Shorea Roxburghii Research Articles

Anticancer properties and metabolomic profiling of Shorea roxburghii extracts toward gastrointestinal cancer cell lines

BackgroundGastrointestinal cancer (GIC) ranks as the highest cause of cancer-related deaths globally. GIC patients are often diagnosed at advanced stages, limiting effective treatment options. Chemotherapy, the common GIC recommendation, has significant disadvantages such as toxicity and adverse effects. Natural products contain substances with diverse pharmacological characteristics that promise for use in cancer therapeutics. In this study, the flower of renowned Asian medicinal plant, Shorea roxburghii was collected and extracted to investigate its phytochemical contents, antioxidant, and anticancer properties on GIC cells.MethodsThe phytochemical contents of Shorea roxburghii extract were assessed using suitable methods. Phenolic content was determined through the Folin-Ciocalteu method, while flavonoids were quantified using the aluminum chloride (AlCl3) method. Antioxidant activity was evaluated using the FRAP and DPPH assays. Cytotoxicity was assessed in GIC cell lines via the MTT assay. Additionally, intracellular ROS levels and apoptosis were examined through flow cytometry techniques. The correlation between GIC cell viability and phytochemicals, 1H-NMR analysis was conducted.ResultsAmong the four different solvent extracts, ethyl acetate extract had the highest phenolic and flavonoid contents. Water extract exhibited the strongest reducing power and DPPH scavenging activity following by ethyl acetate. Interestingly, ethyl acetate extract demonstrated the highest inhibitory activity against three GIC cell lines (KKU-213B, HepG2, AGS) with IC50 values of 91.60 µg/ml, 39.38 µg/ml, and 35.59 µg/ml, while showing less toxicity to normal fibroblast cells. Ethyl acetate extract induced reactive oxygen species and apoptosis in GIC cell lines by downregulating anti-apoptotic protein Bcl-2. Metabolic profiling-based screening revealed a positive association between reduced GIC cell viability and phytochemicals like cinnamic acid and its derivatives, ferulic acid and coumaric acid.ConclusionsThis study highlights the potential of natural compounds in Shorea roxburghii in the development of more effective and safer anticancer agents as options for GIC as well as shedding light on new avenues for cancer treatment.

Characterization of the Fragrant Resin from <i>Shorea roxburghii</i>, a Lac Insect Host Tree of Tropical Deciduous Forest in South India

Characterization of the Fragrant Resin from <i>Shorea roxburghii</i>, a Lac Insect Host Tree of Tropical Deciduous Forest in South India

The ecological interaction between endangered, precious and rare woody species in rich forest community: A case study in Tanphu protection forest, Vietnam

Abstract. Huong PV, Cuong LV. 2022. The ecological interaction between endangered, precious and rare woody species in rich forest community: A case study in Tanphu protection forest, Vietnam. Biodiversitas 23: 6119-6127. The present study was conducted to explore the ecological relationship between endangered, precious, and rare tree species and other woody tree species in the rich forest in Tanphu protection forest, Southeastern region, Vietnam. Thirty 2500 m2 study plots (50 × 50 m) were established in the rich forest in Tanphu protection forest. The results revealed that: the rich forest comprised 38 species of woody trees, in which Dipterocarpus alatus Roxb was the dominant species, Shorea guiso Blume, Shorea roxburghii G.Don and Vitex ajugiflora Dop were co-dominant species; Afzelia xylocarpa (Kurz) Craib, Dalbergia oliveri Gamble ex Prain, Pterocarpus macrocarpus Kurz and Dalbergia cochinchinensis Pierre were four endangered, precious and rare species. In the study area, the eight pairs of species viz. D. oliveri - D. alatus; A. xylocarpa - D. alatus; A. xylocarpa - S. guiso; D. cochinchinensis - D. alatus; D. cochinchinensis - S. roxburghii; P. macrocarpus - D. alatus; P. macrocarpus - V. ajugiflora and P. macrocarpus - S. guiso were positively correlated; while two pairs of species were negatively correlated viz. S. guiso - D. oliveri; S. guiso - D. cochinchinensis. Hence, the findings from this study suggested that when choosing plant combinations, the first priority has to be the species that were positively correlated with endangered, precious, and, rare species, and to avoid the selection of negatively associated species.

