Bioactivities of methyl allyl disulfide and diallyl trisulfide from essential oil of garlic to two species of stored-product pests, Sitophilus zeamais (Coleoptera: Curculionidae) and Tribolium castaneum (Coleoptera: Tenebrionidae)

Two of the major constituents of the essential oil of garlic, Allium sativum L., methyl allyl disulfide and diallyl trisulfide, were tested against Sitophilus zeamais Motschulsky and Tribolium castaneum (Herbst) for contact toxicity, fumigant toxicity, and antifeedant activity. The contact and fumigant toxicities of diallyl trisulfide were greater than that of methyl allyl disulfide to the adults of these two species of insects. These two compounds were also more toxic to T. castaneum adults than to S. zeamais adults. Older T. castaneum larvae were more susceptible to the contact toxicity of the two compound, whereas younger larvae were more susceptible to the fumigant toxicity of these compounds. Both compounds reduced egg hatching of T. castaneum and subsequent emergence of progeny. Diallyl trisulfide totally suppressed egg hatching at 0.32 mg/cm2, and larval and adult emergence at 0.08 mg/cm2. Methyl allyl disulfide significantly decreased the growth rate, food consumption, and food utilization of adults of both insect species, with feeding deterrence indices of 44% at 6.08 mg/g food for S. zeamais and 1.52 mg/g food for T. castaneum. However, it did not affect any nutritional indices of T. castaneum larvae. Diallyl trisulfide significantly reduced all of the nutritional indices in all of the insects tested. Feeding deterrence indices of 27 and 51% were obtained in S. zeamais adults and T. castaneum larvae, respectively, at the concentration of 2.98 mg/g food, whereas feeding deterrence of 85% was achieved in T. castaneum adults at a much lower concentration of 0.75 mg/g food. Hence, diallyl trisulfide is a more potent contact toxicant, fumigant and feeding deterrent than methyl allyl disulfide.     

Activities of garlic oil, garlic powder, and their diallyl constituents against Helicobacter pylori

Chronic Helicobacter pylori disease is reduced with Allium vegetable intake. This study was designed to assess the in vivo anti-H. pylori potential of a variety of garlic substances. The garlic materials all showed substantial but widely differing anti-H. pylori effects against all strains and isolates tested. The MICs (range, 8 to 32 microg/ml) and minimum bactericidal concentrations (MBCs) (range, 16 to 32 microg/ml) of undiluted garlic oil (GO) were smaller than those of garlic powder (GP) (MIC range, 250 to 500 microg/ml; MBC range, 250 to 500 microg/ml) but greater than the MIC of allicin (4. 0 microg/ml) (Table 2) present in GP. Allicin (MIC, 6 microg/ml; MBC, 6 microg/ml) was more potent than diallyl disulfide (MIC range, 100 to 200 microg/ml; MBC range, 100 to 200 microg/ml), its corresponding sulfide, but of a strength similar to that of diallyl tetrasulfide (MIC range, 3 to 6 microg/ml; MBC range, 3 to 6 microg/ml). Antimicrobial activity of the diallyl sulfides increased with the number of sulfur atoms. Time course viability studies and microscopy showed dose-dependent anti-H. pylori effects with undiluted GO, GP, allicin, and diallyl trisulfide after a lag phase of ca. 1 to 2 h. Substantial in vitro anti-H. pylori effects of pure GO and GP and their diallyl sulfur components exist, suggesting their potential for in vivo clinical use against H. pylori infections.     

Chemical constituents and medicinal properties of Allium species

Allium species, belonging to Alliaceae family, are among the oldest cultivated vegetables used as food. Garlic, onions, leeks and chives, which belong to this family, have been reported to have medicinal properties. The Allium species constituents have been shown to have antibacterial and antioxidant activities, and, in addition, other biological properties. These activities are related to their rich organosulfur compounds. These organosulfur compounds are believed to prevent the development of cancer, cardiovascular, neurological, diabetes, liver diseases as well as allergy and arthritis. There have also been reports on toxicities of these compounds. The major active compounds of Allium species includes, diallyl disulfide, diallyl trisulfide, diallyl sulfide, dipropyl disulfide, dipropyl trisulfide, 1-propenylpropyl disulfide, allyl methyl disulfide and dimethyl disulfide. The aim of this review is to focus on a variety of experimental and clinical reports on the effectiveness, toxicities and possible mechanisms of actions of the active compounds of garlic, onions, leek and chives.

