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Articles by R.M. Dharmadasa
Total Records ( 3 ) for R.M. Dharmadasa
  A.S. Siriwardane , R.M. Dharmadasa and Kosala Samarasinghe
  Withania somnifera (L.) Dunal. (Family: Solanaceae) is a therapeutically important medicinal plant in traditional and Ayurveda systems of medicine in Sri Lanka. Witheferin A, is a potential anticancer compound found in W. somnifera. In the present study, attempts have been made to compare witheferin A content, in different parts of (root, stem, bark, leaf) two varieties of (LC1 and FR1) W. somnifera grown in same soil and climatic conditions. Ground sample (1g) of leaves, bark, stem and roots of two W. somnifera varieties were extracted with CHCl3 three times. Thin Layer Chromatographic analysis (TLC) of withaferin A in both plant extracts were performed on pre-coated Silica gel 60 GF254 plates in hexane: ethyl acetate: methanol (2: 14: 1) mobile phase. Densitometer scanning was performed at λmax = 215 nm. HPLC of W. somnifera extracts was performed using Kromasil C18 reverse phase column. Both varieties of W. somnifera differed in withaferin A. After visualizing TLC plates with vanillin-sulphuric acid leaf and bark extracts of both varieties showed high intensity purple colour spots (Rf 0.14) than in stem and roots. The highest amount of withaferin A (3812 ppm) was observed in leaves of variety LC1 while the lowest amount was observed in roots of variety FR1 (5 ppm). According to the results it could be concluded that content of Witheferin A was vary leaf> bark> stem > roots in both varieties. Therefore, there is a high potential of incorporation of leaves and bark of W. somnifera for the preparation of Ayurveda drug leading to anticancer activity instead of roots.
  R.D.K. Lenora , R.M. Dharmadasa , D.C. Abeysinghe and L.D.A.M. Arawwawala
  Background: Plumbago indica Linn. (Family: Plumbaginaceae) is a shrubby perennial herb native to the South Asia and at present it is widely cultivated throughout India and Sri Lanka. Plumbagin (5-hydroxy-2-methyl-1,4-napthoquinone) is a therapeutically important natural naphthoquinone occurs mainly in the roots of P. indica. Materials and Methods: Compared the chemical profile (in terms of qualitative analysis of phytochemicals and TLC fingerprints) and quantified the plumbagin content in P. indica grown under different growing systems: using roots of (a) conventionally field grown, (b) tissue cultured field grown, (c) hydroponically grown plants and (d) in vitro developed callus from leaf explants. Results: The maximum plumbagin content was observed in roots of tissue cultured field grown plants followed by roots of conventionally field grown hydroponically grown plants and callus samples. Conclusion: Among the different growing systems of P. indica maximum plumbagin content was observed in roots of tissue cultured field grown plants.
  R.M. Dharmadasa , G.A.S. Premakumara , P.L. Hettiarachchi and W.D. Ratnasooriya
  Munronia pinnata (Wall.) Theob. (Meliaceae) is therapeutically important medicinal plant used for the control of malaria in traditional medicine in Sri Lanka. This study described the cytotoxic potential of five morphotypes and antimalarial activity of the highest cytotoxic morphotype of M. pinnata using brine shrimp toxicity assay and Plasmodium yoelii murin model, respectively. Four concentrations of (0.1, 1, 5 and 10 mg mL-1) aqueous extracts of stem, roots and leaves of five morphotypes of M. pinnata were screened for cytotoxcity using brine shrimp assay. Either, three doses (3200, 1600, 800 mg kg-1) of the whole plant aqueous extract of the highest cytotoxic morphotype of M. pinnata (WPAE) or vehicle or quinine were orally administered for different groups of mice (n = 6) inoculated with P. yoelii murine model. Antimalarial activity was examined in terms of schizonticidal activity and chemo suppression. Overt signs of toxicity, body weight, rectal temperature, stress and aversive behavior were observed with long term oral administration of high dose of WPAE (n = 10). All parts of five morphotypes of M. pinnata showed potent cytotoxic activity. The order of potency was roots>stems>leaves. The highest cytotoxicity exhibited by morphotype collected from Nilgala forest reserve (MGNG3). The high dose of WPAE of MGNG3 has potent oral antimalarial activity. No signs of overt toxicity, signs of stress and aversive behaviour observed during long term toxicological studies. This study showed, for the first time, that all morphotypes of M. pinnata has marked cytotoxcity and morphotype MGNG3 has potent antimalarial activity as claimed by Sri Lankan traditional practitioners.
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