Rapid screening of toxic glycoalkaloids and micronutrients in edible nightshades (Solanum spp.).

African indigenous vegetables (AIVs) because of their nutrient density have the unique potential to reduce micronutrient deficiencies in sub-Saharan Africa, yet some may also contain anti-nutritive compounds. Vegetable nightshades from Solanum americanum, Solanum nigrum, Solanum scabrum and Solanum villosum are among the major AIVs used as a leafy vegetables and consumed regularly in many countries in sub-Sahara Africa. These under-recognized food crops have not been subjected to extensive studies for their nutritional and antinutritive factors. In this study, 15 entries of the vegetable nightshades were field-grown and the leaves which are the consumed product of commerce chemically profiled by LC/ESI-MS. Twenty-three flavones, eight saponins, and two glycoalkaloids along with a phenolic acid of chlorogenic acid were identified by MS and UV data. Anti-nutrient glycoalkaloids were quantified as total aglycones after acidic hydrolysis using MS detection and found to be within safe-consumption thresholds by comparison with the glycoalkaloid level in the globally consumed Solanum member eggplants. Edible nightshades were also found to be sources of ß-carotene, vitamin E and total polyphenols and exhibited high antioxidant activity. Results of this study support that consumption of vegetable nightshades are safe from the presence of glycoalkaloids and thus, can contribute to the reduction of micronutrient deficiency in sub-Sahara Africa.

Synthesis of novel flavonoid alkaloids as α-glucosidase inhibitors.

A series of novel flavonoid alkaloids were synthesized with different flavonoids and attached nitrogen-containing moieties. These new compounds were screened for inhibitory activity of α-glucosidase, among which compound 23 was found to show the lowest IC50 of 4.13µM. Kinetic analysis indicates that the synthesized compounds 15 and 23 inhibit the enzyme in a non-competitive model with Ki value of 37.8±0.8µM and 13.2±0.6µM. Further docking studies suggest that the preferred binding pocket is close to the catalytic center, correlating to the experimental results. Structure activity relationship studies (SAR) indicate that 4'-hyroxyl group and the 4-position carbonyl group in the flavonoid structure are important for this biological activity. Addition of extra hydrogen bonding and hydrophobic groups on ring A would increase the inhibitory activity.

Substituted 1,6-diphenylnaphthalenes as FtsZ-targeting antibacterial agents.

Bacterial cell division occurs in conjunction with the formation of a cytokinetic Z-ring structure comprised of FtsZ subunits. Agents that disrupt Z-ring formation have the potential, through this unique mechanism, to be effective against several of the newly emerging multidrug-resistant strains of infectious bacteria. Several 1-phenylbenzo[c]phenanthridines exhibit notable antibacterial activity. Based upon their structural similarity to these compounds, a distinct series of substituted 1,6-diphenylnaphthalenes were synthesized and evaluated for antibacterial activity against Staphylococcus aureus and Enterococcus faecalis. In addition, the effect of select 1,6-diphenylnaphthalenes on the polymerization dynamics of S. aureus FtsZ and mammalian ß-tubulin was also assessed. The presence of a basic functional group or a quaternary ammonium substituent on the 6-phenylnaphthalene was required for significant antibacterial activity. Diphenylnaphthalene derivatives that were active as antibiotics, did exert a pronounced effect on bacterial FtsZ polymerization and do not appear to cross-react with mammalian tubulin to any significant degree.