Protective Effects of Shorea roxburghii Phenolic Extract on Nephrotoxicity Induced by Cyclophosphamide: Impact on Oxidative Stress, Biochemical and Histopathological Alterations

AbstractCyclophosphamide (CTX) is one of the most commonly used alkylating agents for the treatment of various cancers; however, CTX‐induced nephrotoxicity is one of the most prevailing side effects of the drug. Shorea roxburghii is a plant with diverse bioactivities including antioxidant, anti‐inflammatory and renoprotective effects. This study investigated the nephroprotective effect of Shorea roxburghii phenolic extract (SRPF) against CTX‐induced nephrotoxicity in rats. The rats were treated with SRPF (100 and 400 mg/kg) for 5 weeks and were concomitantly administered with CTX. The results indicated that treatment with SRPF significantly decreased serum creatinine, blood urea nitrogen (BUN), uric acid as well as renal MDA, IL‐6, TNF‐α, IL‐1β, NF‐kB and caspase‐3 levels. Furthermore, SRPF augmented the activities of renal SOD, CAT, GSH and GPx. SRPF also improved renal histopathological damages caused by CTX administration. In conclusion, these results suggested that SRPF showed substantial protective effects against CTX‐mediated renal toxicity via its antioxidant and anti‐inflammatory effects.

Evaluation of Regulating and Provisioning Services Provided by a Park Designed to Be Resilient to Climate Change in Bangkok, Thailand

Understanding the ecosystem services provided by urban green spaces, in terms of their environmental, economic, and social benefits, is essential for a better management of area. Chulalongkorn University Centenary Park (CU 100) was established to mitigate the effects of climate change, especially flood prevention. This study focused on quantifying the ecosystem services provided by the trees in the park in terms of regulating and provisioning services. A publicly available tool, the i-Tree Eco international software, was used with data obtained from a local weather station as proxies to determine the accuracy of the analysis. Services, quantified in terms of monetary value, included avoided runoff, carbon storage, carbon sequestration, pollution removal, and timber price. The total monetary benefits, obtained from 697 trees (56 species, 49 genera, and 22 families), were estimated at USD 101,400. Of the total services, provisioning services contributed 75% to the total monetary value. Among all regulating services, the avoided runoff contributed about 60%, which was considered as the goal achieved by the park design. Azadirachta indica A. Juss (USD 518.75/tree−1/year−1), Shorea roxburghii G. Don (USD 417.17/tree−1/year−1) and Millettia leucantha Kurz (USD 414.87/tree−1/year−1) provided the greatest benefit, as indicated by a high value of provisioning services in terms of a high timber quality. These results can be used when planning the composition of trees to be planted in urban areas to increase both green spaces and maximize ecosystem services to improve the vitality of human well-being.

Population dynamics and regeneration of Shorea roxburghii, a threatened timber species in Southern region, Viet Nam

Abstract. Bao TQ, Viet LH, Hai NH, Tuan NT, Cuong LV. 2021. Population dynamics and regeneration of Shorea roxburghii, a threatened timber species in Southern region, Viet Nam. Biodiversitas 22: 5649-5656. Despite its wide distribution in South and Southeast Asia, Shorea roxburghii G. Don is classified as Vulnerable in the IUCN Red List of Threatened Species due to over-exploitation for its valuable timber. This study aims to investigate the population dynamics and regeneration of S. roxburghii in southeastern Vietnam, serving for conservation and sustainable development plan. Six plots of 2,500 m2 each (50 m × 50 m) were established at two forest conditions: i) forest with standing volume > 200 m3/ha (SV>200), and ii) < 200 m3/ha (SV<200); to investigate stems with diameter at breast height (DBH) ? 5 cm and that < 5 cm. Moisture (%), pHH2O of the topsoil and the occurrence of regenerating S. roxburghii were collected from 125 points in the study site. The results indicated that mean stem height, DBH, basal area, and aboveground biomass were significantly higher at the forest stand with SV>200 than that at the forest stand with SV<200 for the pool of all species. Similar higher figures were found in SV>200 for the pool of S. roxburghii compared to that in SV<200, except mean DBH, which was larger in SV<200. There were missing stems with DBH < 5 cm in SV<200, while it was numerous in SV>200 (1,313 stems/ha). DBH/stem distributions in both forest types had an inverted-J shape with a peak at 10-15 cm DBH for the pool of all species, while there was no clear pattern for the pool of S. roxburghii in both forest types. Regression analysis indicated that higher total crown area of stems ? 23 tall leads to higher S. roxburghii stems, while the higher total crown area of stems < 23 tall leads to fewer S. roxburghii stems with DBH < 5 cm. It is concluded that the total crown area of forest stand plays an important role in the sustainable regeneration of S. roxburghii. Silvicultural treatment should be applied to reduce stand density and crown area of stems < 23 m tall to enhance sunlight reaching the forest floor for germination, growth, and survival of S. roxburghii. The moisture of the topsoil ranging from 60 - 80% and the pHH2O ranging from 3.8 - 4.6 are suitable conditions for natural regeneration of S. roxburghii.

