Isolation and characterization of larvicidal principle of garlic

A developmental gradient reveals biosynthetic pathways to eukaryotic toxins in monocot geophytes

Numerous eukaryotic toxins that accumulate in geophytic plants are valuable in the clinic, yet their biosynthetic pathways have remained elusive. A notable example is the >150 Amaryllidaceae alkaloids (AmAs), including galantamine, an FDA-approved treatment for Alzheimer's disease. We show that while AmAs accumulate to high levels in many daffodil tissues, biosynthesis is localized to nascent, growing tissue at the leaf base. A similar trend is found in the production of steroidal alkaloids (e.g., cyclopamine) in corn lily. This model of active biosynthesis enabled the elucidation of a complete set of biosynthetic genes that can be used to produce AmAs. Taken together, our work sheds light on the developmental and enzymatic logic of diverse alkaloid biosynthesis in daffodils. More broadly, it suggests a paradigm for biosynthesis regulation in monocot geophytes, where plants are protected from herbivory through active charging of newly formed cells with eukaryotic toxins that persist as above-ground tissue develops.

A developmental gradient reveals biosynthetic pathways to eukaryotic toxins in monocot geophytes

Numerous eukaryotic toxins that accumulate in geophytic plants are valuable in the clinic, yet their biosynthetic pathways have remained elusive. A lead example is the >150 Amaryllidaceae alkaloids (AmAs) including galantamine, an FDA-approved treatment for Alzheimer's disease. We show that while AmAs accumulate to high levels in many tissues in daffodils, biosynthesis is localized to nascent, growing tissue at the base of leaves. A similar trend is found for the production of steroidal alkaloids (e.g. cyclopamine) in corn lily. This model of active biosynthesis enabled elucidation of a complete set of biosynthetic genes for the production of AmAs. Taken together, our work sheds light on the developmental and enzymatic logic of diverse alkaloid biosynthesis in daffodil. More broadly, it suggests a paradigm for biosynthesis regulation in monocot geophytes where plants are protected from herbivory through active charging of newly formed cells with eukaryotic toxins that persist as aboveground tissue develops.

Fermented medicinal herbs improve hematological and physiological profile of Striped catfish (Pangasianodon hypophthalmus)

This study sought to determine the effect of fermented medicinal herbs (FMH), i.e. cutchery ( Kaempferia galanga), turmeric ( Curcuma longa) and curcuma ( Curcuma xanthorrhiza) in combination with molasses and probiotic drink (Yakult), administered orally on the hematological and physiological profile of striped catfish ( Pangasianodon hypophthalmus). A complete randomized design (CRD) experiment was used with four levels of treatments, namely P0 (control), P1 (FMH 100 mL/kg), P2 (FMH 200 mL/kg) and P3 (FMH 300 mL/kg) of feed. The fish were kept in a farm in cages at 75 fish/m ³ and fed with the experimental diets for 60 days. The results revealed that FMH (P2) dietary administration improved hematological and physiological profile of catfish, i.e total erythrocytes of 2.81 x 10 ⁶ cells/mm ³, hematocrit values of 39.00%, hemoglobin levels of 10.73 g/dL, total leukocytes of 11.41 x 10 ⁴ cells/mm ³, blood glucose 97.33 mg/dL, and total serum protein 4.10 mg/dL compared to controls with 1.89 x 10 ⁶ cells/mm ³, 32.33 %, g/dL, 9.67 x 10 ⁴ cells/mm ³, 67.33 mg/dL, and total serum protein of 3.10 mg/dL, respectively. Moreover, the diet improved special growth rate, feed conversion ratio, feed efficiency and the survival rate of catfish. The hematological and physiological profile of catfish improvement are considered to be due to the content of secondary metabolites of FMH, namely curcuminoids, vitamin C, essential oils, tannins, and flavonoids, which trigger immunostimulation. The presence of curcuminoids provide an antioxidant effect on cell membranes reducing erythrocyte cell membrane damage due to oxidation. Similarly, flavonoids are natural antioxidants, which are credited with the ability of reducing free radicals and anti-free radicals.

Antifungal activity of propyl disulphide from neem against Lasiodiplodia theobromae and Neofusicoccum parvum causing stem end rot in mango

AIM

To investigate the antifungal effect of the neem extract volatile propyl disulphide against the fungal plant pathogens.

