INTRODUCTION:

Callistemon is a genus of 34 species of shrubs belonging to the family Myrtaceae. The word Callistemon means anther beauty (Greek :Kalles, beauty, Stemon, A stamen).They are found in the most temperate regions of Australia, mostly along the east coast and south-west and typically favour moist conditions, often by creeks, wheareas others are found on rock outcrops and ledges on mountain tops, so when planted in gardens thrive on regular watering. However some of the species are drought-resistant. The species of this plant was formally described by English botanist William Curtis in 1794.Curtis classified this species within the genus Metrosideros which had been corrected by English Botanist Joseph Banks in 1788.

Genus Callistemon was described by Robert Brown in 1814, as “A genus formed of those species of Metrosideros that have inflorescence similar to that of Melaleuca, and distinct elongated filaments” and transferred to the genus Callistemon in 1913 by botanist Homer Collar Skeels in the United States Department of Agriculture, Bureau of Plant Industry Bulletin. Callistemon is in the Leptospermum alliance of the Myrtaceae with its closest relative the genus Melaleuca (genus which is suitable alternative and is distinguished from Callistemon in having the stamens in 5 bundles situated opposite to petals). Callistemon species are commonly referred as bottle brush because their flowers are arranged in spikes that can grow up to 12 cm. long, and the long stamens, which are coloured white, red, pink and even violet cylindrical, brush like flowers resembling a traditional bottle brush¹.

Photograph 1 Showing Inflorescence of Callistemon lanceolatus

Synonym:

Callistemon citrinus (Linn) ¹⁷.

Common Name:

Crimson Bottlebrush ¹.

Vernacular Names:

English – Bottlebrush; Sanskrit - Naaglingam, Shiv-lingi ; Hindi- Cheel , Kastula; Kannada -Muthuga ; Tamil -Palasu ; Telugu - Seesa Brush ; Gujarathi- Khakda, Khakra; Urdu- Sumbul , Simal¹⁸.

Flowering:

October- December ¹⁷ .

Geographical Distribution:

Indigenous to Queensland and New South Wales, is frequently cultivated throughout India in gardens as ornamental plant. It has also been introduced in lower regions of Himalayas¹.

Morphology:

A handsome shrub or small tree up to 7 cm. in height, leaves are lanceolate shaped sometimes broadly up to 7.5 cm. long, with prominent veins, midrib and oil glands, flowers are crimson red with dark red anthers, in 10 cm. long spikes, capsules are depressed globose. The obvious parts of the flower masses are stamens, with the pollen at the tip of the filament, the petals are inconspicuous. Flower heads vary in colour with species, most are red, but some are yellow, green, orange or white. Each flower head produces a profusion of triple-celled seed capsules around a stem which remain on the plant with the seeds enclosed until stimulated to open when the plant dies or fire causes the release of the seeds¹.

Microscopy:

a b

Photograph 2 Showing Leaf surface (a: Stomata; b: Veins, veinlet termination, vein islet and midrib).

The leaf surface shows the anomocytic type of stomata which is characteristic of family Myrtaceae (Figure 1a). Leaf surface analysis also shows the presence of veins, vein- islets and vein terminations (Figure 1b). Transverse section of leaf (Figure 2a) shows the epidermis layer followed by cuticle layer, and vascular bundles (xylem and phloem), pericyclic fibres, collenchymas, etc. The vascular bundles and pericyclic fibers were stained pink with phloroglucinol and HCl (Figure 2b). The mesophyll is differentiated into palisade and spongy parenchyma. Many covering trichomes emerge from the upper epidermis. Trichomes are unicellular. Strips of collenchyma are present below and above the layer of epidermis².

a b

Photograph 3 Showing a)T.S. of C. lanceolatus leaf (100×); b)Vascular bundles and pericyclic fibres (400×).

The fine powder mounted in glycerin as well as stained (phlorogucinol + HCl). Observation of microscope shows the presence of unicellular trichomes, anomocytic stomata, calcium oxalate crystals, epidermal cells, xylem vessels (Figure 4), pericyclic fibers, etc².

Photograph 4 Showing Powder characteristics of C. lanceolatus leaf (400×).