     

Chemoprotective effect of diallyl trisulfide from garlic against carbon tetrachloride-induced acute liver injury of rats

Diallyl sulfide (DAS), diallyl disulfide (DADS) and diallyl trisulfide (DATS) are principal constituents of garlic oil. We studied the effect of these sulfides on the phase II drug-metabolizing enzymes, and on the rat model of acute liver injury induced by carbon tetrachloride (CCl4). A highly purified form of each sulfide (more than 99% purity) was administered i.p. to rats at a concentration of 10 or 100 micromol/kg body weight for 14 consecutive days. DATS (10 micromol/kg) and DADS at a 10-fold higher dose (100 micromol/kg) significantly increased the activities of glutathione S-transferase (GST) and quinone reductase (QR); whereas DAS did not. In the CCl4-induced acute liver injury model of rats, DATS (10 micromol/kg) significantly suppressed the increase in plasma lactate dehydrogenase (LDH) and aspartate aminotransferase (AST) activities. In conclusion, hepatic phase II enzymes were induced strongly by the trisulfide and weakly by the disulfide, but not by DAS. DATS significantly reduced the liver injury caused by CCl4. DATS may be one of the important factors in garlic oil that protects our body against the injury caused by radical molecules.     

Organosulphur constituents in garlic oil elicit antennal and behavioural responses from the yellow fever mosquito

Garlic (Allium sativum) and its essential oil have long been used for their distinct flavour, therapeutic effects and as a topical and systemic insect repellent. We tested the hypothesis that the yellow fever mosquito, Aedes aegypti L. (Diptera: Culicidae), responds electrophysiologically and behaviourally to specific components of the steam‐distilled essential oil of garlic. In coupled gas chromatographic‐electroantennographic detection analyses of garlic oil, antennae of female Ae. aegypti responded to 14 compounds. Seven of them [diallyl disulphide, diallyl trisulphide, diallyl tetrasulphide, 2‐(2,3‐dithia‐5‐hexenyl)‐3,4‐dihydro‐2H‐thiopyran, 3‐(2,3‐dithia‐5‐hexenyl)‐3,4‐dihydro‐2H‐thiopyran, 6‐methyl‐4,5,8,9‐tetrathiadodeca‐1,11‐diene and 4,5,9,10‐tetrathiatrideca‐1,12‐diene] were isolated or synthesized and tested for their ability to repel host‐seeking female Ae. aegypti. A solution of diallyl trisulphide and diallyl tetrasulphide applied to a human forearm provided protection from female mosquitoes significantly longer than the paraffin oil control. All compounds had mean protection times significantly shorter than an equivalent dose of the ‘gold standard’N,N‐diethyl‐3‐methylbenzamide. Understanding the common moiety in organosulfur compounds that causes repellence could lead to the design of analogues that are more effective than their natural counterparts in repelling mosquitoes.     

Study on the ecological safety of algacides: a comprehensive strategy for their screening

The ecological safety of 14 algacidal materials were appraised using algal growth inhibition tests as well as toxicity test for zooplankton and fish and prawn juveniles. In addition, an integrative analysis for evaluating their potential as algacides was made by comparing the 24-h LC₅₀ and ratio of efficiency to safety (RES) of each material. The results showed that the growth of algae tested were not affected after 96 h of exposure to diallyl trisulfide even when the concentration was 10 mg L⁻¹; there was a similar toxicity between garlic solution and diallyl trisulfide on seven species of aquatic organisms tested. Moreover, both prawn juveniles had lower resistances to garlic solution and diallyl trisulfide than the other 12 materials. According to the RES, green tea, garlic solution, diallyl trisulfide, and the Chinese medical herbs Cortex Fraxini, Herba Houttuyniae, Semen Arecae, and Rhizoma Coptidis are better algacides than the other materials tested in this study.     

Evaluation of insecticidal activity of the essential oil of Allium chinense G. Don and its major constituents against Liposcelis bostrychophila Badonnel

