Trends in drug development for the treatment of AIDS compounds interfering with the initial stages of the HIV replicative cycle

Cryopreservation of Orchids - A Review

BACKGROUND

The orchids are one of the beautiful creations of nature which stand apart from any other assemblage of flowering plants. They are highly evolutionary and ecologically significant group of plants that have effectively occupied almost every habitat on the earth. Indiscriminate collections and extermination of their natural habitats have threatened many species of orchids with extinction, resulting in a severe reduction of their genetic resources in nature according to recent patents. It is necessary to adopt sound scientific protocols for the preservation of orchid species.

METHOD

This cost-effective technique provides large storage time for the conservation of germplasm. Presently, efforts have been made to explore various cryopreservation techniques utilized so far and factors affecting the longevity of the propagules (in vivo and in vitro) while cryopreserving them. The sample to be cryopreserved is freeze-preserved in two ways, a) stepwise at two different subzero temperatures and b) in the rapid method, the samples are placed directly in the liquid nitrogen.

RESULTS

The orchid seeds and pollen are the most suitable propagules for cryopreservation of orchids due to their minute size and less space requirement.

CONCLUSION

Among the tissues (such as seeds, pollen, protocorms etc.) seeds are the most reliable. The present article reviews the cryopreservation techniques and factors effecting the cryopreservation, for in vitro conservation of orchid gene pool.

QSAR based on multiple linear regression and PLS methods for the anti-HIV activity of a large group of HEPT derivatives

Quantitative structure-activity relationships have been developed for a set of 107 inhibitors of the HIV-1 reverse transcriptase, derivatives of a recently reported HIV-1 specific lead: 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT). The activity of these compounds was investigated by means of multiple linear regression (MLR) and PLS regression techniques and topological indexes as well as several tabulated physicochemical substituent constants were used as predictor variables. The results obtained indicate that the anti-HIV activity of the HEPT derivatives is strongly dependent on hydrophobic factors as expressed by the Hansch constant (sigma pi (R1+R2)), and especially dependent on the geometric factors mainly accounted for by the 1 chi N (R2) and 4 chi pN molecular connectivity indexes and also for the molecular volume (Vx), the Taft steric constant (Es(2R1)), and the Verloop parameter for the smallest width value (B1(3R1)). Besides, for this data set, comparison of the quality of MLR and PLS models show that PLS is a better approach to MLR for improving the interpretability of the data and also to exhibit models with a better predictive quality.

Inhibition of human immunodeficiency virus replication by the sulfonated stilbene dye resobene

The anti-HIV sulfonated dye, resobene, was found to be a potent inhibitor of the attachment of HIV to target cells, the fusion of envelope- and CD4-expressing cells, and the cell-to-cell transmission of virus. Resobene inhibited the infection of phenotypically distinct, established human cell lines and fresh human peripheral blood lymphocytes and macrophages by laboratory-derived isolates of human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2), and a panel of biologically diverse primary clinical isolates, including syncytium-inducing and non-syncytium-inducing viruses and strains representative of the various virus clades found worldwide. The compound was also active against all drug-resistant virus isolates tested. Cell-based and biochemical mechanism of action studies demonstrated that the compound inhibits the attachment of infectious virus and fusion of virus-infected cells to uninfected target cells by binding to the cationic V3 loop of the envelope glycoprotein. Resobene effectively inhibited the infection of cell populations which do and do not express cell surface CD4. Resobene prevented infection of the cervical epithelial cell line ME180, suggesting the compound may effectively act as a topical microbicide to prevent the sexual transmission of HIV.