Withania somnifera, commonly known as Ashwagandha, is an important medicinal plant that has been used in Ayurvedic and indigenous medicine for over 3,000 years. In view of its varied therapeutic potential, it has also been the subject of considerable modern scientific attention. The major chemical constituents of the Withania genus, the withanolides, are a group of naturally occurring C28-steroidal lactone triterpenoids built on an intact or rearranged ergostane framework, in which C-22 and C-26 are appropriately oxidized to form a six-membered lactone ring. In recent years, numerous pharmacological investigations have been carried out into the components of W. somnifera extracts. We present here an overview of the chemical structures of triterpenoid components and their biological activity, focusing on two novel activities, tumor inhibition and antiangiogenic properties of withaferin A and the effects of withanolide A on Alzheimer's disease. The most recent attempts in biotechnological production of withanolides are also discussed.

/pdf/steroidal-lactones-from-withania-somnifera-an-ancient-plant-1jii9ajyat.pdf

Steroidal lactones from Withania somnifera, an ancient plant for novel medicine.

Anti-HIV benzylisoquinoline alkaloids and flavonoids from the leaves of Nelumbo nucifera, and structure-activity correlations with related alkaloids.

Lignans neolignans, and related compounds

The Chemistry and Biology of Isoquinoline Alkaloids

In our screening program for antioxidants with DPPH radical scavenging activity, we isolated four yellowish compounds from the fermentation broth of Trichoderma sp. USF-2690 strain isolated from a soil sample: two were novel compounds designated bisorbicillinol (1) and demethyltrichodimerol (2), and two were known compounds bisvertinolone (3) and trichodimerol (4). The structures of 1 and 2 were elucidated by spectroscopic evidence and chemical modification. Two compounds seemed to be the oxidized dimers of sorbicillin. In the evaluation of DPPH radical scavenging activity, bisorbicillinol gave the lowest ED50 value (31.4 μM) among the four compounds, equal to that of BHT (27.0 μM).

Novel DPPH Radical Scavengers, Bisorbicillinol and Demethyltrichodimerol, from a Fungus

Konyanin: a new lignan from hapuophyllum vulcaniclm

The proposed structure of trichodimerol [1], isolated from a culture broth of Penicillium chrysogenum, has been confirmed by an X-ray crystallographic study. The relative stereochemistry of the molecule was established and its solid state conformation was determined. The results show a caged dimeric molecule with a pseudo twofold symmetry and two sorbyl side-chains of almost fully extended conformations. The crystal structure consists of a double-layered network by solvent-mediated hydrogen bonding.

John E. Leet

Papers

Konyanin: a new lignan from hapuophyllum vulcaniclm

Crystal Structure of Trichodimerol

Some Dimeric Benzylisoquinoline Alkaloids With an Unusual Oxygenation Pattern

Sindamine, Punjabine, and Gilgitine: Three New Secobisbenzylisoquinoline Alkaloids

The alkaloidal profile of cocculus pendulus