METHODS AND RESULTS

Postharvest pathogens were isolated and identified as Lasiodiplodia theobromae and Neofusicoccum parvum causing the stem end rot of mango fruit. Antifungal activity of propyl disulphide at different concentrations was determined in comparison with ethanol and distilled water. Both diffusion assays were effective in controlling the mycelial growth of the tested fungi. The high coefficient of determination (R² , 0·970-0·997) of the growth curves indicated the good fit of the experimental data to the Gompertz growth model. Propyl disulphide significantly (P ≤ 0·05) decreased the mycelial growth during the stationary phase (A) and increased the lag phase (λ) than both control (ethanol and distilled water).

CONCLUSION

This compound can potentially be applied to other tropical and subtropical fruits for the successful control of postharvest losses of fresh produce.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report of propyl disulphide from neem extract against plant pathogens and could be beneficial for effective microbial decay prevention in food industries.

A Possible Role for Singlet Oxygen in the Degradation of Various Antioxidants. A Meta-Analysis and Review of Literature Data

The thermodynamic parameters Eact, ΔH≠, ΔS≠, and ΔG≠ for various processes involving antioxidants were calculated using literature kinetic data (k, T). The ΔG≠ values of the antioxidants' processes vary in the range 91.27-116.46 kJmol-1 at 310 K. The similarity of the ΔG≠ values (for all of the antioxidants studied) is supported to be an indication that a common mechanism in the above antioxidant processes may be taking place. A value of about 10-30 kJmol-1 is the activation energy for the diffusion of reactants depending on the reaction and the medium. The energy 92 kJmol-1 is needed for the excitation of O₂ from the ground to the first excited state (¹Δg, singlet oxygen). We suggest the same role of the oxidative stress and specifically of singlet oxygen to the processes of antioxidants as in the processes of proteinaceous diseases. We therefore suggest a competition between the various antioxidants and the proteins of proteinaceous diseases in capturing singlet oxygen's empty π* orbital. The concentration of the antioxidants could be a crucial factor for the competition. Also, the structures of the antioxidant molecules play a significant role since the various structures have a different number of regions of high electron density.

S–S Bond Formation: Nanocatalysts in the Oxidative Coupling of Thiols

Compounds containing sulfur–sulfur bonds (often called disulfides or more specifically disulfanes) are arguably one of the most valuable functional groups in organic synthetic chemistry. They exist extensively in nature, in which they exhibit important biological activities. Furthermore, a diverse range of natural and synthetic disulfides have been discovered that have many applications as pharmaceutical and agriculture chemicals as well as synthetic intermediates. Since thiols are commercially accessible or easily synthesizable materials and their choice as starting materials is widely reported for the synthesis of organic sulfur compounds, unsurprisingly the oxidative coupling of thiols is the best and simplest route for the preparation of disulfides. In recent times, nanocatalysts have shown excellent catalytic activity and reusability in the oxidation of thiols to disulfides. Herein, we summarize the recently reported breakthroughs in the use of nanocatalysts for the oxidative coupling of thiols to their corresponding disulfides, with the goal of stimulating further progress in this field.

Efficacy of attractive toxic sugar baits (ATSB) against Aedes albopictus with garlic oil encapsulated in beta-cyclodextrin as the active ingredient

We tested the efficacy of attractive toxic sugar bait (ATSB) with garlic oil microencapsulated in beta-cyclodextrin as active ingredient against Aedes albopictus in suburban Haifa, Israel. Two three-acre gardens with high numbers of Ae. albopictus were selected for perimeter spray treatment with ATSB and ASB (bait containing no active ingredient). Baits were colored with food dye to verify feeding of the mosquitoes. The mosquito population was monitored by human landing catches and sweep net catches in the surrounding vegetation. Experiments lasted for 44 days. Treatment occurred on day 13. The mosquito population collapsed about 4 days after treatment and continued to drop steadily for 27 days until the end of the study. At the experimental site the average pre-treatment landing rate was 17.2 per 5mins. Two days post-treatment, the landing rate dropped to 11.4, and continued to drop to an average of 2.6 during the following 26 days. During the same period, the control population was stable. Few sugar fed females (8-10%) approached a human bait and anthrone tests showed relatively small amounts of sugar within their crop/gut. Around 60-70 % of males caught near our human bait were sugar positive which may indicate that the males were feeding on sugar for mating related behavior. From the vegetation treated with the toxic bait, we recovered significantly fewer (about 10-14%) males and females stained by ATSB than at the ASB-treated control. This may indicate that the toxic baits alter the resting behavior of the poisoned mosquitoes within the vegetation. Almost no Ae. albopictus females (5.2±1.4) approached human bait after treatment with ATSB. It therefore appears that microencapsulated garlic oil is an effective pesticide against Ae. albopictus when used in an ATSB system.

