Gen info
- Hydrocharitaceae is a flowering plant family with 14 accepted genera and about 135 known species. It holds a number of aquatic plant species, including tape-grass, the well-known Canadian waterweed, and frogbit.
- Halophila is a genus of seagrasses in the family Hydrocharitaceae, the tape-seagrasses. It was described as a genus in 1806.
- Halophila ovalis is a species of seagrass in the family Hydrocharitaceae. It was first
described by Robert Brown as Caulinia ovalis, and transferred to the genus Halophilia by Joseph Dalton Hooker in Flora Tasmaniae in 1858.
-
Etymology: The common name Dugong grass refers to the shape of the leaves and its role as a primary food source for dugongs (a marine mammal). The genus name ovalis derives from Latin, meaning "salt loving."
- Clone: A clone of Halophila ovalis known as Johnson's seagrass occurs only on the southeastern coast of Florida.
- Biodiversity contribution: This seagrass if among the favorite food of dugongs, ergo, the name Dugong grass. The leaf provides surface for small algae to grow on, which tiny snails graze on, which in turn are eaten by larger creatures. As such, seagrasses contribute to the rich biodiversity on the shores. (WildSingapore)
 Botany
• Creeping stems elongated, internodes 1-5 cm; scales orbicular to obovate, keeled, 4-5.5 × 3-3.5 mm, membranous, transparent; lateral shoots scarcely developed. Leaves 1-paired at each node; petiole 1-4.5 cm; leaf blade transparent, oblong-elliptic or ovate, 1-4 × 0.5-2 cm, entire, with 12-16(-25) pairs of cross veins running from midvein to intramarginal veins and diverging from midvein at an angle of 45-60°. Male spathes broadly lanceolate, ca. 4 mm; perianth segments elliptic, ca. 4 mm. Female spathes broadly lanceolate, with a neck at apex, inner one enclosed within outer one; ovary slightly triangular; styles long, slender; stigmas 3, 2-3 cm. Fruit ellipsoid-globose, 3-4 mm in diam.; beak 4-5 mm. Seeds numerous, ca. 1 mm. (Flora of China)
• The seagrass has oval, spoon-shaped leaves and is sometimes also called 'paddleweed' or fan seagrass. It comes in a wide range of sizes (0.5-1.5cm wide and 0.5-2.5cm long) and shapes from oval, to nearly oblong or spoon-shaped. The leaf edge is smooth with no serrations, there is a vein just within the leaf margin (intramarginal vein). The leaf has obvious cross veins (4-25) and is held on a long thin stalk. It has thin, smooth, white rhizomes (underground stems) about 2mm in diameter. The leaves emerge in pairs from these rhizomes. The emerging shoot is encased in a pair of transparent scales. Spoon seagrass has separate male and female plants. Flowers form at the base of the shoot but may extend to above the height of the leaves. Male flower remains low. Round fruits are tiny. (WildSingapore)
• Sometimes confused with other spoon-shaped seaweeds such as Coin seaweed (Halimeda sp.) and Fan seaweed (Avrainvillia sp.) that do not have veins like the spoon seagrass. Unlike hard coin sea-weeds that incorporate calcium in their body structure, spoon seagrass blades are soft and flexible. (5)
Distribution
- Native to the Philippines. (1) (2)
- Also native to Andaman Is., Borneo, Cape Provinces, Caroline Is., China Southeast, Comoros, Egypt, Eritrea, Fiji, Gulf States, Hainan, India, Iran, Japan, Jawa, Kenya, Kuwait, KwaZulu-Natal, Lesser Sunda Is., Madagascar, Malaya, Maluku, Mauritius, Mozambique, Myanmar, Nansei-shoto, New Caledonia, New Guinea, New South Wales, Nicobar Is., Norfolk Is., Northern Territory, Oman, Pakistan, Palestine, Queensland, Rodrigues, Samoa, Saudi Arabia, Seychelles, Society Is., Solomon Is., Somalia, South China Sea, Sri Lanka, Sudan-South Sudan, Sulawesi, Taiwan, Tanzania, Thailand, Tonga, Vietnam, Western Australia, Yemen. (2)
• Occurs around reefs, estuaries, islands, inter-tidal areas, on soft sand or mud substrates. Often found in meadows that dominate a sand bank or other patch of sea floor. The arrangement of the plant, above and below ground, provides stability to the sea floor and habitat for other species. (5)
Constituents
- GC-MS analysis of methanol extract revealed presence of triacylglycerols as major component in purified fractions. Quantitative analysis showed rich phenol content. (see study below) (6)
- GC/MS quantitative analysis of dried powdered H. ovalis yielded: phenols, most abundant (9.44 mg/g), saponins (9.07 mg/g), flavonoids (5.59 mg/g), proteins 5.19 mg/g), carbohydrates (4.82 mg/g), alkaloids (1.06 mg/g) and tannins (0.26 mg/g) (Yuvaraj et al, 2012) (9)
- Phytochemical analysis revealed presence of steroid in hexane, ethanol, and aqueous extracts; alkaloids only in the chloroform extract. Flavonoids, terpenoids, tannins, and phenols were present in the ethyl acetate extract; and steroids, glycosides, saponins, terpenoids, and phenols in the hexane extract. (see study below) (12)
Properties
- Studies have suggest antibacterial, antioxidant, anti-inflammatory, anti-nociceptive, bioremediation properties.