Table - 1: Showing leaf constants:²

S.no	Parameters	Value( in 1 mm² area)
1	Avg. Stomatal number in 25 different fields(100X)	83.0
2	Avg. Stomatal number in 25 different fields (400X)	90.0
3	Stomatal index (100X)	8.7
4	Stomatal index (400X)	9.0
5	Vein- islet number(20X)	4.0-6.0
6	Vein-termination(20X)	3.0-5.0
X= Magnification Power

Phytochemical Analysis:

Phytochemical screening showed the presence of saponins, tannins, carbohydrates, steroids, proteins, amino acids, phenolic compounds and anthraquinone glycosides. Two neolignans, named callislignan A and B together with known C-methyl-flavonoids, a lignan and pentacyclic triterpenoid esters were isolated from the leaves of C. lanceolatus, various types of secondary metabolites, including tri terpenoids and Phloroglucinol derivatives, C-methyl flavonoids and tannins. Six flavonoids, 4',5-dihydroxy-6,8-dimethyl-7-methoxyflavanone, eucalyptin, 8-demethyleucalyptin , sideroxylin, syzalterin and quercetin are also present¹⁹ .^.

Photograph 5 showing Structure of Callislignan A and Callislignan B

Leaf:

Several flavonoids, triterpenoids, tannins, phenolic compounds have been isolated from its leaves. Leaves of Myrtaceous plant pitted with schozogenously developed cavities containing essential oils, composed mainly of monoterpenes, sesquiterpenes

Flowers and leaves:

Found rich in polyphenols gallic acid, gallic acid 4-o-methyl ester, kaempferol, quercetin, ellagic acid,carbohydrate, saponin, alkaloids, phytosterols and proteins

Flowers:

Triterpenoids: betulic acid, α-amyrin, oleanolic acid, β-sitosterol Monoterpenoids:β- pinene1,8-cineol1,8-cineol,Tannins-pyragallol,catechol

Stem bark:

3,3΄-di-O-methyl ellagic acid, 3,3΄,4-tri-O-methyl ellagic acid ,ellagic acid, pyragallol, catechol

Seeds: Gallic acid, ellagic acid, mixture of polyphenols¹.

Photograph 6 showing Structure of Ellagic acid

New Flavone and Phenolic ester from Callistemon lanceolatus:

Phytochemical investigation of the anti-diabetic chloroform fraction of the ethanolic extract obtained from the aerial parts of Callistemon lanceolatus led to the isolation of three new phytoconstituents, one flavone, 8-(100-hydroxyisopranyl)-5,6-dihydroxy-7,40-dimethoxy flavone (1) and two phenolic esters, 2,3,4-tri hydroxyphenethyl tetracontanoate (2) and 2,3,4-tri hydroxyphen ethyl tetracontanoate-4-b-xylopyranoside (3). The isolated compound 1 exhibited significant in vivo blood glucose lowering effect comparable to the standard drugs Pioglitazone and Rosiglitazone in streptozotocin induced diabetic rats without causing any toxic effect on the pancreas and liver²⁰ .

Traditional Uses:

Callistemon species are used for forestry, essential oil production, farm tree/windbreak plantings, degraded-land reclamation and ornamental horticulture, among other applications . In China Callistemon species, especially C. viminalis, are used in traditional chinese medicine pills for treating hemorrhoids. Callistemon are also used as weed control and as bioindicators for environmental management¹⁹.

Physiochemical Parameters:

Ash value of a drug gives an idea of the earthy matter or the inorganic composition and other impurities present along with the drug. The percentage of total ash was 4.48% w/w, acid insoluble ash was 2.55% w/w, water soluble ash was 0.55% w/w, foreign matter was 0.41% w/w, loss on drying was 3.50% w/w and swelling index was 0.65 mL².

Extractive Values:

They are primarily useful for the determination of exhausted or adulterated drugs. Petroleum ether soluble extractive was 8.2% w/w, chloroform soluble extractive was 7.5% w/w, methanol soluble extractive was 35.8% w/w, water soluble extractive was 25.4% w/w and alcohol soluble extractive was 27.3% w/w².

Cultivation:

Propagated by seeds which are very small or by leaves or by layers or by cuttings and root faster when treated with indole butyric acid (2000 ppm) under mist condition¹.

Species of Genus Callistemon In India:

Different Callistemon species introduced from Australia. In India these plants are grown for ornamental purpose throughout the country except in extremely dry and cool places. Callistemon species are native to Queensland and New South Wales and cultivated in India in gardens for its beautiful flowers, uncommonly pretty foliage, gorgeous shade, and large amount of nectar. These are propagated by seeds or cuttings of ripened wood. An annual rainfall between 100-150 cm is required for proper growth of the plant and heavy pruning every two or three years is recommended for maximum flowering. Callistemon species sown at a spacing of 2.0 m and attaining a height of 1.5 m are useful as a wind-break and for shelter-belts, and have been found beneficial for crops such as mustard and wheat. Flowers are the good source of nectar and pollen for bees during the summers ¹.

