They are seed-producing annual, biennial, or perennial plants with leafy green or flowering parts (either fresh or dried) and do not develop persistent woody tissue but die down at the end of a growing season or after flowering. They have savory or aromatic properties used for flavoring food, medicinal purposes, or for fragrances. They exclude vegetables and other plants consumed for macronutrients.
Phytochemicals and Herbs
These are naturally existing plant compounds in herbs reported to possess various biological functions in humans. They can vary according to but not limited to the varieties, genotypes, culture conditions, maturity, storage conditions, and thermal processing of the herbs extracted from (Kyung-Jin & Russel, 2014). Also, they can vary in bioavailability in humans due to food matrix, structure, interactions with other nutrients, site of absorption, and their metabolism (Kyung-Jin & Russel, 2014).
These phytochemicals possess antibacterial, antifungal, anticancer, antimalarial, antiprotozoal, antioxidant properties, etc.
Medicinal plants harbor endophytes (the group of microorganisms inhabiting within the plant host for a particular life cycle without harming the host). It is a prolific source of phytochemical production. Production of these phytochemicals by the endophytes from medicinal plants has shifted the focus from using chemicals to natural resources for drug discovery. Microbial biotransformation is an alternative method for the production of bioactive compounds (Suresh & Abraham, 2020). Interestingly, a single endophyte can produce terpenoids, steroids, alkaloids, flavonoids, etc.
Each phytochemical class comprises a wide range of chemicals with differing potency and some of which are multifunctional. However, carotenoids and flavonoids are the most extensively studied phytochemicals due to their numerous and varied health benefits. Flavonoids also are the most common phytochemicals exhibiting antimicrobial, antioxidant, anticancer, anti-inflammatory, and wound-healing activities.
Table depicting some phytochemical classes with examples and their respective potential benefits
(beta‐carotene, lycopene, lutein,
(perillyl alcohol, limonene, carnosol)
(ellagic acid, resveratrol)
Indoles and Glucosinolates
Indoles and Glucosinolates
Some Herbs and Biological Functions
- can help in atherosclerosis condition
- can boost immune function to effectively fight infections. Hece can treat ailments such as boils, fever, and herpes
- can help in rheumatism and ulcers
- can help treat eczema and skin eruptions
- can help in premenstrual tension, menopause symptoms and period pain.
- can lower blood pressure
- can help treat upper respiratory tract congestion
- can reduce the risk of heart disease by lowering levels of blood fats and cholesterol.
- can fight colds, sinusitis and other respiratory infections
- can treat motion sickness and morning sickness
- can treat poor blood circulation and tinnitus (ringing in the ears)
- can help in dysentery and diarrhea condition
- can help manage AIDS condition
- can treat fatigue experienced during recovery from illness
- can reduce blood pressure and cholesterol levels
- can treat mild to moderate depression.
- can help overcome anxiety and insomnia.
Herbal or Phytomedicine
It refers to the practice of using plants or plant extracts with required phytochemicals for medicinal purposes such as to treat disease and enhance general health and wellbeing, thus helping to return the body to a state of natural balance.
Herbs are used for the prevention, management, and treatment of varied health conditions including chronic and acute cases. Some conditions are cardiovascular disease, prostate problems, depression, inflammation, stress, mental imbalance, renal dysfunction, neuronal disorders, skin infections, insomnia, chronic obstructive pulmonary diseases, low immune function, and more.
Herbs and Drug Discovery
Phytochemicals with novel structures can be exploited in the field of medicine for new drug discovery.
- Kyung-Jin, Y., & Russel, R. M. (2014). Biological functions of plant pigment phytochemicals in Humans. Systems Biology of Free Radicals and Antioxidants, Springer, Berlin, Heidelberg.
- Suresh, A., & Abraham, J. (2020). Phytochemicals and Their Role in Pharmaceuticals. In Advances in Pharmaceutical Biotechnology (pp. 193-218). Springer, Singapore.