Formulation of attractive toxic sugar bait (ATSB) with safe EPA-exempt substance significantly diminishes the Anopheles sergentii population in a desert oasis

Attractive toxic sugar bait (ATSB) is a highly effective method which targets mosquitoes based on their sugar foraging behavior, by presenting baits of attractive compounds in combination with sugar and oral toxin to local mosquito populations. Environmental concerns and insecticide selection-pressure have prompted investigations of novel, ecologically-harmless substances which can be used as insecticides. This study examined the efficacy of microencapsulated garlic-oil as the oral toxin component of ATSB for controlling Anopheles sergentii populations inhabiting desert-surrounded wetlands in Israel. ATSB solution containing 0.4% encapsulated garlic oil was applied to local vegetation around a streamlet located in the lower Jordan Valley. To determine the propensity of bait ingestion, and assess the potential ecological impact of the method, mosquito and non-target specimens were collected and tested for the presence of natural plant- or attractive sugar bait (ASB)-derived sugars. Over the experimental period, biting-pressure values in the ATSB treatment site decreased by 97.5%, while at the control site, treated with non-toxic ASB, no significant changes were observed. Approximately 70% of the mosquitoes collected before both treatments, as well as those captured following the application of ASB at the control site, were found to have ingested sugar prior to capture. Non-target insects were minimally affected by the treatment when ATSB was applied to foliage of non-flowering plants. Of the non-Diptera species, only 0.7% of the sampled non-target insects were found to have ingested ASB-solution which was applied to green vegetation, compared with 8.5% which have foraged on ASB-derived sugars applied to flowering plants. Conversely, a high proportion of the non-target species belonging to the order Diptera, especially non-biting midges, were found to have ingested foliage-applied ASB, with more than 36% of the specimens collected determined to have foraged on bait-derived sugars. These results prove that food-grade, EPA-exempt microencapsulated garlic oil is a highly effective insecticide which can be utilized for mosquito population control. The relatively short half-life of this active ingredient makes it a suitable for use in areas where repeated application is possible, limiting the accumulation of deleterious compounds and ensuring minimal environmental impact when applied in accordance with label recommendations.

Laboratory Evaluation of Larvicidal Activity of the Essential oil of Allium tuberosum Roots and its Selected Major Constituent Compounds Against Aedes albopictus (Diptera: Culicidae)

The aim of this research was to evaluate larvicidal activity of the essential oil of Allium tuberosum Rottler ex Sprengle roots and its constituents against larval mosquitoes (Aedes albopictus Skuse). Essential oil of A. tuberosum was obtained by hydrodistillation and analyzed by gas chromatography and gas chromatography-mass spectrometry. The major constituents of the oil were found to be sulfur-containing compounds, including allyl methyl trisulfide (35.19%), diallyl disulfide (28.31%), diallyl trisulfide (20.91%), and dimethyl trisulfide (12.33%). The essential oil of A. tuberosum exhibited larvicidal activity against the fourth-instar larvae of Ae. albopictus, with an LC50 value of 18 μg/ml. The constituents compounds-diallyl trisulfide (LC50 = 4 μg/ml) and diallyl disulfide (LC50 = 6 μg/ml)-possessed stronger larvicidal activity than allyl methyl trisulfide (LC50 = 27 μg/ml) and dimethyl trisulfide (LC50 = 35 μg/ml) against the fourth-instar larvae of Ae. albopictus. The results indicated that the essential oil of A. tuberosum and its major constituents have good potential as a source for natural larvicides.

