Terpenes - Bitter substances Flashcards
(20 cards)
What are bitter substances?
Iridoids and monoterpene lactones
Sesquiterpene lactones
What are ‘bitters?’
Bitters stimulate the bitter receptors in the taste buds.
Most bitters are:
* Monoterpene secoiridoid glycosides of gentian (esp. amarogentin) and common
centaury
* Sesquiterpene lactone dimers (absinthin) of Artemisia absinthium.
What do bitters do?
- Increase appetite
Effect on digestive function - supports it
* Increase secretion of saliva
* Increases gastric secretions
* Increases gallbladder motility,
* Stimulate bile release, increase bile,
* Increase pancreatic enzymes
It is said that it must be tasted to have the bitter effect. Often used in day to day life, eg aperitifs, coffee
What are the actions of bitters?
- Helps with gastric secretions: Nutrient absorption and healthy bowel flora; Preventative to bacterial and parasitic enteric infection.
- Useful in diabetes, assisting in normalised blood sugar levels.
- Toning effect on the digestive system, toning up sphincters
- Contraindications - hyperacidity but could improve the tone of the oesophageal sphincter. So can help with reflux or gastric ulcers if managed well…go on low dose, 15 minutes before a meal.
What ae iridoids and monoterpene lactones?
Iridoids and monoterpene lactones
* Bitter principle, usually occurs as glycosides.
* Some contain lactone rings, monoterpene lactones.
Which Plants contain aucubin?
- Plantago major and P. lanceolata - plantain
- Euphrasia officinalis - eyebright
- Vitex agnus castus
- Galium aparine
- Rehmannia glutinosa, and
- Harpagophytum procumbens - devil’s claw
Hydrolysed to aucubigenin by bacterial beta-glucosidase in the digestive tract, and further to aucubinines
What are the actions of acubin?
- Vulnerary (eg plantain a wound healing herb)
- Anticarcinogenic
- Aucubin: Anticatarrhal
- Aucubigenin: antibacterial, antifungal and antiviral.
- In vitro studies: Aucubin: antimicrobial, spasmolytic, antiosteoporosis; Aucubin and aucubigenin: anti-inflammatory; Aaucubigenin: antidementia
- In vivo: Hepatoprotective, beneficial for pancreas, neuroprotective.
What about Eyebright, Euphrasia officinalis?
Typically used for conjunctivitis or hayfever
* Antibacterial infections.
* Possibly liver toxicity, antiviral, nerve-regenerating.
* One trial done for Eyebright eyedrops for inflammatory or catarrhal conjunctivitis (clinical trial). Found to be very helpful
What about Devil’s Claw?
Traditionaly useful for dsypepsia, pain, arthritis etc
* Iridoids: harpagide, harpagoside, which get transformed into monoterpene aucubinine B by gut flora.
* Scientific studies confirm the use of devil’s claw as an: analgesic, anti-oxidant, antidiabetic, anti-epileptic, antimicrobial and antimalarial.
* Harpagoside and harpagide are antiinflammatory, particularly their hydrolysed products.
* Clinical studies (extract): Musculoskeletal pain, Osteoarthritis, Acute exacerbations of chronic non-specific low back pain and acute exacerbations.
What are Seco-iridoids?
These include gentiopicroside, amarogentin, swertioside and swertiamarin.
Picro- and amari - both indicate bitterness.
Gentian (Gentiana lutea) is extremely bitter:
* Amarogentin: Immunomodulatory, Antidiabetic (stabilising glucose in vivo)
In vivo, gentiopicroside is:
* Analgesic and anti-inflammatory.
* Antispasmodic in smooth muscle.
* Antiviral, cytoprotective.
* Antihepatotoxic, choleretic.
What are Sesquiterpene lactones?
Another bitter principle (subclass of sesquiterpenes).
* 15-carbon sesquiterpene backbone and
a lactone ring (lact=milk) milky-white, latex. eg is break the stem of dandelion you see a milky juice hence the name,
* They are there as a defense against fungi, bacteria, helminths, and insects.
* Many digestive herbs contain sesquiterpenes lactones eg dandelion, burdock, yarrow, chamomile. Found to be
* Antimicrobial, anti parasitic - most likley by disrupting the cell wall.
* Anti-inflammatory.
* Antioxidant, anticancer.
* Antispasmodic.
* Bitter digestive.
What about Feverfew, Tanacetum parthenium L?
Classic herb that contains Sesquiterpene lactones: parthenolide. Long history is use in folk medicine.
* These days known as anticancer, anti-inflammatory, cardiotonic, antispasmodic, an emmenagogue, and as an enema for worms.
* Research confirming traditional use as the flowers and leaves and parthenolide: analgesic, antiinflammatory and antipyretic activities, and a uterine stimulant.
