INTRODUCTION:

The genus Rhododendron belongs to family Ericaceae, consists of 1000 species worldwide, mostly concentrated in Nepal, India, China and Malaysia¹, from these species 102 represented in India². The species Rhododendron arboreum is distributed in North America, Europe, Australia, India, Bhutan, Nepal, China, Myanmar, Thailand, Sri Lanka, Pakistan and Tibet³. In India, it is distributed in Sikkim, Arunachal Pradesh, Manipur, Meghalaya, Mizoram, Nagaland, Jammu and Kashmir, Uttarakhand, West Bengal^4,5 and Himachal Pradesh⁶. Rhododendron arboreum is an evergreen small tree⁷ with pink to red colour flowers, locally called by various names such as Pu, Billi, Eras and Adrawal⁸ (Table 1). This spectacular plant designated as the state flower of Nagaland⁹, official flower of Chin state¹⁰, national flower of Nepal and the state tree of Uttarakhand¹¹. Its flowers are eaten as raw or processed into juice.

In Nepal, it is marketed in the name of Rohitaka, a drug mention in the Ayurveda for liver and spleen disorders¹¹. This plant is a source of livelihood for the rural population in Himachal Pradesh¹². Traditionally, the plant is used for the treatment of many diseases such as rheumatism, nose bleeding, fever, wounds healing and amoebic dysentery^13,14. Various phytochemicals such as Xanthoprotein, Phenols, Saponins, Protein, Steroids, Tannin, Coumarins, Carbohydrates¹⁵, Carboxylic acid¹⁶, ascorbic acid, anthocyanins¹⁷, alkaloids¹⁸, reducing sugars¹⁹, flavonoids, terpenoids, anthraquinones, phlobatanins and glycosides²⁰, have been reported in the screening of leaves, flower and bark. In this paper, we have aimed to collate the up-to-date information on traditional uses, mineral values, Phytochemistry, pharmacology and toxicity of R. arboreum with the hope that, this review will stimulate the further research.

Table 1: Taxonomy of Rhododendron arboreum.

Scientific classification	Synonyms²¹
Kingdom: Plantae Phylum: Magnolliophyta Class: Angiospermae Order: Ericales Family: Ericaceae Genus: Rhododendron Species: Rhododendron arboreum	R. album Sweet R. windsorii Nutt. R. puniceum Roxb. R. nilagiricum Zenk. R. campbelliae Hook. F. R. cinnamomeum Wall.
Sub Species²²	Local names
Delavayii (red flowers) Nilagiricum (red flowers) Zeylancium (orange-red flowers) Arboreum (rose red or red flowers) Cinnamomeum (red or pink, white flowers)	Laligurans: Nepali Gulamair: Pakistan Rosemaram: Tamil Buransh: Uttarkashi M'saakbai: Myanmar Harduli: Jammu & Kashmir Metapen, Methu: Nagaland Brass: Himachal Pradesh Udongsheng: Arunachal Pradesh

Botanical description:

R. arboreum (Fig 1) is a branched tree, up to 10m tall. Its leaves are evergreen, glabrous from dorsal surface and silvery scales are present on the ventral surface, approx. 8.5cm in length, oblong-lanceolate, leathery and gathered at the end of the branches. The flowers in corymb with terminal inflorescence, Calyx 5-8 lobed and corolla is campanulate, tubular, 5-8 lobed. Stamens inserted at the base of the corolla. The ovary is superior, multilocular, Capsule cylindrical, scaly, curved with numerous winged seeds. The bark is pale brown and flaking²³. The tree flowers in march-may and fruits in April-november²⁴. The cuttings and seeds are used for propagation. The plant growth is best in moist loam without the lime, if sufficient soil-moisture and humus is present, it can also grow on rocky ground²⁵.

Fig. 1: Rhododendron arboreum. A: Tree and B: Flower.

Traditional Uses:

The stem wood of R. arboreum is used as fuel and various wooden products such as handles, packsaddles and gift-boxes are made from it^26-28. The beautiful flowers are used in decorations of houses, due to their sweet-sour taste, they are raw eaten or made into chutneys or juice²⁹. The juice is used as a freshener and useful during headache, stomachache, fever^30,31, nose bleeding, diabetes and rheumatism³²(Table 2). The powder of dried flowers is used as a drug to cure the bloody dysentery³³. It is believed that the paste of bark helps in healing the cuts³⁴, beside these ethnomedicinal properties the nectar of flowers is considered poisonous if consumed in excess³⁵.

Table 2: Traditional uses of R. arboreum.

Ailment/use	Locality
Flowers
Flower buds are used as a vegetable.	Uttarakhand, India³⁶
Honey-mixed drink of flowers is used to cure blurry vision and asthma.	Southern Chin State, Myanmar¹⁰
Flower aqueous extract used as a food colouring agent.	Himachal Pradesh, India¹⁷
Flowers are eaten raw, sauce and jams are also made.	Jammu and Kashmir, India²⁴
Dried flowers fried in ghee is used to stop the blood dysentery.	Tamil Nadu, India³⁷
Crushed flowers are snuffed to stop the nasal bleeding.	Himachal Pradesh, India³⁸
Flower and leaves are fitted with long ropes made of munja grass and tied around the houses and temples for decoration, women also decorate their hair with flowers.	Himachal Pradesh, India^25,39
Menstrual disorders³⁹.
Flowers juice is commercially sold as a health tonic.	Uttarakhand, India⁴⁰
Flower juice and squash are used to cure diabetes.	Uttarakhand, India⁴⁰
Flower juice is used to cure fever, stomach ache and heart-related problems.	Uttarkashi, western Himalaya, India⁴¹
Flower juice helps when Fish bones stuck in the throat.	Sikkim, India⁴²
Leaves
Young leaves are applied on the forehead to reduce headache⁴³.
External parasites	Uttaranchal, India⁴⁴
Dried leaf tincture is used for the treatment of rheumatism and gout.	Homoeopathic materia medica⁴⁵
Asoka aristha an Ayurvedic preparation has estrogenic, oxytocic and prostaglandin synthetase-inhibition effect⁴⁶.
Bark
Leaves and bark are used to reduce the roughness of the skin.	Manoor valley, Pakistan⁴⁷
Bark juice is used to cure coughs, piles and liver disorders.	Allai valley, Pakistan⁴⁸
Stem Wood
Wood is used to make handles, packsaddles, gift-boxes, Gunstocks and posts.	Arunachal Pradesh, India⁴⁹
Fuel.	Arunachal Pradesh, India⁵⁰
Root
The decoction of the roots is used to cure early stage of cancer.	Nagaland, India⁵¹

Nutritional and Minerals value:

Shrestha and Budhathoki found that butanoic acid, 4-heptanoic acid and pentanoic acid were the major constituents in the fatty acid compositions of stem wood⁵². About sixteen amino acids were found in flowers⁵³.

