Introduction To Terpenes And Terpenoids

Enzymatic resections of primary metabolites (amino acids, sugars, vitamins, etc.) produce secondary metabolites. Terpenes are the most common type of secondary metabolite, and they are made up of five-carbon isoprene units linked together in numerous different ways. Terpenes are simple hydrocarbons, whereas terpenoids are a modified family of terpenes with various functional groups and an oxidised methyl group relocated or removed.

Depending on the number of carbon units, terpenoids are classified as monoterpenes, sesquiterpenes, diterpenes, sesterpenes, and triterpenes. The majority of terpenoids, despite their structural differences, are biologically active and are utilised to treat a variety of ailments around the world.

Terpenes and terpenoids can be found in abundance in the essential oils of various plants and flowers. These essential oils are commonly used in perfume and traditional medicine manufacture.

Table of Contents

What are Terpenes?

Terpenes are a natural product that includes compounds with the formula (C5H8)n. These unsaturated hydrocarbons, made up of over 30,000 compounds, are produced mainly by plants, particularly conifers.

Monoterpenes (C10), sesquiterpenes (C15), diterpenes (C20), and so on are the different types of terpenes. Alpha-pinene, a primary component of turpentine, is a well-known monoterpene.

Limonene is a Common Terpene

Terpenes are aromatic compounds found in various plants, although they are most commonly linked with cannabis due to their high concentrations found in the plant. Many plants, such as cannabis, pine, lavender, and the fresh orange peel, have aromatic substances that give them their unique perfume.

August Kekulé, a German scientist, coined “terpene” in 1866. “Terpene” is a reduced version of “terpentine,” an old spelling of “turpentine.”

Classification of Terpenes

Terpenes are categorised according to the number of isoprene units in the molecule; a prefix indicates the number of isoprene pairs required to construct the molecule. Terpenes typically have 2, 3, 4, or 6 isoprene units; tetraterpenes (8 isoprene units) represent a different class of chemicals known as carotenoids, while the others are rare.

  • Hemiterpenes are made up of just one isoprene unit. The only hemiterpene is isoprene, while oxygen-containing compounds like prenol and isovaleric acid are hemiterpenoids.
  • Monoterpenes have the chemical formula C10H16 and are made up of two isoprene units.
  • Sesquiterpenes have the chemical formula C15H24 and are made up of three isoprene units.
  • Diterpenes have the chemical formula C20H32 and are made up of four isoprene units.
  • Sesterterpenes, which have 25 carbons and five isoprene units, are rather uncommon compared to the other sizes.
  • Triterpenes have the chemical formula C30H48 and are made up of six isoprene units.
  • Sesquarterpenes have the chemical formula C35H56 and are made up of seven isoprene units.
  • Tetraterpenes have the chemical formula C40H64 and include eight isoprene units.
  • Polyterpenes are made up of long chains that contain multiple isoprene molecules.

General Properties of Terpenes

  • Although terpenes are colourless; impure samples are frequently yellow. The boiling points of terpenes, sesquiterpenes, and diterpenes are 110, 160, and 220℃, respectively. They are insoluble in water due to their non-polar nature. They are highly combustible and have a low specific gravity since they are hydrocarbons (float on water).
  • Terpenoids (mono-, sesqui-, di-, etc.) have comparable physical properties to terpenes, although they are more polar, and thus slightly more soluble in water and less volatile. The glycosides, which are connected to sugars, are a highly polar derivative of terpenoids. They are soluble in water solids. They, like other hydrocarbons, are highly combustible. Terpenes are irritants that can induce gastrointestinal problems if consumed.

Importance of Terpenes

Terpenes have a significant effect on a cannabis strain’s fragrance and flavour. When combined with cannabinoids and other cannabis plant components, they might produce psychedelic effects. However, because research on the plant’s more than 400 terpenes is still in its early phases, it is challenging to make definitive statements about them.

Terpene is the name given to the components collected from terpentine, a volatile liquid extracted from pine trees. Mono and sesquiterpenes make up the majority of essential oils generated from the sap and tissues of some plants and trees. The di and tri terpenoids are not vaporised by steam. Gums and resins from plants and trees are used to produce them.


  • Natural rubber is one terpene with many uses (i.e. polyisoprene). Other terpenes have been studied as potential precursors for the production of synthetic polymers as an alternative to petroleum-based feedstocks. However, only a few of these applications have made it to the market.
  • Terpenes are frequently utilised in consumer products, such as perfumes, cosmetics, cleaning products, and food and beverage products, such as aromas and tastes.
  • Many terpenes have been found to have pharmacological effects, while most studies have been conducted in the laboratory, and clinical research in humans is still in its early stages.
  • Terpenes are also used in aromatherapy and other traditional therapies.
  • Terpenes are utilised as active ingredients in pesticides in agriculture because of their defensive role in plants.