Efficiency of sulphur in garlic extract and non-sulphur homeopathy in the control of the cattle tick Rhipicephalus (Boophilus) microplus

The objective of the present work was to evaluate the efficacy of a non-sulphur-based homeopathic preparation and a sulphur-containing natural product derived from Allium sativum (Linnaeus) against infestation by the cattle tick Rhipicephalus (Boophilus) microplus (Canestrini) (Acari: Ixodidae). A total of 24 crossbred calves (7 : 8 Holstein : Zebu), aged 6-8 months and maintained in individual stables under tick-free conditions, were divided into three groups. Group 1 (control group) received no treatment; Group 2 was treated with 0.01 g/day of the homeopathic preparation Fator C&MC(®), and Group 3 was treated with 20 g/day of Enxofre-Allium sativum(®). After adaptation to the diet for 1 month, each calf was subjected to artificial infestation with 8000 R. (B.) microplus larvae (aged 7-14 days) twice per week over a 5-month period. Numbers of engorged females were recorded every 14 days and samples of freely released engorged females were collected at 14-day intervals commencing 3 months after the start of the experiment. The engorged females were weighed, incubated for 15 days under biochemical oxygen demand conditions at 27 ± 1 °C and relative humidity >85%, and the weights of the egg masses produced were recorded. Other biological parameters, including reproduction estimate, reduction in oviposition and efficiency of treatment, were determined. A significant reduction in the number of engorged females was detected on animals treated with Enxofre-Allium sativum(®) (Group 3) in comparison with the other two groups. The overall efficiency of the treatment with the sulphur-containing product was 64%, whereas that of the homeopathic preparation was 26%. Under the experimental conditions established, Enxofre-Allium sativum(®) can reduce the intensity of the R. (B.) microplus infestation.

Use of garlic, Allium sativum, to control Aeromonas hydrophila infection in rainbow trout, Oncorhynchus mykiss (Walbaum)

Garlic, Allium sativum, which was fed at 0, 0.05, 0.1, 0.5 and 1.0 g per 100 g of feed for 14 days to rainbow trout, Oncorhynchus mykiss (Walbaum), led to control of experimental infection with Aeromonas hydrophila. At doses of 0.5 and 1.0 g garlic per 100 g of feed, there was a reduction in mortalities to 4% compared with the controls (88%). Moreover, there was a significant increase in growth, feed conversion and protein efficiency. There was stimulation of the number of erythrocytes and leucocytes, a significantly higher haematocrit, enhancement of phagocytic activity, respiratory burst, lysozyme, anti-protease and bactericidal activities following feeding with garlic.

Coactivity of sulfide ingredients: a new perspective of the larvicidal activity of garlic essential oil against mosquitoes

BACKGROUND

The activity of several garlic oil ingredients against Culex pipiens L. larvae was studied. In addition to diallyl sulfide (DS) and diallyl disulfide (DDS), the garlic oils used included one essential oil (EO) and two semi-synthetic garlic essential oils (SSGEO1 and SSGEO2), which resulted from the enrichment of EO with DS and DDS standards respectively. The oils were compared with respect to their toxicity.

RESULTS

The chemical composition of the tested oils was evaluated by means of gas chromatography-mass spectrometry. Experimental data from the tested samples revealed high toxicity. In detail, DDS (6.09 mg L(-1)) was the most active, followed by SSGEO2 (7.05 mg L(-1)) and EO (8.01 mg L(-1)), while SSGEO1 and DS were relatively inactive.

CONCLUSION

The addition of DDS to EO did not change the toxic effect of the essential oil, whereas the presence of DS in excess produced an enriched essential oil with low toxicity. Furthermore, the antagonistic effect of DS and DDS against the other components of EO was shown by the application of two equations obtained from the literature. Their larvicidal performances were correlated, for the first time, with their detailed chemical composition. Data analysis strongly indicated the toxicity of the other EO sulfur ingredients.

Isolation and identification of mosquito larvicidal compound from Abutilon indicum (Linn.) Sweet

Larvicidal activity of crude hexane, ethyl acetate, petroleum ether, acetone and methanol extracts of five medicinal plants, Abutilon indicum, Aegle marmelos, Euphorbia thymifolia, Jatropha gossypifolia and Solanum torvum were assayed for their toxicity against the early fourth-instar larvae of Culex quinquefasciatus. The larval mortality was observed after 24 h exposure. All extracts showed moderate larvicidal effects; however, the highest larval mortality was found in petroleum ether extract of A. indicum. In the present study, bioassay-guided fractionation of A. indicum led to the separation and identification of a beta-sitosterol as a potential new mosquito larvicidal compound with LC50 value of 11.49, 3.58 and 26.67 ppm against Aedes aegypti L, Anopheles stephensi Liston and C. quinquefasciatus Say (Diptera: Culicidae), respectively. 1H NMR, 13C NMR and mass spectral data confirmed the identification of the active compound. beta-sitosterol has been recognized as the active ingredient of many medicinal plant extracts. All the crude extracts when screened for their larvicidal activities indicated toxicity against the larvae of C. quinquefasciatus. This article reports the isolation and identification of the beta-sitosterol as well as bioassay data for the crude extracts. There are no reports of beta-sitosterol in the genus A. indicum, and their larvicidal activities are being evaluated for the first time. Results of this study show that the petroleum ether extract of A. indicum may be considered as a potent source and beta-sitosterol as a new natural mosquito larvicidal agent.