Parts used
Roots, leaves.
Uses
Edibility
- While noted as primary food source for dugongs and green sea turtles, it has a history of traditional human consumption, and recent interest as food supplement. In parts of he Ilocos and Palawan regions, the seagrass is reportedly gathered, pickled, or comsumed fresh as salad vegetable. (8)
- Compared to other seagrasses, its fragile and tender leaf structure make it easy to chew.
Folkloric
- No reported folkloric medicinal use in the Philippines.
- Leaves toasted with drops of sesame oil consume for 3 days to treat iron deficiency. Leaf paste mixed with tumeric applied for various skin ailments, including burns and boils. (9)
Others
- Crafts: Seagrass blades have been utilized as component of accent parts of furniture, handicrafts, and various other household items. (3)
Studies
• Antioxidant / Antibacterial / Anti-Inflammatory: Study of evaluated methanol extract of H. ovalis for antibacterial, antioxidant, and anti-inflammatory activities. The ME inhibited Bacillus cereus growth at MIC 50 µg/mL and other Gm(-) pathogens at 75 µg/ml, except for Vibrio vulnificus. Reducing power and total antioxidant level increased with increased extract concentration. H. ovalis showed strong radical scavenging on DPPH and superoxide radicals with IC50s of 0.13 and 0.65 mg/mL respectively. Me showed noticeable anti-inflammatory activity at IC50 of 78.72 µg/mL. (see constituents above) (6)
• Antinociceptive / Anti-Inflammatory / Sulfated Polysaccharides: Study of
evaluated the antinociceptive and anti-inflammatory effects of sulfated polysaccharides from seagrass H. ovalis (Ho-SP) and Sargassum wightii (Sw-SP). In the formalinn test, Ho-SP significantly reduced licking time in both phases at dose of 10 mg/kg. In hot plate test antinociceptive effect was observed in doses of 5, 10 mg/kg, suggesting analgesic effect via central mechanism at higher dose. Ho-SP inhibited paw edema induced by carrageenan and potentially decreased neutrophil migration by 52%. In Freund's adjuvant-induced arthritic rats, Ho-SP treatment (10 mg/kg) significantly reduced paw volume, along with normal gain in body weight. Results suggest potential for development of anti-nociceptive and anti-inflammatory agents. (7)
• Antioxidant: In a study screening 5 species of seagrasses and 6 species of seaweeds for antioxidant activity by inn vitro methods, methanol and water extracts of seagrass H. ovalis showed highest antioxidant activity with IC50s of 78.95 and 85.40 µg/ml, using NO radical scavenging assays. (10)
• Anticancer / MCF-7 Breast Cancer Cells / Apoptosis Pathway: Study evaluated the anticancer potential of phenolic extract of H. ovalis and characterized the possible molecular mechanism. DAPI staining indicated the phenolic extract induces apoptosis in MCF-cells, evidenced by increased chromatin condensation in treated cells. The phenolic extract also blocked the antioxidant defense system in MCF-7 cells by down-regulating the protein expression of a major transcription factor, Nrf-2 and regulatory antioxidant enzymes, SOD-2 and HO-1. Study suggests the presence of chemo-
preventive compounds in the extract provides a platform studies to identify active principles. (11)
• Stigmasterol / Effect against Ocular Pathogenic Bacteria: Study focused on isolating bioactive compounds from H. ovalis and fractions and its activity against four ocular pathogenic bacteria viz. Corynebacterium xerosis, Bacillus subtilis, Escherichia coli, and Enterococcus faecalis. Gentamycin was used as control. Based on antimicrobial activity and MIC, the chloroform extract showed maximum activity against C. xerosis and E. coli. Ethyl acetate extract showed moderate activity against B. subtilis. Stigmasterol was isolated from the extract. (see constituents above) (12)
• Mercury Bioremediation Potential: Seagrass has a remarkable metal bioaccumulation capacity via direct interaction with both water column and pore water through leaves and roots by ionic uptake. Study in Malita, Davao Occidental, evaluated five species of seagrass for potential in absorbing mercury. In New Argao, H. ovalis showed highest mean percent cover (4.3%) and shoot density (197.l87 shoots/m2), and lowest mean percent cover (1.9%) and shoot density (197.87 shoots/m2) in Culiman. With limited data, conclusions about relations between mercury concentration and shoot density were not drawn. (13)
Availability
- Wild-crafted. |
