Definition
Leonotis herba consists of the dried aerial parts of Leonotis leonurus (L.) R. Br. (Lamiaceae).

Synonyms
Phlomis leonurus L.
Leonotis leonurus (L.) R. Br. var. albiflora Benth.

Vernacular names
wilde dagga (A), lion's ear, minaret flower (E), unfincafincane (X), lebake (S), umhlalampetu (Sh)

Description

Macroscopical
Shrub 2-5 m tall, branching from a thick woody base; stem pale brown and densely pubescent; leaves simple, opposite, petiolate, coriaceous, 50-100 ´ 10-20 mm, linear, acute at apex and base, serrate in the distal half; upper surface bright green, lower surface densely pubescent; inflorescence of 3-11 compact verticils; calyx 12-16 mm long, 4 mm in diameter, calyx teeth 10, subequal, spreading; corolla tubular, bright orange, 40-49 mm long, covered with orange hairs; fruit a nutlet 5-6 ´ 1.5-2 mm, brown.

Microscopical
Characteristic features are: the numerous uniseriate, curved, thick-walled, warty, 2-3 celled non-glandular trichomes of leaf and stem, 60-100 m in length, particularly abundant on margin of lamina and main veins of lower leaf surface; the numerous glandular hairs of leaf and stem, with unicellular stalk and 4-celled head (up to 20 m in diameter) and yellow-brown contents; the less numerous glandular trichomes of leaf lamina, with unicellular stalk and 6-8 celled head, thick-walled, head about 40 m in diameter; cells of the lower epidermis with sinuous walls and striated cuticle, lacking stomata; cells of the upper epidermis with sinuous walls and numerous raised anomocytic stomata; single palisade layer; abundant crystal sand in cells of the mesophyll; occasional yellow hairs of the corolla.

Crude drug
Supplied in bundles comprising young leafy twigs, the leaves having a characteristic aromatic-pungent odour, bright yellow-green colour and rough texture; occasional flowers and fruits are present.

Geographical distribution
Locally common at forest margins, on rocky hillsides and river banks and in tall grassland of the Eastern and Western Cape Provinces, Kwazulu-Natal and Mpumalanga.

Quality standards

Identity test:
Thin layer chromatography on silica gel using as solvent a mixture of toluene:diethyl ether:1.75m acetic acid (1:1:1). Reference compound: thymol (0,1% in chloroform)

Method according to the current edition of the British Herbal Medicines Pharmacopoeia, using Spray Reagent D for visualisation.

Major compounds:
yellow-mustard (Rf :0,19); yellow-mustard (Rf: 0,38); blue-mauve (Rf: 0,4); thymol (pink): Rf:0,8.

Ethanol (70%) extractive value: not less than 22%

Volatile oil content: not less than 0,15% (0,15-0,18%).

Purity tests

Assay

Major chemical constituents

1. Diterpenoid labdane lactones: premarrubiin 0.00933-0.01567%, marrubiin (possibly an artifact derived from premarrubiin during extraction)

2. Tannins, quinones, saponins, alkaloids and triterpene steroids were detected in preliminary tests in our laboratories; iridoids were not detected.

Dosage forms
Used mainly in the form of an aqueous decoction, orally, per rectum and as a topical application.

Medicinal uses (traditional)

Internal
For the treatment of cough, cold, influenza, chest infections, diabetes, hypertension, eczema, epilepsy, delayed menstruation, intestinal worms, constipation, spider bites and scorpion stings and as an antidote for snakebite.

External
For the relief of haemorrhoids, eczema, skin rashes and boils.

Pharmacology /bioactivity
Anti-nematodal activity has been demonstrated in vitro against Caenorhabditis elegans for aqueous and 100% ethanol extracts of the dried aerial parts of South African plants, at concentrations of 1.0mg/ml. A hexane extract proved inactive at a concentration of 2.0mg/ml. The same study found water and ethanol extracts to be inactive in an in vitroassay for anti-amoebic activity.

