Thevetia or oleander is acknowledged by different names in different parts of world like be-still nuts in Hawaii, cascaveleria in Brazil, cerebra Thevetia in India, yee tho in Thai, lucky nut is West Indies etc. Oleander itself consist of two plant species – Nerium oleander (common oleander) and Thevetia peruviana (yellow oleander) belonging to family apocynaceae or dogbane.
Thevetia is an evergreen shrub or tree, having funnel shaped bright yellow or sometimes orange-red colour flowers which is a most attractive feature and therefore it is utilised mostly for landscaping. It is planted as ornamental plant in gardens and parks in tropical and subtropical regions, tolerates most soils and is drought tolerant.
Characteristics of Thevetia
Thevetia belongs to class of cardio tonic glycoside .Almost all parts of plants are utilised for therapeutic purposes although they are associated with toxic effects like plants produces milky latex which is highly poisonous.
Seeds kernels consist of phytosterolin and glucoside, thevetin, nerrifolin, acetylnerrifolin, thevefolin, cerebrine, peruvoside and ruvoside and fatty oil constituting more than 60% of the kernel. Seeds consist of around 60-65% oil and 40-45% of protein.
Oils physical properties like saponification value 120-125% and 0.24-0.25% of unsaponified matters makes it promoting factor for production of soap and also its production cost is less as it does not require any bleaching of oil and also having good leathering property. Researches have also showed that it is heat stable and no changes in physicochemical properties and parameters like iodine value, peroxy value and saponification value were recorded on heating at temperature of 180 C, 200 C, and 220 C.
Health Benefits of Thevetia
As discussed earlier almost all parts of plants are utilised for therapeutic purposes. The milky sap consists of thevetin that act as heart stimulant but in its natural form it is toxic. Thevetia is mostly used for the treatment of cardiac insufficiency. Seeds are having cardio tonic, abortifacient, purgative, insecticidal and for treatment of dropsy and rheumatism. Latex of plant is applied to sores and tooth cavities, tincture of bark is used as s bitter, tonic and cathartic aqueous extract is applied to boils, blisters and skin diseases.
Treatment of congestive heart failure : Thevetin is associated with cardio tonic activity. It inhibits Na-K-ATPase enzyme which is responsible for exchange of Na+ and K+ cation between extracellular and intracellular cell wall. Oleandrin binds to proteins causing it to lose its function. After entering of Na+ during depolarisation it cannot be transported back to extracellular membrane, this facilitates the transport of other proteins and therefore useful for treating cardiomyocytes.
Treatment of cancer : Oleandrin and oleadrigenin inhibits proliferation of tumour cells and stimulate apoptosis of cells. Studies have proved its invitro potential for cancers of colon, leukaemia, prostrate, and pancreas. Oleandrine also increases cascase 3 activity in radio damaged tumour cells and thus induces radiation induced apoptosis. Long term use shows positive potential for the treatment of leiomyosarcoma, Ewing’s sarcoma, prostate cancer or breast cancer. Root paste is generally applied to tumours.
Other uses of Thevetia
- In soap industry
- In cooking oil and making of grease and lubricants- due to its thermally stable property.
- Biological pest control-Thevetia seed oil was used to make paints with anti-bacterial, anti-fungal properties. The paint exhibited inhibitory activity against Escherichia coli, staphylococcus aureous, bacillus subtilis and candida albicans. Thevetia oil paint acts as self-preservative and thus protects woods from subterranean termite attacks.
- In livestock feed formulation
- Development as biodiesel
Adults (18 yrs. of age or more) – In patients with congestive heart failure it is recommended to ingest 1.8-3.2 mg by mouth as initial dose followed by average daily dose of 0.6mg/day.
Toxics Effects Associated with Thevetia
Thevetia causes both GIT and cardiac effects. The gastrointestinal effects include diarrhoea (which may contain blood), nausea, abdominal pain and vomiting. Effects on heart includes Tachyarrhythmia, bradyarrythmia, premature ventricular contraction or AVblockage .Effects on CNS are also observed that includes drowsiness, tremor ,seizures, collapse and coma may lead to death. On topical administration it may cause skin irritation, eye inflammation and allergic reactions characterised by dermatitis.
Management of Oleander Poisoning
The patient should be immediately admitted to hospital. The treatment usually depends on severity of poisoning and it involves immediate Gastric Decontamination, and correction of arrhythmia and electrolyte balance. The continuous monitoring of ECG at least for 24hrs and of electrolyte and potassium level should be done.
Ensure adequate air ways and ventilation. Dehydration can be corrected by giving normal saline and antiemetic can be used in case of severe vomiting. Electrolyte imbalance If serum potassium level exceeds 6mmol/l gives 50ml of 50% glucose and 10 units of soluble insulin IV. Administration of IV calcium may lead to cardiac arrhythmia; therefore its use should be avoided in treating hyperkalaemia . Avoid rectal or oral administration of sodium polystyrene sulfonate resin as it may lead to hypokalaemia when used along with digoxin-specific antibody fragments.
Gastric decontamination- Earlier vomiting or performing gastric lavages were used for the treatment of poisoning but it may lead to hypovolemic. Use of activated charcoal for absorbing plant toxins is more preferred in treatment of poisoning. Correction of arrhythmia-Bradycardia (<40 bpm) or hypotension (systolic pressure <70mmHg) can treated by administering bolus dose of atropine (2-3mg) or else give small bolus dose of atropine (0.3-0.6mg) or and infusion (mg/h) to maintain heart rate around 70-80bpm.
Ventricular arrhythmia should be treated by administering phenytoin or lidocaine. Phenytoin should be infused slowly IV at a rate of 50mg/min until the dysrhythmia is under control. You can increase dose of phenytoin upto 1000mg/kg. Lidocaine can be administered at a dose of 1mg/kg IV bolus followed by continuous IV infusion of 1-4 mg/min.
The use of anti-digoxin FabIV is best preferred for treatment of oleander poisoning as it binds with oleander and reduces its blood concentration. Administer around 400mg over 20mins followed by 400-800mg for 4-5 hrs. By infusion.
If anti-digoxin FabIV is not available, Use fructose-1, 6-biphosphatase (FDP) as antidote at a dose of 50mg/kgIV. FDP is produced from glucose by phosphofructokinase (PFK) during glycolysis and is broken down to pyruvate. In poisoning conditioning, Hypotension interferes with ATP production during glycolysis due to the production of lactate which inhibits rate limiting PFK enzyme. Thus FDP helps in production of ATP when PFK is inhibited.it also chelates calcium and stimulate Na-K-ATPase enzyme.
Although benefit to risk ratio is less in Thevetia, it can be useful for treating cardiac insufficiency when taken in appropriate dose level. Many of the researches are carried on in developing antidotes for oleander poisoning as antidigoxin FabIV is very expensive.