Gen info
• Exallage is a genus of flowering plants in the family Rubiaceae. The genus is found from tropical and subtropical Asia to the southwestern Pacific. (6)

Botany
• Hedyotis auricularia is a suberect or diffused, prostrate, branched, hairy herb, with the branches 15 to 45 centimeters long. Leaves are ovate-lanceolate or lanceolate, 2 to 7.5 centimeters long, and 0.8 to 1.5 centimeters wide, smooth or scabrid on the upper surface, and often hairy beneath. Flowers are white with very short stalks and borne in axillary, very dense cymes. Calyx-teeth are small, shorted than the indehiscent fruit. Fruit is crowded, ovoid, about 1.5 millimeters in diameter, and clasped by a persistent calyx.

• Diffuse to trailing hers; stem 4-angled, bluish, villous when young. Leaves 2-7 x 1-2.5 cm, elliptic-ovate or elliptic-lanceolate, base rounded or cuneate, apex shortly acuminate, lateral nerves 4 or 5 pairs, glabrous; stipules broadly ovate, pectinate on margins. Flowers fascicled at axils; pedicels c. 1 mm long. Calyx tube c. 1 mm long, 4-lobed. Corolla white, campanulate; tube c. 1 mm long; lobes 4, reflexed, hairy at throat. Stamens 4, included. Capsule c. 2 mm across, globose, pubescent, indehiscent. Seeds many, black, 3-angled. (eFloraOfIndia)

Distribution
- Native to the Philippines.
- In open places and thickets at low and medium altitudes in Ilocos Norte, Benguet, Bulacan, Rizal, Camarines, and Albay Provinces in Luzon; and in Mindanao.
- Also native to Andaman Is., Assam, Bangladesh, Borneo, Caroline Is., China South-Central, China Southeast, East Himalaya, Hainan, India, Jawa, Laos, Lesser Sunda Is., Malaya, Myanmar, Nansei-shoto, Nepal, New Guinea, Northern Territory, Queensland, Sri Lanka, Sumatera, Thailand, Vanuatu, Vietnam. (6)

Constituents
- Anthraquinones, iridoid glycosides and alkaloids are common constituents of Hedyotis species.
- Yields tritepenoids, saponins, alizarin, and alkaloid hedyotine.
- Study yielded an alkaloid, auricularine.
- Studies have yielded lignans, triterpenoids, sterols, coumarins, saponins, indole and carboline alkaloids, anthraquinones, flavonoids and their glycosides, and iridoids and their glycosides. (9)
- Phytochemical studies demonstrated presence of three glycosides, namely: hydroxy-1- methoxy ethyl glucopyranoside, ursolic acid and oleanolic acid as well as 1'-O-ethyl—D galactopyranoside, 2-formyl-5- hydroxymethyl furan, 5-stigmasta and 22-diene 3-O-D- glucopyranoside) and β-sitosterol. (9)

Properties
- Emollient, antidysenteric, antidiarrheal.
- Studies have suggested hypotensive, bronchodilating, antioxidant, anti-inflammatory, antibacterial properties.

Uses
Edibility
- Leaves are edible.
- In Sikkim, India, boiled with rice.
Folkloric
- No reported folkloric medicinal use in the Philippines.
- Plant used as an emollient and prescribed for dysentery and cholera in India.
- Decoction or extract of leaves or whole crushed leaves are taken for treatment of intestinal problems, including dysentery and cholera. Paste of leaves applied to abscesses and wounds. Boi8led leaves rubbed on aching body parts or applied as poultice on cracked skin. Leaf juice used for eye problems. (7)
- In southern India, decoction of green leaves and roots used for treatment of colitis.
- In Sri Lanka used for dysentery, diarrhea, and lowering blood pressure.
- In Chinese medicine, used for: cold and pyrexia, coughing with lung heat, swelling pain in the throat, enteritis, dysentery, hemorrhoids and hemorrhage, metrorrhagic and metrostaxis, venomous snake bites, mastitis, furuncles, eczema, injuries from falls. (8)
- Phytochemical analysis revealed presence of steroids, phenols, and tannins as common in leaf and stem extracts; additionally the leaf extract yielded flavonoids and alkaloids. (see study below) (10)

