- Avicennia marina is a historic plant, well known for many centuries in traditional and folk medicine.
- It is the most widespread mangrove in the tropical and subtropical regions of the Indo-West Pacific area.
- The genus name Avicennia honors the famous physician Avicenna or Ibn Sina.
Grey mangroves is a shrub or tree growing to a height of 3 to 10 m (9.8 to 32.8 ft), or up to 14 meters (46 ft) in tropical regions. Habit is a gnarled arrangement of multiple branches. Bark is smooth, light-grey, with thin, stiff, brittle flakes, sometimes whitish, as referred to in the common name. Leaves are thick, 5 to 8 cm (2.0 to3.1 in) long, bright and glossy green on the upper surface, silvery-white or grey, with very small matter hairs on the surface below. Aerial roots (pneumatophores) grow to a height of about 20 cm (7.9 in), and a diameter of 1 cm (0.39 in), which allow the plant to absorb oxygen that is deficient in the habitat. Roots anchor the plant during sea water inundation in soft substrate of tidal systems. Flowers are white to golden yellow, less than a centimeter (0.39 in) across, occurring in clusters of three to five. Fruit contains large cotyledons that surround the new stem of a seedling. (2)
Grey mangrove is a medium to large tree growing up to 30 m. Trunk is smooth or slightly flaky grey. An extensive lateral root system stretches just below the soil surface with pencil-like breathing roots- pneumatophores-sticking vertically out of the muddy ground to take in oxygen. Pneumatophores may grow to a height of 15-20 cm. Leaves are elliptic or oblong-obovate with a round tip, pale green lower surface measuring 4.5 by 9 cm, the upper surface covered with glandular dots. Stems are characteristically square in shape, unlike other rounded Avicennia species. Flowers are small, regular,, orange to dark orange, 5-8 mm, waxy surface, occurring in terminal clusters with 2-12 flowers. Corolla with 4 equal lobes, ovary with short style and a median ring of hairs that do not conceal the stigma. Fruits are light green, ovoid with a broad base and sharp apical beak, measuring about 2 cm across. All avicennia species exhibit crytovivipary, in which embryo germinates within the fruit, without enlarging enough to break through the fruit wall. (8)
- Native to the Philippines.
- Also native to Aldabra, Andaman Is., Bangladesh, Bismark Archipelago, Borneo, Cape Provinces, China, Christmas I., Cocos Is., Comoros, Djibouti, Egypt, Eritrea, Gulf States, Hainan, India, Iran, Jawa, Kenya, KwaZulu-Natal, Lesser Sunda Is., Madagascar, Malaya, Maluku, Mozambique, Myannmar, Nansei-shoto, New Caledonia, New Guinea, New South Wales, New Zealand, Nicobar Is., Norfolk Is., Northern Territory, Oman, Pakistan, Queensland, Saudi Arabia, Seychelles, Sinai, Socotra, Solomon Is., Somalia, Australia, Sri Lanka, Sudan, Sulawesi, Sumatera, Sumatera, Taiwan, Tanzania, Tasmania, Thailand, Victoria, Vietnam, Yemen. (1)
- Rich in various classes of phytochemicals including carbohydrates, alkaloids, carotenoids, hydrocarbons, free fatty acids, esters, phenolics, steroids, triterpenes, glycosides, tannins, aliphatic alcohols, acids, and amino acids. (3)
- Study of bark isolated three triterpenoids: lupeol, taraxerol, and betulinic acid (Bell and Duewell, 1961) (3)
- It is highly resistant to environmental stresses and can tolerate extreme weather conditions, high winds, and various pests and diseases, high salinity and anaerobic soil.
- Studies have suggested antiviral, antioxidant, antifungal, antibacterial, hypoglycemic, neurobehavioral, apoptotic, anticancer, anthelmintic, anti-inflammatory, phytoremediative properties.
- Fruits are edible.
- The plant has been used in traditional folk medicine of ancient populations all over the world for thousands of years. (3)
- No reported folkloric medicinal use in the Philippines.
- It has been used for the treatment of ulcers. abscess, rheumatism, burns, small pox, snakebites.
- In Persian folk medicine, used for the treatment of small pox lesions. (3)
- Leaves used to treat burns; bark resin used as contraceptive. (8)
- Wood: timber used for building houses, furniture, and boats.
- Fuel: Wood used as fuel.
- Tanning: Bark used for tanning leather.
