Medicinal plants of India with anti-diabetic potential.

A Cook's tour is presented of the organosulfur chemistry of the genus Allium, as represented, inter alia, by garlic (Allium sativum L.) and onion (Allium cepa L.). We report on the biosynthesis of the S-alk(en)yl-L-cysteine S-oxides (aroma and flavor precursors) in intact plants and on how upon cutting or crushing the plants these precursors are cleaved by allinase enzymes, giving sulfenic acids—highly reactive organosulfur intermediates. In garlic, 2-propenesulfenic acid gives allicin, a thiosulfinate with antibiotic properties, while in onion 1-propenesulfenic acid rearranges to the sulfine (Z)-propanethial S-oxide, the lachrymatory factor (LF) of onion. Highlights of onion chemistry include the assignment of stereochemistry to the LF and determination of the mechanism of its dimerization; the isolation, characterization, and synthesis of thiosulfinates which most closely duplicate the taste and aroma of the freshly cut bulb, and additional unusual compounds such as zwiebelanes (dithiabicyclo[2.1.1]hexanes), a bis-sulfine (a 1,4-butanedithial S,S′-dioxide), antithrombotic and antiasthmatic cepaenes (α-sulfinyl disulfides), and vic-disulfoxides. Especially noteworthy in the chemistry of garlic are the discovery of ajoene, a potent antithrombotic agent from garlic, and the elucidation of the unique sequence of reactions that occur when diallyl disulfide, which is present in steam-distilled garlic oil, is heated. Reaction mechanisms under discussion include [3, 3]- and [2, 3]-sigma-tropic rearrangements involving sulfur (e.g. sulfoxide-accelerated thio- and dithio-Claisen rearrangements) and cycloadditions involving thiocarbonyl systems. In view of the culinary importance of alliaceous plants as well as the unique history of their use in folk medicine, this survey concludes with a discussion of the physiological activity of the components of these plants: cancer prevention, antimicrobial activity, insect and animal attractive/repulsive activity, olfactory–gustatory–lachrymatory properties, effect on lipid metabolism, platelet aggregation inhibitory activity and properties associated with ajoene. And naturally, comments about onion and garlic induced bad breath and heartburn may not be overlooked.

The Organosulfur Chemistry of the Genus Allium – Implications for the Organic Chemistry of Sulfur

http://www.sld.cu/galerias/pdf/sitios/mednat/natural_medicines_used_in_the_traditional_chinese_medical_system_for_therapy_of_diabetes_mellitus.pdf

Natural medicines used in the traditional Chinese medical system for therapy of diabetes mellitus

OBJECTIVE —To conduct a systematic review of the published literature on the efficacy and safety of herbal therapies and vitamin/mineral supplements for glucose control in patients with diabetes. RESEARCH DESIGN AND METHODS —We conducted an electronic literature search of MEDLINE, OLDMEDLINE, Cochrane Library Database, and HealthSTAR, from database inception to May 2002, in addition to performing hand searches and consulting with experts in the field. Available clinical studies published in the English language that used human participants and examined glycemic control were included. Data were extracted in a standardized manner, and two independent investigators assessed methodological quality of randomized controlled trials using the Jadad scale. RESULTS —A total of 108 trials examining 36 herbs (single or in combination) and 9 vitamin/mineral supplements, involving 4,565 patients with diabetes or impaired glucose tolerance, met the inclusion criteria and were analyzed. There were 58 controlled clinical trials involving individuals with diabetes or impaired glucose tolerance (42 randomized and 16 nonrandomized trials). Most studies involved patients with type 2 diabetes. Heterogeneity and the small number of studies per supplement precluded formal meta-analyses. Of these 58 trials, the direction of the evidence for improved glucose control was positive in 76% (44 of 58). Very few adverse effects were reported. CONCLUSIONS —There is still insufficient evidence to draw definitive conclusions about the efficacy of individual herbs and supplements for diabetes; however, they appear to be generally safe. The available data suggest that several supplements may warrant further study. The best evidence for efficacy from adequately designed randomized controlled trials (RCTs) is available for Coccinia indica and American ginseng. Chromium has been the most widely studied supplement. Other supplements with positive preliminary results include Gymnema sylvestre , Aloe vera , vanadium, Momordica charantia , and nopal.