Callistemon macropunctatus (Dum Cours.) Court

Synonym: Callistemon coccineus F. Muell.

Biological activity: Extract of leaves showed activity against Micrococcus pyogene and against E.coli

Callistemon viminalis [Soland. Ex Gaertn.]Cheel

Common Name: Weeping bottle brush

Chemical constituent: Leaves-Essential oil containing cineol, α-pinene, amyl alcohol, a sesquiterpene and a phenol, flowers-petunidin-3-monoside, in aerial parts viminadione A and viminadione B has been isolated by bio-assay guided fractionation of the aerial parts.

Biological Activities: Aqueous extract of the flowers and leaves showed anti-bacterial activity against gram positive bacteria Essential oil of leaves exhibited in vitro anthelmintic activity against earthworms, tapeworms and hookworms.

Callistemon linearis DC.

Common Name: Narrow leaf Bottle brush

Chemical constituent: oil from seed contain β-sitosterol.

Callistemon phoeniceus Lindl.

Common Name: Fiery bottle brush

Chemical Constituent: Flowers contain cyanidine-3-glucoside, bark contain saponins .

Biological activity: The aqueous extract of flowers showed anti-bacterial activity against gram positive bacteria .

Callistemon rigidus

Common Name: Stiffy bottlebrush

Chemical Constituent: Essential oil contain cineol,3,4,7-trihydroxy flavonol and its 3-glucoside,3,4,7-tri hydroxyflavone and its 7-galactoside. Leaf-triterpenoid named Melaleucin.

Callistemon salignus (Smith) DC

Common Name: Swamp bottlebrush/White bottlebrush/ Willow bottlebrush

Biological activity: An aqueous extract of flowers showed anti-bacterial activity against gram positive bacteria.

Chemical Constituent: Triterpenoids in bark.

Callistemon lanceolatus (Sm.) Sweet

Synonym: Callistemon lanceolatus DC, Callistemon citrinus (Curt.)Skeels, Callistemon citrinus Stapf ¹.

Chemical Constituents: Flavonoids, Tannins, Saponins, Steroids, Triterpenoids and Essential oils².

Biological Activities: Anti-diabetic, Anti-inflammatory, Anti-microbial¹.

Biological Activities of Callistemon lanceolatus D.C.

1. Anthelmentic Activity:

The aqueous and methanolic extract of stem bark and seed capsule of C. lanceolatus at a concentration of 12.5, 25, 50 and 100 mg/ml exhibited anthelmentic activity in a dose dependent manner. Significant activity was observed by aqueous extract of seed capsule followed by methanolic extract of seed capsule at same concentration and least activity is observed by aqueous extract of stem bark when compared with the standard Albendazole³.

2. Insecticidal Activity:

C. lanceolatus claimed for the management and control of rice moth, Corcyra cephalonica (an insect pest of stored commodities). There was a marked decline in egg hatchability in the pest after the exposure of the freshly laid eggs to volatile oils at a concentration of 20,40,80 and 160 µl for 12,24,48 and 72 hrs respectively indicating the Insectcidal properties of the oils of C. lanceolatus⁴.

3. Anti-microbial Activity:

A) The methanolic leaf extract of C. lanceolatus was assessed for the in-vitro Anti-microbial potential. The extract showed maximum zone of inhibition against Staphylococcus aureus and minimum zone of inhibition against Candida albicans and no activity against Klebssiella pneumoniae and Escheria coli⁵.

B) Chloroform, ethanol and aqueous extracts of the leaves of Callistemon citrinus were used to study the antimicrobial potential using Streptomycin as a standard drug. The chloroform extract exhibited moderate to significant anti-microbial activity against all the tested microbial strains. The alcoholic extract exhibited moderate anti-microbial activity. The aqueous extract was devoid of any anti-microbial activity. The results showed that the chloroform extract was more potent than the ethanolic extract¹⁶.

4. Cardioprotective Activity:

A) The ethanolic leaf extract of C. lanceolatus showed significant Cardioprotective Activity against Doxorubcin induced myopathy in rats. The extract at a concentration of 200 mg/kg significantly reduced the elevated serum enzyme levels; restored the ECG and blood pressure to normal and also increased the tissue Antioxidant level while decreased the Malondialdehyde level⁶.

