During the growth of plants, a series of metabolic and biochemical processes are carried out, forming and accumulating a variety of chemical substances that constitute the chemical composition of plants. There is a wide variety of plant extracts with different chemical compositions. Generally plants contain the following types of chemical components: alkaloids, glycosides, organic acids, resins (including resin acids, resin alcohols and resin hydrocarbons), volatile oils, polysaccharide (including starch, inulin, gum and mucilage), amino acids, proteins and enzymes, tannins, phytochromes (including chlorophylls, carotenoids, flavonoids, betaines and quinones), oils, waxes and inorganic components (trace elements).
Plant extracts can be classified by dosage form as: water-soluble plant extracts (including water, propylene glycol extracts, butylene glycol extracts and glycerol extracts), oil-soluble plant extracts (including extracts of various plant oils such as sunflower oil, coconut oil, olive oil and sometimes myristic isopropyl extract), essential oils, spray dry powders, enzymatically hydrolyzed plant protein powders, pure active ingredients, peeled fruit liposome microcapsules dry powders, polysaccharide or other polymeric microcapsules and extracts absorbed by porous microspheres. Fresh fruit or vegetable juices are also used in professional salons or home beauty salons. Plant extracts use different plant parts with different active ingredients, including: roots, stems, leaves, skins, flowers, corollas, fruits, seeds and buds. This classification makes more sense in terms of preparation, use, storage and transportation, and is widely used by some plant extract manufacturers.