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.

Comparison of distillation and ultrasound-assisted extraction methods for the isolation of sensitive aroma compounds from garlic (Allium sativum)

A comparative study of traditional simultaneous distillation extraction (SDE), microwave assisted hydrodistillation extraction (MWHD) and ultrasound-assisted extraction (USE) is presented, for the extraction of essential oils from fresh garlic (Allium sativum) cloves. Each method is evaluated in terms of qualitative and quantitative composition of the isolated essential oil. The highly reactive sulfur molecules of the garlic volatile fraction show variable response to the different isolation methods. The application of ultrasound for the extraction of the essential oil is considered to cause a lesser damage of thermal-sensitive molecules, thus, providing a better approach of the compounds primarily responsible for the characteristic odor and taste of freshly chopped garlic. All heat-involving isolation procedures have been shown to differentiate the volatile-fraction profile as analyzed by GC-MS. Especially when grouping the compounds into cyclic and acyclic, the percentage concentrations drop from 77.4% to 8.7% for the acyclic while that of the cyclic compounds increase from 4.7% to 70.8%. The observed fact may be attributed to the effect of the heat applied, which changes from harsh thermal treatment (SDE) to short time thermal (MWHD) and room-temperature isolation (USE). The use of USE proves to be crucial in order to provide reliable insight into garlic's chemistry.

Topical application of garlic reduces northern fowl mite infestation in laying hens

Northern fowl mites (NFM) are external parasites that can lower egg production and cause anemia and even death in laying hens. An experiment was conducted with New Hampshire Red and Single Comb White Leghorn laying hens. Hens were individually caged and provided a complete laying diet and water ad libitum. Hens were assigned to groups in a way that assured that treatments, within each breed, would be applied to comparable numbers of birds with light and heavy mite infestations. Each hen was sprayed around the vent with either water or 10% garlic juice in water. Spraying continued each week for 3 wk. During the fourth week, each bird was scored for the presence of NFM on its skin and feathers. A small snippet of feathers was removed from below the vent of each hen and placed in a labeled petri dish with a round, white filter paper insert. The NFM content of each dish was scored by two individuals approximately 1 h after sampling. There was no significant difference in the NFM scores for hens based on breed or future treatment. After the birds were treated for 3 wk, there was no significant difference in external NFM scores based on breed. There were significantly fewer NFM on the birds treated with garlic juice compared with controls, based on external and petri dish scoring (P < 0.002 and P < 0.04, respectively). The reduction in external NFM score was also significant (P < 0.004), with controls declining approximately 0.2 units, whereas garlic-treated hens had a 1.8-unit decrease in external NFM score. Topical application of garlic juice may be an effective way to decrease NFM in laying hens.

Traditional antihelmintic, antiparasitic and repellent uses of plants in Central Italy

The uses of 51 plants of Marche, Abruzzo and Latium, distributed in 28 families, are listed here. Memories and news of continued use of the plants in these sectors were collected from farmers and shepherds in person (mostly old people). The plants most frequently used as antiparasitics and repellents are Juglans regia, Lupinus albus, Ruta graveolens, Fraxinus ornus, Datura stramonium, Artemisia absinthium, Allium cepa, while R. graveolens, Cucurbita maxima, A. absinthium, Allium sativum are the most commonly used as antihelmintics.

Metabolites of diallyl disulfide and diallyl sulfide in primary rat hepatocytes

The objectives of this study were to analyse and identify the metabolites of diallyl disulfide (DADS) and diallyl sulfide (DAS) in primary rat hepatocytes prepared by collagenase perfusion. According to the results, allyl mercaptan (AM) and allyl methyl sulfide (AMS) were the metabolites of DADS. The highest amount of AMS (0.93 +/- 0.08 microg/ml at 90 min) was much less than that of AM (46.2 +/- 6.6 microg/ml at 60 min). Combined with the Purge and Trap using a gas chromatography-mass spectrometry (GC-MS) system, it is very useful to detect the trace amounts of metabolites in primary rat hepatocytes. Results also showed that AMS was a metabolite of DAS. The highest amount of AMS in the extracellular fluid of hepatocytes was 0.63 +/- 0.16 microg/ml at 30 min of incubation.