Table 3: Nutritional and Minerals value of R. arboreum^19,52,
53

Wood (stem)		Leaves
Physicochemical Parameters	Value (%)	Parameters			Value (%)
Ash content	0.75	Moisture content			0.78
Extractives	4.39	Total ash			1.6
Hollocelluloses	69.82	Acid insoluble ash			0.32
Hemicelluloses	22.00	Sulphated ash			0.0214
Alpha-celluloses	47.98	Water soluble extractives			12.00
Pentosans	16.84	Alcohol soluble extractives			9.65
Lignins	24.88
Flower
Physicochemical parameters	Value (%)		Minerals	Value (ppm)
Moisture	79.40 ± 0.10		Mn	50.2
Ash	2.30 ± 0.05		Fe	405
Crude fat	1.52 ± 0.08		Zn	32
Crude fiber	2.90 ± 0.05		Cu	26
Total nitrogen	0.58 ± 0.07		Na	385
Total protein	1.68 ± 0.05		Cr	08
Carbohydrate	12.20± 0.12		Co	‹0.5
Organic matter	97.70± 0.20		Cd	‹1
Insoluble Ash	1.29 ± 0.05		Mo	‹0.5
Soluble Ash	1.15 ± 0.08		Ni	2
			Pb	3
			As	‹0.5

The nutritional value⁵⁴ (Table 3) and the trace elements, Na (476), Mg (545), K (2348), Ca (4181), P (563), Si (9656) and Al (4689) ppm were reported in the R. arboreum ⁵⁵.

Phytochemistry:

Various phytochemicals have been identified and isolated from the different part of R. arboreum (Tables 4). About 34 compounds were reported by Painuli et al, among them, beta-amyrin, heptadecane, 22-stigmasten-3-one, tetradecane, methyl ester, linoleic, linoleyl alcohol, beta-citronellol, dodecane, L-ascorbic acid, 2, 6-dihexadecanoate, alpha-amyrin and dibutyl phthalate were the major compounds detected in the GC-MS analysis of methanolic leaf extract⁵⁶. In the study of ethanolic leaf extract, 13 compounds were identified and the compound geraniol formate, 1-hexadecene, 1, 2, 3, propanetriyl ester, 1-octadecanol and docosanoic acid were the major⁵⁷. In another study 26, 24 and 17 compounds were reported by Gautam et al in the chloroform, ethyl acetate and hexane fraction respectively⁵⁸. Two flavonoids, 3-Hydroxy-4-(5-hydroxy-7-methoxy-4-oxo-4H-chromen-2-yl) phenyl β-D-glucopyranoside, (8S)-8,9-Dihydro-13,16-dimethoxy-10H-8,11epoxy-4,7-etheno-1,3 benzodioxacyclododecin-10-one and two flavonoid glycoside, Rutin, Pectolinaroside (= 5-Hydroxy-6-methoxy2-(4-methoxyphenyl)-4-oxo-4H-chromen-7-yl 6-O-(α-Lrhamnopyranosyl)-β-D-glucopyranoside and a phenol derivative, terephthalic acid dimethyl ester were reported in the leaves^59,60. Harborne and Williams in 1971 separated the phenolic compounds from alcoholic leaf extracts by two-dimensional chromatography and identified as gossypetin, kempferol, azaleatin, caryatin, quercetin and leucoanthocyanidins⁶¹. The presence of compounds, quercetin, rutin, coumaric acid in methanolic flower extract⁶² Gallic acid in the leaves, three triterpenoids (ursolic acid, β-sitosterol and lupeol) in the flowers and leaves⁶³ were confirmed by HPTLC and the phenolic compounds, quercitrin, syringic acid, epicatechin and quercetin-3-O-galactoside in the methanolic leaves extract by RP-HPTLC⁶⁴.

Table 4: Phytochemicals of R. arboreum.

Compound names

Plant part

Flavonoid

Quercetin-3-O-galactoside

(C₂₁H₂₀O₁₂)

Flower^65-67

Leaves⁶⁸

Quercetin

(C₁₅H₁₀O₇)

Flower^69,70

Leaves⁷¹

Sterol

β-Sitosterol

(C₂₉H₅₀O)

Leaves⁷¹

Flavonol glycoside

Rutin

(C₂₇H₃₀O₁₆)

Leaves⁷¹

Quercitrin

(C₂₁H₂₀O₁₁)

Flower⁷²

Triterpenoid

3-O-acetylbetulinic acid

(C₃₂H₅₀O₄)

Bark⁷³

β-sitosterol-3-O-beta-Dglucosidose

(C₃₂H₅₀O₄)

Bark⁷³

3-β-acetoxyurs-11-en-13 β, 28-olide

(C₃₂H₄₈O₄)

Bark^73,74

Betulin

(C₃₀H₅₀O₂)

Bark^73,74

Lupeol

(C₃₀H₅₀O)

Bark^73,74

3-O-acetylursolic acid

(C₃₂H₅₀O₄)

Bark^73,75

Betulinic acid

(C₃₀H₄₈O₃)

Bark^73,75

Taraxerol

(C₃₀H₅₀O)

Bark^74,75

Epifriedelinol

(C₃₀H₅₂O)

Leaves^68,76

3,10-Epoxyglutinane

(C₃₀H₅₀O)

Leaves^71,76

Pentacyclic triterpenoid

Ursolic acid

(C₃₀H₄₈O₃)

Flower⁷²

Bark⁷³ Leaves^68,71,76

α- amyrin

(C₃₀H₅₀O)

Leaves⁷⁶

β- amyrin

(C₃₀H₅₀O)

Leaves⁷⁶

Friedelin

(C₃₀H₅₀O)

Leaves⁷⁶

15- oxoursolic acid

(C₃₀H₄₆O₄)

Bark⁷⁷

Other

Leuco-pelargonidin

(C₁₅H₁₄O₆)

Bark⁷⁵

4,4,6a,6b,11,12,14b-Heptamethyl-16oxo-1,2,3,4,4a,5,6,6a,6b,7,8,9,10,11,12,12a,14a,14b-octadecahydro-12b,8a(epoxymethano)picen-3-yl acetate

(C₃₂H₄₈O₈)

Bark⁷⁸

Pharmacological properties:

Adaptogenic activity:

The methanolic extract exhibited potent anti-stress activity due to the presence of high quantity of quercetin and gallic acid as compared to hydroethanol and aqueous extract as revealed by HPTLC analysis. The said compounds might be responsible for the activity⁷⁹.

