More about phytochemicals
In natural product chemistry, phytochemicals are generally in the category of the secondary metabolites from plants, which are distinguished from primary metabolites (e.g. nucleic acids, amino acids, carbohydrate, fat, etc.)
A phytochemical or a secondary metabolite is not crucial for normal living cells in normal growth, development, and reproduction, but acts in a defense role to protect a plant from any possible harms in the ecological environment. A phytochemical or a secondary metabolite is usually synthesized in plants for particular needs, while the primary metabolites have generally the shared biological purposes across all species. Secondary metabolites may often created by modified synthetic pathways for primary metabolite, or share substrates of primary metabolite origin. Plants have been evolving to adapt the environment with genetic encoding of useful & diverse synthases for secondary metabolite(s).
Phytochemicals are a general term for a broad range of natural products, and include all individual members of antioxidants of plant origin. “Phytochemicals” is not a term parallel to a few individual antioxidant names listed in this site as the most popular antioxidant models.
The differences between herbs and phytochemicals
“Herb” is a word related to culture or tradition for any whole plants or their parts, while “phytochemical” is more a scientific term for particularly chemicals of health benefits in plants. The same phytochemical isolated from different plants share the same biological properties regardless of its sources, while herbs containing the same phytochemicals may be used for difference purposes based on culture and tradition. Herbs have been used as drugs for millennia, while human has just been learning phytochemicals in herbs for a very short period time about a century.
Diverse Biological Activities of Phytochemicals
Phytochemicals are diverse natural products of different biological activities:
A small fraction of known phytochemicals have antioxidant activity and protect plants and human body against oxidative damage. As discussed by scientists, phytochemicals as antioxidant may reduce the risk of developing certain types of cancer. Examples of antioxidant phytochemicals include ascorbic acid (vitamin C), EGCG (from green tea), OPC (from grape seed and pine bark), etc.
Many phytochemicals have anticancer activities as discussed in scientific publications. Efficient treatment or cure of cancers still remain difficulties, given that any anticancer drugs are associated with high degree of toxicities. Natural products of anticancer activities are much less toxic or non-toxic. Examples of phytochemcials as anticancer drugs include paclitaxel (Taxol® as marketed by Bristol-Myers Squibb). Paclitaxel is isolated from the bark of the Pacific yew tree and is used to treat lung, ovarian, breast cancer, head and neck cancer, and advanced forms of Kaposi's sarcoma, Taxus brevifolia. Another example of phytochemcials is saponins isolated from beans that inhibit the DNA replication in certain cell lines, and suppress the growth of cancer cells. Capsaicin isolated from hot peppers has been demonstrated DNA-protecting effect against carcinogens.
Some phytochemicals may have hormonal activity. Isoflavones isolated from in soy have human estrogens-like properties and help to reduce menopausal symptoms and osteoporosis.