- Fodder: Branches are lopped and given to cattle as fodder. (9) Leaves are said to be more nutritious than the queen of forages, alfalfa. (10)
• Inhibitory against HIV and HSV: Study evaluated the antiviral activity of methanol, ethanol, water, chloroform, and n-hexane extracts against HIV-1 and HSV. The methanol extract showed highest antiviral activity and the most polar fraction (fraction D) inhibited HSV with TI and SI values of 57.1 and 133 respectively. It showed mild activity against HIV with SI of 6.25 (fraction 3). Fraction D disturbs viral replication after penetrating the cell. A. marina was able to inhibit replication of HSV after entry but did not show significant potency against HIV-1. Results suggest potential for an anti-HSV drug discovery. (4)
• Antioxidant / Fruit, Leaves, Stem Bark: Study evaluated the antioxidant activity, total phenolic and coumarin content of leaves, fruits, and stem barks of A. marina. Antioxidant activity by DPPH radical scavenging assay showed the fruit to have highest antioxidant activity with IC50 of 85.246 ppm, followed by stem bark and leaves. The fruit also showed higher total phenolic and coumarin content than stem bark and leaves. Total phenolic and coumarin content of fruits were 49.119 mg GAE/g and 8.894 x 10-3 mg CE/g, respectively. Leaves showed total coumarin content of 8.418 x 10-3 mg CE/g. (5)
• Hypoglycemic / Antioxidant / Neurobehavioral Effects / Leaves: Study evaluated the effect of supplementation with alcoholic extract of Avicennia marina leaves in improving diabetes-associated diabetes-associated pathological changes. Results showed reduced blood glucose, improved blood parameters and organ functions. There was also improvement in locomotory behavior. Results suggest supplementation with the alcoholic extract reduced oxidative stress and blood sugar levels, protected the liver, and improved neurobehavioral changes associated with diabetes in mice. (6)
• Nanoparticles / Leaves: Study reports on the cost-effective and eco-friendly biosynthesis of AgCl@TiO2 nanocomposites using the aqueous and ethanolic leaf extracts of A. marina mangrove plant as reducing and stabilizing agent. (11)
• Antibacterial / Leaves: Study evaluated the antibacterial activity of different solvent extracts (acetone, methanol, diethylether, ethanol, ethyl acetate, petroleum ether, and aqueous extracts) against 12 bacterial strains. The chloroform extracts showed maximum antibacterial activity against Enterococci sp. while the ethyl acetate extract showed minimum activity against Klebsiella pneumonia, Enterococci sp., Salmonella sp. and Shewanella sp. (12) Study evaluated the antibacterial activity and phytochemical content of A. marina collected from polluted and unpolluted site from backwaters of Attipatuputhunagar. Phytochemical screening yielded alkaloids, phenols, tannin, flavonoids, amino acids, diterpenes, oxalate, cardiac glycosides, quinone, anthocyanin, leucoanthocyanin and xanthoprotein, with the ethanol extract showed higher phytochemical content compared to the aqueous extract. The ethanol extract of leaf exhibited significant antibacterial property against tested bacteria i.e., S. typhi, S. aureus, E. coli, and K. pneumonia. (17)
• Apoptotic / Anti-Inflammatory / Antioxidant / Leaves: Study evaluated the effect of hydroalcoholic leaf extract of Avicennia marina on apoptotic, inflammatory, oxidative stress, and lipid peroxidation indices and liver histology of type 1 diabetic rats. Results showed significantly higher levels of Bcl-2, SOD, CAT, and GPx in DM groups receiving 100 and 200 mg/kg in a dose dependent manner. The levels of Bax, caspase-9, MDA, and HOdG-8 were significantly lower in a dose dependent manner, along with lower serum levels of TNF-α, IL-1ß, and IL-6. Study showed A. marina extract improved histological changes in the liver of diabetic rats in a dose dependent manner. (13)
• Heavy Metals Phytoremediation / Roots and Leaves: Study showed mangrove species, Avicennia marina, is capable of taking up selected heavy metals via the roots and accumulate in the leaves, which suggest a potential for phytoremediation. The concentration of heavy metals in leaf samples were in the order of Fe > Cu > Co > Cd > Ni > Cr. Among all plant parts, leaves showed highest concentration of all studied metals, except for Co. The observed concentration of studies heavy metals in seedling as compared to mature plant suggest the capability of accumulating is also increasing with growth of the plant. Since mangrove trees are used in folklore medicine and as fodder for livestock, study suggests that harvesting of aerial part of the plants can be effective in removing the accumulated metals from the contaminated sites. It should be noted that the litter fall of the plant leaves can return the toxic metals to the environment. (14)
