Tropical Agricultural Research & Extension 13(2): 2010 SALACIA RETICULATA WIGHT: A REVIEW OF BOTANY, PHYTOCHEMISTRY AND PHARMACOLOGY KKIU Arunakumara* and S Subasinghe Department of Crop Science, Faculty of Agriculture, University of Ruhuna, Mapalana, Kamburupitiya, Sri Lanka Accepted: 05 April 2010 ABSTRACT Salacia reticulata is a large woody climbing shrub naturally found in Sri Lanka and Southern region of India. It is widely used in treating diabetes, a chronic disorder in metabolism of carbohydrates, proteins and fat due to absolute or relative deficiency of insulin secretion with/without varying degree of insulin resistance. The decoction of S. reticulata roots is also used in the treatment of gonorrhea, rheumatism, skin diseases, haemorrhoids, itching and swelling, asthma, thirst, amenorrhea and dysmenorrheal. Presence of mangiferin (a xanthone from the roots), kotalanol and salacinol (from the roots and stems) have been identified as the antidiabetic principles of S. reticulata. Chemical constituents such as 1,3- diketones, dulcitol and leucopelargonidin, iguesterin, epicatechin, phlobatannin and glycosidal tannins, triterpenes, and 30-hydroxy-20(30) dihydroisoiguesterin, hydroxyferruginol, lambertic acid, kotalagen- in 16-acetate, 26-hydroxy-1,3-friedelanedione, maytenfolic acid have also been detected in the roots of S. reticulata. The antidiabetic property of Salacia is basically attributed to the inhibitory activity of in- testinal enzymes (α-glucosidase and α-amylase). Inhibition of intestinal enzymes delays glucose absorp- tion into the blood and suppresses postprandial hyperglycemia, resulting in improved glycemic control. Furthermore, mangiferin has been reported to inhibit aldose reductase activity delaying the onset or progression of diabetic complications. Though diabetes has now become an epidemic affecting millions of people worldwide, neither insulin nor other modern pharmaceuticals has been shown to modify the course of diabetic complications mainly due to the multifactorial basis that involves both genetic and environmental risk factors. Therefore, effort is being devoted to find new therapeutics aimed at multi- ple targets, which has become a new paradigm in drug discovery. In this context, the discoveries on S. reticulata have lead to increase the consumption of the species across the world and it has now become a subject of broad studies for diabetes management. Key words: Salacia reticulata, Mangiferin, Kotalanol, Salacinol, Diabetes INTRODUCTION commercial exploitation of their discoveries will result in the sharing of benefits with Sri Lanka. Di- Medicinal plants are an important element of the abetes has now become an epidemic affecting mil- indigenous medical systems in Sri Lanka, where lions of people worldwide. However, neither insu- about 35 % of the population, even at present, de- lin nor other modern pharmaceuticals has been pends on traditional systems of medical care (Smith shown to modify the course of diabetic complica- et al. 2006). The Sri Lankans appeared to have de- tions mainly due to the multifactorial basis that in- veloped a system whereby they select and continue volves both genetic and environmental risk factors. to use plants that they find the most effective for Therefore, new therapeutics aimed at multiple tar- health care purposes. Out of 1,414 medicinal plant gets have been extensively investidated. In this con- species available in Sri Lanka, about 250 species text, the discoveries on S. reticulata have lead to are commonly used, while 50 species are heavily increase the consumption of the species across the used (Pushpakumara et al. 2002). Despite the coun- world and it has now become a subject of broad try is blessed with a rich diversity of medicinal studies for diabetes management. In order to meet plants, commercial exploitation of the important the ever increasing demand, commercial exploita- species is yet to be developed. Some of the long tion of the species simultaneously with the scien- reputed Sri Lankan species have however been ex- tific investigations is of paramount important. The tensively investigated in other countries and subject present paper reviewed botany, uses, phytochemis- of several publications even with no reference to try and pharmacology of Kothala himbatu (S. retic- Sri Lankan participation. The recent example of ulata). Kothala himbatu (Salacia reticulata), a species widely known for its antidiabetic properties has MEDICINAL PLANTS AND DIABETES been investigated in Japan and the United States and patented (Pushpakumara et al. 2002). Though Diabetes is a chronic disorder in metabolism of car- extensively investigated, it is unlikely that any bohydrates, proteins and fat due to absolute or rela- *Corresponding author: [email protected] 42 KKIU ARUNAKUMARA & S SUBASINGHE : A REVIEW OF SALACIA RETICULATA tive deficiency of insulin secretion with/without the subject of broad studies for diabetes manage- varying degree of insulin resistance (Barar 2000; ment (He et al. 2009; Yuhao et al. 2008). Yoshino et al. 2009). It has now become an epi- demic affecting millions of people worldwide GEOGRAPHICAL DISTRIBUTION OF SALA- (Torben 2002) and the World Health Organization CIA RETICULATA predicts that the number of people affecting diabe- tes may increase several fold in the near future. Di- Salacia species (e.g. S. oblonga, S. prinoides, S. abetes can be defined as a disease where the body reticulata), known as ‘Ponkoranti’ in Ayurvedic either produces little insulin/ceases to produce insu- medicine, are widely distributed in Sri Lanka, In- lin, or becomes progressively resistant to its action dia, China, Vietnam, Malaysia, Indonesia and other (Ranjan and Ramanujam 2002). Therefore, the dis- Asian countries, where these species have been ease can be classified into two groups; type I used for thousands of years in traditional medicines (insulin-dependent) and type II (insulin- particularly for the treatment of diabetes (He et al. independent), which is more common accounting 2009; Yuhao et al. 2008). S. reticulata is known to 90 % of the diabetic population (Yoshino et al. be distributed in Sri Lanka and the Southern region 2009). However, neither insulin nor other modern of India (Matsuda et al. 2002). Though rare, this pharmaceuticals has been shown to modify the species could also be found in evergreen forests of course of diabetic complications (Grover et al. Western Ghats (Ravikumar and Ved 2000). In Sri 2002) mainly due to the multifactorial basis that Lanka, S. reticulata is known to be found mainly in involves both genetic and environmental risk fac- dry zone, which includes districts such as Ham- tors (Kaplan and Junien 2000; Loktionov 2003; banthota, Anuradapuraya, Pollonnaruwa, Monara- Reich and Lander 2001). Therefore, effort is being gala, Kurunegala and Puttalm. However, documen- devoted to find new therapeutics aimed at multiple tary evidence is lacking on the precise locations in targets, which has become a new paradigm in drug which the species is abundantly distributed. discovery (Zhang 2005). In this context, it is of considerable interest to note that some natural prod- BOTANICAL DESCRIPTION AND PROPA- ucts could act on multiple targets to influence mul- GATION tiple biological activities, producing significant physiological effects, and thereby providing bene- S. reticulata WIGHT (Sinhala: Kothala himbatu) is fits that cannot be obtained with a single compound a large woody climbing shrub belongs to family (Yuhao et al. 2008). Hippocrateaceae (Matsuda et al. 2002). The green- ish grey color bark of the plant is smooth, with Medicinal plants, since times immemorial, have white inside. The average dimension of a leaf is 3 – been used in virtually all cultures in controlling and 6 inches long and 1 – 2 inches broad (Sandhu and preventing diabetes. As per recent literature, more Singh 2005). They are opposite and elliptic-oblong, than 800 plants are reported to have antidiabetic base acute, apex abruptly acuminate, margin properties (Eddouks and Maghrani 2004). Eth- toothed with minute rounded teeth, leathery, hair- nopharmacological surveys indicate that more than less, shiny, lateral nerves about seven pairs, promi- 1200 plants are used in traditional medicine for nent beneath. S. reticulata produces greenish white their alleged hypoglycemic activity (Kesari et al. to greenish yellow color flowers as clustered (2-8) 2007). Hypoglycemic activity of herbal prepara- in leaf axils (Ravikumar and Ved 2000). Flowers tions containing Salacia species have been reported are bisexual, calyx lobes entire, anthers dehiscing in many human studies (Collene et al. 2005; Hea- transversely. Fruits are globose, tubercular, pinkish cock et al. 2005; Jayawardena et al. 2005; Kajimo- orange when ripe. They contain 1 - 4 seeds to et al. 2000). The roots and stems of S. reticulata (Ravikumar and Ved 2000, Subasinghe et al. 2008). and the roots of S. oblonga have been extensively The plant flowers in December under Indian condi- used for the treatment of rheumatism, gonorrhea, tions (Sandhu and Singh 2005), whereas in Sri skin diseases, and particularly as a specific remedy Lanka, flowering starts in late November and seeds for the initial stages of diabetes in the Ayurvedic are available from March to June (Subasinghe et al. system of traditional medicine (Matsuda et al. 2008). 2002; Yoshino et al. 2009). According to Kumar (2000), at least two Sri Lankan plants (Salacia re- A mature S. reticulata plant produces thousands of ticulata and