Antidiarrheal activity:

The ethyl acetate fraction of flower in dose-dependent manner (100, 200 and 400 mg/kg, orally) significantly (p<0.05-0.001), reduced the number of diarrheal feces (24.55 - 73.65%) in the magnesium sulfate induced diarrhea and (91.36% - 66.03%) decreased the gastrointestinal transit of Charcoal Meal, (2.64 ± 0.37 - 1.43 ± 0.29) inhibit the intestinal contents and (3.87 ± 0.45 to 2.21 ± 0.67) decrease in the weight of intestinal contents in Castor oil-induced enter pooling. The fraction significantly (p<0.05 – 0.01) inhibited the number of diarrheal faeces (24.48 -71.07 %) in the castor oil induced diarrhoea at the above said concentrations⁸⁰.

Antiinflammatory and antinociceptive activity:

The flower extracts showed significant antiinflammatory activity against (Carrageenan > 5-HT >PG (E2) > Histamine) phlogistic agents induced hind paw edema in rats. The aqueous extract showed maximum activity as compared to 50% ethanol and methanol extract⁸¹. The acetone extract of leaves of R. arboreum at 3000 ug/ml possessed 50.56% erythrocyte membrane stabilizing activity⁸². In a study, the ethanolic leaf extract showed significant activity as compared to reference drug indomethacin⁸³. Verma et al in 2010, found that the dose (100, 200 and 400 mg/kg) of ethyl acetate extract inhibit, 15.9%, 30.7% and 51.2%, respectively the inflammation in arachidonic acid paw edema and 36%, 44.8% and 56.8% protection in the paw volume of Freund’s adjuvant-induced paw arthritis in rats. The ethyl acetate extract significantly increased the resistance against analgesy meter induced pain and it is also significant, in the acetic acid-induced writhing and significantly increased the reaction time (1.79 fold to 2.76 fold) in the hot plate method of antinociceptive activity. The presence of tannins, saponins and flavonoids (hyperin) in the extract might be responsible for activity⁶⁵. In another study, the ethyl acetate, chloroform and methanol extract at a dose of (200 mg/kg i.p) showed 82%, 67.89% and 65.09%, analgesic effect in acetic acid-induced writhing respectively. The ethyl acetate fraction exhibits maximum inhibition (90.58%) as compared to chloroform fraction (67.47%) and methanol crude (50.44%) in the lipoxygenase inhibitory assay⁸⁴.

Antioxidant and antimutagenic Activity:

The fractions (hexane, chloroform and ethyl acetate) of R. arboreum leaf extract, decreased the production of nitric oxide radicals, prevented degradation of deoxyribose and inhibited the lipid peroxidation. The presence of phytochemicals, vitamin E and 3,7,11,15-tetramethyl-2-hexadecen-1-ol might be responsible for the antioxidant activity. Furthermore, the ethyl acetate fraction showed high antimutagenic activity in the pre-incubation mode, 83.48% against TA-98 strain and 76.869% against TA-100 strain of Salmonella typhimurium. The activities might be due to the synergistic effect of phytochemicals reported in the GC-MS profiling⁵⁸. Prakash et al found that the methanolic leaf extract was moderate in antioxidant effect as compared to standard quercetin⁸⁵, while another study revealed that the ethanolic flower extract was high in antioxidant effect and nitric oxide synthase activation⁸⁶.

Anticancer activity:

It was found that the ethanolic leaves extract exhibit dose-dependent, significant activity against Agrobacterium tumefaciens induced tumour in potato disc. The leaf extract was significant in comparison with TAM and flower extract was statically insignificant in MCF-7 tumour cell line. The isolated compound quercetin and rutin from ethanol extract might be responsible for antitumor activity⁷¹. The isolated compound, 15- oxoursolic acid showed 32.8±1.54µM, 10.3±0.01µM, 9.2±0.23µM, 4.9±0.02µM, 2.3±0.04µM, IC₅₀values against A498, NCI-H226, H157, Hep G2 and MDR 2780AD cell lines respectively. The presence of OH group at carbon 3, carbonyl group at carbon 17 responsible for cytotoxicity⁷⁷. It was reported that the concentration up to 5000µg/ml of aqueous leaf extract was found non-cytotoxic against S. cerevisiae, strain BY4741. The extract inhibited cell proliferation (75.30% - 25.41%) in Vero and (87.66% - 60.12) in HELA cells and lowered the expression of HIF-1α to 0.332 fold and VEGE to 0.24 fold⁸⁷.

Antidiabetic activity:

Bhandary and Kawabata found that ethyl acetate soluble part was more effective in α-glucosidase inhibitory activity than the water-soluble part. The isolated compound, hyperin inhibit α-glucosidase in a dose-dependent manner having (IC₅₀=0.76 mM) for maltase and (IC₅₀=1.66 mM) for sucrose⁶⁶. Verma et al in 2013 found that blood glucose level was reduced in STZ induced diabetic rats by compound Hyperin significantly, by reducing the levels of triglycerides, VLDL, LDL and total cholesterol as compared to diabetic control rats. The activity of enzymes glycogen phosphorylase, glucose-6- phosphatase and glycosylated haemoglobin, significantly dose-dependent decreased while glycogen synthase and hexokinase activity increased. The compound-treated rats showed improvements in the histological features of pancreas⁶⁷. The isolated compounds from methanolic bark extract showed less than 13% inhibition against β-glycosidase. The compound, 3-O-acetylursolic acid inhibited (IC₅₀=3.3±0.1 µM ) the α- glycosidase more than a standard inhibitor, Acarbose (IC₅₀=545 ±7.9 µM). The compound 3-β-acetoxyurs-11-en-13 β, 28-olide inhibited maximum (76.3±6%) glycation⁷³. In another study, there was a marked decrease in the blood glucose level at 200 mg/kg dose of aqueous extract when compared to metformin at a dose of 10 mg/kg treated rats group⁸⁸. Verma et al in 2012 demonstrated that ethyl acetate fraction significantly reduced, maximum blood glucose level as compared to other fractions 5h after in the STZ induced diabetic rats. The active fraction significantly decreased the serum urea, creatinine, haemoglobin A1C and blood glucose level in the diabetic rats but increased the level of insulin similar to glybenclamide treated rats. The dose of 400 mg/kg of the active fraction significantly reduced the LDL (42.3±9.4 mg/dL), VLDL (10.3±6.9 mg/dL), total cholesterol (64.5±6.5 mg/dL), TGs and significantly increased, HDL as compared to diabetic untreated rats⁸⁹.