Antinociceptive, Anti-Hyperalgesia and Antiallodynic Activities of Polyphenol Rich Extract from Shorea roxburghii against Cyclophosphamide Induced Peripheral Neuropathy.

Cyclophosphamide (CYP) is a widely used antineoplastic and immunosuppressive drug, however, despite its efficacy, it has shown extensive multiple organ toxicities, including peripheral neuropathy which significantly affects the quality of life of cancer patients. This study elucidated the protective properties of Shorea roxburghii polyphenol extract (SLPE) in CYP-induced peripheral neuropathy. Rats were treated with SLPE (100 and 400 mg/kg) for five weeks plus CYP once a week from the second week of SLPE treatment. Using UHPLC-QTOF-MS, 54 polyphenolic compounds were identified in SLPE extract. After the treatment period the antinociceptive, anti-hyperalgesia and antiallodynic effects was evaluated using formalin paw edema, acetic acid abdominal writhing, hot plate, tail immersion and von Frey filament tests. While the locomotive and motor coordination effects were evaluated by open field and rotarod tests. The administration of CYP led to significant increases in mechanical and thermal hyperalgesia, in addition to hyper-nociceptive responses in the formalin and acetic acid writhing tests. CYP also significantly reduced locomotive activity and motor coordination. SLPE significantly protected against CYP-induced mechanical and thermal hyperalgesia. Furthermore, SLPE displayed robust antinociceptive effect by counteracting formalin and acetic acid induced hyper-nociception. In addition, SLPE increased the locomotive activity as well as the grip and motor coordination of the CYP treated rats. In conclusion, these results revealed the protective effects of SLPE against CYP-induced peripheral neuropathy and could be an effective therapeutic remedy for chemotherapy induced peripheral neuropathy.

Phytochemical and nutritional compositions and antioxidants properties of wild edible flowers as sources of new tea formulations

In this research, 4 wild flowers of Thailand were initially analysed for phytochemicals, nutritional compositions as well as their antioxidants properties. Bauhinia variegata L. (BV), Gmelina arborea Roxb. (GA), Shorea roxburghii G. Don (SR) and Viburnum inopinatum Craib (VI) were collected from Queen Sirikit Botanic Garden (QSBG) edible collection. VI contained the highest dietary fiber (25.26%), vitamin C (3.47 mg/100 g) as well other minerals including calcium (790 mg/100 g), potassium (2370 mg/100 g). SI, on the other hand had higher fat (32.30%) and iron (7.53 mg/100 g) to the others. Protein was maximum in BV (10.26 g/100 g), while GA contained the highest values carbohydrate (68.43%) and sodium (14.07 mg/100 g). Screening tests for bioactive compounds showed that flavonoids and saponins were mostly found in both water and ethanolic extracts of flowers. Tannin and polyphenols were detected in flowers of SR and VI. Moreover, terpenoids were detected only in ethanolic extracts of SR and VI. Thereafter, quantitative measurements of antioxidative compounds from the water and ethanolic extracts of these flowers were compared. Total phenolic contents were the highest in both extracts of BV and GG. GA gave the highest total flavonoid content and anti-oxidative properties by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assays. The phenolic compounds were also characterised using High Performance Thin Layer Chromatography (HPTLC) and Thin Layer Chromatography/ Compact Mass Spectrometer (TLC/ CMS). The QSBG tea products that incorporated these wild flowers were formulated. The total phenolic contents, total flavonoid contents and antioxidants of these formulations were also reported.

