolysates and the related mechanism

“…In recent years, researchers have used the hydrolysis and other techniques to prepare antihypertensive peptides from food-derived proteins (Tu, Cheng, Lu, & Du, 2018). Many studies revealed that garlic has antitumor (Song & Milner, 2001), antimicrobial (Arbach et al, 2019;Horita et al, 2016), antioxidant (Chen & Huang, 2019), reducing blood lipid (Shabani, Sayemiri, & Mohammadpour, 2019), anticardiovascular disease (Amor et al, 2019), and antidiabetic activities. Garlic (Allium sativum L.) belongs to the genus Allium of the Liliaceae family, which has been widely planted all over the world, mainly for cooking and medicinal applications (Ebrahimi Pure, Ghods Mofidi, Keyghobadi, & Ebrahimi Pure, 2017).…”

The Disulfide Stress Response and Protein S-thioallylation Caused by Allicin and Diallyl Polysulfanes in Bacillus subtilis as Revealed by Transcriptomics and Proteomics

“…Garlic (Allium sativum) has been historically used as a medicinal plant for the treatment of infectious diseases, such as tuberculosis, due to the production of volatile reactive sulfur compounds. The main thiol-reactive sulfur ingredient of garlic is the diallyl thiosulfinate (allicin), which acts as antimicrobial and inhibits the growth and survival of several important human pathogens, including multi-drug resistant bacteria, fungi, and parasites [1][2][3][4][5][6][7][8][9]. Upon garlic tissue damage, the enzyme cysteine-S-lyase alliinase is released from the vacuole into the cytosol to synthesize allyl sulfenic acid and dehydroalanine from the odor-less precursor alliin.…”

“…Allicin and diallyl polysulfanes DAS2-6 showed different extents of thiol-reactivity and microbicidal effects, with DAS4-6 and allicin being more potent antimicrobials compared to diallyl diand trisulfides (DAS2-3) [3,9]. The effects of garlic polysulfanes DAS2-6 were compared on the growth and the minimal inhibitory concentration (MIC) of Bacillus subtilis, Helicobacter pylori, Staphylococcus aureus, and fungi, which showed that the antimicrobial activity of polysulfanes increases with longer sulfur chain length [9,[15][16][17]. However, the stability of DAS5-6 is also strongly decreased compared to DAS2-4, and polysulfanes of longer chain length tend to rearrange to a mix of shorter polysulfanes when incubated with glutathione (GSH) in vitro [9,18].…”

“…The thiol-reactive modes of actions of allicin and diallyl polysulfanes and their reactions with low molecular weight (LMW) thiols have been investigated in Escherichia coli, S. aureus, and B. subtilis [7,9,19]. The mode of action of garlic sulfur compounds was attributed to S-thioallylation of LMW and protein thiols, causing rapid depletion of the reduced thiol pool upon allicin and DAS4 stress [5,7,8,19,20].…”

“…The mode of action of garlic sulfur compounds was attributed to S-thioallylation of LMW and protein thiols, causing rapid depletion of the reduced thiol pool upon allicin and DAS4 stress [5,7,8,19,20]. Treatment of GSH with allicin and polysulfanes in vitro results in a thiol-disulfide exchange reaction and the formation of GSH conjugated S-thioallylated di-, tri-, and tetra-sulfanes, and allyl thiols or allyl persulfides [3,9,13]. The S-thioallylated di-and trisulfanes were the major GSH conjugates measured upon GSH exposure to DAS3-6 in vitro [9].…”