Inhibition of Helicobacter pylori by garlic extract (Allium sativum)

The antibacterial effect of aqueous garlic extract (AGE) was investigated against Helicobacter pylori. Sixteen clinical isolates and three reference strains of H. pylori were studied. Two different varieties of garlic were used. The concentration of AGE required to inhibit the bacterial growth was between 2-5 mg ml-1. The concentration, for both AGE types, to inhibit 90% (MIC90) of isolates was 5 mg ml-1. The minimum bactericidal concentration (MBC) was usually equal to, or two-fold higher than, minimum inhibitory concentration (MIC). Heat treatment of extracts reduced the inhibitory or bactericidal activity against H. pylori; the boiled garlic extract showed a loss of efficacy from two- to four-fold the values of MIC and the MBC obtained with fresh AGE. The antibacterial activity of garlic was also studied after combination with a proton pump-inhibitor (omeprazole) in a ratio of 250:1. A synergistic effect was found in 47% of strains studied; an antagonistic effect was not observed.

Biochemistry and technology of chickpea (Cicer arietinum L.) seeds

Chickpea is an important source of proteins, carbohydrates, B-group vitamins, and certain minerals, particularly to the populations of developing nations. India contributes over 75% of the chickpea production in the world where it is mostly consumed as dhal, whole seeds, and several types of traditional, fermented, deep fried, sweetened, and puffed products. In this review, the world production and distribution, genetic background, biochemical and nutritional quality, and developments in storage and processing technology of chickpea are discussed. Future research needs, to improve the utilization of chickpea as human food, are addressed.

Allium sativum (garlic) inhibits lipid synthesis by Candida albicans

The effect of aqueous garlic extract on the macromolecular synthesis of Candida albicans was studied. Protein and nucleic acid syntheses were inhibited to the same extent as growth, but lipid synthesis was completely arrested. Blockage of lipid synthesis is likely an important component of the anticandidal activity of garlic.

Pigeonpea as an important food source

Pigeonpea is an important source of proteins, carbohydrates, B-group vitamins, and certain minerals. India contributes over 90% of the pigeonpea production in the world where it is mostly consumed as dehusked splits or dhal. In African countries and Latin America, it is mainly consumed as canned peas. In this review, world production and distribution, genetic background, and biochemical and nutritional properties, storage and processing of pigeonpea are discussed. Future research needs to improve the utilization of pigeonpea as human food are also addressed.

Inhibition of mycobacteria by garlic extract (Allium sativum)

Thirty strains of mycobacteria, consisting of 17 species, were inhibited by various concentrations of garlic extract incorporated in Middlebrook 7H10 agar. The concentration required ranged from a low of 1.34 mg/ml to a high of 3.35 mg/ml of media. When there were multiple strains of a species, a mean inhibitory concentration was determined for that species. Six strains of Mycobacterium tuberculosis required a mean inhibitory concentration of 1.67 mg/ml of media.

The genus Allium. Part 2

Allium is a genus of some 500 species belonging to the family Liliaceae. However only a few of these are important as food plants, notably onion, garlic, chive, leek, and rakkyo. Such plants have been used for many centuries for the pungency and flavoring value, for their medicinal properties, and, in some parts of the world, their use also has religious connotations. The flavors of members of the genus Alliums, in addition to having certain characteristics, are also complex, being derived enzymically from a number of involatile precursors. In addition to there being variation of flavor between different alliums, there are also considerable changes that occur as a result of cooking and processing. Of course, these are of importance to the consumer and food technologist-processor. The review will introduce the subject by an historical perspective and will set this against data on the present cultivation and usage of commercially cultivated alliums. The chemical composition of these plants will be discussed, emphasis being given to nonvolatile constituents which are, perhaps, less often considered. Discussion of the volatile constituents, which will include mention of the methods currently used for their analysis and for the determination of "flavor strength", will be mainly concerned with literature taken from the last 5 years. In considering the extent and nature of allium cultivation and processing, factors affecting the nutritional value and quality will be highlighted. The medicinal properties of garlic and onion oils have been much studied over the last decade and the review will include critical assessment of this area and also will touch on the more general properties (antimicrobial, antifungal, antibacterial, and insecticidal) of these oils. Finally mention will be made of the antinutritional, toxic, or otherwise undesirable effects of alliums, for example, as inadvertent components of animal diets, tainting of milk and other food products. It is our intention to review the literature up to mid-1984.

