Triterpene Production in Centella Asiatica (L.) Urban (Pegaga) Callus and Cell Suspension Cultures

Centella asiatica or locally known as ‘Pegaga’ is one of the most common medicinal plants used by diverse ancient cultures and tribal groups. Its medicinal values are mainly attributed to the presence of the triterpene constituents. As there is still no information available on the triterpene production in cultured tissues, studies were carried out in determining the triterpene distribution particularly asiatic acid, madecassic acid, asiaticoside and madecassoside in intact plants of the twelve accessions of C. asiatica collected throughout Malaysia as well as in the callus and cell suspension cultures. Results obtained from the studies revealed that twelve accessions of C. asiatica differed both in their morphologies and their triterpene contents. The triterpenes constituents were detected at a range of 0.134 to 1.655 mg/g dry weight in the whole plant intact tissues. Triterpenes were also successfully detected in the callus (0.014 to 0.773 mg/g dry weight) and cell suspension cultures (0.005 to 0.084 mg/g dry weight), the amount that were lower than that produced in the intact tissues. However, manipulating the physical culture conditions, feeding of precursor, elicitation as well as amino acid addition managed to increase the triterpenes content in cultured tissues. Studies on the effects of the medium composition show that full strength of the basal Murashige and Skoog medium supplemented with B5 vitamins and sucrose (3-4%) increased the triterpenes content in both callus and cell suspension cultures. An interaction of auxincytokinin has observed being important for both callus and cell suspension cultures in enhancing triterpenes production. Higher triterpenes content was obtained in callus treated with 2,4-D and kinetin while the combination of kinetin and dicamba enhanced the triterpenes production in cell suspension cultures. The precursor-feeding studies revealed that lower concentrations of squalene (0.16 mg/L in callus and 0.8 mg/L in cells) were preferred for triterpenes production. Squalene at 0.16 mg/L had successfully triggered the production of madecassoside, asiaticoside and madecassic acid in callus cultures while asiatic acid and madecassic acid content was increased in cells treated with 0.8 mg/L squalene. The elicitor studies exhibited that the different elicitors showed distinctive effects on triterpenes production. Nevertheless, supplementation of succinic acid at 3 and 4 mg/L was found the best in increasing the triterpenes production in callus and cell suspension cultures, respectively. Addition of amino acid into the culture media was also found to promote the triterpenes production in in vitro cultures. The study further concluded that the combinations of the optimized factors namely medium composition, precursor feeding, elicitation and amino acid addition is a very useful strategy in enhancing the triterpenes production particularly the asiatic acid and madecassic acid in in vitro cultures of C. asiatica

Characterization Of Spatial Variability Of Soil Engineering Properties At USM Engineering Campus

Studies on the spatial variability of soil engineering properties are limited in the south-east Asia. Understanding the variability of soil properties is significant to land management practices including planning and adopting conservation works for soil erosion, slope stability, landslide control and soil hydrological response modeling. This study examines the spatial variability of soil engineering properties (moisture content, bulk density, particle size distribution, organic content and specific gravity) in a flat region under tropical climate using geostatistical and statistical methods. Soil samples were taken from a 137 ha area of the Universiti Sains Malaysia. The study area was divided into a number of geo-grid reference points and soil samples were collected at grid intersection points. The Global Positioning System (GPS) was used for locating the sample position. Large spatial variability of soil fines content and moisture content were found to exist in the study area and the degree of variability was heterogeneous among different soil properties. About 74–84% of the observed total variability in soil properties was due to spatial structure. All the soil properties tested, exhibited strong spatial dependency and were spatial dependent up to distances of 181–256m. The study indicated geostatistical analysis in conjunction with conventional statistical analysis could reveal spatial variability nature of soil properties and the causes behind the variability. The variability of the soil properties observed is largely due to topographic conditions and land disturbances

Bioassay-Guided Isolation of Cytotoxic Cycloartane Triterpenoid Glycosides from the Traditionally Used Medicinal Plant Leea indica

Leea indica is a medicinal plant used traditionally to cure cancer. In this study, the cytotoxic compounds of L. indica were isolated using bioassay-guided approach. Two cycloartane triterpenoid glycosides, mollic acid arabinoside (MAA) and mollic acid xyloside (MAX), were firstly isolated from L. indica. They inhibited the growth of Ca Ski cervical cancer cells with IC50 of 19.21 μM (MAA) and 33.33 μM (MAX). MRC5 normal cell line was used to calculate selectivity index. MAA and MAX were about 8 and 4 times more cytotoxic to Ca Ski cells compared to MRC5. The cytotoxicity of MAA was characterized by both cytostatic and cytocidal effects. MAA decreased the expression of proliferative cell nuclear antigen, increased sub-G1 cells, and arrested cells in S and G2/M phases. This study provides the evidence for the ethnomedicinal use of L. indica and paves the way for future mechanism studies on the anticancer effects of MAA

Electrospun SnO2-CuO semiconductor composite nanofibers and its electrochemical properties