• Toxicological Studies: Study reports on the hematological, biochemical, and pathological effects in rats produced by salt-tolerant plant Avicennia marina given at oral doses of 1 or 4 g/kg for three consecutive days or 0.5 kg/day for 28 consecutive days. Dose of 1 g/kg did not cause significant changes in body or liver weights while 4 g/kg reduced both liver and body weights. Both doses significantly increased leucocyte (mainly neutrophils) counts with no significant effect on RBC, Hb or Hct. Except for a slight statistically significant effects (decrease in plasma glucose, increase in Na, Ca, Cu, Mg, and cholesterol, AST and ALT) there were no significant effects on plasma biochemistry. There were prominent Kupffer's cells and monocellular infiltration. In the kidneys, there was shrinkage and cellular degeneration of glomeruli and patches of medullary hemorrhage. There was significant decrease in the number of platelets . Subchronic treatment produced significant reduction of glutathione concentration (20%). Histopathological findings with subchronic treatment were milder in nature than those seen after acute treatment. (15)
• Cytotoxicity / Effect on HeLa Cells Viability: Cervical cancer is caused by infection with Human Papilloma Virus (HPV) which attacks the reproductive organs of sexually active women. Study evaluated the effect of A. marina leaf extract on viability of HeLa cells. Leaf powder was extracted using n-hexane, ethyl acetate, and ethanol solvents. LC50 was reported at 98.55 ppm. Phytochemical screening yielded saponins, steroids/triterpenoids, flavonoids, and tannins. Total Phenol was 1915.92 mg/g GAE. LC-MS test yielded caffeine and diosmetin. The ethanol extract of leaves was cytotoxic to HeLa cell viability with IC50 of 115.345 g/mL. (16)
• Antioxidant / Secondary Metabolites / Fruits: Study of fruit of mangrove Avicennia marina led to the isolation of a new caffeic acid derivative, maricaffeolylide A (1), and a new megastigmane derivative, maricyclohexane A (2). Catechol (1) showed antioxidant activity with an EC50 of 24 ± 0.3 µm. (18)
• Antifungal / Candida albicans / Limited Inhibitory Effect / Leaves: Study evaluated the inhibitory effect of aqueous extract of Avicennia marina on Candida albicans in vitro. Results showed limited inhibitory effect of aqueous extract on clinical and standard species of Candida albicans. (19)
• Antiviral / Herpes simples Type 1 and Polio Virus: Study evaluated a leaf extract of A. marina for in vitro antiviral activity on herpes simplex virus type-1 (HSV-1) and vaccine strain of polio virus (Sabin) in Vero cell line. The crude hot glycerin extract of fresh leaf exhibited antiviral activity against HSV-1 and poliovirus in vitro. The extract affected both viruses before adsorption more than after virus attachment to the cells. The extract was more effective on HSV-1. The extract probably blocks attachment of viruses to cells through binding to receptors of viruses or binding to the viruses ligands. Possibly, there could also be an effect on post attachment stages of viral replication. On cytotoxicity testing, the hot glycerin extract was less cytotoxic than the alcoholic one, which may be due to solvent type, cell line use, or other unknown factors. (20)
• Biological Screening for Anticancer Activity / Leaves: Study evaluated A. marina for the presence of active biological constituents, applications in traditional and alternative medicine, and in-vitro anticancer activity of leaf extracts on various cancer cell lines (HL-60, HepG2, NCI-H23, and HEK-293T) by XTT bioassay. Results showed methanolic and aqueous extract of A, marina exhibited cytotoxicity against HL-60 and NCI-H23 cell line with proficient IC50 values and insignificant toxicity against normal cell line (HEK-293T). (21)
• Nanoparticles / Larvicidal Against Dengue Fever Mosquito / Aedes aegypti: Study evaluated the impact of various doses of A. marina extract and its silver nanoparticles against 4th instar of Ae. aegypti as a source of green nano insecticides. Results showed A. marina synthesized AgNPs showed high larvicidal toxicity against 4th instar larvae of mosquitoes than extracts alone at 17.53 times. Results suggest synthesized AgNPs of A. marina have potential as a perfect non-harmful compound for the control of Ae. aegypti larvae. (22)
• Polyisoprenoids / Anticancer / Leaves: Study evaluated the anticancer effect of polyisoprenoids from Avicennia marina and A. lanata leaves by selectivity index, cell cycle inhibition, and apoptosis activity. The polyisoprenoid extract of leaves from both A. marina and A. lanata exhibited anticancer activity against WiDr cells with IC50 of 154.987 µg/mL and 305.928 µg/mL, respectively. Cell cycle analysis showed inhibition occurred in the G0-G1 phase and apoptosis occurred in the early-apoptosis development. Results suggest the polyisoprenoids can be used as anticancer agents against WiDr colon cancer cells. Mechanism may be through inhibition of cell cycle and induction of apoptosis. (23)
• Anthelmintic / Leaves: Study evaluated the anthelmintic properties of chloroform, methanol, and aqueous extracts of Avicennia marina leaves on Indian earthworm Pheretima posthuma using concentrations of 25, 50, and 75 mg/ml to determine time of paralysis (vermifuge) and time of death (vermicidal). All extracts showed dose dependent and significant activity at higher concentration. The methanolic extract showed peak activity at 75 mg/ml. (24)
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