Deodorant Activity of Black Cumin Seed Essential Oil against Garlic Organosulfur Compound.

The deodorant activity of black cumin (Nigella sativa L.) seed, a spice used to flavor curry and vegetable foods in Southwest Asia, against garlic (Allium sativum L.) organosulfur compounds related to human malodor was evaluated. Black cumin seed essential oil showed remarkable deodorant activity against garlic essential oil. The mode of action of this deodorant activity was presumed to be that black cumin seed essential oil covalently reacted with the organosulfur compounds in garlic. Therefore, thymoquinone, which is a major constituent in black cumin seed essential oil, and allyl mercaptan, which is one of the organosulfur compounds produced by cutting garlic, were reacted in vitro, and the products were purified and elucidated using spectroscopic data. As a result, these substances were identified as different allyl mercaptan adducts to dihydrothymoquinone. This chemical reaction was presumed to play a key role in the deodorant activity of black cumin seed essential oil.

Inhibitory Activities of Sulfur Compounds in Garlic Essential Oil against Alzheimer's Disease-Related Enzymes and Their Distribution in the Mouse Brain.

Alzheimer's disease (AD) is the most common neurodegenerative disease. Garlic reportedly has various physiological effects, including a role in protecting against dementia. However, the action mechanisms of garlic on AD are not entirely clear. In this study, we investigated the inhibitory activity of garlic essential oil (GEO) against AD-related enzymes and evaluated the distribution of active substances in GEO to the brain. We found that several sulfur compounds in GEO significantly inhibited AD-related enzymes. Sulfur compounds were detected in the serum and brain 6 h post administration. The ratios of allyl mercaptan (24.0 ± 3.9%) and allyl methyl sulfide (49.8 ± 15.6%) in the brain were significantly higher than those in GEO, while those of dimethyl trisulfide (0.89 ± 34.8%), allyl methyl trisulfide (0.41 ± 19.0%), and diallyl trisulfide (0.43 ± 72.8%) in the brain were significantly lower than those in GEO. Similar results were observed in the serum, suggesting that the organosulfur compounds were converted to allyl mercaptan or allyl methyl sulfide in the body. Although allyl mercaptan and allyl methyl sulfide are not the main components of GEO, they might be key molecules to understand the bioactivities of GEO in the body.

α-Glucosidase and Pancreatic Lipase Inhibitory Activities of Diterpenes from Indian Mango Ginger (Curcuma amada Roxb.) and Its Derivatives.

Enzymatic inhibitions of crude extracts and their constituents from Zingiberaceae against both rat intestinal α-glucosidase and porcine pancreatic lipase were investigated. Structure-activity relationships using their derivatives were also investigated. The rhizomes extract of mango ginger, Curcuma amada showed remarkable inhibitory activity in the screening test. Two natural labdane diterpenes 1 and 2 and a drimane sesquiterpene 3 were major constituents isolated from this hexane extract. Among them, (E)-labda-8(17),12-diene-15,16-dial (1) was the most prominent compound and showed inhibitory activity against both α-glucosidase and lipase. Derivatives 4-10 from compound 1 were prepared and evaluated using inhibitory assays with these enzymes. The reduced derivative 4 maintained α-glucosidase inhibitory activity, but had decreased pancreatic lipase inhibitory activity compared with parent compound 1. Other tested derivatives of compound 1, including acetates 5-7 and oxidative derivatives 8-10, had very weak α-glucosidase inhibitory activity. Most of these compounds showed moderate pancreatic lipase inhibitory activity. However, only sesquiterpene albicanal (3) showed drastically decreased pancreatic lipase activity compared with 1. These findings suggested that molecular size was essential for enzymatic inhibitory activities of these compounds. These results demonstrated that mango ginger may be useful for the prevention of obesity and being overweight.

Deodorizing Substance in Black Cumin (Nigella sativa L.) Seed Oil.

A deodorizing substance in black cumin (Nigella sativa L.), a spice for curry and vegetable foods in Southwest Asia, was examined. The essential oil prepared from the seeds of this plant exhibited strong deodorizing activity against methyl mercaptan, which is a main factor in oral malodor. After purification with silica gel column chromatography, the active substance in black cumin seed oil was identified as thymoquinone. This monoterpenic quinone functions as the main deodorizing substance in this oil against methyl mercaptan. Metabolite analysis suggested that the deodorizing activity may be generated by the addition of a reactive quinone molecule to methyl mercaptan. In the present study, the menthane-type quinone and phenol derivatives exhibited deodorizing activities via this mechanism.

Inhibitory Activities of Sesame Seed Extract and its Constituents against ß-Secretase.

The need for a preventive agent against dementia led us to screen natural plant resources. Among the herbs and spices tested, sesame seed prepared from Sesamum indicum seeds showed potent ß-secretase inhibitory activity. The active principles were determined to be sesamin and sesamolin, typical lignans in S. indicum. The IC(50) values of sesamin and sesamolin were 257 and 140 µM, respectively. These compounds were investigated in a preliminary absorption experiment. After oral administration, these compounds were detected in an intact form in the brain and serum. These results suggest that consumption of sesame seeds may prevent dementia by sesamin and sesamolin, the constituents in sesame seeds.

Inhibitory Activities of Essential Oil Obtained from Turmeric and Its Constituents against ß-Secretase.

The need for a preventive agent against dementia led us to screen natural plant resources. Among the herbs and spices tested, turmeric, from rhizomes of Curcuma longa, showed high potency against ß-secretase. The active principles were determined as α-turmerone, ß-turmerone and ar-turmerone, with IC(50) values of 39, 62 and 92 µM respectively. In this study, the efficiency of collecting the essential oil using steam distillation of the volatile substance was disclosed The active principles were explored, and four sesquiterpenoids and five monoterpenoids were revealed as active principles against ß-secretase; On the other hand, α-turmerone, ß-turmerone and ar-turmerone were also investigated in a pharmacokinetic absorption experiment. After oral administration, these compounds were detected in an intact form in the brain and serum. These results suggest that consumption of-turieric constituents may prevent dementia.

Insect antifeedants, pterocarpans and pterocarpol, in heartwood of Pterocarpus macrocarpus Kruz.

The insect antifeedant activities of pterocarpans and a sesquiterpene alcohol from the dichloromethane extract of Pterocarpus macrocarpus Kruz. (Leguminosae) were evaluated against the common cutworm, Spodoptera litura F. (Noctuidae), and the subterranean termite, Reticulitermes speratus (Kolbe)(Rhinotermitidae). Three pterocarpans, (-)-homopterocarpin (1), (-)-pterocarpin (2), and (-)-hydroxyhomopterocarpin (3) and the sesquiterpene alcohol, (+)-pterocarpol (5), were isolated from the dichloromethane extract of the heartwood of P. macrocarpus under guidance by a biological assay. Among these natural products, the most active insect antifeedant against both S. litura and R. speratus was 1. On the other hand, sesquiterpene alcohol 5 showed less insect antifeedant activity than the other pterocarpans against both insect species. While its methylated derivative, (-)-methoxyhomopterocarpin (4), showed high biological activity, 3 showed less insect antifeedant activity in this study. Interestingly, racemic 1 did not show insect antifeedant activity against S. litura. However, all of the test pterocarpans and isoflavones showed antifeedant activity against the test termites. Additionally, since these compounds were major constituents of P. macrocarpus, these antifeedant phenolics may act as chemical defense factors in this tree. In Thailand, lumber made from this tree is used to make furniture and in building construction due to its resistance to termite attack.