INDIAN LABURNUM: A Golden Shower of Exquisiteness & Healing

 

Anything that paints the woods yellow in hot and dry summers of India, is Indian laburnum. Popularly known as amaltas in the Hindi-speaking belt of India, it is one of the most beautiful landscape trees with gorgeous hanging bunches of yellow flowers. It is botanically known as Cassia fistula and belongs to the Fabaceae family of plants. Indian laburnum is the official state flower of Kerala and is ritually used during the Vishu festival in April. It is both the national tree and national flower of Thailand. It is commonly cultivated in Buddhist monasteries in Sri Lanka. Due to its umpteen health benefits, this plant finds use in many traditional healthcare systems in the Indian subcontinent.

NAMES IN DIFFERENT LANGUAGES

English: Indian laburnum, Golden shower tree, Golden rain tree, Shower pudding-pipe, Cassia stick tree, Purging cassia

Hindi: Amaltas, Sonhali, Amartas, Sundaraj, Girimalah, Dhanbehera, Siyar-ki lathi

Sanskrit: Aaragvadh (helps to cure diseases), Raajavriksha Shampaak (improves digestive process), Chaturangul, Suvarnaka, Kushtasudana (cures skin diseases), Vyadhighata (cures diseases), Kritamala, Arevata (detoxifying), jvarantaka (useful in fever), Pragraha

Assamese: Hunaru Phool

Bengali: Sonali, Bandarlati, Amultas

Dogri: Karangal, Keyaal, Sinaru

Gujarati: Garmalo

Kannada: Kakke, Aaragu, Aaragina, Konde

Malayalam: Vishu konnai, Swarnaviram, Kanikonna, Kritamalam

Marathi: Bahava

Oriya: Sunari, Sonari

Pahari (H.P.): Alhya, Aleeya, Alhi, Alsh, Kaniar, Kanair

Punjabi: Alis, Ambaltas, Amaltas, Girdnali, Kaniyaar

Tamil: Konrai

Urdu: Amaltas

DISTRIBUTION

Amaltas is native to the Indian subcontinent. However, it has been widely introduced, mostly in the countries of the southern hemisphere, as an ornamental tree. In India, it is distributed up to 1300 m altitude throughout the country.

MORPHOLOGY

Indian laburnum is a small to medium-sized evergreen (deciduous in some areas in Northern India during dry pre-monsoon summer) tree growing up to 20 m tall. Young branches have smooth and pale grey bark, while it is rough and dark grey in mature ones. Leaves are large, 15-40 cm long, compound with 4-8 pairs of leaflets and alternately arranged. Each leaflet is 4-13 x 2-7 cm in size, opposite or subopposite, oblong-ovate, entire, glabrous above and pubescent below and has an acute apex. Bright yellow, large and showy flowers are arranged in 30-60 cm long terminal drooping racemes. Calyx is of 5 sepals, greenish-yellow, oblong, obtuse, and pubescent. Corolla has five subequal, obovate and shortly clawed petals. Each flower has 10 stamens, where the upper three have erect filaments, the lower three have curved filaments and the median four have erect filaments. Pistil is sessile or stalked with a pubescent ovary. Fruit is a 40-60 cm long, cylindrical, pendulous, indehiscent, and green pod which turns dark brown after ripening.

CHEMICAL CONSTITUENTS

The main chemical constituents in the pod are glucoside (rhein), tryptophan, glutamic acid and anthraquinone (fistulic acid). Leaves contain glucosides (senoside A & B), and the stem bark contains tannins, lupeol, β-litosterol, hexacosanol, fistucacidin, rhein, barbaloin, etc.

USES

I. SACRED VALUE

Golden shower tree is considered sacred in some parts of the world. It is cultivated in the Budha vihars in Thailand, Cambodia, and Sri Lanka. In Laos, people offer golden shower flowers in temples on New Year's Day and hang bunches of golden shower flowers in their homes to bring good luck and happiness. In Kerala, its flowers are offered to Lord Shri Krishna during the celebration of the Vishu festival. It is considered a pious tree in other parts of India as well and grown inside the courtyards. The Bhil and Saharia tribes of Rajasthan keep the dry pods of this tree under the children's pillow to protect them from getting frightened during sleep.

II. FOR LANDSCAPING

Golden shower tree is a feast to the eyes and a visual celebration when in full bloom. It is one of the most hardy, heavy blooming and beautiful flowering trees that has been introduced in many countries of the world as a landscape tree. It gives an exquisite effect when planted closely on both sides of roads.