Water-distilled essential oil from the dried bulbs of Allium chinense (Liliaceae) was analyzed by gas chromatography–mass spectrometry (GC–MS). Eighteen compounds, accounting for 98.4% of the total oil, were identified and the main components of the essential oil of A. chinense were methyl allyl trisulfide (30.7%), dimethyl trisulfide (24.1%), methyl propyl disulfide (12.8%) and dimethyl disulfide (9.6%) followed by methyl allyl disulfide (3.4%) and methyl propyl trisulfide (3.6%). The essential oil exhibited contact toxicity against the booklice (Liposcelis bostrychophila) with an LC₅₀ value of 441.8 μg/cm² while the two major constituents, dimethyl trisulfide and methyl propyl disulfide had LC₅₀ values of 153.0 μg/cm² and 738.0 μg/cm² against the booklice, respectively. The essential oil of A. chinense possessed strong fumigant toxicity against the booklice with an LC₅₀ value of 186.5 μg/l while methyl allyl trisulfide (LC₅₀ = 90.4 μg/l) and dimethyl trisulfide (LC₅₀ = 114.2 μg/l) exhibited stronger fumigant toxicity than methyl propyl disulfide (LC₅₀ = 243.4 μg/l) and dimethyl disulfide (LC₅₀ = 340.8 μg/l) against the booklice. The results indicated that the essential oil and its major constituents have potential for development into natural insecticides or fumigants for control of insects in stored grains.     

The Inhibitory Effects of Garlic (<Emphasis Type="Italic">Allium sativum</Emphasis>) and Diallyl Trisulfide on <Emphasis Type="Italic">Alexandrium tamarense</Emphasis> and other Harmful Algal Species

Using cell suspension ability as an indicator, we studied the inhibitory effect of garlic (Allium sativum) and diallyl trisulfide on six species of red tide causing algae. This included: the inhibition by 0.08% garlic solution of five algal species — Alexandrium tamarense, Scrippsiella trochoidea, Alexandrium catenella, Alexandrium minutum and Alexandrium satoanum; the effects of garlic concentration on the inhibition of A. tamarense, S. trochoidea and Chaetoceros sp.; the effects of inhibitory time on the rejuvenation of algal cells; and the effects of heating and preservation time on algal inhibition by garlic solution. In addition, whether or not the ingredients of garlic solution had a possible algicidal effect was studied by comparing inhibition of A. tamarense by garlic solution and man-made diallyl trisulfide. The results showed that 1) inhibition by garlic solution was significant on A. tamarense, A. satoanum, A. catenella and S. trochoidea, and the least effective was a concentration of 0.04% on A. tamarense and S. trochoidea. Moreover, the higher the concentration, the stronger was the inhibition, and a high inhibitory rate (IR) could be maintained for at least three days when the garlic concentration was above 0.04%. For A. tamarense, it was also found that the longer the inhibitory time and the higher the concentration, the lower was the rate of resumed cell activity. On the contrary, garlic solution could not inhibit A. minutum or Chaetoceros sp.; 2) The IR to A. tamarense was reduced slightly as the heating time of the garlic solution was lengthened, but the average IR was still above 80%. There was no significant difference between the IR of the supernatant and sediment of the garlic solution. Furthermore, no change of algal inhibition was found when the garlic solution was preserved at 20°C for several days; 3) As with garlic solution, diallyl trisulfide inhibited A. tamarense strongly; the IR was above 93% and was maintained for at least three days, as long as the concentration was 3.2–10.0 mg L⁻¹. Thus, diallyl trisulfide may have been the major ingredient in garlic solution which inhibited the algae but, in addition, more than one ingredient may have been inhibiting the algae. In conclusion, garlic was a good algal inhibitor with many advantages, such as being common, cheap, non toxic and with high efficiency, and diallyl trisulfide, one of the components of garlic, was similarly effective in algal inhibition. It would be useful, therefore, to further study garlic as an environmentally friendly algal inhibitor.     

Allylsulfide constituents of garlic volatile oil as antimicrobial agents.

Six different mixtures of garlic distilled oils containing diallyl disulfide (DDS) and diallyl trisulfide (DTS), ranging from 1 to 51% and 88 to 38% respectively, have been assayed against a number of yeasts (C. albicans, C. tropicalis and B. capitatus), gram-positive bacteria (S. aureus and B. subtilis) and gram-negative bacteria (P. aeruginosa and E. coli). Results obtained support a specific antifungal more than an antibacterial activity and implicate DDS as the active constituent. Incubation of garlic extracts made up of 1% DDS and 88% DTS resulted, in fact, in the absence of growth inhibition against all the tested microorganisms, whereas garlic oils with higher quantities of DDS showed significant inhibitory activity, increasing with the increase of DDS amount.     

