Salam Leaf
Syzygium polyanthum (Wight.) Walp.
Myrtaceae
Figure 1 : Syzygium polyanthum. (a) Tree habit; (b) trunk; (c) opposite leaf arrangement; (d) adaxial leaves; (e) abaxial leaves; (f) flower buds; (g) flowering inflorescence; (h) early fruits structure; (i) unripe fruits. (Photos courtesy of Institute for Medical Research, 2015)
DEFINITION
Salam leaves consist of the powder of dried leaves of Syzygium polyanthum (Wight.) Walp. (Myrtaceae).
SYNONYM
Eugenia holmanii Elmer, Eugenia junghuhniana Miq., Eugenia lambii Elmer, Eugenia lucidula Miq., Eugenia microbotrya Miq., Eugenia pamatensis Miq., Eugenia polyantha Wight, Eugenia resinosa Gagnep., Syzygium micranthum Blume ex Miq., Syzygium microbotryum (Miq.) Masam., Syzygium pamatense (Miq.) Masam [ 1 ].
VERNACULAR NAMES
Indian laurel, Indonesian bayleaf (English); daun salam, serai kayu, kelat putih, kelat merah, kelat samak, palong (Malay) [ 2 , 3 ].
CHARACTER
| Colour | Greenish brown |
| Odour | Aromatic [ 2 ] |
| Taste | Bitter |
IDENTIFICATION
Plant Morphology
Syzygium polyanthum is a deciduous tropical tree, grows up to 30 m height, 60 cm in diameter, with spreading branches and round trunk; bark surface fissured and scaly. Leaves simple, opposite, glabrous, oblong-elliptical to narrowly elliptical or lanceolate, 5–16 cm long, 2.5–7 cm wide; 6–11 pairs of secondary veins distinct on abaxial leaves and a distinct intramarginal vein; petiole up to 12 mm long. Inflorescence a panicle with 2–8 cm long, usually borne below the leaves and sometimes axillary. Flowers small,sessile, bisexual, white or pink, fragrant; stamens are numerous, about 3 mm long; calyx cup-shaped, about 4 mm long; petals 4, free, 2.5–3.5 mm long. Fruits 1-seeded berry, globose or round, up to 12 mm in diameter, green when immature, dark red to purplish-black when ripe [ 2 , 4 , 5 ]
Microscopy
Powdered material consists of numerous fragments of vascular bundles with spiral, annular or pitted vessels; druse or solitary crystals of calcium oxalate, isolated; fragment of single fibre; fragment of abaxial epidermis cells with stomata usually anomocytic type; fragments of parenchyma cells, with large, slightly and regularly thickened cells, in surface view.
Figure 2: Microscopic characters of Syzygium polyanthum leaves powder of 0.355 mm size. (a) Spiral vessel (magnification 20x); (b) annular vessel (magnification 20x); (c) pitted vessel (magnification 20x); (d) solitary prism calcium oxalate crystal (magnification 20x); (e) druse calcium oxalate crystal (magnification 40x); (f) fibre (magnification 40x); (g) abaxial epidermal cells with anomocytic stomata (magnification 20x); (h) rectangular parenchyma cells (magnification 2x). [Scale bars: a, b, c, d, g = 20 µm; e = 10 µm; f = 100 µm; h = 200 µm]
Chemical Tests
Observed colour of solution after treatment for the presence of triterpenes :
| Test for the presence of triterpenes | Red color |
Thin Layer Chromatography (TLC)
Figure 3 : TLC chromatogram of gallic acid (S), methanol extract of Syzygium polyanthum dried leaves powder (L) observed under (a) UV at visible light (b) UV at 254 nm.