Protective effects of ethyl acetate extract from Shorea roxburghii against diabetes induced testicular damage in rats.

Diabetic mellitus is a chronic metabolic disorder that is associated with several complications including testicular dysfunction. This research investigated the protective action of the ethyl acetate extract from Shorea roxburghii (SRE) on diabetes induced testicular damage in rats. Diabetic rats were orally administered with SRE at doses of 100 and 400 mg/kg for 4 weeks. SRE improved the body weight gain, testes weight, testes index and increased serum concentration of testosterone. Furthermore, SRE increased the testicular antioxidant enzymes including superoxide dismutase, catalase and glutathione peroxidase. In addition, SRE ameliorated testicular inflammatory mediators such as myeloperoxidase, tumor necrosis factor alpha, interleukin 6, p38 MAPK and nuclear factor kappa B activation and decreased testicular cell apoptosis in the treated diabetic rats. SRE also raised sperm parameters after treatment of diabetic rats. Conclusively, our results suggested that SRE ameliorated diabetes induced testicular damage by inhibiting oxidative stress and inflammation.

GROWTH PERFORMANCE OF DIPTEROCARP SPECIES PLANTED ON ABANDONED MINING AREA IN SOUTHERN THAILAND

Dominant Dipterocarp trees hold a significant importance in the ecology and economics of the declining tropical forests of Asia. Of equal importance is the restoration of these Dipterocarp forest using the technique of matching species with silvicultural practices. The study aimed to investigate the effect of the Acacia mangium nurse trees on the survival and growth of six Dipterocarp species planted on abandoned mining areas in the Phangnga Forestry Research Station, Thailand, namely; Dipterocarpus alatus Roxb., Dipterocarpus gracilis Blume, Hopea odorata Roxb., Shorea gratissima (Wall. ex Kurz) Dyer, Shorea roxburghii G. Don, and Parashorea stellata Kurz. The approximately 1.5-year-old Dipterocarp seedlings were planted at a 6-year-old A. mangium plantation cover and at open plots. The survival rate, diameter at root collar (D0), total height (H) and the relative growth rate (RGR) of D0 and H of the seedlings were compared. Soil samples at the open and the A. mangium plots were collected and its physical and chemical properties were analyzed. The results indicated that the survival rates of the Dipterocarps planted at the A. mangium plot were higher than those at the open plots. The survival rates (75-100%) of the 1 to 3-year-old D. alatus, H. odorata, S. gratissima, S. roxburghii, and P. stellata were relatively high at the A. mangium plot, but not for D. gracilis. The D0 of S. roxburghii, D. alatus, H. odorata, and P. stellata were higher at the A. mangium plot. However, the D0 and H of S. roxburghii, D. alatus, and H. odorata at the open plot were high and similar to that of the A. mangium plot. RGRD0 and RGRH of S. roxburghii, D. alatus, and H. odorata were high both at the A. mangium and the open plots. Generally, the Dipterocarp seedlings were growing better under the A. mangium nurse trees, thus suggesting the possibility of their improved survival and growth in mined out areas. Moreover, the findings also suggest that S. roxburghii, D. alatus, and H. odorata can be planted at open areas with poor soil conditions and extreme environments. Lastly, thinning interventions are also needed to improve the growth of Dipterocarp trees.

Growth prediction for rubber tree and intercropped forest trees to facilitate environmental services valuation in South Thailand

