The purpose of this file is to introduce the topic of secondary plant metabolites,this subject is considered as a separate topic for different reasons.People who are studying different aspects of plants will find it useful to consider the complex higher molecules of plants without becoming too involved in the primary production of the building blocks of these compounds.It also allows people interested in an aspect of plants to find the information without having it swamped in different information of plant biochemistry.
The file is written for myself and hopefully for others interested in plants.The file will contain information of the many different complex compounds plants produce that are useful to people and are quite unique to particular plants.It is intended to be of use to herbalists,medical students,crop protectionists and interested gardeners.
The file will give practical information that will allow people studying to carry out simple tasks with little expensive equipment to obtain plant products for their own use.Some mention will also be made of the products of fungi that have similar uses to those mentioned.
Primary plant metabolites can be considered as those metabolites essential to the life of the plant.The plant synthesizes sugars,amino acids and nucleotides.These simple molecules are used to produce polymers essential in the life of the plant.This aspect of the plants biochemistry can be considered as distinct from the production of more complex molecules produced by more diverse pathways.Secondary metabolites are unique to plants or a group of plants,it was initially thought they were of use to a plant but morphine produced by poppies is of no use to the plant but is of use in medicine to help heal people who are suffering.
Secondary metabolites are also used as food,flavours,colour dyes,poisons,perfumes,scented oils in aromatherapy, industrial products such as rubber and oils.It is estimated that 1/4 of prescription drugs contain at least one chemical originally identified and extracted from a plant.
It can be seen that plant secondary metabolites have been used in a wide variety of uses,they have been used for centuries in cases and only more recently discovered in other instances.Herbal remedies have been used for centuries but more recently the compounds that are active have been identified and this has enabled them to be extracted and purified,synthetic organic chemists have then been able to produce the molecules in vitro and so produce them on larger scales.The technologies used in this process are quite complex and beyond the scope of small scale producers.However with a pestle and mortar a fine oil to extract the organicly soluble molecules it is possible to get some solutions of useful products.More refined techniques would involve the use of chromatography to separate the different molecules present and infrared spectroscopy to correctly identify the molecules.Mass spectroscopy can also be used to identify molecules.
Gas chromatography and high performance liquid chromatography are techniques that can be used to test the quality of the extracts as these will vary from crop to crop.In the production of products it is not always necessary to produce very pure samples.Some oils are obtained by mechanical expression but this is only possible when the oils are at high percentage in the part of the plant where they reside.
With Chamomile oil the oil resides in the flowers and stalks and is extracted by steam distillation.This will involve heating a water solution containing the stalks and flowers to boiling and passing the steam through a condenser.The oils that are required will liquify at a temperature lower than the water and so the oils can be collected from the condenser with something like a bubble cap and tray at the point where the temperature is correct.
It is important that the scale of the production is matched to the system for which it is intended.The sustainability of the production and the technology involved in the production of the product must be gauged.The end user will want to pay a price that makes the use of the product beneficial.The producer will want to ensure the product is sold at a price that will ensure return on time and investment.Considering the diversity of the secondary plant metabolite products it is difficult to list them all here,but the technologies used are similar and the market for a widely used product quickly determine acceptable prices of a given quality to supply demand.
The marketing of many of these products is also a difficult area,an open market scenario where aggressive advertising and market techniques stimulate demand are ethically questionable dealing with many of the plant products.There are different laws in different countries that define what is acceptable and what is not.Chamomile oil for example is used as a flavouring,as a scent,a hair dye and as a medicinal product for stomach cramps,period pains,insomnia, skin irritation and for ulcers.The investment in Chamomile oil production should not therefore lead to aggressive marketing leading to its over use for medicinal purposes when it might not be the best solution for an individuals needs.The amount of oil likely to be needed should be estimated and the level of investment in the production of chamomile oil made to give a return on investment with a suitable profit margin.
Considering these problems home production becomes attractive in that consumers are directly linked to production.They are not therefore likely to become over dependant on a product when they know how much is involved in its production.
Plants produce secondary metabolites as defences against fungi,bacteria,insects and viruses.They also produce them as colourful pigments to attract insects for pollination.The exact nature of the role of many secondary metabolites is not known although they have been identified and extracted.
Plant Protection Agents
Plants produce a range of complex molecules in response to attack from pathogens or insects.Tannins and thick oils may exude from wounds in plants these help prevent infection and help heal the wound.Plants may also produce chemicals that prevent attack from harmful organisms.There are now hundreds of cases of secondary metabolites that have been isolated and identified that are responsible for the plants resistance to attack from a particular organism.
Plants produce dyes to colour their petals,fruits and sometimes their stems and foliage.These have been extracted for centuries and used to dye wool and cotton.Modern chemistry has allowed the production of modern dyes to colour faabric but the soft natural colours are often sought after are still used today.