| Test Solutions | Weigh about 0.5 g of S. polyanthum dried leaves powder of 0.355 mm size in a 25 mL screw-capped sample bottle. Add 5.0 mL of methanol and sonicate the mixture for 20 min at room temperature. Filter the mixture solution with 0.45 µm syringe filter. Use the filtrate as test solution. |
| Standard solution | Dissolve gallic acid standard [CAS no.: 149-91-7] in methanol to produce a standard concentration 0.125 mg/mL. |
| Stationary Phase | HPTLC Glass Silica Gel 60 F254, 10 x 10 cm. |
| Mobile phase | Toluene : ethyl acetate : formic acid; (5 : 5 : 1) (v/v/v) |
| Application |
|
| Development distance | 7 cm |
| Drying | Air drying |
| Detection |
|
High Performance Liquid Chromatography (HPLC)
| Test solution | Weigh about 0.5 g of S. polyanthum dried leaves powder of 0.355 mm size in a 25 mL screw-capped sample bottle. Add 5.0 mL of methanol and sonicate the mixture for 20 min at room temperature. Filter the mixture solution with 0.45 µm syringe filter. Use the filtrate as test solution. | |||||||||||||||||||||
| Standard solution | Dissolve gallic acid standard [CAS no.: 149-91-7] in methanol to produce a standard concentration 0.125 mg/mL. | |||||||||||||||||||||
| Chromatographic system |
Detector: UV 271 nm Column: C18 (5.0 µm, 4.6 mm I.D x 250 mm) Column oven temperature: 30°C Flow rate: 1.0 mL/min Injection volume: 1.0 µL |
|||||||||||||||||||||
| Mobile Phase (gradient mode) |
|
|||||||||||||||||||||
| System suitability requirement |
Perform at least five replicate injections of gallic acid standard (0.125 mg/mL). The requirements of the system suitability parameters are as follow:
|
|||||||||||||||||||||
| Acceptance criteria |
|
(a)
(b)
Figure 4 : Whole HPLC chromatogram of (a) gallic acid standard solution (0.125 mg/mL) at tr = 8.605 min and (b) methanol extract of Syzygium polyanthum dried leaves powder showing peak corresponding to gallic acid standard solution at tr = 8.615 min.
(a)
(b)
Figure 5 : HPLC chromatogram highlighting the eluation region of gallic acid in (a) gallic acid standard solution (0.125 mg/mL) at tr = 8.605 min and (b) methanol extract of Syzygium polyanthum dried leaves powder showing peak corresponding to gallic acid standard solution at tr = 8.615 min.
Figure 6 : UV spectrum of gallic acid standard solution (0.125 mg/mL) and methanol extract of Syzygium polyanthum dried leaves powder.
PURITY TESTS
The purity tests, except foreign matter test, are based on S. polyanthum dried leaves powder of 0.355 mm particle size.
| Foreign Matter |
| Not more than 2% |
| Ash Contents | |
| Total ash | Not more than 6% |
| Acid-insoluble ash | Not more than 1% |
| Water-soluble ash | Not less than 1% |
| Loss on Drying |
| Not more than 10% |
| Extractive Values | |
| Water-soluble extracts | |
| Hot method | Not less than 8% |
| Cold method | Not less than 4% |
| Ethanol-soluble extracts | |
| Hot method | Not less than 10% |
| Cold method | Not less than 9% |
SAFETY TESTS
The safety tests are based on S. polyanthum dried leaves powder of 0.355 mm particle size.
| Heavy Metals | |
| Arsenic | Not more than 5.0 mg/kg |
| Mercury | Not more than 0.5 mg/kg |
| Lead | Not more than 10.0 mg/kg |
| Cadmium | Not more than 0.3 mg/kg |
| Microbial Limits | |
| Total bacterial count | Not more than 105 cfu/g |
| Total yeast and mould count | Not more than 104 cfu/g |
| Bile-tolerant gram negative | Not more than 104 cfu/g |
| Specific Pathogens | |
| Salmonella spp. | Absent in 25 g |
| Escherichia coli | Absent in 1 g |
| Staphylococcus aureus | Absent in 1 g |
| Pseudomonas aeruginosa | Absent in 1 g |
CHEMICAL CONSTITUENTS
Aqueous methanol (50:50) extract of S. polyanthum leaves was found to contain phenolics (eg; hydroxychavicol). Dimers (eg; 4-allyl-1-hydroxy-2-(2’-allyl-4’-hydroxy-5’-methoxyphenoxy)benzene, 4-allyl-2-hydroxy-1-(2’-ally-4’-hydroxy-5’-methoxyphenoxy)benzene. Hydroxyl benzoic acid (eg; 3,4,5-trihydoxy benzoic acid, 4-hydroxy-3-methoxy benzoic acid, 4-hydroxy-3,5-dimethoxy benzoic acid [ 6 , 7 ].
