NMR spectroscopy in the structural elucidation of oligosaccharides and glycosides.

Saponins occur widely in plant species and exhibit a range of biological properties, both beneficial and deleterious. This review, which covers the literature to mid 1986, is concerned with their occurrence in plants and their effects when consumed by animals and man. After a short discussion on the nature, occurrence, and biosynthesis of saponins, during which the distinction between steroidal and triterpenoid saponins is made, the structures of saponins which have been identified in a variety of plants used as human foods, animal feedingstuffs, herbs, and flavorings are described. Many of these compounds have been characterized only during the last 2 decades, and modern techniques of isolation, purification, and structural elucidation are discussed. Particular consideration is given to mild chemical and enzymatic methods of hydrolysis and to recent developments in the application of NMR and soft ionization MS techniques to structural elucidation. Methods currently used for the quantitative analysis of saponins, sapogenols, and glycoalkaloids are critically considered; advances in the use of newer methods being emphasized. The levels of saponins in a variety of foods and food plants are discussed in the context of the methods used and factors affecting these levels, including genetic origin, agronomic, and processing variables, are indicated. Critical consideration is given to the biological effects of saponins in food which are very varied and dependent upon both the amount and chemical structure of the individual compounds. The properties considered include membranolytic effects, toxic and fungitoxic effects, adverse effects on animal growth and performance, and the important hypocholesterolemic effect. A final section deals briefly with the pharmacological effects of saponins from ginseng, since use of this plant is increasing in certain sections of western society as well as being traditional in the Orient.

The chemistry and biological significance of saponins in foods and feedingstuffs.

time, probably by stimulation of the hepatic microsomal enzyme system3. Similar properties were exhibited by its roots. However, the petroleum ether extract (PEE) of the roots enhanced pentobarbitone sleeping time, probably due to CNS depression4. The PEE of the seed of Pongomia pinnata was further tested for nootropic activity in an experimental model of Alzheimer’s disease (created by ibotenic acid induced lesioning of nuclear basalis magnocellularis). It reversed both, the cognitive deficits and the reduction in cholinergic markers after 2 weeks of treatment. Reversal of perturbed cholinergic function appears to be the possible mechanism5.

/pdf/pharmacology-of-medicinal-plants-and-natural-products-55vzicfceo.pdf

Pharmacology of medicinal plants and natural products

Since the initial recognition that diet plays a role in the etiology of certain cancers, particularly cancers of the breast and colon, considerable progress has been made in identifying dietary patterns associated with cancer risk. There is general agreement that a high-fat, low-fiber diet, like that consumed by much of the industrialized world, increases cancer risk and that plant-based diets, rich in whole grains, legumes, and fruits and vegetables, are protective. It has been, however, considerably more difficult to identify specific foods, types of food, or components of foods that influence cancer risk. The recent workshop on The Role of Soy Products in Cancer Prevention, sponsored by the National Cancer Institute, had two objectives: I) to evaluate the role of soybeans, food products derived from soybeans, and specific components of soybeans in the dietary prevention of cancer and 2) to recommend research initiatives and approaches for further studies of the effect of soy intake on human cancer risk. The meeting was chaired by Stephen Barnes and organized by Mark Messina.

The Role of Soy Products in Reducing Risk of Cancer

Steroidal glycoalkaloids (SGAs) such as α-solanine found in solanaceous food plants--as, for example, potato--are antinutritional factors for humans. Comparative coexpression analysis between tomato and potato coupled with chemical profiling revealed an array of 10 genes that partake in SGA biosynthesis. We discovered that six of them exist as a cluster on chromosome 7, whereas an additional two are adjacent in a duplicated genomic region on chromosome 12. Following systematic functional analysis, we suggest a revised SGA biosynthetic pathway starting from cholesterol up to the tetrasaccharide moiety linked to the tomato SGA aglycone. Silencing GLYCOALKALOID METABOLISM 4 prevented accumulation of SGAs in potato tubers and tomato fruit. This may provide a means for removal of unsafe, antinutritional substances present in these widely used food crops.

http://science.sciencemag.org/content/sci/341/6142/175.full.pdf

Biosynthesis of Antinutritional Alkaloids in Solanaceous Crops Is Mediated by Clustered Genes

Medicinal plants as a source of antioxidants.

The genus Alnus has been reviewed for its chemical constituents and biological activities including traditional importance of some common species. The plants of this genus contain terpenoids, flavonoids, diarylheptanoids, phenols, steroids, and tannins. Diarylheptanoids are the dominant constituents within the genus Alnus, few of them exhibited antioxidant effects and inhibitory activity against nuclear factor kappaB activation, nitric oxide and tumor necrosis factor-α production, human umbilical vein endothelial cells, farnesyl protein transferase, cell-mediated low-density lipoprotein oxidation, HIF-1 in AGS cells, and the HIV-1-induced cytopathic effect in MT-4 cells. Some ellagitannines showed hepatoprotective activity even in a dose of 1 mg/kg which is ten-fold smaller compared with the dose of traditional flavonoid-based drugs. The members of genus Alnus are well known for their traditional uses in the treatment of various diseases like cancer, hepatitis, inflammation of uterus, uterine cancer, rheumatism, dysentery, stomachache, diarrhea, fever, etc. The aim of the present review is to summarize the various researches related to the chemistry and pharmacology of genus Alnus.

Bioactive constituents and medicinal importance of genus Alnus.

Essential oils from inflorescences and roots of Eupatorium adenophorum Spreng (Asteraceae) have been investigated for their antimicrobial, phytotoxic and antioxidant activities. Based on GC–MS, the oil from inflorescences is dominated by sesquiterpenes (55.9 %) with γ-cadinene (18.4 %), γ-muurolene (11.7 %), 3-acetoxyamorpha-4,7(11)-diene-8-one (7.4 %) and bornyl acetate (6.3 %) as the major constituents. The oil obtained from the roots contained both sesquiterpenes (34.3 %) and monoterpenes (32.5 %) in almost equal proportions with E,E-cosmene (19.9 %), γ-muurolene (10.1 %), isothymol (7.5 %), β-cadinene (7.0 %) and α-phellandren-8-ol (5.9 %) as the major constituents. Both oils exhibited significant antifungal activity against five phytopathogenic fungi. The inflorescence oil showed higher antibacterial activity against Klebsiella pneumoniae, while the root oil was more effective against Staphylococcus aureus. The oils strongly inhibited or delayed germination and seedling growth of the weed Phalaris minor in a dose-dependent manner. As evidenced by a DPPH assay, the essential oils also exhibited significant free radical scavenging activity.

Om Prakash Sati

Papers

Medicinal plants as a source of antioxidants.

Bioactive constituents and medicinal importance of genus Alnus.

Chemical analysis of essential oils of Eupatorium adenophorum and their antimicrobial, antioxidant and phytotoxic properties

Comparative evaluation of two Trichoderma harzianum strains for major secondary metabolite production and antifungal activity

Chemical composition and antifungal activity of Artemisia nilagirica essential oil growing in northern hilly areas of India