The extraction of botanicals is divided into 3 stages

The process of extracting components from medicinal materials involves three main stages: wetting and penetration, desorption and dissolution, and component dissolution.

1. **Wetting and Penetration Stages**:

* The ability of a solvent to wet the surface of a medicinal material depends on the properties of both the solvent and the material, as well as the adhesion layer where the liquid contacts the solid.

* If the adhesion between the medicinal material and the solvent is greater than the cohesive force between the solvent molecules, the material is easily wetted.

* Medicinal materials are generally wettable by solvents due to the presence of polar groups like proteins, pectins, sugars, and cellulose, which interact well with polar solvents such as water and alcohol.

* After wetting, the solvent penetrates the gaps and cracks in the material, aided by hydrostatic pressure and capillary action. This causes the cells to swell and restore permeability, allowing the solvent to penetrate deeper into the cells.

* If the solvent is not suitable or if the material contains components that hinder extraction (e.g., fatty oils), wetting and penetration may be difficult. In such cases, pre-treatment like degreasing or drying may be necessary. Adding surfactants to the solvent can also help improve wetting.

2. **Desorption and Dissolution Stages**:

* Once the solvent enters the cells, soluble components gradually dissolve, and volatile substances may expand or form condensates.

* The concentration of the extract increases, and osmotic pressure rises, causing some cell walls to swell and rupture, facilitating the diffusion of dissolved components outward.

* Some components may be strongly adsorbed to others, requiring desorption before they can dissolve. Solvents like water or alcohol with desorption effects are used, and additional agents like acids, alkalis, oils, or surfactants may be added to enhance solubility.

* The dissolution stage involves the transfer of desorbed components into the solvent through capillary and intercellular spaces.

3. **Component Dissolution Stage**:

* As the solvent dissolves the drug components, the intracellular fluid's concentration increases, creating a concentration and osmotic pressure difference between the inside and outside of the cells.

* Pure solvent or dilute solution outside the cells permeates into the cells, while the concentrated liquid inside diffuses outward.

* Diffusion continues until the concentrations inside and outside the cells equalize, and osmotic pressure reaches equilibrium.

This process highlights the importance of selecting the appropriate solvent and pre-treatment methods to ensure effective extraction of medicinal components.