Methanol extract of S. polyanthum leaves was found to contain acyl benzene derivatives (eg: 10-oxo-10-(2,3,5-trihydroxy-4methylphenyl)decanoic acid, 1-(2,3,5-trihydroxy-4-methylphenyl)deca-1-one, (4Z)-1-(2,3,5trihydroxy-4-methylphenyl)-4-oxobutanoic acid, gallic acid, myricetin, quercitrin, alangionoside O aglycone, campesterol, campest-4en-3-one, cycloartenone) [ 8 ].
Ethyl acetate extract of S. polyanthum leaves was found to contain phloroglucinol (eg; anthuminoate, anthuminone). Pheophorbides (eg; pheophorbide-a, methyl pheophorbide-a, methyl hydropheophorbide-a, pheophorbide-b, hydropheophorbide-b) [ 9 ].
MEDICINAL USES
Uses described in folk medicine, not supported by experimental or clinical data
Traditionally, the extract of the bark and infusion of the leaves is given for diarrhea. Meanwhile, the poultices of the bark, root and leaves are used for itching[10].
Biological and pharmacological activities supported by experimental data
Antihyperglycemic activity
Methanol-water (50:50) extract of S. polyanthum dried leaves (100 mg/kg) was administered orally to male adult alloxan-induced diabetic Wistar rats (300 – 400 g) and observed for 21 days. The extract reduced the blood glucose level from 330 mg/dL to 145 mg/dL compared to control treated group, glibenclamide from 345 mg/dL to 160 mg/dL [ 7 ].
Methanol extract of S. polyanthum dried leaves powder (1000 mg/kg) was administered orally to male streptozotocin-induced diabetic Sprague Dawley rats (200 – 250 g body weight) twice daily for duration of six days. The extract reduced the blood glucose levels from 16 mmol/L to 7 mmol/L comparable to control treated group, metformin from 16 mmol/L to 6.5 mmol/L [ 11 ].
Methanol extract of S. polyanthum dried leaves powder (1 mg/kg) was treated on isolated jejunum of healthy male Sprague Dawley rats (200 – 250 g) to measure the glucose absorption from rat’s intestine. The extract showed reduction in the glucose absorption (146.5 mg/dL/g tissue weight) compared to acarbose treated group (128 mg/dL/g tissue weight) and negative control (198.2 mg/dL/g tissue weight) [ 11 ].
Antihyperuricemia activity
Aqueous decoction of S. polyanthum dried leaves powder (200 mg/kg) was administered orally to potassium oxanate-induced male white mice Balb-C strain (20 – 30 g, aged 2 – 3 months) one hr after induction of hyperuricemia. The extract showed a decrease in uric acid levels by 79.35% compared to positive control, allopurinol (93.55%) [ 12 ].
Protein tyrosine phosphatase 1B inhibitory activity
Aqueous and methanol extracts of S. polyanthum leaves (25 µg/mL) inhibited the enzyme activity of protein tyrosine phosphatase 1B (PTP1B) with IC50 of 3.57 and 1.03 µg/mL respectively comparable to phosphatase inhibitor (RK-682) control (IC50 = 2.05 µg/mL) using PTP1B inhibitory assay [ 13 ].
Antioxidant activity
Aqueous extract of S. polyanthum dried leaves (0.02 g/mL) showed antioxidant activity with free radical scavenging activity with percentage of (DPPH) (≈ 85%) comparable to ascorbic acid (% of DPPH ≈ 95%) using 2,2-diphenyl-2-picrylhydrazyl radical scavenging activity assay [ 14 ].
