Antimicrobial and cytotoxic constituents from leaves of Sapium baccatum.

Human telomeric DNA (hTelo), present at the ends of chromosomes to protect their integrity during cell division, comprises tandem repeats of the sequence d(TTAGGG) which is known to form a G-quadruplex secondary structure. This unique structural formation of DNA is distinct from the well-known helical structure that most genomic DNA is thought to adopt, and has recently gained prominence as a molecular target for new types of anticancer agents. In particular, compounds that can stabilize the intramolecular G-quadruplex formed within the human telomeric DNA sequence can inhibit the activity of the enzyme telomerase which is known to be upregulated in tumor cells and is a major contributor to their immortality. This provides the basis for the discovery and development of small molecules with the potential for selective toxicity toward tumor cells. This review summarizes the various families of small molecules reported in the literature that have telomeric quadruplex stabilizing properties, and assesses the potential for compounds of this type to be developed as novel anticancer therapies. A future perspective is also presented, emphasizing the need for researchers to adopt approaches that will allow the discovery of molecules with more drug-like properties in order to improve the chances of lead molecules reaching the clinic in the next decade.

Recent advances in targeting the telomeric G-quadruplex DNA sequence with small molecules as a strategy for anticancer therapies

Recent progress of antibacterial natural products: Future antibiotics candidates.

Bulky α,β-dehydroamino acids: their occurrence in nature, synthesis, and applications

Natural products, especially those derived from higher plants, have attracted scientists from ancient time because of their potential therapeutic values. Drug development from natural sources showed that natural products or natural product-derived drugs comprised about 28% of all new chemical entities launched to the market. These are originated from terrestrial plants, microbes, marine organisms, etc. However, until recently an insignificant part of the plants has been scientifically evaluated for their medicinal properties. Bangladesh is a rich repository of medicinal plants, many of which are widely used in the Ayurvedic, Unani, herbal and other traditional systems of medicines. In our laboratory, we have extensively investigated over 48 medicinal plants and several microbial strains that have resulted in the isolation and characterization of 133 compounds, including 33 new molecules. Terpenoids, alkaloids, flavonoids and glycosides were the major classes of constituents. The crude extractives and several purified molecules demonstrated statistically significant inhibition of growth of microorganisms. On the other hand, usnic acid obtained from the lichen, Parmelia kamtschandalis , demonstrated even better of inhibition of microbial growth as compared to the standard antimicrobial agents, whereas dehydroaltenusin extracted from a Streptomyces sp. exhibited significant HIV-inhibitory activity. DOI: http://dx.doi.org/10.6000/1927-5951.2011.01.01.14

A Review on Phytochemicals from Some Medicinal Plants of Bangladesh

Chemotaxonomic significance of polyoxygenated flavonoids from the leaves of Micromelum minutum

Two new coumarins were isolated from the methanol extract of the leaves of Clausena heptaphylla. Their structures were established as lunamarin A (1) and lunamarin B (2) on the basis of spectral data, including 2D NMR.

Lunamarins A and B: Two Novel Terpenoid Coumarins from Clausena Heptaphylla

http://www.rsc.org/suppdata/cc/c2/c2cc31277h/c2cc31277h.pdf

Mohammad H. Sohrab

Papers

Chemotaxonomic significance of polyoxygenated flavonoids from the leaves of Micromelum minutum

Lunamarins A and B: Two Novel Terpenoid Coumarins from Clausena Heptaphylla

The prenylated dioxopiperazine alkaloid Cristatin A has selective telomeric DNA G-quadruplex stabilising properties.

Kauren diterpenes from Wedelia calendulacea

6-Substituted-7-oxygenated coumarins from the leaves of Micromelum minutum