Molluscicidal activity of 80% ethanolic extracts of dried leaf, stem and fruits of Sudanese plants against Biomphalaria pfeifferi and Bulinus truncatus could not be demonstrated in vitro (concentration 200mg/litre).

Anticonvulsant activity of an aqueous extract of dried leaf has been demonstrated in vivo in the mouse (dose: 200.0mg/kg IP) . In an in vitro assay for antiphage activity of aqueous fresh leaf+stem extracts of Greek plants, no activity was demonstrated against Bacteriophages MS2, PHI-CHI-174, T-7, T2, T4 or Bacteriophage-OPS7 . Extracts of shade-dried roots of Ethiopian plants were examined for anti-fertility activity in the rat, both in vitro (uterine stimulant activity) and in vivo (anti-implantation effects). Weak uterine stimulant activity was shown for 95% ethanol extracts but not for aqueous or n-butanol extracts (conc. 2.0%). Anti-implantation activity was shown by both n-butanol nd (%% ethanolic axtracts but not by aqueous extracts (dose: 0,93g/kg intragastrically) .

Brine shrimp lethality assay: preliminary results showed no effect on brine shrimps in the concentrations tested.

Antibiotic activity assay
No in vitro antimicrobial activity was observed in preliminary assays, in the concentrations used.

Contraindications
Not recommended for use by pregnant women

Adverse reactions
First time users may experience dizziness, nausea or sweating

Precautions

Treatment should be continued for one week. If symptoms persist, additional or alternative therapy should be sought. The use of this herb to treat diabetes, hypertension epilepsy or snakebite cannot at this stage be recommended, owing to lack of clinical data.

Dosage
1 table spoonful of chipped dried herb (.10,0g ) added to  3 cupfuls (.500ml ) of boiling water, boil for 10 minutes, allow to cool overnight, strain and use clear liquid for both internal and external use. If fresh material is used, 3-4 young twigs (leaf and stem) are boiled with one litre of water.

Dosage: (internal use)
Adults: Half a cupful (.90ml)
Elderly patients: Quarter of a cupful (.45ml)
Children 6-12 yrs: Quarter of a cupful (.45ml)
Children 2-6 yrs : Two teaspoonsful (.8ml)
To be taken two to three times daily.
For external use, the decoction may be applied to the affected area using a clean cloth.

References

1. Iwarsson, M. (1985). Leonotis, in Flora of Southern Africa 28(4): 31-37. Botanical Research Institute, Pretoria.
2. Laonigro, G., Lanzetta, R., Parrilli, M., Adolfini, M. and Mangoni, L. (1979). The configuration of the diterpene spiroethers from Marrubium vulgare and from Leonotis leonurus. Gazetta Chimica Italia 109 (3/4): 145-150.
3. McGaw, L.J., Jager, A.K. and van Staden, J.V.( 2000). Antribacterial, anthelmintic and anti-amoebic activity of South African medicinal plants. Journal of Ethnopharmacology 72(1/2): 247-263.
4. Abdel-Aziz, A., Brain, K. and Bashir, A.K. (1990). Screening of Sudanese plants for molluscicidal activity and identification of leaves of Tacca leontopetaloides (L.) O. Ktze (Taccaceae) as a potential new exploitable resource. Phytotherapy Research 4(2): 62-65.
5. Bienvenu, E., Amabeoku, G.J., Eagles, P., Scott, G. and Springfield, E.P. (2002). Anticonvulsant activity of aqueous extract of Leonotis leonurus (Lamiaceae). Phytomedicine 217(2): 217-223.
6. Yannitsaros, A. (1996). Screening for antiphage activity of plants growing in Greece. Fitoterapia 67(3): 205-214.
7. Desta, B. (1994). Ethiopian traditional herbal drugs. Part III: anti-fertility activity of 70 medicinal plants. Journal of Ethnopharmacology 44(3): 199-209.