Cardioprotective activity:

The whole plant ethanolic extract of R. arboreum, dose-dependent significantly decreased the activity of ALT, AST, LDH enzymes and decreased the levels of MDA in serum, heart tissue and increased the activity of SOD, catalase, GPx and GSH in isoproterenol-treated rats. There was marked improvement seen in the vacuolation, myocardial degeneration and inflammatory cell infiltration in the ethanolic extract treated groups⁹⁰. Parcha et al found that ethanolic flower extract was more effective than aqueous extract, which significantly decreased the release of lactate dehydrogenase, creatine kinase at a dose of (70 mg/ml i.p.) in albino rats, while the n-butanol fraction of ethanolic extract showed maximum cardioprotective activity among all the extracts⁹¹.

Hypolipidemic effect:

The oral administration (300 mg/kg) of arboreum plus (Hyppophaeramnoides fruit juice + Rhododendron arboreum flower juice, 1：4) significantly reduced the total cholesterol, triglycerides, low-density lipoprotein and atherogenic index. There was no significant difference found in the arborium plus treated and atorvastatin (5mg/kg/d) treated rabbits⁹². The flower juice of R. arboreum significantly reduced the serum LDL, TG, TC, AL, hsCRP and significantly increased the HDL in (1% w/w cholesterol +10% v/w groundnut oil) fed hypercholesteremic Zealand rabbits⁹³.

Hepatoprotective activity:

The ethyl acetate fraction of flower extract of R. arboreum significantly, dose-dependent decreased the level of SGPT, SLAP, SGOT, gamma-GT, bilirubin and MDA production in CCl4 treated rats. The activities of GSH, GST and GR increased to normal levels. The standard drug silmarin and ethyl acetate fraction both were almost similar in activity⁹⁴. In another study, the ethanolic leaf extract significantly reduced the serum enzyme ALP, SGOT, SGPT, Triglyceride, total bilirubin, cholesterol and excretion of ascorbic acid in urine to the normal level in CCl4 treated rats⁹⁵.

Immunomodulatory activity:

The ethanolic leaf extract treated mice showed significant suppression to the immune response. The ethanolic extract treated group was more effective then levamisole treated and control group. There was no significant difference found in serum glutamate oxaloacetate transaminase, serum glutamate pyruvate transaminase, serum total bilirubin and in the weight of spleen and liver ⁹⁶. Rawat et al reported that TMS-10 (ursolic acid), CMS-3 (kaempferol) and RAM fr2 fraction, showed 79.67±0.57%, 67.67±2.08% and 40.3±1.5% stimulation respectively toward the phagocytic activity of neutrophils and also stimulated the phagocytosis in killed Candida albicans. The 1mg/ml concentration of TMS-10, CMS-3 and RAM fr2 had 7, 6.7 and 6.3 mean particle numbers respectively⁹⁷.

Toxicity study:

The oral administration of 2000 mg/kg of flower fractions and 200 mg/kg hyperin was found nontoxic in acute toxicity study of Wistar rats^67,89, however, in another study, the intraperitoneally induced 300 mg/kg dose of ethanolic leaf extract was found toxic in albino mice^83,95. Nisar et al reported that the methanolic extracts of various part of R. arboreum were found toxic at 1000 µg/ml against Artemia salina. The leaves exhibit significant cytotoxicity (LD₅₀= 20 µg/ml) and flower (LD₅₀=64.23 µg/ml), stem, roots had moderate (LD₅₀=85µg/ml) and bark least (LD₅₀=545ug/ml). The presence of glycosides, alkaloids and flavonoids in the extract might be responsible for activity⁹⁸.

Antibacterial activity:

The methanolic crude extracts of flower, leaf, stem and roots of R. arboreum possessed potent to significant activity against B. subtilus, Salmonella typhi and S. aureus⁹⁸. The ethanol extract, methanol extract and isolated quercetin showed 12.5mg/ml, 50mg/ml and 25 mg/ml, respectively the lowest effective concentration against E. coli and S. aureus⁶⁹. In another study, the ethanolic flower extract (50mg/ml) showed 20±1mm, 19±1mm and 17±1mm zone of inhibition against E. coli., S. epidermidis and S. aureus respectivly⁵³. Prakash et al found that methanolic leaf extract was more effective against gram-positive bacteria than acetone extract⁹⁹. Chauhan et al reported that the growth of inhibition of S. aureus was 60-40% in methanolic leaf extract and 50-50% in the methanolic flower extract. The leaf extract was fairly effective, then flower extract¹⁰⁰. The zone of inhibition of methanol and aqueous leaves extracts for S. aureus, Klebsiellapneumoniae, Streptococcus pyogene and E. coli was 12.50±1.10^a, 11.50±0.90^c, 11.50±0.50 ^b,11.00±0.80^d and 6.50±0.10^d, 8.00±0.50^c, 8.50±0.55^b, 10.00±0.82 respectively¹⁰¹. In 2013 Sharma found ethanolic flower extract effective against B. subtilis, S. aureus, Salmonella typhi and Escherichia coli bacteria¹⁰².

Antifungal activity:

Saklani & Chandra reported the zone of inhibition at concentration 50 mg/ml for ethanolic flower extract as, (10mm) for Aspergillus flavus, (9mm) Candida albicans, (8mm) Aspergillus parasiticus and for the water extract, (10mm) for Candida albicans, (9mm) Aspergillus parasiticus and (8mm) for Aspergillus flavus⁵³.The methanol extract showed 17mm, 25mm, 28mm, 28mm, 29mm, 32mm and the ethyl acetate extract 16mm, 22mm, 24mm, 25mm, 28mm, 28 mm of inhibition against F. solani, A. niger, M. canis, C. flavus, C. albacan and D. glaberata respectively at 50µg/ml. The isolated compound, 3β-acetoxyurs-11, 12- epoxy-13β, 28- olide inhibit, 39 mm, 32 mm, 42 mm, 28 mm, 41 mm, 44 mm and Lupol inhibit, 32 mm, 28 mm, 38 mm, 17 mm, 40 mm, 36 mm and Betulin inhibit, 40 mm, 23 mm, 43 mm, 35 mm, 44 mm, 39 mm against D. glaberata, F. solani, C. flavus, M. canis, C. albacan and A. niger respectively at 10 mg/ml concentration. The high activity of compounds (betulin and 3β-acetoxyurs-11, 12- epoxy-13β) might be due to their hydrophilic nature⁷⁴. Saranya and Ravi reported that the fungus Trichodermaviride and Candida albicans had 9.00±0.50^a and 8.00±0.40^b zone of inhibition for methanol extract and 5.00±0.30^a and 4.00±0.20^b for aqueous leaves extract respectively¹⁰¹.

