Browsing by Author "Samarasinghe, K.G.B.A."

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    Antioxidant Properties and α-Amylase Inhibition Activities of Four Different Curcuma Species in Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2020) Samarasinghe, K.G.B.A.; Kaliyadasa, P.E.; Marasinghe, P.
    The genus Curcuma belongs to the family Zingiberaceae comprises rhizomatous annual or perennial herbs. Curcuma has a long history of traditional uses ranging from folk medicine to its culinary uses. This study was undertaken to study the biological activities of rhizomes and leaves of four Curcuma species available in Sri Lanka namely, Curcuma albiflora, Curcuma aromatica, Curcuma longa, and Curcuma zedoaria. Fresh rhizomes and leaves of four Curcuma species were collected from their natural habitats in Wet and Dry Zones of Sri Lanka. Rhizomes and leaves were cleaned and cut into small pieces and oven-dried at 45 °C and 40 °C respectively for 12 hrs. Dried samples were ground into a fine powder. Methanol extracts from rhizomes and leaves were screened for total polyphenol content (TPC), antioxidant activity, and α-amylase inhibition activities. The TPC of dried rhizomes of Curcuma longa was the highest of all tested as 5.530 ± 0.012 g of GA equivalents per 1 g of the dried rhizome. The Methanol extracts of the rhizome and leaf samples of four species showed moderate antioxidant activity in the DPPH radical scavenging assay with IC50 values ranging from 150.253 ± 0.273 ppm to 389.051 ± 0.426 ppm. Interestingly the rhizome extracts of Curcuma aromatica, Curcuma longa, and Curcuma zedoaria exhibited higher α-amylase inhibitory activities (13.915 ± 0.023, 6.455 ± 0.117 and 9.492 ± 0.024 respectively) than the Acarbose drug which is an antidiabetic drug (28.273±0.615 ppm). The results revealed that the Sri Lankan Curcuma species have a potency to be used as a source of antioxidant and antidiabetic agents and it is important to increase the value of the unexplored medicinal herbs available in Sri Lanka. Keywords: Antioxidant, Anti-diabetic, Biological Activities, Curcuma
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    Evaluation of The Relationship Between Spad Reading and Biochemical Profile of Fresh Leaves of Selected Tea Cultivars [Camellia Sinensis (L.) O. Kuntze]
    (Uva Wellassa University of Sri Lanka, 2017) Samarasinghe, K.G.B.A.
    Biochemicals in fresh tea leaves affect to the quality of made tea and are difficult to evaluate by traditional chemical extraction methods. Therefore, this study was conducted to investigate a simple method to evaluate foliar biochemicals using SPAD reading of three widely grown tea cultivars (Camellia sinensis (L.) 0. Kuntze), viz: TRI 2025, TRI 3035 and TRI 4046 in the Uva region. Fresh leaf samples of different developmental stages were randomly collected from Wewasse and Glen Alpine estates, Badulla. Leaves were placed in an ice box immediately after detaching from the bush and transported to Agricultural Chemistry laboratory of Uva Wellassa University. Study was conducted as two experiments during the period from July to December 2017. Average of five SPAD readings on each side of the midrib per leaf were taken to produce a single SPAD reading for each leaf Leaves of each cultivar were categorized in to seven samples according to the SPAD reading (i.e. SPAD 20, 30, 40, 50, 60, 70 and 80). Chlorophyll a, b and carotenoids were extracted and quantified in the first experiment while total polyphenols, reducing sugars and proteins were extracted and quantified in the second experiment. The relationship between chemical components and SPAD reading was estimated using regression analysis and Pearson Correlation coefficient. In the first experiment, the highest positive correlation (0.999) was recorded in between SPAD reading and total chlorophylls of cultivar TRI 3035. In the experiment 02, the polyphenols, reducing sugars and proteins of all cultivars were shown a strong, negative, non-linear relationship with SPAD reading (R2>0.90). The results revealed that the SPAD meter readings can be used to assess the relative chlorophyll content and approximate concentrations of the selected biochemicals in fresh tea leaves simply and non-destructively. Thus, the findings will be useful in the decision making of harvest time and quality control in tea sector. Keywords: Biochemicals, Correlation, SPAD reading, Tea cultivars
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    Evaluation of the Relationship between SPAD Reading and Biochemical Profile of Fresh Leaves of Selected Tea Cultivars (Camellia sinensis (L.) 0. Kuntze)
    (Uva Wellassa University of Sri Lanka, 2018) Samarasinghe, K.G.B.A.; Jayasinghe, H.A.S.L.; Alakolanga, A.G.A.W.
    Biochemicals in fresh tea leaves affect to the quality of made tea and are difficult to evaluate by traditional chemical extraction methods. Therefore, this study was conducted to investigate a simple method to evaluate foliar biochemicals using SPAD reading of three widely grown tea cultivars (Camellia sinensis (L.) 0. Kuntze), viz: TRI 2025, TRI 3035 and TRI 4046 in the Uva region. Fresh leaf samples of different developmental stages were randomly collected from Wewasse and Glen Alpine estates, Badulla. Leaves were placed in an ice box immediately after detaching from the bush and transported to Agricultural Chemistry laboratory of Uva Wellassa University. Study was conducted as two experiments during the period from July to December 2017. Average of five SPAD readings on each side of the midrib per leaf were taken to produce a single SPAD reading for each leaf. Leaves of each cultivar were categorized into seven samples according to the SPAD reading (i.e. SPAD 20, 30, 40, 50, 60, 70 and 80). Chlorophyll a, b and carotenoids were extracted and quantified in the first experiment while total polyphenols, reducing sugars and proteins were extracted and quantified in the second experiment. The relationship between chemical components and SPAD reading was estimated using regression analysis and Pearson Correlation coefficient. In the first experiment, the highest positive correlation (0.999) was recorded in between SPAD reading and total chlorophylls of cultivar TRI 3035. In the experiment 02, the polyphenols, reducing sugars and proteins of all cultivars were shown a strong, negative, non-linear relationship with SPAD reading (R2 > 0.90). The results revealed that the SPAD meter readings can be used to assess the relative chlorophyll content and approximate concentrations of the selected biochemicals in fresh tea leaves simply and non-destructively. Thus, the findings will be useful in the decision making of harvest time and quality control in tea sector.