Iridoids are a large group of monoterpenoids.
They are characterised by skeletons in which a 6-membered ring, having an oxygen atom is attached to cyclopentane ring (iridane skeleton).
They occur in plants combined with sugar and hence are classified as glycosides, further divided into four main groups:
1) Iridoid glycosides (aucubin and harpagoside),
2) Non-glycosylated or simple iridoids (loganin),
3) Secoiridoids (gentio-picroside), and
4) Bisiridoids, formed by dimerisation of iridoids and secoiridoids
General Iridoids Skeleton
Secoiridoids
Acubin
Euphrasia officinalis L. Euphrasia rostkoviana Hayne (Scrophulariaceae) Europe Plantago lance olate L.(Plantaginaceae)
Acubin
Harpagoside
Harpagophytum procumbens (Burch.) DC. Ex Meisn. (Pedaliaceae)
Harpagoside
Gentiopicroside
Gentiana lutea L. (Gentianaceae)
Gentiopicroside
Iridoids are monoterpenes obtained from iridane skeleton that is derived from geranyl pyrophosphate.
These are natural esterified products and are common in plants of
Lamiaceae,
Gentianaceae and
Valerianaceae families.
These compounds are rich in oxygen and the esters are derived from hemiterpenes; for example, valeric acid gets esterified into valrate and didrovaltrate; these compounds are derived from valerian ( Valeriana officinalis of Valerianaceae family).
There is a wide range of health benefits of iridoids.
They deliver support against a variety of physical, chemical, or biological stressors.
On the human body, iridoids exert a normalising effect, which targets imbalances without affecting the systems already functioning well.
They produce these effects without any side effects. Few benefits of iridoids are as follows:
Neuroprotective:
Anticancer and Anti-Tumour:
Asperulosidic acid is obtained from the dried morinda or noni fruit, and inhibits formation of melanoma (skin cancer) cells. Aucubin is a newly discovered iridoid, and produces anti-tumour effects on cell cultures of breast colon, blood, skin, lung, throat, and nose cancers.
Anti-Ageing:
In a recent study, noni seeds were believed of no value and were discarded while producing noni fruit juice and oil. However, in a more recent study in Japan, it was reported that the iridoid americanin in noni seed can be a useful ingredient in cosmetics for whitening skin and preventing wrinkles due to its ability to increase elastin production (elastin is a vital skin protein and is the reason for soft, glowing, and youthful skin).
Antibacterial
Antiviral: This property of iridoids has been reported in a number of studies. These compounds are also active against viruses that cause encephalitis and herpes simplex type 1.
Anti-Inflammatory
Antioxidant: This property of iridoids is supposed to be more powerful than that of more traditional plant antioxidants like flavonoids or polyphenols obtained from citrus fruits and green tea. The highest concentration of iridoids is in gentian plant family, and one of the best sources of simple and complex iridoids is noni fruit.
Liver Protection
Cardiovascular Protection: Two iridoids present in olive oil, i.e., oleacein and oleuropein, have great cardioprotective properties. People who consume olive oil have low-fat deposition in the abdomen, liver, and heart, thus causing less cardiac stiffness. They tend to have better resilience against stress, and suffer less from cholesterol problems and hypertension. Iridoids in olive oil protect the heart and arteries from the harmful effects of stress.
Blood Sugar Control
Protection of the Arteries
Anti-Allergic