CONCLUSION:

On the basis of evidences in literature R. arboreum is full of nutrients, minerals and used in a wide range of ethnomedical treatments, various pharmacological activities have been reported by its compounds, fractions and extracts such as, antidiabetic, adaptogenic, antidiarrheal, anti-inflammatory, antinociceptive, antioxidant, anticancer, cardioprotective, hepatoprotective, immunomodulatory and antimicrobial which supports its ethnomedicinal use and benefits, however in some studies R. arboreum found toxic after a certain dose. In the present and past, most of the biological activities have been done on mixture (extracts/fractions), only a few are on isolated compounds and their mechanisms are not clear, so further studies should be carried out to elucidate the exact mechanisms of action and toxicity to ensure their eligibility to be used as medicines. The various classes of compounds such as ester, terpenes, hydrocarbon alkane, organic compounds, steroids, flavonoids and fatty acids are present in R. arboreum as reported in GC-MS profiling, which have numerous pharmacological and industrial importance. Some of the compounds that belong to class phenolics, flavonoids, flavonoid glycosides, sterol and terpenoids have already been isolated from leaves, flowers and bark and the rest are yet to explore, so further study is recommended on the purification and isolation of the compounds from R. arboreum, which may add a novel or compatible therapeutic agent in the pharmaceutical world.

ACKNOWLEDGEMENT:

Authors are grateful to Principal of Bhoj Mahavidyalaya Bhopal, Madhya Pradesh, India for his honorary guidance and encouragement for carrying out research activity.

CONFLICT OF INTEREST:

The authors declare no conflict of interest.

REFERENCES:

1. Singh KK, Rai LK, Gurung B. Conservation of Rhododendrons in Sikkim Himalaya: an overview. World Journal of Agricultural Sciences. 2009; 5(3): 284-296.

2. Panda S, Kirtania I. Variation in Rhododendron arboreum Sm. complex (Ericaceae): insights from exomorphology, leaf anatomy and pollen morphology. Modern Phytomorphology. 2016; 9: 27-49.

3. Purohit CS. Rhododendron arboreum Sm. - An Economically Important Tree of Sikkim. Popular Kheti. 2014; 2(3): 193-198

4. Mao AA. The genus Rhododendron in north-east India. Botanica Orientalis: Journal of Plant Science. 2010; 7: 26-34.

5. Sekar KC, Srivastava SK. Rhododendrons in Indian Himalayan region: diversity and conservation. American Journal of Plant Sciences. 2010; 1: 131-137

6. Samant, Pant S, Singh M, Lal M, Singh A, Sharma A, Bhandari S. Medicinal plants in Himachal Pradesh, north western Himalaya, India. The International Journal of Biodiversity Science and Management. 2007; 3(4): 234-251.

7. Tabassum IF, Udayan PS, Somashekar RK, Ved DK, Mohammed AJ. Prioritization of medicinal plants in sholas of Western Ghats: A case study. Academia Journal of Medicinal Plants. 2018; 6(1): 6-10.

8. Rawat P, Rai N, Kumar N, Bachheti RK. Review on Rhododendron arboreum-a magical tree. Oriental Pharmacy and Experimental Medicine. 2017; 17(4): 297-308.

9. Paul A, Khan ML, Das AK, Dutta PK. Diversity and distribution of rhododendrons in Arunachal Himalaya, India. Journal American Rhododendron society. 2010; 64: 200-205.

10. Ong HG, Ling SM, Win TTM, Kang DH, Lee JH, KimYD. Ethnobotany of wild medicinal plants used by the Müün ethnic people: A quantitative survey in southern Chin state, Myanmar. Journal of herbal medicine. 2018; 13: 91-96.

11. Keshari P, Pradeep PS. Pharmacognostical and chromatographic evaluation of market sample of Rhododendron arboreum stem bark as a source plant for Rohitaka in Nepal. Journal of Pharmacognosy and Phytochemistry. 2017; 6(5): 296-306.

12. Sharma N, Kala CP. Utilization pattern, population density and supply chain of Rhododendron arboreum and Rhododendron campanulatum in Dhauladhar Mountain Range of Himachal Pradesh, India. Applied Ecology and Environmental Sciences. 2016; 4(4): 102-107.

13. Singh KJ, Thakur AK. Medicinal plants of the Shimla hills, Himachal Pradesh: a survey. International Journal of Herbal Medicine. 2014; 2(2): 118-127.

14. Sharma P, Patti P, Agnihotry A. Ethnobotanical and Ethnomedicinal uses of floristic diversity in Murari Devi and surrounding areas of Mandi district in Himachal Pradesh, India. Pakistan Journal of Biological Sciences. 2013; 16(10): 451-468.

15. Kiruba S, Mahesh M, Nisha SR, Paul ZM, Jeeva S. Phytochemical analysis of the flower extracts of Rhododendron arboreum Sm. ssp. nilagiricum (Zenker) Tagg. Asian Pacific Journal of Tropical Biomedicine. 2011; 1(2): S284-S286.

16. Kiruba S, Mahesh M, Paul ZM, Nisha SR, Jeeva S. Preliminary phytochemical studies of the leaf extracts of Rhododendron arboreum Sm. ssp. nilagiricum (Zenker) Tagg. Asian Pacific Journal of Tropical Biomedicine. 2012; 3(2): S1338-S1340.

17. Devi S, Vats CK, Dhaliwal YS. Quality Evaluation of Rhododendron arboreum Flowers of Different Regions of Himachal Pradesh for Standardization of Juice Extraction Technique. International Journal of Advances in Agricultural Science and Technology. 2018; 5(1): 51-57.

18. Keshari P. Comparative pharmacognostic evaluation of Tecomellaundulata and Rhododendron arboreum as two different sources of Rohitaka. International Journal of Green Pharmacy. 2018; 12(04): 242-252

19. Tewari D, Sah AN, Bawari S. Pharmacognostical Evaluation of Rhododendron arboreum Sm. from Uttarakhand. Pharmacognosy Journal. 2018; 10(3): 527-532.