Diallyl sulfide content and antimicrobial activity against food-borne pathogenic bacteria of chives (Allium schoenoprasum)

Chives, a member of the Alliaceae family, have been used in food and medicine in Thailand for a long time. Diallyl sulfides (diallyl monosulfide, dially disulfide, diallyl trisulfide, and diallyl tetrasulfide) are believed to be responsible for the antimicrobial activity of plants in this family. In this study, chive oil was examined for its diallyl sulfide content and its antimicrobial activity against some strains of food-borne pathogenic bacteria. Chive oil had a very low concentration of diallyl monosulfide in comparison with the other diallyl sulfides. They inhibited all pathogenic bacteria used in this study with a different degree of inhibition. Chive oil was also shown to be able to inhibit Escherichia coli O157:H7 in a food model. This study is the first report describing not only the diallyl disulfide content of chive oil, but also its antimicrobial activity against food-borne pathogens in both a test tube and food model.     

Fumigant activity of essential oils and their components from Eucalyptus codonocarpa and E. dives against Tetranychus urticae (Acari: Tetranychidae) at three temperatures

Essential oils derived from eighteen species of the Myrtaceae family native to Australia, and major constituents of two oils selected from these oils were tested for their fumigant activity against adult females and eggs of Tetranychus urticae Koch (Acari: Tetranychidae) at 5, 15 and 25°C. Essential oils of Eucalyptus codonocarpa and Eucalyptus dives showed the highest fumigant activity against female adults at 10 μl/l at 15 and 25°C. Among major constituents of the two essential oils, piperitone was the most effective against female adults, followed by terpinene‐4‐ol at 10 μl/l at all three temperatures. The two essential oils and these two constituents lowered egg hatchability at 10 μl/l at 25°C. Our results suggest that piperitone should be further investigated as a potential fumigant against T. urticae.     

Inhibition of soybean lipoxygenase and mouse skin tumor promotion by onion and garlic components

Onion and garlic essential oils were previously shown to inhibit mouse skin tumor promotion, as were the enzymes, lipoxygenase, and cyclooxygenase. In the present study, the inhibition of soybean lipoxygenase (EC 1.13.11.12) by onion and garlic components and related compounds was investigated. The IC50 values as well as the kinetic inhibition constants were determined for the most active compounds. Di-(1-propenyl) sulfide, an analog of the substrate moiety required for oxygenase action, was the only irreversible inhibitor observed with Ki = 59 microM and k3 = 0.53/min. Inhibition in the presence of substrate was uncompetitive at 88 and 132 microM linoleic acid with Ki = 129 microM. At 173 microM linoleic acid, however, inhibition was competitive with Ki = 66 microM. Dially trisulfide, allyl methyl trisulfide, and diallyl disulfide were competitive inhibitors, while 1-propenylpropyl sulfide and (E, Z)-4,5,9-trithiadodeca-1,6,11-triene 9-oxide (ajoene) were mixed inhibitors. Nordihydroguaiaretic acid (NDGA), the most potent lipoxygenase inhibitor, was a competitive inhibitor with Ki = 0.29 microM. The results indicate a relative potency of inhibition for structural features in the following order: di(1-propenyl) sulfide greater than an alkenyl trisulfide greater than an alkenyl disulfide. Di(n-propyl) disulfide, a major onion oil component, inhibited neither lipoxygenase nor promotion. Di(1-propenyl) sulfide and ajoene inhibited both. This suggests that the inhibition of lipoxygenase may be involved in antipromotion.     

Essential oils of citrus fruit stimulate oviposition in the Mediterranean fruit fly Ceratitis capitata (Diptera: Tephritidae)

Female Mediterranean fruit flies (medfly) Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) perceive both qualitative and quantitative aspects of citrus fruit chemistry. However, the behavioural and biological adjustments of this response remain largely unknown. In the present study, the ovipositional responses of gravid female medflies to essential oils (i.e. the most critical resistance factor to medfly infestation) of various citrus fruits are investigated. In dual‐choice (treatment versus distilled water control) experiments, females lay significantly more eggs into pre‐punctured hollow oviposition hemispheres (domes) provided with 1 µL of citrus peel oil from sweet orange, satsuma mandarin, bitter orange, grapefruit and lemon compared with odourless domes. No‐choice tests show a weak effect of lemon essential oils in stimulating oviposition. The female ovipositional response to sweet orange oil (the most active in eliciting oviposition) is dose‐dependent. Additionally, limonene, the most abundant chemical in all citrus oils, stimulates oviposition, whereas linalool, a representative compound of immature citrus fruit associated with high toxicity against immature stages of fruit flies, has a significant deterrent effect. In further no‐choice tests, females lay approximately 23% fewer eggs in limonene (93%) (amount found in orange oil) and 60% fewer eggs in limonene 93% plus linalool 3% (approximately 10‐fold the amount found in orange oil) mixtures, relative to sweet orange oil. The results suggest that the limonene content accounts largely (but not completely) for the ovipositional responses observed in sweet orange oil, whereas high linalool proportions are capable of significantly masking and/or disrupting its stimulatory effects in citrus oils. The importance and practical implications of these findings with respect to understanding how citrus fruit chemistry influences the ovipositional responses of medfly is discussed.     

