Three salacia species, viz; S chinensis, S reticulata, and S oblonga are used as antidiabetic medications in ethno or traditional systems of medicine including Ayurveda and Unani. These Salacia species have been used by traditional medicine practitioners in India, Japan, and Korea for the treatment for hyperglycemia (high serum or blood-glucose levels). Pre-clinical research and rare clinical trials studying antidiabetic effects of Salacia have shown promise. This review summarises the pharmacological investigations carried out on three species of Salacia with respect to diabetes-mellitus.
Salacia chinensis L.
Synonym: S. prinoides DC
Distribution: S. chinensis is the commonly studied among plants of the family Hippocrataceae. It is distributed in China, Cambodia, India, Indonesia, Laos, Malaysia, Myanmar, Philippines, Sri Lanka, Thailand, and Vietnam.
Description: S. chinensis is a described as a climbing shrub. It reaches height up to 4 m tall. Branchlets are angular in shape, with leaves placed on stalks which are 8-10 mm long. Leaf blade is elliptical in shape, narrowly ovate-round or obovate-elliptical, leathery, base wedge-shaped, margin sparsely toothed, tip nearly acute. Flowers are small and yellow-green in color. Flower stalks are 6-10 mm. Berry is oval or round in shape round, and 1 cm in diameter. Berries attain red color upon ripening. They are having one seed.
Proanthocyanidins, triterpenes: salasones A-E; salaquinone A and foliasalacins A-C and sesquiterpene, salasol A, glycosides: foliasalaciosides E 1-3, F, G, H, and I, lignan, and catechin and mangiferin.
In Ayurveda, the plant has been described as Saptchakra. In Siddha system of medicine, S. chinensis administered as a remedy for type 2 diabetes-mellitus.
Sivaprakshan et al first reported a clinical study of a formulation based on S. chinensis in the treatment of diabetes mellitus. Kadal, (a proprietary Siddha medicine) consisting of roots and bark of S. chinensis, and triphala (combination of fruits of Terminalia chebula Retz., Terminalia belerica Roxb. and Emblica officinalis Linn.) was administered to 25 patients diagnosed with type 2 diabetes-mellitus. Kadal was administered orally in a dose of 500 mg 2x/day, whereas Triphala was administered orally at 2.5 g 3x/day with water as vehicle for a period of 48 days. A significant hypoglycemic effect of Kadal was observed.
Salacia reticulata Wight
Distribution: Southern India and northern Sri Lanka.
Description: S. reticulata is a climbing, perennial, woody shrub. The plant has dichotomous branching pattern. Bark is smooth, greenish grey in colour, thin, and white internally. Leaves: opposite and elliptic-oblong. Leaf-base is acute, apex abruptly acuminate, margin are toothed with minute rounded teeth. Flowers are bisexual and arranged as 2-8 clustered in leaf axils. They are greenish-white to greenish-yellow in color. Fruit is a drupe which is globose and tubercular. The drupe assumes pinkish-orange color on ripening. Seeds 1-4 in number and resembles with almond.
The roots and stems of S reticulata are used in Ayurveda to relieve dry mouth.
Mangiferin, salacenonal and kotalanol (having potential natural alpha-glucosidase inhibiting activity.
A randomized, single-center, double-blind, and crossover trial investigated the efficacy of an herbal tea containing S. reticulata (Kothala Himbutu tea) in 51 patients diagnosed with type 2 diabetes mellitus. All participants in the study had history of type 2 diabetes mellitus for longer than 6 months, with evidence of stable glycemic control over the preceding 6 months (assessment by glycosylated Hb).
The participants were randomised either to receive an herbal tea containing S. reticulata for 3 months followed by placebo in similar tea bags for a further 3 months (n=28), or to receive the tea and placebo in reverse order (n=23). All patients were instructed with detailed advice on diet, activity, and above-all, lifestyle modification.
Glycosylated Hb was determined after admission, after 90 days, and on completion of the study at 180 days. Liver function test and renal function test were estimated biochemically at baseline and at 90 and 180 days months. Adverse events, if any, were recorded. No significant differences were observed between the 2 groups in age, body mass index, male/female ratio, glycemic control, or baseline laboratory tests. All patients completed both phase of the clinical trial. Glycosylated Hb at the end of treatment was found to be significantly lower as compared the treatment with placebo.