The genus Allium--Part 1

Alliums have been grown for many centuries for their characteristic, pungent flavor and medicinal properties. The present review, which includes references published up to the middle of 1984, is primarily concerned with the chemical composition, flavor, and physiological properties of these crops, their extracts, and processed products. Special emphasis is placed upon the relationship between the organoleptically and biologically active components of onion and garlic. Following a brief historical introduction, current production of commercially important alliums is described and their botanical origins and interrelationships are explained. Following consideration of the major economic diseases and pests of alliums, the agronomic, husbandry, and practices associated with their cultivation are described, particular emphasis being placed upon the storage and processing of onion and garlic. The detailed, overall chemical composition and nutritional value of members of the genus Allium are presented in Section 7; after an outline of the origin and nature of flavor components and precursors, the flavor volatiles of individual members are presented. The effects of agronomic, environmental, and processing practices on chemical and flavor content and quality are considered in Section 9. The following section deals critically with the human and animal studies which have been conducted into the medical and therapeutic properties of alliums, emphasis being placed upon the studies into the antiatherosclerotic effect of onion and garlic and their essential oils. After a study of antimicrobial properties of alliums and their effects on insects and animals, an overview is presented which highlights unexplored or inadequately studied areas and suggests rewarding areas for future research.

The genus Allium--Part 3

Allium is a genus of some 500 species belonging to the family Liliaceae. However, only a few of these are important as food plants, notably onion, garlic, chive, leek, and rakkyo. Such plants have been used for many centuries for their pungency and flavoring value, for their medicinal properties, and in some parts of the world, their use also has religious connotations. The flavors of members of alliums, in addition to being characteristic, are also complex, being derived enzymically from a number of involatile precursors. As well as there being variation of flavor between different alliums there are also considerable changes that occur as a result of cooking and processing. These are, of course, of importance to the consumer and food technologist/processor. The review will introduce the subject by an historical perspective and will set against this data on the present cultivation and usage of commercially cultivated alliums. The chemical composition of these plants will be discussed, emphasis being given to nonvolatile constituents which are, perhaps, less often considered. Discussion of the volatile constituents, which will include mention of the methods currently used for their analysis and for the determination of "flavor strength," will be mainly concerned with literature taken from the last 5 years. In considering the extent and nature of allium cultivation and processing, factors affecting the nutritional value and quality will be highlighted. The medicinal properties of garlic and onion oils have been extensively studied over the last decade and the review will include critical assessment of this area; it will also touch on the more general properties (antimicrobial, antifungal, antibacterial, and insecticidal) of these oils. Finally, mention will be made of the antinutritional, toxic, or otherwise undesirable effects of alliums, for example, as inadvertant components of animal diets, tainting of milk, and other food products. It is our intention to review the literature up to mid-1984.

Allium sativum (garlic)--a natural antibiotic

Allium sativum (garlic) has been recognized not only as a spice but also as a substance which exerts a control on microorganisms. Recent publications indicate that garlic extract has broad-spectrum antimicrobial activity against many genera of bacteria and fungi. The active component (allicin) has been isolated and characterized. Because many of the microorganisms susceptible to garlic extract are medically significant, garlic holds a promising position as a broad-spectrum therapeutic agent. Furthermore, garlic plants may also play an important role in the ecological control of pathogenic microorganisms in nature.

The metabolic fate of [35S]-diallyl disulphide in mice

Diallyl disulphide (DADS) is a major constituent of garlic oil. Uptake of [35S]-labelled diallyl disulphide by mouse liver is highest at 90 min after treatment with [35S]-DADS, 70% of the radioactivity is present in the liver cytosol of which 80% is metabolized to sulphate.

Current problems in the control of mosquitoes

Since the incidence of mosquito-borne disease was drastically reduced by the use of DDT in the 1950s, the problem has again worsened and no single method of eradication seems likely to achieve lasting success. It now seems that the best hope lies in the combination of various methods of chemical control and perhaps genetic control to rid the Third World of its most important disease sector.