Bioactivity of fenchone and Plectranthus glandulosus oil against Prostephanus truncatus and two strains of Sitophilus zeamais

The toxic, repellent and reproduction inhibitory effects of Plectranthus glandulosus essential oil and one of its major compounds, fenchone, were evaluated against adult Prostephanus truncatus (Horn) and for two strains of Sitophilus zeamais Motschulsky from Cameroon and Germany. Maize grains were coated with the oil at 0, 10, 20, 40 and 80 μl/40 g grain and fenchone at 0, 20, 40, 80 and 120 μl/40 g grain. Mortality was assessed over a 7‐day period, followed by the determination of F₁ progeny production. The repellence of the two products was evaluated at five rates (0.5, 1, 3, 5, 10 μl/half disc) in a choice bioassay on filter paper. The oil and fenchone caused significant dose‐dependent mortality to the three insects, with the oil achieving 100% and 90% mortality for the two S. zeamais strains and P. truncatus, respectively, within 1 day of exposure at the dosage of 80 μl/40 g grain. The insects were less susceptible to fenchone compared with the crude oil. The German strain of S. zeamais was susceptible to the oil than the Cameroonian strain. At the dosage of 20 μl/40 g grain, S. zeamais F₁ progeny emergency was completely inhibited by the oil, while 80 μl/40 g grain treatment with fenchone prevented also insect emergence. Plectranthus glandulosus oil generally evoked a maximum per cent repellency of 100% for the three insects, but fenchone caused 55–60% to S. zeamais and 80% to P. truncatus. These results suggest that fenchone, though a major constituent of P. glandulosus oil, may only be a minor component of its bioactivity.     

Effects of allyl mercaptan and various allium-derived compounds on cholesterol synthesis and secretion in Hep-G2 cells

The present study was undertaken to compare the effects of allyl mercaptan (AM), a major metabolite of garlic, with several garlic constituents and extracts on cytotoxicity, cholesterol synthesis and its secretion in Hep-G2 cells. The cells were grown in Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% fetal bovine serum (FBS), and treated with 5, 25, 50, 125, 250 and 500 microg/ml of AM, diallyl disulfide (DD), diallyl trisulfide (DT), steam-distilled garlic oil (SD) or vinyl-dithiin oil of garlic (VD) for 4 h. At concentrations up to 50 microg/ml, no significant cytotoxic effect was found in any group, but at concentrations above 250 microg/ml, the cell viability decreased drastically in all groups compared to the control. The treatment of cells with 25 microg/ml (non-cytotoxic concentration) of AM, DD, DT, SD for 4 h significantly inhibited [3H]acetate incorporation into cholesterol compared to that of the control (P < 0.05). The secretion of cholesterol into the medium was also significantly decreased in all groups except for VD. The treatment of cells with those allium constituents had no effect on either [3H]acetate incorporation into fatty acids or [3H]glycerol incorporation into triglyceride or phospholipid.     

Biological activity of volatile di-n-propyl disulfide from seeds of neem, Azadirachta indica (Meliaceae), to two species of stored grain pests, Sitophilus oryzae (L.) and Tribolium castaneum (Herbst)

Head space volatiles, including 73% di-n-propyl disulfide, were collected from freshly crushed neem seeds. This compound along with previously reported diallyl disulfide (di-2-propenyl disulfide) were toxic when applied topically or as a fumigant to Tribolium castaneum adults and 8-, 12-, and 16-d-old larvae, and Sitophilus oryzae adults. Di-n-propyl disulfide significantly decreased the growth rate and dietary utilization with moderate inhibition of food consumption in both insects. The total coefficient of deterrence for this compound ranged between 68.5 and 178.6, which suggests that it has medium to very good deterrent activity vis-à-vis the treatment concentration and instar. Di-n-propyl disulfide and diallyl disulfide presented a similar effect on efficiency of conversion of ingested food, which is reduced 3-fold; this implies that both compounds are physiological toxicants. Present studies clearly demonstrate that di-n-propyl disulfide could be a potent toxicant, fumigant, and feeding deterrent for stored grain pests, if a suitable formulation and application procedure are developed.     