/pdf/systematic-review-of-herbs-and-dietary-supplements-for-2bv10wr1xi.pdf

Systematic Review of Herbs and Dietary Supplements for Glycemic Control in Diabetes

A review on the role of antioxidants in the management of diabetes and its complications

S-allyl cysteine sulphoxide (SACS), a sulphur containing amino acid of garlic which is the precursor of allicin and garlic oil, has been found to show significant antidiabetic effects in alloxan diabetic rats. Administration of it at a dose of 200 mg/kg body weight decreased significantly the concentration of serum lipids, blood glucose and activities of serum enzymes like alkaline phosphatase, acid phosphatase and lactate dehydrogenase and liver glucose-6-phosphatase. It increased significantly liver and intestinal HMG CoA reductase activity and liver hexokinase activity.

Antidiabetic effects of s-allyl cysteine sulphoxide isolated from garlic allium sativum linn

Treatment of alloxan diabetic rats with the antioxidant S-allyl cysteine sulfoxide (SACS) isolated from garlic (Allium sativum Linn)., ameliorated the diabetic condition almost to the same extent as did glibenclamide and insulin. In addition, SACS controlled lipid peroxidation better than the other two drugs. Furthermore, SACS significantly stimulated in vitro insulin secretion from B cells isolated from normal rats. Hence it can be surmised that the beneficial effects of SACS could be due to both its antioxidant and its secretagogue actions. The former effect is more predominant and the latter is only secondary. These effects highlight the therapeutic value of garlic, which is a component of many diets.

Antiperoxide effect of S-allyl cysteine sulfoxide, an insulin secretagogue, in diabetic rats.

On oral administration of onion (Allium cepa L) and garlic (A sativum L) sulfoxide amino acids viz, S-methylcysteine sulfoxide (SMCS) and S-allylcysteine sulfoxide (SACS) to alloxan-diabetic rats for a month, their diabetic condition, being characterized by glucose intolerance, weight loss, depletion of liver glycogen, etc, was ameliorated as comparable to rats treated with glibenclamide and insulin However, only the last two drugs significantly increased the conversion of labelled acetate to liver cholesterol which indicates a deterrent effect of the allium products against the synthesis of a risk factor

Anti-diabetic effects of onion and garlic sulfoxide amino acids in rats.

Experimenteller Nachweis eines hypolipidamischen Effektes des Knoblauch-Inhaltstoffes Allicin nach Langzeit-Futterungsversuchen mit Ratten, wobei die Allicin-Wirkung sich starker auf die Leber als auf das Blutserum auswirkt.

Lipid lowering effect of allicin (diallyl disulphide-oxide) on long term feeding to normal rats

Cholesterol containing diet significantly increased not only the body weight, but also the weight of liver and adipose tissue of rats. This is accompanied by a significant increase in blood lipids, atherogenic index and lipid peroxidation and a significant decrease in reduced glutathione level, superoxide dismutase and catalase activities in tissues. Treatment with S-allyl cysteine sulphoxide reverses the deleterious effects of cholesterol diet significantly and almost as effectively as gugulipid.

K. T. Augusti

Papers

Antidiabetic effects of s-allyl cysteine sulphoxide isolated from garlic allium sativum linn

Antiperoxide effect of S-allyl cysteine sulfoxide, an insulin secretagogue, in diabetic rats.

Anti-diabetic effects of onion and garlic sulfoxide amino acids in rats.

Lipid lowering effect of allicin (diallyl disulphide-oxide) on long term feeding to normal rats

Antiperoxide effects of S-allyl cysteine sulphoxide isolated from Allium sativum Linn and gugulipid in cholesterol diet fed rats