Terminalia catappa: A Review of Its Botanical Identity, Phytochemistry, And Clinical Potential

Terminalia catappa L. is a huge tropical tree belonging to the Combretaceae family, and is indigenous to tropical regions of Australia, Africa, and Asia. Flowering plants of family Combretaceae include over 500 species and 14 genera [1]. There are 190 species in Terminalia, a few of which are economically significant as decorative plants and plants that yield timber. The generic name comes from the Latin word "terminalis," which describes the leaves clustering at the tips of the shoots [2]. Triterpenoids (ursolic acid, 2á, 3â, 23-trihydroxyurs-12-en-28-oic acid), flavonoids (isovitexin, vitexin, isoorientin, rutin), and tannins (punicalagin, punicalin, terflavins A and B, tergallagin, tercatin, chebulagic acid, geranin, granatin B, and corilagin) constitute the phytochemicals of this plant [3]. T. catappa L, frequently referred to as India almond or tropical almond, is a medium-sized to larger perennial tropical tree [1]. The tree has horizontal branches and an erect, homogeneous crown, reaching a height of 35 meters [2]. Wide propagating trees known as tropical almonds are currently prevalent throughout the coasts of the tropics. The species has historically played a significant role in coastal populations by offering a variety of non-wood goods and services [3]. Tropical almond is an underrated fruit that is high in vitamins, antioxidants, and pigments. Particularly, humans, birds, and animals consume their fruits [4]. Terminalia catappa leaves have been used for a variety of ethnomedical purposes. In Suriname, a tea prepared from the leaves is used to treat diarrhoea and dysentery. The leaves are also believed to have anti-cancer, antioxidant, and anticlastogenic properties, and Fallen leaves are used as an herb to cure liver conditions in Taiwan [5]. This study intended to explore Terminalia catappa L.'s medicinal potential, emphasizing its therapeutic applications and prospects in contemporary healthcare, given its broad pharmacological profile and historic usage.

Botanical identity [6]:

• Botanical name: Terminalia catappa L. belongs to the family Combretaceae
• Synonyms: T.?arjuna (Roxb.) Wight and Arn., T.?bellirica (Gaertn.) Roxb., T.?chebula Retz. and T.?catappa L.
• Common name:  Indian Almond tree.

Taxonomical classification [7]:

VERNACULAR NAMES:

Table 1: Vernacular Names of Terminalia catappa by Geographic Region

Fig.no. 01: Leaves of Terminalia catappa L.

Fig.no. 02: Terminalia catappa L. Tree

Size

The medium- to large-sized Terminalia catappa L. tree can grow to a height of 25–40 m and has a similar crown spread when left in the open. The trunk's diameter at breast height reaches 50–150 cm at maturation.

Flowers

The blooms have a slightly nasty odor, are small (4-6 mm across), white or cream, have five lobes, and are placed on long (8-25 cm) axillary spikes. Only a few bisexual blooms are found around the base of a spike, with most of the flowers being male.

Leaves

The leaves are frequently clustered around the tips of the inverted branchlets, forming tight spirals. The leaf blade has five to twelve pairs of secondary veins and is simple, widely obovate, and is 8 to 25(-38) x 5 to 14(-19) cm (3 to 10[-15] × 2-61-7] in). The blunt, rounded leaf tip taper progressively to a narrow, subcordate base. A layer of soft, appressed brown hairs covers new leaves. Mostly glabrous (shiny), leathery, and dark green, mature leaves can become brilliant to dark crimson, then bright yellow, and finally fall.

Fruit

On the base of the flower spike, one to five fruits grow. The fruit is a smooth-skinned, ovoid to oblong, sessile drupe that is laterally compressed. When it reaches full maturity, its color shifts from green to yellow to either bright red or dark purplish-red. Fruits vary considerably in size, with the longest being 2.5 cm and the shortest being 10 cm. Encased in a subtle cream-colored, seldom red, testa, the kernel is made up of two delicate, intricately interwoven cotyledons.

Bark

The bark is shallowly cracked and ranges in color from gray to dark gray-brown.

Rooting habit

The lateral root system of the trees is often fibrous, spreading, and close to the surface. High water tables can cause the development of shallow lateral root systems.

Global distribution [15]:

Terminalia catappa L. is found naturally throughout tropical Asia, the Pacific Ocean, and near-coastal regions of the Indian Ocean. From the Seychelles, it stretches over Southeast Asia, India, the Andaman Islands, and nearby islands. Northern Australia, as far south as the Tropic of Capricorn, and Papua New Guinea. The species can be found throughout the South Pacific, including Fiji, Vanuatu, and the Solomon Islands. Brazil, the Caribbean, and East Africa are only a few of the tropical regions where Terminalia catappa L. has been introduced and often naturalized. Puerto Rico and Florida have recognized it as naturalized. The species was likely brought to Hawaii before 1800 and is already naturalized at low elevations, mostly along the shores of the beaches.

Traditional uses [16]:

Traditionally, Terminalia catappa L. (Combretaceae), also known as tropical almond or Indian almond, has been utilized as an antidiabetic, vermifuge, antioxidant, hepatoprotective, anti-inflammatory, and anti-cancer agent. Based on studies, the plant's leaves and bark contain chemopreventive, antidepressant, antifungal, anti-inflammatory, hepato-protective, and antioxidant properties. It has been previously documented that T. catappa L. extracts, when used as a component in topical treatments for wound healing, decreased the wound healing characteristics in rats. In animal models, the ethanol extract of T. catappa L. leaves displayed anti-inflammatory effects.

