Physalins are steroidal constituents of Physalis

Physalis

Physalis is a genus of plants in the nightshade family , native to warm temperate and subtropical regions throughout the world. The genus is characterised by the small orange fruit similar in size, shape and structure to a small tomato, but partly or fully enclosed in a large papery husk derived...

plants which possess an unusual 13,14-seco-16,24-cyclo-steroidal ring skeleton (where the bond

Covalent bond

A covalent bond is a form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms. The stable balance of attractive and repulsive forces between atoms when they share electrons is known as covalent bonding....

 that is normally present between the 13 and 14 positions in other steroids is broken while a new bond between positions 16 and 24 is formed; see figure below). Since the isolation and the structure determination of Physalin A and Physalin B in 1969, more than a dozen Physalins were isolated from Physalis species, Physalis alkekengi

Physalis alkekengi

Physalis alkekengi , is a relative of P. peruviana , easily identifiable by the larger, bright orange to red papery covering over its fruit, which resemble Chinese lanterns. It is native from southern Europe east across southern Asia to Japan...

, Physalis angulata

Physalis angulata

Physalis angulata is a widely-distributed herbaceous annual plant with common name of Fisalia, belonging to the nightshade family Solanaceae. It is known by several names, including Cutleaf groundcherry, Wild tomato, Camapu and Winter cherry...

, and Physalis lancifolia. These compounds have antimicrobial

Antimicrobial

An anti-microbial is a substance that kills or inhibits the growth of microorganisms such as bacteria, fungi, or protozoans. Antimicrobial drugs either kill microbes or prevent the growth of microbes...

, and antiparasitic effects.