Abstract. Nattharom N, Roongtawanreongsri S, Bumrungsri S. 2020. Growth prediction for rubber trees and intercropped forest trees to facilitate environmental services valuation in South Thailand. Biodiversitas 21: 2019-2034. Tree growth parameters are necessary for valuing ecological services of trees in both natural forest and agroforest. These parameters are difficult to measure annually, and thus often lack the information needed in valuation. This study aimed to use regression analysis to create growth models for diameter at breast height (DBH), total height (TH), and merchantable height (MH) of Hevea brasiliensis Mull-Arg. (rubber tree) and five economic forest trees that are preferred by rubber farmers for intercropping, including Hopea odorata Roxb., Shorea roxburghii G.Don., Swietenia macrophylla King., Dipterocarpus alatus Roxb., and Azadirachta excelsa (Jack) Jacobs. Data were collected from 39 rubber plantations that contain rubber trees and the intercropped tree species at different ages in three provinces in South Thailand. The data were modelled using regression analysis with curve fitting to find the best-fitted curve to a given set of points by minimizing the sum of the squares of the residuals and standard error of the regression of the points from the curve. The results arrived at 21 models for the DBH, TH, and MH growth of rubber and the intercropped trees, in the forms of, power, sigmoid and exponential trends that vary according to the type of trees. The models can be used to predict tree growth parameters, which are useful for determining the value of ecosystem services such as carbon dioxide sequestration, oxygen production, and timber production.

Shorea roxburghii Leaf Extract Ameliorates Hyperglycemia Induced Abnormalities in High Fat/Fructose and Streptozotocin Induced Diabetic Rats.

This study investigated the hypoglycemic effect of the methanol extract of Shorea roxburghii leaves (SRL) in high fat diet/high fructose solution (HFDHF) and streptozotocin (STZ) induced type 2 diabetes mellitus (T2DM) in rats as well as evaluating its ameliorative potentials in altered biochemical and hematological parameters in the treated rats. T2DM was induced in Sprague Dawley (SD) rats by feeding with HFDHF for 4 weeks and administering STZ (35 mg/kg, i. p.). Diabetic rats were given SRL extract at doses of 100 and 400 mg/kg for 30 days. The food and water intake were monitored on a daily basis, while the fasting blood glucose (FBG) levels and body weight were measured weekly. Biochemical and hematological parameters as well as histopathological studies of the pancreas were also evaluated. SRL significantly decreased FBG and improved the body weight, food and water intake of treated diabetic rats. Furthermore, biochemical and hematological parameters including liver and kidney function enzymes, lipid profiles, white blood and red blood cells parameters were markedly ameliorated by SRL. Histopathological analyses of the pancreas indicated reconstitution of β-cells architecture in SRL treated rats. The results of this study suggest that SRL has antidiabetic potential and can be considered for the treatment of T2DM.

Impacts of a strong El Niño event on leaf phenology and carbon dioxide exchange in a secondary dry dipterocarp forest

This study evaluates the impacts of the 2015/2016 El Niño event on the phenology and carbon dioxide (CO2) exchange in a secondary dry dipterocarp forest (DDF). In western Thailand, El Niño events significantly reduced rainfall and increased air temperature, leading to prolonged dry season with low soil water content and high vapor pressure deficit (VPD). During 2014–2017, leaf phenology was monitored and CO2 exchanges in this forest were measured by an eddy covariance method. During El Niño year, dry dipterocarp species were shed their leaves earlier when compared to neutral years (i.e. with no El Niño event). The species Shorea siamensis Miq. and Sindora siamensis Teijsm.&Miq. showed complete deciduousness during the dry season 2015/2016 as typically observed for these species, but the leafless period was longer than during non-El Niño years. Shorea roxburghii G.Don and Shorea obtusa Wall. showed untypically complete deciduousness during the El Niño year. For the species Sindora siamensis, however, the timing of first leaf expansion was not affected by the strong El Niño. In addition, El Niño resulted in a decline of the annual gross primary productivity (GPP) and evapotranspiration (ET) by 9.6 and 14.1%, respectively. The net ecosystem productivity (NEP) was only affected by El Niño during the dry months, but not during the following wet season therefore the total annual NEP was not significantly affected. Our result demonstrates that El Niño events have a strong impact on canopy duration of DDF ecosystem. However, our study suggests that the carbon loss during this prolonged dry season of 2015/2016 can be compensated in this young secondary DDF during the following wet season, leading to increased NEP on a yearly basis.

