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Family Proteaceae
Grevillea
Grevillea robusta A. Cunn. ex R.Br.
SILKY OAK

Scientific names Common names
Grevillea robusta A. Cunn. ex R. Br. River oak (Engl.)
Grevillea robusta var. compacta auct. Silk oak (Engl.)
Grevillea robusta var. forsteri L.H.Bailey Silky oak (Engl.)
Grevillea umbratica A. Cunn. ex Meisn. Silver oak (Engl.)
Grevillea venusta A. Cunn. ex Meisn.  
Grevillea robusta A.Cunn. ex R.Br. is an accepted name The Plant List

Other vernacular names
BURMESE: Khadaw hmi.
FRENCH: Chene d'Australie, Grevillée robuste.
GERMAN: Australische seideneiche.
HAWAIIAN: Oka-kilika, Haiku-keokeo.
INDONESIAN: Salamander.
JAVANESE: Salamandar.
NDEBELE: Kangiyo.
NEPALI: Kangiyo.
SPANISH: Agravilla, Roble australiano, Helecho, Roble plateado, Grevilea, Roble de seda.
SWAHILI: Mgrivea, Mukima.
TAMIL: Savukkumaram.
THAI: Son-india.
URDU: Bekkar, Bahekar.
VIETNAMESE: Tr[ax]i bam. Tr[ax]l b[af]n, Ng[aa]n hoa.

Botany
Grevillea is a deciduous medium-sized tree that grows to 30 meters or taller. Bark is fissured, sometimes pustulate, dark grey to dark brown. Crown is conical and dense, with branches projecting upward. Leaves are alternate, fernlike, pinnate, 11 to 21 pairs of pinnae, 4 to 9 centimeters long, and dark green. Leaflets are lanceolate, with entire or lobed margins. The flowers are yellow to orange, numerous, paired, on long slender stalks 1 to 2 centimeters, with 4 narrow yellow or orange sepals 12 millimeters long. Fruits are podlike, broad, slightly flattened, 2 centimeters long, black, with 1 to 2 seeds, 10 to 13 millimeters long.

Distribution
- Native to Australia.
- Exotic to China, Eritrea, Ethiopia, India, Indonesia, Jamaica, Kenya, Laos, Malawi, Malaysia, Mauritius, Nepal, Pakistan, Philippines, South Africa, Sri Lanka, Tanzania, Uganda, USA, Vietnam, Zambia and Zimbabwe.
(10)
- Recently introduced to the Philippines.

- Grown as shade tree or ornamental for shape and foliage.

Constituents
• Study isolated six new 5-alkylresorcinals and eight known compounds.
• Plant yields a small amount of gum resin.
• Leaves contain rutin.
• Intense yellow and green dyes from the leaves.
• Study yielded seven phenolic compounds from the methanolic extract of leaves – Grevirobstol A, B, C and Robustaside A, B, C and D.
• Study isolated three new compounds from the leaves: graviquinone (1), cis-3-hydroxy-5-pentadecylcyclohexanone (2), and methyl 5-ethoxy-2-hydroxycinnamate (3), together with 38 known compounds. (see study below) (12)

• 1-BuOH-soluble fraction of methanol extract of leaves yielded two 5-alkylresorcinol glucosides, named grevillosides G and H (1, 2), and grevilloside E methyl ester (3), along with one known megastigmane glucoside, staphylionoside D (4). (13)
• The 1-Bu-BuOH soluble fractions of a methanol extract of leaves isolated two 5-alkylresorcinol glucosides, named grevillosides G and H (1, 2), and grevilloside E methyl ester (3), along with one known megastigmane glucoside, staphylionoside D (4). (15)

Properties
• Flowers rich in vitamin C. Leaves and twigs reported to be high in aluminum. (12)

Uses
Edibility
• Flowers are a rich source of nectar which can be directly sucked from the flower, shaken into a bowl or washed out in a small amount of water.
• Aborigines in Australia reported to drink the nectar straight from the flowers.
Folkloric
- No known folkloric medicinal use in the Philippines.
- In Kenya, natives of the Kakamega Forest use the plant to treat sore throats, earache, chest problems, flu and toothache.
- In North Garo Hills, Meghalaya, NE India, bark and leaves used for headaches and dizziness. (14)
Others
Dye: Yellow and green dye from the leaves; used for dyeing silk.

Wood: Used for joinery, cabinetry and panelling. Wood makes a good charcoal.
Gum or resin: Natural gum has potential as adhesive.
Ornamental: Grown for its attractive foliage. Leaves used in flower arrangements.