20. Nisar M, Ali S, Qaisar M. Preliminary phytochemical screening of flowers, leaves, bark, stem and roots of Rhododendron arboreum. Middle-East Journal of Scientific Research. 2011; 10(4): 472-476.

21. Kharwal AD, Rawat DS. Ethnobotanical studies and distribution of different Rhododendron species in Himachal Pradesh, India. Plant Sciences Feed. 2013; 3(3): 46-49.

22. Srivastava P. Rhododendron arboreum: an overview. Journal of Applied Pharmaceutical Science. 2012; 2(1): 158-162.

23. Cullen J. Hardy rhododendron species: A Guide to Identification. Timber press. 2005; pp. 133-199.

24. Dangwal LR, Singh T, Singh A. Exploration of wild edible plants used by Gujjar and Bakerwal tribes of District Rajouri (J&K), India. Journal of Applied and Natural Science. 2014; 6(1): 164-169.

25. Chauhan NS. Medicinal and aromatic plants of Himachal Pradesh. Indus Publishing Company, New Delhi. 1999; pp. 353-355.

26. Ranjitkar S, Sujakhu NM, Jati R, Xu J, Schmidt-Vogt D. Yield and household consumption of Rhododendron arboreum as a fuelwood species in Eastern Nepal. Biomass and bioenergy. 2014; 61: 245-253.

27. Chettri N, Sharma E. A scientific assessment of traditional knowledge on firewood and fodder values in Sikkim, India. Forest Ecology and Management. 2009; 257(10): 2073-2078.

28. Kumar M, Sharma CM. Fuelwood consumption pattern at different altitudes in rural areas of Garhwal Himalaya. Biomass and Bioenergy. 2009; 33(10): 1413-1418.

29. Sharma P, Agnihotry A, Sharma PP, Sharma L. Wild edibles of Murari Devi and surrounding areas in Mandi district of Himachal Pradesh, India. International journal of Biodiversity and Conservation. 2013; 5(9): 592-604.

30. Semwal DP, Saradhi PP, Kala CP, Sajwan BS. Medicinal plants used by local Vaidyas in Ukhimath block, Uttarakhand. Indian Journal of Traditional Knowledge. 2010; 9(3): 480-485

31. Sharma P, Samant SS. Diversity, distribution and indigenous uses of medicinal plants in Parbati Valley of Kullu district in Himachal Pradesh, Northwestern Himalaya. Asian journal of advanced basic sciences. 2014; 2(1): 77-98.

32. Krishna H, Attri BL, Kumar A. Improvised Rhododendron squash: processing effects on antioxidant composition and organoleptic attributes. Journal of food science and technology. 2014; 51(11): 3404-3410.

33. Sharma PK, Chauhan NS, Lal B. Conservation of Phyto-diversity of Parvati Valley in Northwestern Himalayas of Himachal Pradesh-India. Medicinal and Aromatic Plant Science and Biotechnology. 2010; 4(1): 47-63.

34. Rana SK, Oli PS, Rana HK. Traditional botanical knowledge (TBK) on the use of medicinal plants in Sikles area, Nepal. Asian Journal of Plant Science and Research. 2015; 5(11): 8-15.

35. Bhattacharyya D. Rhododendron species and their uses with special reference to Himalayas–a review. Assam university Journal of Science and Technology. 2011; 7(1): 161-167.

36. Joshi SK, Ballabh B, Negi PS, Dwivedi SK. Diversity, distribution, use pattern and evaluation of wild edible plants of Uttarakhand, India. Defence Life Science Journal. 2018; 3(2): 126-135.

37. Shanmugam S, Annadurai M, Rajendran K. Ethnomedicinal plants used to cure diarrhoea and dysentery in Pachalur hills of Dindigul district in Tamil Nadu, Southern India. Journal of Applied Pharmaceutical Science. 2011; 1(8): 94-97.

38. Uniyal SK, Singh KN, Jamwal P, Lal B. Traditional use of medicinal plants among the tribal communities of Chhota Bhangal, Western Himalaya. Journal of ethnobiology and ethnomedicine. 2006; 2(1):14.

39. Kumari K, Srivastva H, Mudgal VD. Medicinal importance and utilization of Rhododendron- A Review. Research in Environment and Life Sciences. 2015; 8(4): 761-766.

40. Negi VS, Maikhuri RK, Rawat LS, Chandra A. Bioprospecting of Rhododendron arboreum for livelihood enhancement in central Himalaya, India. Environment & We: International Jouranl of Science and Technology. 2013; 8: 61-70.

41. Nand K, Naithani S. Ethnobotanical uses of wild medicinal plants by the local community in the Asi Ganga Sub-basin, Western Himalaya. Journal of Complementary Medicine Research. 2018; 9(1): 34-46.

42. Tiwari ON, Chauhan UK. Rhododendron conservation in Sikkim Himalaya. Current Science. 2006; 90(4): 532-541.

43. Khare CP. Indian medicinal plants: an illustrated dictionary. Springer Science & Business Media. 2007; pp. 546-547.

44. Pande PC, Tiwari L, Pande HC. Ethnoveterinary plants of Uttaranchal—A review. Indian Journal of Traditional Knowledge. 2007; 6(3): 444-458.

45. Skidel Rhododendron. Text Book of Materia Medica. Sree Bharati Press, Calcutta. 1980; 540.

46. Middelkoop TB, Labadie RP. Evaluation of Asoka Aristha an indigenous medicine in Sri Lanka. Journal of ethnopharmacology. 1983; 8(3): 313-320.

47. Rahman IU, Afzal A, Iqbal Z, Ijaz F, Ali N, Bussmann RW. Traditional and ethnomedicinal dermatology practices in Pakistan. Clinics in dermatology. 2018; 36(3): 310-319.

48. Haq F. The ethno botanical uses of medicinal plants of Allai Valley, Western Himalaya Pakistan. International Journal of Plant Research. 2012; 2(1): 21-34.

49. Paul A, Khan ML, Arunachalam A, Arunachalam K. Biodiversity and conservation of Rhododendrons in Arunachal Pradesh in the Indo-Burma biodiversity hotspot. Current Science. 2005; 89(4): 623.

50. Paul A, Khan ML, Das AK. Utilization of rhododendrons by Monpas in western Arunachal Pradesh, India. Journal American Rhododendron Society. 2010; 64(2): 81-84.

51. Zhasa NN, Hazarika P, Tripathi YC. Indigenous knowledge on utilization of plant biodiversity for treatment and cure of diseases of human beings in Nagaland, India, A case study. International Research Journal of Biological Sciences. 2015; 4(4): 89-106.

