- Davallia is a genus of about 40 species of fern. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), it is the only genus in the family Davalliaceae, which is placed in the suborder Polypodiineae, oder Polypodiales.
- Species are epiphytic ferns with fronds arising from long aerial rhizomes
, which grow on and over thick bark on trees on on rock crevices. (9)
Rabbit's foot fern is an epiphytic, dimorphic fern with finely divided, thickish, and long-creeping rhizomes. Stems are 1 cm or more in diameter. Sterile leaves are pinnate, sub-opposite, broadly deltoid, up to 20 cm long; base tripinnate and narrowly deltoid. Fertile leaves are more deeply lobed, with each lobe bearing several sporangia.
- Widespread in the Philippines.
- Also found in the Malay Peninsula to Polynesia.
- Cultivated as a hanging plant or air plant.
- Study yielded 4 new compounds: 3' -O-p-hydroxybenzoylmangiferin, 4'-O-p-hydroxybenzoylmangiferin, 6' -O-p-hydroxybenzoylmangiferin, and 3-O-p-hydroxybenzoylmangiferin, as well as eight known
compounds - mangiferin, 2-C-b-D-xylopyranosyl-1,3,6,7-tetrahydroxyxanthone, 4b-carboxymethyl-(À)-epicatechin, 4b-carb-oxymethyl-(À)-epicatechin methyl ester, eriodictyol, eriodictyol-8-C-b-D-glucopyranoside, icariside E5, and icariside E3.
- Rhizomes yielded 9(11),18-diene, ferna-7,18-diene, filica-3,18-diene, filica-3,18,20-triene, fern-9(11)-en-19α-ol, fern-7-en-19α-ol and filic-3-en-19α-ol. (5)
- Isolation and purification from the n-butanol layer of an aqueous extract of rhizome identified 12 compounds, viz. four new compounds: 30-O-p-hydroxybenzoylmangiferin (1), 40-O-phydroxybenzoyl-mangiferin (2), 60-O-p-hydroxybenzoylmangiferin (3), and 3-O-p-hydroxybenzoylmangiferin (4); eight known compounds: mangiferin (5), 2-C-b-D-xylopyranosyl-1,3,6,7-tetrahydroxyxanthone (6), 4b-carboxymethyl-()-epicatechin (7), 4b-carboxymethyl-()-epicatechin methyl ester (8), eriodictyol (9), eriodictyol-8-C-b-D-glucopyranoside (10), icariside E5 (11), and icariside (12). (see study below) (2)
- Study of rhizomes yielded ferna-9(11),18-diene, ferna-7,18-diene, filica-3,18-diene, filica-3,18,20-triene, fern-9(11)-en-19α-ol, fern-7-en-19α-ol and filic-3-en-19α-ol. (2)
Study yielded a xanthone glycoside, 2-C-ß-D-xylopyransyl-1-3-6-7-tetrahydroxyxanthne together with mangiferin (2-C-ß-D-glucopyranosyl-1,2,5,7-tetrahydroxanthone. (7)
- Considered antibacterial, antioxidant, tonic, laxative, purgative, anti-inflammatory.
- No known medicinal use in the Philippines.
- Rhizomes used as herb tonic; for treatment of osteoporosis, arthralgia and arthritis.
- In Fiji, used as antibacterial; used for asthma, sore throat.
- In Tahiti, used for dysmenorrhea, uterine hemorrhage, and to promote healthy pregnancy.
- In New Caledonia, used for fish poisoning.
- In Moorea, French Polynesia, used as laxative and purgative; for fractures and sprains. For newborns having difficulty sleeping, leaves are boiled in water, and the baby bathed in the cooled tea until calmed. (1)
- In Tajiti and Fiji, used for the treatment of asthma. In Tahiti, used for dysmenorrhea; also for uterine hemorrhage and leucorrhea. (1)
- In Chinese medicine, used for physique ache, inflammation, cancer and bone injuries.
- In Samoa, leaves used externally as poultice for arthritis.
- Decorative: Ornate leafs used for floral decorations in fiestas and religious rituals.
- Gu-Sui-Bu: An ingredient of the Chinese traditional medicine, Gu-Sui-Bu. made up of six different fems, used for treating inflammation, cancer, aging, blood stasis, body aches, and bone injuries. (8)
• Phenolics / Antioxidant / Rhizomes: Study of an aqueous extract of rhizomes showed a high content of phenolic compounds with strong DPPH scavenging activity. Solvent partitions of the aqueous extract showed the n-butanol layer to have the highest phenol content (806.3 ± 12.3 mg CE/g dry weight) and DPPH scavenging potential (IC50 = 3.93 ± 0.31 lg dry weight/ml). (see constituents above) (2)
• Gusuibu / Antioxidant: Gusuibu is a known folk remedy in traditional Chinese medicine, composed of six different fern ingredients: Drynaria fortunei, Pseudodrynaria coronans, Davallia divaricata Bl., Davallia mariesii, Davallia solida (Forst.) Sw., and Humata griffithiana. In the study, all the extracts of six sources exhibited reducing power in a concentration dependent manner. The ethanol extract of Davallia solida showed the highest radical scavenging activity (26.89 µg extract/ml). Results suggest the total polyphenol compounds in the extracts of the six folk medicinal ferns used as "Gusuibu" contributes significantly to the antioxidant capacities. (3)
• Gusuibu / Suppressive Action on Heat-Labile Enterotoxin-Induced Diarrhea: Study evaluated the suppressive action of ethanol extracts of six sources of folk medicinal ferns (Drynaria fortunei, Pseudodrynaria coronans, Davallia divaricata, D. mariesii, D. solida, and Humata griffithiana) used as Gusuibu on heat-labile enterotoxin (LT)-induced diarrhea. Except for DF, the rest, including D. solida might be a candidate for the treatment of LT-induced diarrhea. (6)