Composite metal oxide had attracted attention across numerous fields of application due to their synergic combination of properties from their single constituents. Further modification of composite metal oxide into nanostructure, especially 1-dimensional structure was proven to further improve active surface area, carrier transport properties, etc. In this study, a n-type p-type SnO2-CuO composite nanofibers was synthesized through multi-needle electrospinning techniques. The FESEM confirmed the 1-dimensional nanostructures with diameter>100nm whereas XRD showed the coexistence of both SnO2 and CuO crystallite phases within the SnO2-CuO composite. The electrochemical properties of the synthesized samples were subsequently analyzed, concluding that SnO2-CuO composite improved the voltage range of SnO2 as well as the conductivity of the CuO nanofibers. However, from the perspective of the overall performance, the advantages of SnO2 was balanced out by the deficient of CuO, with specific capacity of 249.1F/g for SnO2-CuO, greater than CuO (104.4F/g) but lower than SnO2 (350.4F/g). Altering the ratio of Sn:Cu would be favorable to further improve the performance of the SnO2-CuO material system

Metal oxide nanofibers in solar cells

The motivation to improve the performance of sensitized photovoltaic (PV) cells by enhancing both the surface area and carrier diffusion properties of its photoanode had drawn attention toward utilizing metal oxide nanofibers (NFs). Owing to the anisotropic carrier transport characteristic, NFs had surpassed the nanoparticles analog in achieving higher photoconversion efficiency (PCE) in sensitized PV while preserving the benefit of high surface area. However, the higher density of delocalized trap states in nanostructured materials, compared to the bulk materials, hampered further improvement in the PCE of NF-based sensitized PV cells. This chapter offers a brief explanation of the photoconversion mechanism of sensitized PV cells, followed by a discussion of the importance of utilizing metal oxide NFs as the charge extractor for this specific application. Details on the formation of delocalized trap states and how it impairs the carrier diffusion coefficient are provided. Some techniques for eradicating the effect brought about by the delocalized trap states are offered and reviewed, and challenges for future development of metal oxide NF-based sensitized PV cells are discussed

Effect of Garlic and Turmeric Powders on In Vitro Digestibility of the Cooked Rice

Consumers nowadays are interested in foods with low glycemic index (GI) and high indigestible carbohydrate content. In Asia, white rice is the staple food and is generally considered as a readily digestible and high GI food. Occasionally, white rice is cooked by mixing with other ingredients such as herbs and spices. This study is carried out to determine the total phenolic content and the effect of in vitro digestibility on cooked white rice with added garlic and turmeric powders. Rice cooked with addition of turmeric powder (3 % w/w) showed the highest total phenolic content (92.02 mg GAE/100 g) among all the cooked rice samples. The effect of incorporating garlic powder (3 % w/w) and turmeric powder (3 % w/w) into the rice preparation was determined using an in vitro digestion protocol. Results show that by incorporating either garlic or turmeric powder into the rice, starch digestibility was significantly reduced. Rice with added turmeric powder showed a greater reduction in digestibility with significantly lower fraction of rapidly digestible starch (41.5 %; white rice 57.6 %) beside higher fraction of slowly digestible starch (36.1 %; white rice 28.4 %) and resistant starch fraction (22.6 %; white rice 14%). Overall, both spices were able to inhibit starch digestion which can be considered as a potential ingredient in lowering starch digestibility in the cooked rice

The modified Gompertz model demonstrates a variable growth rate between two Centella asiatica phenotypes

Centella asiatica, a weakly aromatic plant that flourishes in wet tropical and sub-tropical areas as a medicinal species since ancient times. It contained important terpenoids that impart important medicinal values. Currently, studies on the terpenoid content of various Centella asiatica phenotypes have shown not only variable content but variable growth rates of different phenotypes that can affect future selection of phenotypes. The use of mathematical growth modelling can reveal important growth constants and discriminate between faster and slower growth phenotypes. Two Centella asiatica phenotypes from South Africa is modelled using the modified Gompertz model and the results showed that the C. asiatica Type-1 exhibited a faster growth rates and a shorter lag period at 0.152 day-1 and 2.313 day than another phenotype; C. asiatica Type 2 with a growth rate and a lag period of 0.067 day-1 and 3.363 day, respectively. The data indicates that different phenotypes of C. asiatica can have different growth rates and lag period and this can be important for selection of phenotypes to be used as the best bioactive peptides producer

Modelling the growth kinetics of callus cultures from the seedling of Jatropha curcas L. according to the modified Gompertz model

One of the most important preliminary investigation of callus attributes is the growth characteristics. Most often than not, callus growth curve is sigmoidal in characteristics. In this work, we model callus growth from the seedling of Jatropha curcas L. according to the modified Gompertz model from published literature to acquire essential growth constants. These growth constants can be obtained with better precision using model such as the modified Gompertz. Parameters obtained from the fitting exercise were maximum callus growth rate (μm), lag time (l) and maximal callus production (Ymax) of 0.193 d-1, 2.91 days and 0.38 g callus/25 mL culture, respectively. Growth parameter constants extracted from the modeling exercise will be helpful for additional secondary modelling implicating the consequence of media conditions as well as other factors on the growth of callus from this plant