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Item Leaf flavonoids as chemotaxonomic characters in genus Sida L. (Bevila)(Tropical Agricultural Research, 2001) Perera, N.I.S.; Senanayake, S.P.; Jayasekera, L.R.Theflavonoid distribution pattern of five species of genus Sida was studied to identify the species since the existing classification was mainly based on morphological and anatomical characters. Four main flavonoids and one minor flavonoid were isolated by preparatory paper chromatography. Trace amounts of six flavonoids were observed in two-dimensional paper chromatography. The major flavonoid compounds in S. acuta. S. rhombifolia. S. alnifolia. and S. cordifolia were glycosylated and methylated flavonols where as S. humilis had minor flavonoids. There are remarkable variations in the substitution patterns of these flavonol compounds. The presence ofquercetin 3-methyl ether and the compound C is a common character to S. rhombifolia and S. cordifolia. and hence these two species may be considered as related taxa in the genus Sida. Kaempferol glycosides were the major Jlavonoids in the S. alnifolia in contrast to the S. rhombifolia. which was characterised by the presence of methylated quercetin. This is in agreement with the recent revision of the genus in which they are considered as different entities. The habit ofS. humilis. prostrate trailing, is different from other species, which are erect herbs. This dissimilarity of morphology agreed with its characteristic flavonoid pattern of possessing minor flavonoids.Item Host tree specificity and seed germination of Dendrobium aphyllum (Roxb.) C.E.C.Fisch. in Sri Lanka(Journal of the National Science Foundation of Sri Lanka, 2013) Harshani, H.B.C.; Senanayake, S.P.; Sandamali, H.Tree species can be considered as hosts for many epiphytes. Orchids as epiphytes display a biased distribution among hosts. It is possible that the barks of these hosts have some chemical and physical characteristics that influence for the seed germination of orchids. Dependence on symbiotic fungi for the seed germination is also a crucial factor for orchid distribution. Dendrobium aphyllum is an orchid species with restricted distribution in sub montane region of Sri Lanka. Aims of this study were (1) to determine the host tree specificity of the epiphytic D. aphyllum using physical and chemical bark characteristics of the host (2) to isolate and identify the symbiotic fungi in D. aphyllum roots and (3) to determine the effect of tree bark extracts on symbiotic seed germination of D. aphyllum. Methanol, dichloromethane, hexane and water were used to extract the chemical compounds in tree barks. Aqueous and organic bark extracts of non host species (Erythrina sp. ,Erythrina berteroana, Eurya accuminata, Semecarpus marginata, Symplocaceae cochinchinensis ) inhibited seed germination of D. aphyllum. However, the effect of host tree species (Eurya ceylanica, Actinodaphne stenophylla, Eurya sp., Antidesma zeylanicum, Citrus maxima, Semecarpus nigra-viridis and two Syzygium spp.) on seed germination fluctuated with the concentration of host bark extracts. Bark physical characteristics such as bark texture, peeling behavior and bark thickness showed positive correlation with host tree specificity of D. aphyllum.. Symbiotic fungus Rhizoctonia sp. was isolated as the associate in D. aphyllum roots.Item Leaf flavonoid glycosides as chemosystematic characters in Ocimum(Biochemical Systematics and Ecology, 1993) Grayer, R.J.; Kitea, G.C.; Veitcha, N.C.; Eckerta, M.R.; Marin, P.D.; Senanayake, S.P.; Paton, A.J.Abstract Thirty-one accessions of nine species belonging to three subgenera of Ocimum (basil, family Lamiaceae) were surveyed for flavonoid glycosides. Substantial infraspecific differences in flavonoid profiles of the leaves were found only in O. americanum, where var. pilosum accumulated the flavone C-glycoside, vicenin-2, which only occurred in trace amounts in var. americanum and was not detected in cv. Sacred. The major flavonoids in var. americanum and cv. Sacred, and also in all other species investigated for subgenusOcimum, were flavonol 3-O-glucosides and 3-O-rutinosides. Many species in subgenus Ocimum also produced the more unusual compound, quercetin 3-O-(6?-O-malonyl)glucoside, and small amounts of flavone O-glycosides. The level of flavonol glycosides produced was reduced significantly in glasshouse-grown plants, but levels of flavone glycosides were unaffected. A single species investigated from subgenusNautochilus, O. lamiifolium, had a different flavonoid glycoside profile, although the major compound was also a flavonol O-glycoside. This was identified as quercetin 3-O-xylosyl(1??2?)galactoside, using NMR spectroscopy. The species investigated from subgenus Gymnocimum, O. tenuiflorum (=O. sanctum), was characterised by the accumulation of flavone O-glycosides. These were isolated, and identified as the 7-O-glucuronides of luteolin and apigenin. Luteolin 5-O-glucoside was found in all nine species of Ocimumstudied, and is considered to be a key character for the genus.