B) Kaempferol, 3-O-β-D-galacturon-O-pyranoside and Quercetin isolated from the ethanolic leaf extract of C.lanceolatus showed Cardioprotective activity against Doxorubicin induced Cardiotoxicity⁷.

5. Hypoglycaemic Activity:

The ethanolic extract, petroleum ether and chloroform fractions of leaves of C.lanceolatus claimed significant Hypoglycaemic activity in Streptozotocin induced Diabetic rats. Chloroform fraction (150mg/kg b.w) significantly lowered blood glucose level with insignificant ulceration compared to the standard drug Glibenclamide. Reduction in the lipid peroxidation and glutathione levels and elevation in the antioxidant enzyme activity was also observed⁸.

6. Anti-diabetic Activity:

A) Daily oral treatment with methanolic fruit extract of C.lanceolatus (400mg/kg) for 3 weeks resulted in significant reduction in blood glucose, serum cholesterol, TG’s, AST and ALT levels. Also the pancreas and liver histology showed significant recovery with the extract administation⁹.

B) Daily oral treatment of ethyl acetate and hexane fractions of dichloromethane extracts (oral dose of 400mg/kg b.w) for 3 weeks resulted in significant reduction in blood glucose, serum cholesterol and triglycerides in Streptozotocin and Streptozotocin-nicotinamide induced diabetic rats¹⁰.

C) Phytochemical investigation of the anti-diabetic chloroform fraction of the ethanolic extract obtained from the aerial parts of Callistemon lanceolatus DC led to the isolation of , 8-(100-hydroxyisopranyl-5,6-dihydroxy-7,40-dimethoxy flavone which exhibited significant in vivo blood glucose lowering effect comparable to the standard drugs Pioglitazone and Rosiglitazone in Streptozotocin induced diabetic rats without causing any toxic effect on the pancreas and liver²⁰ .

7. Anti-Inflammatory Activity :

The methanolic leaf extract of C.lanceolatus , showed significant Anti-inflammatory activity on Carrageenan induced paw edema in rats, comparable with Diclofenac sodium².

8. Anti-Fungal Activity:

Essential oil of Callistemon lanceolatus and 1,8-cineole, exhibited moderate to high anti-fungal activity. Even at the lowest concentration of 0.227 mg/ml, the essential oil caused more than 50% mycelia inhibition of most of the fungi except A.niger. Aspergillus oryzae, Fusarium oxysporum, Fusarium sp. and Mucor sp. were found most susceptible fungi against the essential oil and their 100% growth inhibition was achieved at a concentration of 0.681 mg/ml¹¹.

9. Hepatoprotective action:

Methanolic extract of dried leaves of Callistemon lanceolatus showed the hepatoprotective activity which was performed by use of CCl₄ induced hepatic damage in Wistar strains of albino rats of either sex. Activity is confirmed as the extracts showed significant decrease in serum SGPT, SGOT,ALP and total billirubin level¹².

10.Calcium Channel Blocking Activity:

The crude methanolic extract of the fruits of Callistemon citrinus was screened for possible spasmolytic activity on isolated rabbit’s jejunum preparation. The extract produced a relaxing effect on spontaneous contraction of rabbit’s jejunum. The fruit of Callistemon citrinus was found to have a spasmolytic effect on rabbit’s jejunum through the calcium channel blocking mechanism¹³.

13. Anti-Thrombin Activity:

Chromogenic bioassay result showed anti-thrombic activity of methanolic extract of Callistemon lanceolatus¹⁴.

14.Neuroprotective Activity:

Neuroprotective effects of C-methyl flavonoids isolated from Callistemon lanceolatus evaluated by its protection of PC 12 cells against a beta-induced toxicity¹⁵.

CONCLUSION:

Callistemon lanceolatus as much attractive by its appearance is also contained of vast medicinal properties. Callistemon lanceolatus has been proved to be effective as anti-bacterial, hepatoprotective, cardioprotective, neuroprotective, anti-diabetic, anthalmentic agent and many more. Hence in this review article effort has been taken to collect and compile the details regarding Callistemon lanceolatus, which will be useful to the society to venture into the further unrevealed pharmacological actions of Callistemon lanceolatus and also venture into the field of alternative system of medicine.

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Received on 29.09.2015 Modified on 16.10.2015

Res. J. Pharmacology & P’dynamics. 7(4): Oct.-Dec., 2015; Page 165-170

DOI: 10.5958/2321-5836.2015.00033.6