The extract also inhibited the bleaching of β-carotene with percentage of scavenging activity (≈ 95%) comparable to butylated hydroxytoluene (BHT) (% of scavenging activity ≈ 95%) using β-carotene bleaching inhibition assay [ 14 ].
Methanol extract of S. polyanthum dried leaves powder (6.25 – 100 µg/mL) showed free radical scavenging activity in a concentration-dependent manner with effective concentration at 50% (EC50) of 20.9 ± 0.26 µg/mL comparable to BHT control (EC50 = 18.50 ± 0.19 µg/mL) using DPPH scavenging assay. The extract also inhibited the bleaching of β-carotene (% of inhibition activity = 91.43 ± 2.52%) compared to BHT control (% of inhibition activity = 92.69 ± 3.15%) [ 15 ].
Methanol-water (50:50) extract of S. polyanthum dried leaves scavenged DPPH radicals with 95% inhibition activity compared to BHT control (70%) using DPPH free radical scavenging assay. The extract also inhibited β-carotene bleaching activity with 70% inhibition activity compared to BHT control (90%) using β-carotene bleaching assay [ 7 ].
Clinical studies
Lowering hyperuricemia levels
A quasi-experiment was conducted to study the effects of boiled water (decoction) of S. polyanthum leaves in decreasing hyperuricemia levels in 24 hyperuricemia patients (4 male and 20 female). Patients with impaired kidneys and taking gout medication were excluded. The patients were given boiled water of S. polyanthum leaves every morning for 14 days. The dose given was 0.36 g/kg bodyweight. The uric acid level of the patients were measured before the treatment (a pre-test) and on the 14th day (a post-test). Results showed that the level of uric acid were decreased significantly (p < 0.05) from 7.279 mg/dL (before treatment) to 6.76 mg/dL (after treatment) [ 16 ].
SAFETY INFORMATION
Preclinical studies (Toxicology studies)
14-days oral toxicity study
Aqueous extract of S. polyanthum dried leaves powder (2000 mg/kg) was administered orally as a single dose to male Wistar rats and were monitored daily for two weeks. No toxicity effect and mortality were observed with lethal dose at 50%, LD50 > 2000 mg/kg [ 17 ].
Oral single dose acute toxicity study on female Sprague Dawley rats ( aged between 8 and 12 weeks old) using aqueous extract of S. polyanthum leaves showed no toxic effect on the parameters observed , including behavior, body weight, food and water intake. All rats were observed for 14 days prior to necropsy. No death was found throughout the study period. Necropsy revealed no significant abnormality. Approximate lethal dose (LD50) is 2,000 mg/kg body weight [ 18 ].
Others (Adverse reaction, contraindication, side effect, warning, precaution)
Information and data have not been established.
DOSAGE
Information and data have not been established.
STORAGE
Store below 30°C. Protect from light and moisture.
REFERENCES
- The Plant List. [Internet] Syzygium polyanthum (Wight) Walp.; 2013 [cited on 8th June 2015]. Available from: http://www.theplantlist.org/tpl1.1/record/kew-200120.
- Quattrocchi UFLS. CRC world dictionary of medicinal and poisonous plants: common names, scientific names, eponyms, synonyms, and etymology Volume V R-Z. United States: CRC Press; 2012; p.476-477.
- Mat-Salleh K, Latiff A. Tumbuhan ubatan Malaysia. Malaysia: Pusat Pengurusan Penyelidikan Universiti Kebangsaan Malaysia. 2002; p.432.
- PROSEA (Plant Resources of South-East Asia) Foundation Bogor, Indonesia. [Internet] Syzygium polyanthum (Wight) Walpers; 1999 [cited on 28th August 2015]. Available from: http://proseanet.org/prosea/e-prosea_detail.php?frt=&id=598.