Caution !
Poison:
The flower buds, fruit and seeds are cyanogenic. Contact with leaves may cause contact dermatitis due to tridecylresorcinol, a chemical compound related to the allergen toxicodendron. (10)
Contatct dermatitis:
A report on a case of severe acute dermatitis venenata due to exposure to sawdust of Grevillea robusta. (2) (3)
Grevillol:
Bracelets made from the wood of Grevellia were shown to be a source of allergic contact dermatitis. The responsible allergen was grevillol, a phenolic with a long side chain resembling the sensitizing uroshiols from poison ivy. source

Studies
Cytoxicity:
Study isolated 6 new 5-alkylresorcinols and 8 known compounds, all of which showed marginal toxicity against MCF-7, NCI-H460 and SF-268 ki cell lines. (1)
Leishmanicidal:
One of 75 Myanmar timber extracts examined for leishmanicidal activity. source
Cardiovascular:
Several his-resorcinols were isolated from Grevellia robusta, the most potent, striatol, exhibiting inhibitory activity on the Ca-ATPase system suggesting a potential for cardiovascular activity. (5)
Gum Adhesive:
A natural gum from the plant has been studied and analysis showed that with suitable modifications, the gum from G robusta can be used as a wood adhesive. (9)
Scavenging Activity / Cytotoxicity / Inhibition of L-DOPA / Leaves: Study isolated three new compounds from the leaves. Graviquinone, compound 1, showed strongest cytotoxicity against MCF-7, NCI-H460, and SF-268 cell lines. Methyl 2,3-dihydroxycinnamate (4), graviphane (13), and dehydrograviphane (14) showed very potent DPPH scavenging activity. Compounds 4 and bis-norstriatol (17) showed strong inhibition of L-DOPA. (see constituents above) (12)
Gum Adhesive:
Study evaluated a crude methanolic extract of leaf of Grevillea robusta and various soluble partitionates for cytotoxic, thrombolytic, membrane stabilizing and antimicrobial activities. The crude ME shoed highest cytotoxic activity in brine shrimp lethality bioassay with LC50 values of 1.50±0.45 µg/ml. Extractives showed 69.95±0.11% clot lysis. A chloroform soluble fraction inhibited hemolysis of RBC induced by heat and hypotonic solution. A chloroform partitionate showed highest zone of inhibition against Salmonella typhi. (16)


Availability
Recently for introduced.
Ornamental cultivation.

Godofredo U. Stuart Jr., M.D.

Last Update December 2015


Photos © Godofredo Stuart / StuartXchange
SOURCES

Additional Sources and Suggested Readings
(1)
Cytotoxic 5-Alkylresorcinol Metabolites from the Leaves of Grevillea robusta / Ta-Hsien Chuang and Pei-Lin Wu / J. Nat. Prod., 2007, 70 (2), pp 319–323 / DOI: 10.1021/np0605687
(2)
Dermatitis Due to Grevillea Robusta (Australian Silk Oak) / STANTON B. MAY, M.D. / Arch Dermatol. 1960;82(6):1006.
(3)
Contact dermatitis from Grevillea'Robyn Gordon' / Contact Dermatitis / Volume 15 Issue 3, Pages 126 - 131
(4)
Antibacterial Activity of Selected Australian Native Plant Extracts
(5)
Investigation of plant-derived phenolic compounds as plasma membrane Ca2+-ATPase inhibitors
with potential cardiovascular activity
/ Drug development research / 1999, vol. 46, no 3-4 (165 p.) (2 p.3/4), pp. 235-249

(6)
Handbook of occupational dermatology / Lasse Kanerva, P. Elsner, Jan E. Wahlberg
(7)
Grevillea robusta - Silky Oak / Aussie Gardening
(8)
Phenolic constituents from Grevillea robusta / Amany S Ahmed et al / Phytochemistry, Vol 53, Issue 1, January 2000, Pages 149-154 / doi:10.1016/S0031-9422(99)00484-7 /
(9)
Studies on Gum from Grevillea robusta as a Wood Adhesive / J G Mwangi / Associate Professor, Wood Science and Technology Department, Moi University, P.O. Box 3900, Eldoret, Kenya
(10)
Grevillea robusta A.Cunn. ex R.Br.
/ Synonyms /The Plant List
(11)
Grevillea robusta / Common names / Botany / WorldAgroFiorestry
(12)
Chemical Constituents and Biological Studies of the Leaves of Grevillea robusta / Ta-Hsien Chuang*, Hsiu-Hui Chan, Tian-Shung Wu and Chien-Fu Li / Molecules 2011, 16, 9331-9339 / doi:10.3390/molecules16119331
(13)
5-Alkylresorcinol glucosides from the leaves of Grevillea robusta Allan Cunningham. / Yamashita Y, Matsunami K, Otsuka H, Shinzato T, Takeda Y / Journal of natural medicines 64:4 2010 Oct pg 474-7
(14)
Indigenous uses of medicinal plants in North Garo Hills, Meghalaya, NE India / Sharma M.*, Sharma C.L. and Marak, P.N. / Research Journal of Recent Sciences, Vol. 3(ISC-2013), 137-146 (2014)
(15)
5-Alkylresorcinol glucosides from the leaves of Grevillea robusta Allan Cunningham. / Yamashita Y, Matsunami K, Otsuka H, Shinzato T, Takeda Y / Journal of natural medicines 64:4 2010 Oct pg 474-7
(16)
Pharmacological Activities of Grevillea robusta, a Medicinal Plant of Bangladesh / Md. Sharif Ullah, Md. Al Amin Sikder, Tasnuva Sharmin and Mohammad A. Rashid / Bangladesh Pharmaceutical Journal 17(2): 135-137, 2014

It is not uncommon for links on studies/sources to change. Copying and pasting the information on the search window or using the DOI (if available) will often redirect to the new link page.
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