Salacia oblonga Wall.
Distribution: S. oblonga is found in limited regions of India and Sri Lanka.
Description: S. oblonga is a small tree or climbing shrub. Leaves are ovate or ovate-lanceolate. The flowers are greenish yellow in color, arranged in short-congested cymes. Fruits are globose, c 3 cm. in diameter, tuberculate, light brown or orange in color, when ripe. Seeds 1-8 in number, angular in shape and are imbedded in the pulp.
The roots as well as the stems of S. oblonga have been used extensively in Ayurveda, the traditional Indian Medicine for the treatment of diabetes-mellitus. In Japan, the roots of S. oblonga have been sold as a dietary-supplement for controlling high blood sugar levels.
Dosages of Salacia-based Preparations
Although no authentic information is available as regard dosages of Salacia based formulations. However, a typical dose of Salacia-based formulations is 2.5 to 5.0 g/day of the whole plant, or a comparable amount as a standardized herbal extract.
- Krishnaa V, Rangaswami S. Proanthocyanidins of Salacia chinensis Linn. Tetrahedron. 1967; 26:2441-2446.
- Kishi A, Morikawa T, Matsuda H, Yoshikawa M. Structures of new friedelane—and norfriedelane-type triterpenes and polyacylated eudesmane-type sesquiterpene from Salacia chinensis Linn. (S prinoides DC., Hippocrateaceae) and radical scavenging activities of principal constituents. Chem Pharm Bull (Tokyo). 2003;51(9):1051-1055.
- Morikawa T, Kishi A, Pongpiriyadacha Y, Matsuda H, Yoshikawa M. Structures of new friedelane-type triterpenes and eudesmane-type sesquiterpene and aldose reductase inhibitors from Salacia chinensis. J Nat Prod. 2003; 66(9):1191-1196.
- Nakamura S, Zhang Y, Pongpiriyadacha Y, Wang T, Matsuda H, Yoshikawa M. Megastigmane glycosides from the leaves of Salacia chinensis. ChemInform. 2008; 39(21):547-553.
- Zhang Y, Nakamura S, Pongpiriyadacha Y, Matsuda H, Yoshikawa M. Absolute structures of new megastigmane glycosides, foliasalaciosides E(1), E(2), E(3), F, G, H, and I from the leaves of Salacia chinensis. Chem Pharm Bull (Tokyo). 2008;56(4):547-553.
- Yoshikawa M, Zhang Y, Wang T, Nakamura S, Matsuda H. New triterpene constituents, foliasalacins A (1)-A (4), B (1)-B (3), and C, from the leaves of Salacia chinensis. Chem Pharm Bull (Tokyo). 2008; 56(7):915-920.
- Sivaprakasam K, Rao KK, Yashoda R et al. Siddha remedy for diabetes mellitus. J Res Ayurveda Siddha. 1984; 5(1-4):25.
- Karunanayake EH, Sirimanne SR. Mangiferin from the root bark of Salacia reticulata. J Ethnopharmacol. 1985; 13(2):227-228.
- Tezuka Y, Kikuchi T, Dhanabalasingham B, Karunaratne V, Gunatilaka AAL. Salacenonal: A Novel Nortriterpenoid Aldehyde of Biogenetic Significance from Salacia reticulata. Nat Prod Res.1993; 3(4): 273 – 276.
- Yoshikawa M, Murakami T, Yashiro K, Matsuda H. Kotalanol, a potent alpha-glucosidase inhibitor with thiosugar sulfonium sulfate structure, from antidiabetic ayurvedic medicine Salacia reticulata. Chem Pharm Bull (Tokyo). 1998; 46(8):1339-1340.
- Jayawardena MH, de Alwis NM, Hettigoda V, Fernando DJ. A double blind randomised placebo controlled cross over study of an herbal preparation containing Salacia reticulata in the treatment of type 2 diabetes. J Ethnopharmacol. 2005; 28; 97(2):215-218.
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