- Ariyanti EE, Irawanto R, Hapsari L, Mudiana D, Distribution of Syzygium spp. (Klampok) in some areas of Bromo Tengger Semeru National Park, East Java. Proceedings of the Society for Indonesian Biodiversity-International Conference. 2012;(1):135-142.
- Eisuke K, Ryo N, Maria D.P.T GP, Jun K. Identification of hydroxychavicol and its dimers, the lipase inhibitors contained in the Indonesia spice, Eugenia polyantha. Food Chemistry. 2013;(136);1239-1242.
- Raden Arthur AL, T Sanro. Preliminary studies of Indonesian Eugenia polyantha leaf extracts as inhibitors of key enzymes for type 2 diabetes. Journal of Medical Sciences. 2013;13(2):103-110.
- Azis S, Ken T, Shigetoshi K, T Yasuhiro. Protein tyrosine phosphatase 1B (PTP1B)-inhibiting constituents from the leaves of Syzygium polyanthum. Planta Medica. 2012;78(12):1378-1381.
- Lee WH, Intan S. Antioxidant activity, total phenolic and total flavonids of Syzgium polyanthum (Wight) Walp leaves. International Journal of Medicinal and Aromatic Plants. 2012;2;219-228.
- Burkill IH. A dictionary of the economic products of the Malay Peninsula. Vol. 1: Published on behalf of the Governments of the Straits Settlements and Federated Malay States by the Crown Agents for the Colonies; 1935. p.973.
- Tri W, Nor Adlin Y, Mohd Zaini A, A Mariam. Antihyperglycemic effect of methanol extract of Syzygium polyanthum (Wight.) leaf in streptozotocin-induced diabetic rats. Nutrients. 2015;7(9):7764-7780.
- Muhtadi, Suhendi A, Nurcahyanti W, Sutrisna EM. Anti hyperuricemia activity of Salam (Syzygium polyanthum Walp.) and Meniran (Phyllanthus niruni Linn.) herbs extracts in oxonate-induced mice. Paper presented at: Joint Conference on Chemistry; 2014 November; Diponegoro University, Semarang, Indonesia: 2014. p.1-8.
- Azis S, Shigetoshi K, T Yasuhiro. Protein tyrosine phosphate 1B inhibitory activity of Indonesian herbal medicines and constituents of Cinnamomum burmannii and Zingiber aromaticum. Journal of Natural Medicines. 2013;67:264-270.
- Azizah O, Nor Juwariah M, Nurul Syakirin I, SK Chang. Phenolics, flavonoids content and antioxidant activities of 4 Malaysian herbal plants. International Food Research Journal. 2013;21(2):759-766.
- Shanmugapriya P, Roziahanim M, Suthagar PP, Lee WC, R Surash. Potential antiradical activity and cytotoxicity assessment of Ziziphus mauritiana and Syzygium polyanthum. International Journal of Pharmacology. 2012;8(6):535-541.
- Darussalam M, Rukmi DK. The role of boiled water of Syzygium polyanthum leaves in decreasing hyperuricemia levels. In: Proceedings of the International Seminar, Scientific Journal Workshop and Signing Memorandum of Understanding (MoU); 2016 Jan 26; Universitas Terbuka, Indonesia. Indonesia: SEAMOLEC; 2016 [cited on 21st February 2017]. p.1-10. Available from: http://www.scientific-journals.net.
- Widharna RM, Ferawati, Tamayanti WD, Hendriati L, Hamid IS, Widjajakusuma EC. Antidiabetic effect of the aqueous extract mixture of Andrographis paniculata and Syzygium polyanthum leaf. European Journal of Medicinal Plants. 2015;6(2):82-91.
- Elda Nurafnie IR, Nor Azlina Z, Hemawathy CK, Farah Huda M, Izwah H, Teh BP. Acute oral toxicity study of selected Malaysian medicinal herbs on Sprague Dawley rats. Institute for Medical Research, Ministry of Health; 2019. Report no.: NON-GLP/2019/04/01.