52. Shrestha RM, Pratapsingh BN. The chemical compositions of Rhododendron arboreum,“Laligunras”. Journal of Nepal Chemical Society. 2012; 30: 97-106.

53. Saklani S, Chandra S. Evaluation of in vitro antimicrobial activity, nutritional profile and phytochemical screening of Rhododendron arboreum. World journal of pharmacy and pharmaceutical sciences. 2015; 4(6): 962-971.

54. Solanki SN, Huria AK, Chopra CS. Physico-chemical characteristics of buransh (Rhododendron arboreum) a nutritious and edible flower. Journal of hill agriculture. 2013; 4(1): 50-52.

55. Hammerton J, Joshi LR, Ross AB, Pariyar B, Lovett JC, Shrestha KK, Gasson PE. Characterisation of biomass resources in Nepal and assessment of potential for increased charcoal production. Journal of environmental management. 2018; 223: 358-370.

56. Painuli S, Rai N, Kumar N. Gas chromatography and mass spectrometry analysis of methanolic extract of leaves of Rhododendron arboreum. Asian Journal of Pharmapsutical and clinical Research. 2016; 9(1): 101-104

57. Jegan BS, Selvaraj D. Bioactive components of the leaves of Rhododendron arboreum sm. Ssp. Nilagiricum.World journal of pharmacy and pharmaceutical sciences. 2016; 5(7): 713-722.

58. Gautam V, Kohli S, Arora S, Bhardwaj R, Kazi M, Ahmad A, Ahmad P. Antioxidant and Antimutagenic Activities of Different Fractions from the Leaves of Rhododendron arboreum Sm. and Their GC-MS Profiling. Molecules. 2018; 23: 2239.

59. Shaifulla KMS, Kamil M, Ilyas M. Chemical constituents of Rhododendron arboreum, Indian Drugs. 1991; 29: 83-84.

60. Kamil M, Ilyas M. Flavonoidic constituents of Rhododendron arboreum leaves. Fitoterapia. 1995; 66: 371-372.

61. Harborne JB, Williams CA. Leaf survey of flavonoids and simple phenols in the genus Rhododendron. Phytochemistry. 1971; 10(11): 2727-2744.

62. Swaroop A, Gupta AP, Sinha AK. Simultaneous determination of quercetin, rutin and coumaric acid in flowers of Rhododendron arboreum by HPTLC. Chromatographia. 2005; 62: 649-652.

63. Shilajan S, Swar G. Simultaneous estimation of three triterpenoids‑ursolic acid, beta‑sitosterol and lupeol from flowers, leaves and formulations of Rhododendron arboreum Smith. using validated HPTLC method. International Journal of Green Pharmacy. 2013; 7(3): 206-210

64. Sharma N, Sharma UK, Gupta AP, Sinha AK. Simultaneous determination of epicatechin, syringic acid, quercetin-3-O-galactoside and quercitrin in the leaves of Rhododendron species by using a validated HPTLC method. Journal of food composition and analysis. 2010; 23(3): 214-219.

65. Verma N, Singh AP, Amresh G, Sahu PK, Rao CV. Anti-inflammatory and anti-nociceptive activity of Rhododendron arboreum. Journal of Pharmacy Research. 2010; 3(6): 1376-1380.

66. Bhandary MR, Kawabata J. Antidiabetic activity of Laligurans (Rhododendron arboreum Sm.) flower. Journal of Food Science and Technology Nepal. 2008; 4: 61-63.

67. Verma N, Amresh G, Sahu PK, Mishra N, Rao CV, Singh AP. Pharmacological evaluation of hyperin for antihyperglycemic activity and effect on lipid profile in diabetic rats. Indian Journal of Experimental Biology. 2013; 51(1): 65-72.

68. Rangaswami S, Sambamurthy K. Chemical examination of the leaves of Rhododendron nilagiricum Zenk. Proceedings Mathematical Sciences. 1959; 50(6): 366-373.

69. Sonar PK, Singh R, Khan S, Saraf SK. Isolation, characterization and activity of the flowers of Rhododendron arboreum (Ericaceae). Journal of Chemistry. 2012; 9(2): 631-636.

70. Bhandari L, Rajbhandari M. Isolation of quercetin from flower petals, estimation of total phenolic, total flavonoid and antioxidant activity of the different parts of Rhododendron arboreum smith. Scientific World. 2014; 12(12): 34-40.

71. Sonar PK, Singh R, Bansal P, Balapure AK, Saraf SK. R. arboreum flower and leaf extracts: RP-HPTLC screening, isolation, characterization and biological activity. Rasayan Journal of Chemistry. 2012; 5(2): 165-172.

72. Rangaswami S, Sambamurthy K. Crystalline chemical components of the flowers of Rhododendron nilagiricum Zenk. In Proceedings of the Indian Academy of Sciences. 1960; 51: 322-327.

73. Raza R, Ilyas Z, Sajid A, Nisar M, Khokhar MY, Iqbal J. Identification of Highly Potent and Selective alpha-Glucosidase Inhibitors with Antiglycation Potential, Isolated from Rhododendron arboreum. Records of Natural Products. 2015; 9(2): 262.

74. Nisar M, Ali S, Qaisar M, Gilani SN, Shah MR, Khan I, Ali G. Antifungal activity of bioactive constituents and bark extracts of Rhododendron arboreum. Bangladesh Journal of Pharmacology. 2013; 8(2): 218-222.

75. Hariharan V, Rangaswami S. Chemical investigation of the bark of Rhododendron arboreum Sm. Current Science. 1966; 35(15): 390-391.

76. Gupta NC. Chemical investigation on the leaves of Rhododendron arboreum and Cocculus pendulus (Forsk.) Diels. Current science. 1978; 47(20): 768-769.

77. Ali S, Nisar M, Qaisar M, Khan A, Khan AA. Evaluation of the cytotoxic potential of a new pentacyclic triterpene from Rhododendron arboreum stem bark. Pharmaceutical biology. 2017; 55(1): 1927-1930.

78. Nisar M, Ali S, Tahir MN, Ahmad B, Hameed S. 4, 4, 6a, 6b, 11, 12, 14b-Heptamethyl-16-oxo-1, 2, 3, 4, 4a, 5, 6, 6a, 6b, 7, 8, 9, 10, 11, 12, 12a, 14a, 14b-octadecahydro-12b, 8a-(epoxymethano) picen-3-yl acetate. Acta Crystallographica Section E: Structure Reports Online. 2013; 69(4): o573.