Antioxidant Potential of Stem Bark Extract of Shorea roxburghii against CCl 4 induced Liver Damage in Wistar Rats

The aim of the present study was to evaluate the antioxidant potential of the stem bark extract of Shorea roxburghii (S. roxburghii) on CCl4 induced liver toxicity. Stem bark extract of Shorea roxburghii (SRE) was prepared using ethyl acetate. Administration of S. roxburghii inhibited the elevation marker enzymes such as aminotransferase (AST), alkaline phosphatase (ALP) and alanine aminotransferase (ALT) and liver lipid peroxides in CCl4-treated Wistar rats. The natural antioxidant enzymes such catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) and lipid peroxidation were significantly improved after the treatment of S.roxburghii. In this study, the results indicate that S.roxburghii can inhibit lipid peroxidation and improve the activities of antioxidant enzymes. The quantitative analysis of biochemical parameters, marker enzymes, antioxidant activities and histological study suggest the administration of the stem bark extract of S.roxburghii protecting the liver from CCl4 toxicity.

Quantitative Determination of Stilbenoids and Dihydroisocoumarins in Shorea roxburghii and Evaluation of Their Hepatoprotective Activity.

A simultaneous quantitative analytical method for 13 stilbenoids including (−)-hopeaphenol (1), (+)-isohopeaphenol (2), hemsleyanol D (3), (−)-ampelopsin H (4), vaticanols A (5), E (6), and G (7), (+)-α-viniferin (8), pauciflorol A (9), hopeafuran (10), (−)-balanocarpol (11), (−)-ampelopsin A (12), and trans-resveratrol 10-C-β-d-glucopyranoside (13), and two dihydroisocoumarins, phayomphenols A1 (14) and A2 (15) in the extract of Shorea roxburghii (dipterocarpaceae) was developed. According to the established protocol, distributions of these 15 polyphenols (1–15) in the bark and wood parts of S. roxburghii and a related plant Cotylelobium melanoxylon were evaluated. In addition, the principal polyphenols (1, 2, 8, 13–15) exhibited hepatoprotective effects against d-galactosamine (d-galN)/lipopolysaccharide (LPS)-induced liver injury in mice at a dose of 100 or 200 mg/kg, p.o. To characterize the mechanisms of action, the isolates were examined in in vitro studies assessing their effects on (i) d-GalN-induced cytotoxicity in primary cultured mouse hepatocytes; (ii) LPS-induced nitric oxide (NO) production in mouse peritoneal macrophages; and (iii) tumor necrosis factor-α (TNF-α)-induced cytotoxicity in L929 cells. The mechanisms of action of these polyphenols (1, 2, and 8) were suggested to be dependent on the inhibition of LPS-induced macrophage activation and reduction of sensitivity of hepatocytes to TNF-α. However, none of the isolates reduced the cytotoxicity caused by d-GalN.

Subcritical Water Extraction of Resveratrol from Barks of Shorea Roxburghii G. Don.

This study investigated subcritical water extraction of trans-resveratrol and its glycosylated form, trans-piceid, from barks of Shorea roxburghii G. Don. The effects of extraction temperature (100-190°C) and water flow rate (2-4 mL/min) at the pressure of 10 MPa were determined on the amounts of compounds extracted. The amount of trans-resveratrol and trans-piceid in the extracts increased with increasing temperature and flow rate, although the increase in flow rate from 3 to 4 mL/min had no significant effect on the extraction yield. Thus the flow rate of 3 mL/min was taken to be the most suitable. At suitable condition (190°C, 3 mL/min), the amount of trans-resveratrol and trans-piceid were 23.18 and 350.28 μg/g dry weight, respectively. With equal extraction duration, the amount of trans-resveratrol and trans-piceid compound obtained from extraction using 190°C subcritical water were higher than those from extractions with ambient water and 80% ethanol.

Tropical tree water use under seasonal waterlogging and drought in central Cambodia