Actions of feverfew:
* Anti-inflammatory, inhibiting: Prostaglandin synthesis (anti-inflammatory), Serotonin release from aggregating platelets, Parthenolide: binds to IκB kinase complex,
* Antispasmodic in vitro (only fresh
leaves have this activity which confirms traditional knowledge).
* Clinical studies: migraine headache, prophylactic treatment and arthritis.
Cross-reactivity between members of the Compositae family is common.
* For example, someone sensitised to the
sesquiterpene lactones in one plant may react to chamomile.
What about Artemisia annua L.?
Sweet Annie os Wormwood - has a tradition of use for intermittent fevers (malarial infections) - though not preventative.
* Isolation of artemisinin in 1970s.
* Anti-proliferative for a range of human cancer cell types, releasing a high concentration of free radicals inside them (endoperoxide bridge).
Antimalarial action
* Can kill immature plasmodia in erythrocytes.
* Artemisinin contains the endoperoxide bridge, two bonded oxygen atoms releasing deadly free radicals inside plasmodia - which kills plasmodia inside the red cells by interacting the the haem.
* Traditionally prepared Artemisia annua formulation is however still used and it is claimed that its action is superior to the single purified drug.
What are diterpenes?
We find these in Grindelia, rosemary, ginkgo, andrographis, vitex and white horehound. They contain:
* 20 carbon atoms, too large to be volatile, and are usually found in oleoresins and resins.
* Soluble in high percentage ethanol/water solvents.
What about Grindelia robusta?
- Contains Grindelic acid
- Antispasmodic, anti-inflammatory, antibacterial and antitussive effect, herb traditionally used for bronchitis.
- Bitter (like many terpenes), aromatic also contains borneol, alphapinene, plus antiinflammatory triterpene aglycones.
What about White horehound, Marrubium vulgare L?
Many cough remedies contain diterpenes such as White horehound, traditionally used for respiratory issues as well as digestive ones.
- Traditionally: antihypertensive, respiratory
disease, lack of appetite, dyspepsia, diabetes. - Marrubiin and other diterpenoids are:
- Antimicrobial
- Analgesic
- Anti-hypertensive
- Antidiabetic
- Antioxidant
- Vasorelaxants
What about Carnasol and Carnosic acid?
Found in sage and rosemary, these are Diterpenes
* Aromatic bitter.
* Antioxidant.
* Anticarcinogenic (in vitro, in vivo).
* Anti-inflammatory.
* Carnosic acid, protective effects upon neuronal cells.
* Found in sage and rosmary.
* Rosemary is neuroprotective, chemopreventive, antitumoral, antimetastatic and potential in the treatment of angiogenesis-related malignancies.
What about Andrographis paniculata?
A very bitter herb, used for jaundice, health tonic for the liver, and diterpenes likely most important thing here
* Andrographolide (diterpene)
* Antiplatelet activity - so anti inflammatory
* Immunomodulatory activity
* Hepatoprotective, choleretic effect in vivo.
* Extract: anticancer effects, cell differentiation-inducing activity in vitro.
What about Vitex agnus-castus L.?
Traditionally used for gynae, but it has puzzled researchers foe years on how it works. Good for PMS
- Diterpenes (clerodadienols): thought to be prolactin-suppressive principle(s) with dopaminergic properties - which is why it has an effect on PMS
- Improve premenstrual mastodynia and symptoms of the premenstrual syndrome.
What about Ginkgolides?
Ginko also contains diterpenes
- Diterpene lactones (or terpene trilactones as have three lactones rings each). Ginkgolides, alongside bilobalides (closely related).
- Flavonoids at first seen as important in Gingko, but research suggested the ginkgolides and bilobalide were more important.
Anti-PAF (platelet) effects. Ginkgolides: platelet-activating factor (PAF) antagonists so useful for allergies or anti-asthma.
* Anti-allergenic, anti-asthmatic as a broncho dilator.
* Ginkgolides and extract of Ginkgo, a potent thrombolytic effect on the PAF-induced thrombus in vivo.
* High doses of ginkgolides control mast cell degranulation - related to allergic results
Gingkolides and whole plant also have heart and brain effects as well
* Ginkgolides prevent metabolic damage from cerebral ischaemia in vivo - so lack of oxygen getting to brain
* Reduced infarct size in myocardial occlusion in vivo
* Improved arrhythmias in vivo induced myocardial ischaemia
* Studies suggest that ginkgo has neuroprotective properties under conditions such as hypoxia/ischaemia, seizure activity and peripheral nerve damage if taken soon after the event.
Use of Gingko leaf only started since 1960s, traditionally only fruit used.