Bioactive constituents

According to the study, Terminalia catappa L. leaves included terpenoids, alkaloids, tannins, steroids, cardiac glycosides, flavonoids, phenols, saponins, and coumarins [17]. Punicalin, punicalagin, gallic acid, and a derivative of isovitexin were found in T. catappa leaves. Eleven chemical constituents, including gallic acid, catechin, chlorogenic acid, caffeic acid, ellagic acid, epicatechin, rutin, quercitrin, isoquercitrin, quercetin, and kaempferol, were also identified by chemical characterization of the phenolic-rich extracts of T. catappa. Additionally, the leaf and stem bark revealed eight chemical constituents, including gallic acid, catechin, caffeic acid, ellagic acid, resveratrol, rutin, quercetin, quercetin, and kaempferol phenolic compounds, respectively [18].  T. catappa seeds that have been air-dried have 52.02% fat, 25.42% protein, 14.6% fiber, and 5.98% sugar. Likewise, its gum is said to include uronic acids (19%), galactose (20%), arabinose (59%), mannose (1%), and xylose (1%). Phosphorus (P) is the most prevalent macro-element in T. catappa's defatted kernels (1804 mg/100g), followed by potassium (K) (1718 mg/100g), magnesium (Mg) (729.09 mg/100g), calcium (Ca) (415.01 mg/100g), and sodium (Na) (37.60 mg/100g). Iron (Fe) (16.15 mg/100 g) is the most abundant microelement, followed by manganese (Mn) (4.25 mg/100 g), copper (Cu) (4.63 mg/100 g), and zinc (Zn) (9.67 mg/100 g). Leucine, isoleucine, valine, phenylalanine, tryptophan, methionine, lysine, threonine, histidine, tyrosine, arginine, aspartic acid, glutamic acid, glycine, alanine, serine, cysteine, and proline are among the necessary amino acids that can be found in its nuts and seeds. Along with a few non-essential amino acids, the nectar of the flower contains the five essential amino acids—arginine, histidine, lysine, methionine, and threonine [4].

Fig. No. 03: Chemical constituents of Terminalia catappa L.

Pharmacological uses [2]:

Antimicrobial activity

The methanolic and chloroform extracts exhibit strong antibacterial action against both Gram-positive and Gram-negative bacteria. T. catappa root extract in chloroform exhibits antibacterial action against Staphylococcus aureus and Escherichia coli.

Anti-inflammatory, analgesic, and modulatory activity

In both acute and chronic animal models, ethanolic leaf extracts of T. catappa show an anti-inflammatory action on ear edema caused by 12-O-tetradecanoylphorbol-13-acetate (TPA).
T. catappa leaves were used to isolate a novel fetal hemoglobin-inducing chemical (T. catappa distilled water active fraction), which functions in concert with other compounds and has been shown to have a dual modulatory effect on intrinsic erythropoiesis. Tender leaf extract has been shown to have analgesic and anti-inflammatory properties without interfering with the estrous cycle. Additionally, the dosage does not result in sleepiness.

Wound?healing activity

When T. catappa ointment is applied to a wound, it is hypothesized that the area of the wound is reduced by 97% in comparison to the control (81%) and the conventional medication, betadine ointment. The accelerated induction of epithelialization by T. catappa ointment implies that the bark extracts have a significant wound-healing effect.

Antidiabetic activity

In animal models generated by alloxan, the aqueous and cold extract of fresh and tender leaves of T. catappa has the ability to lower lipids and elevated blood glucose levels. Histopathological research also supports its potential as an antidiabetic. Additionally, rats have been shown to exhibit hypocholesterolemic effects from T. catappa fruit extract and T. catappa fallen dry leaf decoction.

Antioxidant and radical scavenging activity

The DPPH, nirtic oxide, reducing power, and H2O2 assays have all shown that T. catappa has dose-dependent antioxidant activity.

Hepatoprotective activity

In patients with CCl4-induced liver injury, treatment with chloroform leaf extracts of T. catappa at concentrations of 20 mg/kg, 50 mg/kg, or 100 mg/kg dramatically lowers serum ALT, AST, and liver LPO levels. The hepatoprotective benefits are further confirmed by morphological inspection. This may point to a novel mechanism for T. catappa's hepatoprotective benefits.

Anticancer activity

The development of aberrant crypt foci and β-catenin-accumulated crypts may be inhibited by T. catappa, which has a strong short-term chemopreventive effect on a variety of biomarkers of colon carcinogenesis caused by the carcinogen azoxymethane. As a result, T. catappa might offer a potent chemopreventive agent against cancer.

Antiaging activity

T. catappa inhibited ERK, JNK, and p38 activation, which reduced the production of MMP-1, -3, and -9. Consequently, it can be applied as an anti-aging substance.

Toxicological and safety profile

It is impossible to overlook the potential for organ toxicity, including hepatotoxicity and nephrotoxicity, due to the unpredictable consumption of herbal products. Plant extracts' toxicological profiles are crucial for testing potential harm to living things in vivo and investigating the best ways to use them. In general, these tests of toxicity are essential for determining the level of risk in biological systems. evaluated the oral toxicity of Terminalia catappa aqueous leaf extract (TCA) in male Wistar rats, both acutely and subacutely. The Organization for Economic Co-operation and Development (OECD) classed TCA as practically non-toxic since its LD50 value was found to be higher than 5000 mg/kg bwt. Under OECD Test Guideline 425, the acute oral toxicity of T. catappa was also assessed in female albino Wistar rats. According to the study, the n-hexane extract's LD50 value is greater than 5000 mg/kg, demonstrating an outstanding safety profile and a low risk of toxicity from acute doses in animals [4].

Table 2: Summary of Toxicological Evaluations of T. catappa Leaf Extracts