Abstract
BACKGROUND
Olive leaf extract, and key constituents including oleuropein and hydroxytyrosol, are generating clinical and research interest as cardiovascular risk modifiers. Positive effects have been reported on blood pressure, inflammation, immune function, and insulin resistance, and olive leaf extracts are used clinically by herbalists and naturopaths.
METHODS
Five Australian practitioner-only and four over-the-counter (OTC) olive leaf liquid extracts were analysed for secoiridoids, phenylethanoids, flavonoids and pentacyclic triterpenes, in a specialist olive chemistry laboratory, using high performance liquid chromatography and gas chromatography. Key compounds quantified included oleuropein, hydroxytyrosol, oleacein, luteolin, maslinic acid, oleanolic acid, erythrodiol and uvaol.
RESULTS
Both practitioner and over-the-counter olive leaf extracts on the Australian marketplace demonstrated considerable variation in phytochemical profiles. Of particular note was a lack of label claims for oleuropein content in practitioner products, and a more than 4 fold variation in oleuropein concentration between different practitioner extracts. In contrast, the oleuropein concentrations in sampled OTC products were largely consistent with label claims. Pentacyclic triterpenoid concentrations also showed significant differences, and may be reflective of different solvents used in extraction.
DISCUSSION
This research demonstrates considerable variability between olive leaf extracts, raising the question for practitioners as to whether clinical results from different olive leaf extracts will be consistent, comparable, or reliable.
Olive leaf extract, and key constituents including oleuropein and hydroxytyrosol, are generating clinical and research interest as cardiovascular risk modifiers. Positive effects have been reported on blood pressure, inflammation, immune function, and insulin resistance, and olive leaf extracts are used clinically by herbalists and naturopaths.
METHODS
Five Australian practitioner-only and four over-the-counter (OTC) olive leaf liquid extracts were analysed for secoiridoids, phenylethanoids, flavonoids and pentacyclic triterpenes, in a specialist olive chemistry laboratory, using high performance liquid chromatography and gas chromatography. Key compounds quantified included oleuropein, hydroxytyrosol, oleacein, luteolin, maslinic acid, oleanolic acid, erythrodiol and uvaol.
RESULTS
Both practitioner and over-the-counter olive leaf extracts on the Australian marketplace demonstrated considerable variation in phytochemical profiles. Of particular note was a lack of label claims for oleuropein content in practitioner products, and a more than 4 fold variation in oleuropein concentration between different practitioner extracts. In contrast, the oleuropein concentrations in sampled OTC products were largely consistent with label claims. Pentacyclic triterpenoid concentrations also showed significant differences, and may be reflective of different solvents used in extraction.
DISCUSSION
This research demonstrates considerable variability between olive leaf extracts, raising the question for practitioners as to whether clinical results from different olive leaf extracts will be consistent, comparable, or reliable.
| Original language | English |
|---|---|
| Publication status | Published - 2019 |
| Externally published | Yes |
| Event | 11th Herbal and Naturopathic International Conference - Melbourne, Australia Duration: 29 Mar 2019 → 31 Mar 2019 |
Conference
| Conference | 11th Herbal and Naturopathic International Conference |
|---|---|
| Country/Territory | Australia |
| City | Melbourne |
| Period | 29/03/19 → 31/03/19 |