79. Roy JD, Handique AK, Barua CC, Talukdar A, Ahmed FA, Barua IC. Evaluation of phytoconstituents and assessment of adaptogenic activity in vivo in various extracts of Rhododendron arboreum (leaves). Indian Journal of Pharmaceutical and Biological Research. 2014; 2(2): 49-56.

80. Verma N, Singh AP, Gupta A, Sahu PK, Rao CV. Antidiarrheal potential of standardized extract of Rhododendron arboreum Smith flowers in experimental animals. Indian journal of pharmacology. 2011; 43(6): 689.

81. Agarwal SS, Kalpana S. Anti-inflammatory activity of flowers of Rhododendron arboreum (Smith) in Rat’s hind paw oedema induced by various phlogistic agents. Indian Journal of Pharmacology. 1988; 20(2): 86.

82. Kumar D, Arora S, Kumar M, Thakur MK, Singh AP. Membrane stabilizing activity and antioxidant effect of Sidacordata (Burm F.) Bioss and Rhododendron arboreum Sm. leaves. International Journal of Pharmaceutical Sciences and Research. 2014; 5(1): 165-170.

83. Sharma UR, Surendra V, Jha SK, Nitesh SC, Prakash T, Goli D. Evaluation of anti-inflammatory activity of Rhododendron arboreum herb extract on experimental animal. Archives of Pharmaceutical Science and Research. 2009; 1(1): 58-61.

84. Nisar M, Ali S, Muhammad N, Gillani SN, Shah MR, Khan H, Maione F. Antinociceptive and anti-inflammatory potential of Rhododendron arboreum bark. Toxicology and industrial health. 2016; 32(7): 1254-1259.

85. Prakash D, Upadhyay G, Singh BN, Dhakarey R, Kumar S, Singh KK. Free-radical scavenging activities of Himalayan rhododendrons. Current Science. 2007; 92(4): 526-532.

86. Acharya K, Giri S, Biswas G. Comparative study of antioxidant activity and nitric oxide synthase activation property of different extracts from Rhododendron arboreum flower. International Journal of PharmTech Research. 2011; 3(2): 757-762.

87. Painuli S, Joshi S, Bhardwaj A, Meena RC, Misra K, Rai N, Kumar N. In vitro antioxidant and anticancer activities of leaf extracts of Rhododendron arboreum and Rhododendron campanulatum from Uttarakhand region of India. Pharmacognosy Magazine. 2018; 14(57): 294-303.

88. Vijayaragavan T, Mani TT. Anti Diabetic Activity of Rhododendron arboreum Sm Linn. Bark in Experimental Rats. Journal of Pharmacy Research. 2012; 5(6): 3483-3485.

89. Verma N, Amresh G, Sahu PK, Rao CV, Singh AP. Antihyperglycemic and antihyperlipidemic activity of ethyl acetate fraction of Rhododendron arboreum Smith flowers in streptozotocin induced diabetic rats and its role in regulating carbohydrate metabolism. Asian Pacific journal of tropical biomedicine. 2012; 2(9): 696-701.

90. Mudagal MP, Goli D. Preventive effect of Rhododendron arboreum on cardiac markers, lipid peroxides and antioxidants in normal and isoproterenol-induced myocardial necrosis in rats. African Journal of Pharmacy and Pharmacology. 2011; 5(6): 755-763.

91. Parcha V, Yadav N, Sati A, Dobhal Y, Sethi N. Cardioprotective effect of various extract of Rhododendron arboreum Sm flower on Albino rats. Journal of Pharmacognosy and Phytochemistry. 2017; 6(4): 1703-1707.

92. Murty D, Rajesh E, Raghava D, Raghavan TV, Surulivel MKM. Hypolipidemic effect of arborium plus in experimentally induced hypercholestermic rabbits. Yakugaku Zasshi. 2010; 130(6): 841-846.

93. Thangaraj V. Hypolipidemic effect of Rhododendron arboreum Sm. linn flower juice in experimentally induced hypercholestermic rabbits. International Journal of Pharmaceutical and Biomedical Research. 2013; 4(1): 46-49.

94. Verma N, Singh AP, Amresh G, Sahu PK, Rao CV. Protective effect of ethyl acetate fraction of Rhododendron arboreum flowers against carbon tetrachloride-induced hepatotoxicity in experimental models. Indian journal of pharmacology. 2011; 43(3): 291-295.

95. Prakash T, Fadadu SD, Sharma UR, Surendra V, Goli D, Stamina P, Kotresha D. Hepatoprotective activity of leaves of Rhododendron arboreum in CCl4 induced hepatotoxicity in rats. Journal of Medicinal Plants Research. 2008; 2(11): 315-320.

96. Sonar PK, Singh R, Verma A, Saraf SK. Rhododendron arboreum (Ericaceae): Immunomodulatory and related toxicity studies. Oriental Pharmacy and Experimental Medicine. 2013; 13(2): 127-131.

97. Rawat P, Bachheti RK, Kumar N, Rai N. Phytochemical analysis and evaluation of in vitro immunomodulatory activity of Rhododendron arboreum leaves. Asian Journal of Pharmaceutical and clinical research. 2018; 11(8): 123-128.

98. Nisar M, Ali S, Qaisar M. Antibacterial and cytotoxic activities of the methanolic extracts of Rhododendron arboreum. Journal of Medicinal Plants Research. 2013; 7(8): 398-403.

99. Prakash V, Rana S, Sagar A. Studies on antibacterial activity of leaf extracts of Rhododendron arboreum and Rhododendron campanulatum. International Journal of Current Microbiology and Applied Sciences. 2016; 5(4): 315-22.

100. Chauhan P, Singh J, Sharma RK, Easwari TS. Anti-bacterial activity of Rhododendron arboreum plant against Staphylococcus aureus. Annals of Horticulture. 2016; 9(1): 92-96.

101. Saranya D, Ravi R. The leaf of Nilgiri Rhododendron: a potent antimicrobial agent against medically critical human pathogens. International Journal of Pharmacognosy. 2016; 3(6): 251-256.

102. Sharma BC. In vitro antibacterial activity of certain folk medicinal plants from Darjeeling Himalayas used to treat microbial infections. Journal of Pharmacognosy and Phytochemistry. 2013; 2(4): 1-4.

Received on 20. 03.2019 Modified on 29.04.2019

Research J. Pharm. and Tech. 2019; 12(9):4565-4574.

DOI: 10.5958/0974-360X.2019.00785.6