Diallyl sulfides in garlic activate both TRPA1 and TRPV1

We searched for novel agonists of TRP receptors especially for TRPA1 and TRPV1 in foods. We focused attention on garlic compounds, diallyl sulfide (DAS), diallyl disulfide (DADS), and diallyl trisulfide (DATS). In TRPA1 or TRPV1 heterogeneously expressed CHO cells, all of those compounds increased [Ca²⁺]_i in concentration-dependent manner. The EC₅₀ values of DADS and DATS were similar to that of allyl isothiocyanate (AITC) and that of DAS was 170-fold larger than that of AITC. Maximum responses of these sulfides were equal to that of AITC. The EC₅₀ values of these compounds for TRPV1 were around 100 μM against that of capsaicin (CAP), 25.6 nM and maximum responses of garlic compounds were half to that of CAP. The Ca²⁺ responses were significantly suppressed by co-application of antagonist. We conclude that DAS, DADS, and DATS are agonist of both TRPA1 and TRPV1 but with high affinity for TRPA1.     

Antithrombotic and anticancer effects of garlic-derived sulfur compounds: a review

Garlic (Allium sativum L.) has a long history as being a food having a unique taste and odor along with some medicinal qualities. Modern scientific research has revealed that the wide variety of dietary and medicinal functions of garlic can be attributed to the sulfur compounds present in or generated from garlic. Although garlic produces more than 20 kinds of sulfide compounds from a few sulfur-containing amino acids, their functions are different from one another; e.g., allicin, methyl allyl trisulfide, and diallyl trisulfide have antibacterial, antithrombotic, and anticancer activities, respectively. The present paper reviews the physiological functions of garlic in the limited study fields of its antithrombotic and anticancer effects. Before describing these effects, however, we will discuss briefly some characteristics of garlic as a plant and some modes of absorption of orally-administered sulfur compounds from garlic.     

Chemical Constituents and Insecticidal Activities of Ajania fruticulosa Essential Oil

The insecticidal activity and chemical constituents of the essential oil from Ajania fruticulosa were investigated. Twelve constituents representing 91.0% of the essential oil were identified, and the main constituents were 1,8‐cineole ( 41.40% ), (+)‐camphor ( 32.10% ), and myrtenol (8.15%). The essential oil exhibited contact toxicity against Tribolium castaneum and Liposcelis bostrychophila adults with LD₅₀ values of 105.67 μg/adult and 89.85 μg/cm², respectively. The essential oil also showed fumigant toxicity against two species of insect with LC₅₀ values of 11.52 and 0.65 mg/l, respectively. 1,8‐Cineole exhibited excellent fumigant toxicity (LC₅₀ = 5.47 mg/l) against T. castaneum. (+)‐Camphor showed obvious fumigant toxicity (LC₅₀ = 0.43 mg/l) against L. bostrychophila. Myrtenol showed contact toxicity (LD₅₀ = 29.40 μg/cm²) and fumigant toxicity (LC₅₀ = 0.50 mg/l) against L. bostrychophila. 1,8‐Cineole and (+)‐camphor showed strong insecticidal activity to some important insects, and they are main constituents of A. fruticulosa essential oil. The two compounds may be related to insecticidal activity of A. fruticulosa essential oil against T. castaneum and L. bostrychophila.     

Effects of allyl sulfides on the growth of predominant gut anaerobes

At a small supplied concentration (3–5 mM), diallyl disulfide (DADS) and diallyl monosulfide (DAMS), compounds previously shown to have both tumoricidal and protective effects against carcinogenesis, affected the growth of components of the normal anaerobic gut microflora. Organisms that were affected by DAMS and DADS includedBacteroides ruminicola, Bacteroides succinogenes, Butyrivibrio fibrisolvens, Ruminococcus albus, Ruminococcus flavefaciens, Ruminococcus bromii, andPeptostreptococcus productus. Organisms found unaffected, over the same supplied concentration range, includedBacteroides fragilis, Bacteroides vulgatus, Fusobacterium necrophorum, Fusobacterium nucleatum, andSelenomonas ruminantium. In addition to their direct effects upon host cell physiology, the active components of garlic oil may exert modifying effects on the nature and function of the predominant gut microflora of warm-blooded animals.