betulin

Betulin is a naturally occurring pentacyclic triterpene of the lupane class. It is one of the most abundant triterpenoids in the bark of birch trees, especially Betula papyrifera (paper birch) and Betula pendula. The compound has the molecular formula C30H50O2 and a rigid lupane skeleton bearing a hydroxyl group, giving it properties of a lipophilic solid that is sparingly soluble in water and soluble in many organic solvents.

Extraction and occurrence: Betulin is commonly isolated from birch bark by solvent extraction, using methanol, ethanol, or similar solvents, often after drying and pulverizing the bark. Purified betulin typically crystallizes as white needles or flakes.

Chemical properties and derivatives: Betulin serves as a major starting material for chemical transformations, notably the oxidation to betulinic acid and the preparation of numerous semi-synthetic derivatives such as esters and ethers. These derivatives are pursued to improve solubility, stability, and biological activity.

Applications and biology: In industry, betulin is used as a starting point for synthesizing betulinic acid and related compounds for pharmaceutical research, and as an ingredient in some cosmetic formulations due to its emollient character. Pharmacologically, betulin itself often shows limited activity in vitro, whereas its oxidized form betulinic acid and related derivatives have been studied for antiviral, anti-inflammatory, and anticancer effects. Research continues into developing delivery methods and more potent, selective derivatives.

Safety and availability: Betulin is a natural product obtainable from birch bark and is not approved as a therapeutic agent. Handling requires standard laboratory precautions; as a lipophilic compound, it should be managed to avoid inhalation of dust and prolonged skin contact.