III. MEDICINAL USES

1. Good Laxative

The fruit pulp of Indian laburnum is a gentle laxative/purgative. Traditionally, fruit pulp (5-10 g) is soaked in a glass of water overnight, filtered in the morning and used to relieve constipation.

2. Antifungal Activity

One of the Sanskrit names of Indian laburnum, i.e., kushtasudana, is derived from its traditional use to cure skin diseases (boils, ringworm, etc.) in humans. Recent experimental studies in culture conditions and on animal models have proved that leaf, flower, and seed extracts when applied externally are quite effective in inhibiting the growth of pathogenic fungi such as Candida albicans, Trichophyton mentagrophytes, T. rubrum and Epidermophyton floccosum. The anti-fungal activity is attributed to the presence of rhein.

3. Wound Healing

Leaf paste of Indian laburnum has traditionally been used for the healing of wounds. This can be attributed to the anti-inflammatory and antimicrobial properties of this plant. Experimental studies on rats have demonstrated good wound closure and improved regeneration of tissues at the site of the wound.

4. Antibacterial Activity

Leaf and seed extracts of Indian laburnum have been reported to have considerable anti-bacterial activity against human pathogenic bacteria such as Bacillus cereus, B. subtilis, B. megaterium, Staphylococcus epidermidis, S. haemolyticus, S. aureus, Streptococcus pyogenes, Pseudomonas aeruginosa, Klebsiella pneumonia and Escherichia coli in culture conditions.

5. Antioxidant Potential

The stem bark of Indian laburnum is rich in polyphenolic compounds. These polyphenols have a free radical scavenging potential and antioxidant properties.

6. Antitumour Potential

Many studies were carried out on cancer cell lines (hepatocellular carcinoma, human cervical cancer, colon adenocarcinoma and breast adenocarcinoma) and animal models to assess the effect of seed and pulp extract on tumour development. It was reported that rhein significantly curtailed the proliferation of cancer cells through the activation of MAP kinase. The results from animal models have shown that treatment with seed extract prolonged the lifespan and reduced the size of the tumours in mice.

7. Hepatoprotective potential

Some experimental studies using rats have reported that leaf extract of Indian laburnum has hepatoprotective effect through decreasing the alkaline phosphatase (ALP) levels, serum glutamic oxaloacetic transaminase (SGOT), bilirubin and serum glutamic pyruvic transaminase (SGPT). Further human studies are required to be carried out.

8. Anti-Diabetic Effect

The anti-diabetic effect of the bark extract of Indian laburnum was studied on experimentally induced diabetic rats. The results obtained were encouraging showing a significant decrease in the serum glucose level.

9. Cholesterol Lowering Potential

Indian laburnum extract has shown potential for reducing cholesterol levels in animal studies.

CAUTION

Many research studies (1, 2, 3) on animal models have shown that Indian laburnum is generally safe when used in low doses. Overdose can produce side effects like cramps, abdominal pain, diarrhoea, nausea, and vomiting. The readers are advised not to consume any part of this plant on their own. Seek advice from a registered medical practitioner.

REFERENCES

• Acharya Balkrishna. 2008. Secrets of Indian Herbs for Good Health. Divya Prakashan, Haridwar.
• Akbar, S. 2020. Handbook of 200 Medicinal Plants: A Comprehensive Review of Their Traditional Medical Uses and Scientific Justifications. Springer Nature, Switzerland.
• Bennet, S.S.R., Gupta, P.C., and Rao, R.V. 1992. Venerated Plants. Indian Council of Forestry Education and Research, Dehradun.
• Chauhan, N.S. 1999. Medicinal and Aromatic Plants of Himachal Pradesh. Indus Publishing Company, New Delhi.
• Mwangi, R.W., Macharia, J.M., Wagara, I.N. and Bence, R.L. 2021. The medicinal properties of Cassia fistula L: A review. Biomedicine & Pharmacotherapy 144: 112240.
• Rahmani, A.H. 2015. Cassia fistula Linn: Potential candidate in health management. Pharmacognosy Res. 7(3): 217–224.
• Ravindran, P.N. 2020. Sacred & Ritual Plants of India: Lore, Symbolism, Traditions. Notion Press, Chennai.
• Sharma, A., Kumar, A. and Jaitak, V. 2021. Pharmacological and chemical potential of Cassia fistula L - a critical review. J. Herbal Medicine 26: 100407; https://doi.org/10.1016/j.hermed.2020.100407.
• Singh, R., Khanam, H. and Pandey, J. 2023. The Biological Properties and Medical Importance of Cassia fistula: A Mini Review. Chemistry Proceedings 14 (1): 95; https://doi.org/10.3390/ecsoc-27-16149.