Summary In central Cambodia, rapid growing non-endemic species are planted for future timber production. However, less is understood about the impact of the introduction of non-endemic species on the transpiration characteristics of the forest, which has been composed of native species that adapted to the highly seasonal environments. Sap flux of two native and one non-endemic tree species in central Cambodia was measured to reveal its seasonal trends and variability in the Monsoon Asia region. Measurements were carried out in a 10- to 15-year-old forest in the dry and rainy seasons that were defined by differing rainfall patterns. The seasonal trend in depth to water table differed from that of rainfall; groundwater table depth reached zero late in the rainy season and increased gradually after the onset of the dry season. The ratio of sap flux to an equilibrium evaporation condition of the native species, Popel ( Shorea roxburghii ), showed a sharp decline at the end of the dry season, whereas that of a non-endemic species, eucalyptus ( Eucalyptus camaldulensis ), decreased in the mid rainy season while Tbeng ( Dipterocarpus obtusifolius ) did not show a clear trend. The ratio of sap flux to an equilibrium evaporation was negatively correlated with the depth to water table in Popel, but was positively correlated in eucalyptus, possibly because of the negative effects of flooding. In addition to the large seasonal variation, intra-species variation in sap flux was also large and was a major controlling factor for tree-level water uptake at this young forest site in both dry and rainy seasons. In conclusion, the transpiration characteristics of this forest were species-specific and were controlled more by the fluctuating depths to groundwater rather than the onset of the rainy/dry seasons defined by rainfall events.

Antioxidant activity of the stem bark of Shorea roxburghii and its silver reducing power

A detailed study has been performed on the antioxidant activity of the acetone and methanol extracts of the stem bark of the plant, Shorea roxburghii. The total phenolic content and antioxidant activity of the extracts were determined by DPPH, radical scavenging, ferric ion reducing power, hydroxyl radical, ABTS. radical scavenging and hydrogen peroxide scavenging activities. Reducing efficiency of the S. roxburghii towards silver nanoparticles has been evaluated using surface plasmon resonance and transmission electron microscope. Spherical shapes of particles with 4–50 nm have been reported. Formation of silver nanoparticles ascertains the role of the water soluble phenolic compounds present in S. roxburghii. Both acetone and methanol extracts of S. roxburghii stem bark was found to be a potent antioxidant. This work provides a scientific support for the high antioxidant activity of this plant and thus it may find potential applications in the treatment of the diseases caused by free radical. The extract of this plant could be used as a green reducing agent for the synthesis of Ag nanoparticles.

EXPLAINING RARITY OF THE NARROWLY ENDEMIC DIPTEROCARPUS CF. CONDORENSIS BY IN SITU PHYSIOLOGICAL MEASUREMENTS

Comparative physiological attributes, obtained by chlorophyll fluorescence and gas exchange techniques, of restricted Dipterocarpus cf. condorensis and widespread Shorea roxburghii species that are actually co-located in Ta Kou Nature Reserve - Binh Thuan Province, provided essential information for understanding rarity of D. condorensis. The narrowly endemic D. condorensis had similar photosynthetic performance to the locally abundant S. roxburghii in more common habitats in which ground water tables are deep (>20m), but had significantly higher photosynthetic activities in its specific habitat, where the ground water level is shallow (<10m). These differences are probably the consequence of evolutionary trade-offs, and represent specializations of the endemic D. condorensis which is only successful in habitat where the ground water is accessible. However, while adaptive in this habitat, these traits may reduce success in other more common habitats in this region.

Reproductive ecology of Shorea roxburghii G. Don (Dipterocarpaceae), an Endangered semievergreen species tree of peninsular India

Shorea roxburghii is an Endangered semievergreen tree species restricted to peninsular India in the Eastern Ghats. Leaf shedding and leaf flushing are annual events while flowering is not annual, but when it does flower, in March, it shows massive blooming. Massive blooming, drooping inflorescence with pendulous flowers, ample pollen production, gradual pollen release as a function of anther appendage and aerodynamic pollen grains - all suggest anemophily. The characteristics of nectar secretion, hexose-rich sugars and amino acids in nectar are additional adaptations for entomophily. The plant is functionally self-incompatible, obligately outcrossing and ambophilous. The natural fruit set does not exceed 15% despite the plant being ambophilous. Scarabaeid beetle by causing flower damage and bruchid beetle by using buds, flowers and fruits for breeding greatly affect fruit set rate and thus the success of sexual reproduction in this plant species is also affected. Seeds are non-dormant, the embryo is chlorophyllous while the fruits are on the plant. Healthy seeds germinate as soon as they reach the forest floor but their establishment is seemingly affected by resource constraints due to the rocky habitat. The study suggests that non-annual flowering, massive flowering for a short period, high bud/flower and fruit infestation rate, absence of seed dormancy and rocky habitat could attribute to the endangered status of S. roxburghii.