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What are Terpenoids?

Terpenoids, also known as isoprenoids, are a class of chemical compounds produced from isoprene. Isoprene, a 55-carbon molecule, and terpenes are examples of naturally occurring organic chemicals. These are multicyclic structures with functional groups that contain oxygen. Terpenoids make up the majority of known natural compounds.

Terpene and terpenoids are sometimes used interchangeably; however, they are distinct because terpenes are simple hydrocarbon molecules, whereas terpenoids are complex compounds with several functional groups.

A Simple Terpenoid Structure

Plant terpenoids are used in traditional herbal medicines for their fragrant properties. The aroma of eucalyptus, the flavours of cinnamon, cloves, and ginger, the golden colour of sunflowers, and the red colour of tomatoes are all terpenoids. Citral, menthol, camphor, salvinorin A in the herb Salvia divinorum, cannabinoids in cannabis, and ginkgolide and bilobalide in Ginkgo biloba are examples of well-known terpenoids.

Structure and Classification

Terpenoids are terpenes that have had their methyl groups moved or removed or oxygen atoms added. Terpenoids are classified as hemiterpenoids, monoterpenoids, diterpenoids, sesquiterpenoids, etc.

Terpenoids Analogue Terpenes Number of Isoprene Units Number of Carbon Atoms General Formula
Hemiterpenoids Isoprene 1 5 C5H8
Monoterpenoids Monoterpenes 2 10 C10H16
Sesquiterpenoids Sesquiterpenes 3 15 C15H24
Diterpenoids Diterpenes 4 20 C20H32
Sesterterpenoids Sesterterpenes 5 25 C25H40
Triterpenoids Triterpenes 6 30 C30H48
Tetraterpenoids Tetraterpenes 8 40 C40H64
Polyterpenoid Polyterpenes >8 >40 (C5H8)n

Terpenoids are classified as linear, acyclic, monocyclic, bicyclic, tricyclic, tetracyclic, pentacyclic, or macrocyclic, depending on the kind and number of cyclic structures they include. The Salkowski test can be performed to determine whether terpenoids are present.


Hydrolysis of carbocationic intermediates formed from geranyl pyrophosphate is a common source of terpenoids, at least those with an alcohol functional group. Sesquiterpenoids are produced by hydrolysis of intermediates from farnesyl pyrophosphate, while diterpenoids are produced from geranylgeranyl pyrophosphate, and so on.

Importance of Terpenoids

Terpenoids, also called isoprenoids, are the most abundant and structurally diverse natural compounds discovered in plants. In vitro, preclinical, and clinical research have all established that this family of chemicals has essential pharmacological properties.

The wide range of terpenoid structures and activities has generated greater interest in their commercial application, resulting in the registration of some with well-established medicinal applications as pharmaceuticals on the market.

Difference between Terpenes and Terpenoids

Both terpenes and terpenoids are organic compounds. Terpenes are simply hydrocarbons, whereas terpenoids are modified terpenes with various functional and oxidised methyl groups. Terpenes are hemiterpenes, monoterpenes, diterpenes, sesquiterpenes, and so on, whereas terpenoids are hemiterpenoids, monoterpenoids, diterpenoids, sesquiterpenoids, and so on.

Frequently Asked Questions on Terpenes And Terpenoids


What effects does terpene have on the human body?

Terpene has been utilised for a variety of medical purposes since ancient times. It is a popular aromatherapy product due to its fragrant characteristics. Aside from that, it’s a terrific antibiotic. Because of its anti-inflammatory and antioxidant features, it is extremely good for the skin. The amount of dose to be utilised must always be considered.


Can we use terpene oil for cooking?

Terpene can be found in nature. It’s made from various plants and flowers and has been used as a flavouring ingredient since antiquity. However, it is never good to use it as a frying or cooking oil. This is also found in many of today’s most popular vaping devices. Terpene is unquestionably edible, but it is necessary to identify and recognise the many types of Terpene oil. On the other hand, terpenes prepared in an industrial setting should never be consumed.


Mention the function of terpenoids.

Terpenes and derived terpenoids, also known as isoprenoids, are the most abundant class of plant secondary metabolites, with basic growth and development activities and more specialised roles in plant-environment interactions, stress resistance, and defence against predators and diseases.


Where do we find terpenoids?

Terpenoid biosynthesis is found in bacteria, fungi, plants, and various phyla of invertebrates. Terpenoid structures are extremely complex and conduct a wide range of biological functions.


Which vitamins are referred to as terpenoids?

Vitamins A is a terpene, and vitamins E and K possess long terpene chains connected to an aromatic molecule. Vitamin D has the structure of a steroid, with ring B split open and the three remaining rings unmodified.


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