Studies
• Chemical Constituents: Study of whole plant yielded a new glycoside, 1 '-deoxy-6 '-O-(1-hydroxymethyl-2-hydroxy-l-methoxy )ethylglucopyranoside, along with 1 '-0-ethyl-beta-D-galactopyranoside, 2-formyl-5-hydroxymethylfuran, stigmasta-5,22-diene-3-O-beta-D-glucopyranoside, ursolic acid and oleanolic acid. (3)
• Hypotensive / Bronchodilation / Alkaloid: A new water soluble alkaloid isolated from Hedyotis auricularia showed both hypotensive and bronchodilating properties. The maximum dose produced no mortality. (5)
• Anti-Inflammatory: Study evaluated aqueous ethyl alcohol extract of ground and dried plants for anti-inflammatory activity. Lipopolysaccharides (LPS) treated with LPS-stimulated cells were compared to 0.1% dimethyl sulfoxide as reference. Nitric cytoplasmic, LOX, COX, and myeloperoxidase (MPO) activity were measured. Percentages of COX and LOX enzyme inhibition were calculated. Results showed anti-inflammatory potential on LPS-treated murine macrophages. (9)
• Antihypertensive / Aerial Parts: Study evaluated the potential of extracts of O. auricularia fresh aerial parts for treatment of hypertension in an animal model. Results showed significant improved blood pressure and tissue histology compared to animal group receiving an allopathic medication. (9)
• Antimicrobial Activity / Aerial Parts: Study evaluated the antimicrobial activity of aqueous and ethanolic extracts from pulverized leaves against Gram(+) and Gram(-) bacteria using modified agar well diffusion method. The extracts exhibited concentration dependent zones of inhibition on Gram positive and negative bacteria. (9)
• Antioxidant Activity / Stalks and Leaves: Study of Oldenlandia auricularia leaves extract showed antioxidant activity by DPPH radical scavenging assay. Curcumin was used as standard substance. (9)
• Antibacterial Activity: Study evaluated the antibacterial efficacy of plant extracts against four pathogenic bacteria i.e., Pseudomonas aeruginosa Proteus mirabilis, Klebsiella pneumonia, and Staphylococcus aureus using well diffusion agar technique. Results showed antibacterial activity and potential of the plant as a valuable reservoir of antimicrobial agents. (see constituents above) (10)

Availability
Wild-crafted.

Additional Sources and Suggested Readings
(1)
Phytochemical studies and pharmacological activities of plants in genus Hedyotis/oldenlandia / Nordin Lajis and Rohaya Ahmad / Studies in Natural Products Chemistry, Vol 33, Part 13, 2006, Pages 1057-1090
(2)
HEDYOTIS AURICULARIA: A NEW REMEDY FOR COLITIS / Can Med Assoc J. 1929 November; 21(5): 591.
(3)
Contribution to the study on chemical constituents of Hedyotis auricularia L.,(Rubiaceae) / Kim Phi Phụng, Phạm Đình Hùng /TC Hoá học . -2007. -Vol 45. -No 2. -p. 233-236.
(4)
Structure of auricularine, a bis-indole alkaloid from Hedyotis auricularia / Kozhiparambil K Purushothaman, Ayyapath Sarada / Phytochemistry,1981,Volume: 20, Issue: 2, Pages: 351-352
(5)
PHARMACOLOGICAL ACTIONS OF AN ALKALOIDAL FRACTION ISOLATED FROM HEDYOTIS AURICULARIA, LINN. AND H. HISPIDA, RETZ. N.O.-(RUBIACEAE): PRELIMINARY STUDY. / AMITA MUKHERJEE,N K DUTTA,S R CHAVAN / Ind.Jour.Med,Res.,55,10,October.1967pp1103-1106
(6)
Exallage auricularia / KEW: Plants of the World Online
(7)
Exallage auricularia / Ken Fern: Tropical Plants Database / Useful Tropical Plants
(8)
Hedyotis auricularia / School of Chinese Medicine / Medicinal Plant Images and Database
(9)
A review on potency of Oldenlandia auricularia plant extract / Sanjeeva Kumar, Blessy Jacob, D Visagaperumal, Vineeth Chandy / JETIR: Journal of Emerging Technologies and Innovative Research, 2023; 10(4) / ISSN: 2349-5162
(10)
Exploring the Antibacterial activity of leaf, stem, and root extracts of Exallage auricularia (Gatekola/Eared-Leaf Diamond Flower) / Nimantha Wickramaratne, Thilina Buddika Dayananda, Damith Krishantha et al / 4th CINEC INTERNATIONAL RESEARCH SYMPOSIUM (CIRS), 2023: Sri Lanka

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