Accession in Centella asiatica; Current Understanding and Future Knowledge

Centella asiatica is described as a potential cure-all because of its wide usage. The accessions in Centella asiatica make standardisation important before using it. In Malaysia alone, there are more than 15 accessions of Centella asiatica with each having variation in their secondary metabolites. There are several reports from India to Korea, from Madagascar to Malaysia and from Thailand to South Africa about variations in chemical profiling of secondary metabolites and the reasons for these variations in Centella asiatica. Despite all these reports, there has been no attempt to bring all these variations together and discuss them under one heading resulting into scattered information about accession in Centella asiatica. In this review, we discuss the impact of accessions in Centella asiatica and what more need to be done to our knowledge of accession in Centella asiatica

Exploring the Acetone Evaporation and Airborne Neurotoxicity Bioassay Against Adult Mosquito in the Enclosed Environment of Peet Grady Chamber

Mosquito has comprehensive and sensitive olfactory neuro-sensory located at antenna utilized for detecting airborne organic compounds in search of blood host. Mosquito is also known to have similar neurotransmitters function with human at neural synapses e.g. acetylcholinesterase, esterases and oxidases enzymes. Thus, there is potential use mosquito in predicting neurotoxicity of exogenic volatile organic compounds (VOC) e.g. manufactured acetone. Hence, the study evaluates the suitability to conduct bioassay of VOC neurotoxicity against mosquito in Peet Grady chamber that is commonly used for insecticidal bioassay. Acetone as the representative of VOC is easily evaporized at laboratory temperature of 26 to 29 °C without heating. The acetone evaporation profile on liquid surface and porous solid surface under the Peet Grady chamber is studied to ascertain the consistency of vaporization rate with homogenized distribution. The study showed the acetone has shown consistent vaporization rate of 23 mg/min from liquid surface and 116.3 mg/min from porous surface (filter paper) without heating, in a linear regression of very high positive correlation (r = 1.000) between time and mass of acetone vaporized. However, the non-homogenized distribution of acetone vapours in the Peet Grady chamber directly affected the accuracy to elucidate the neurotoxicity bioassay against mosquito in term of mosquito knockdown. The study suggests the positioning of mosquitoes in the Peet Grady chamber should be lower than the point of acetone vaporization, whereby the mosquitoes are knockdown by acetone vapours within the 20th minute upon reaching concentration of 170.3 to 196.1 ppm

Synthesis, characterization and cytotoxicity studies of nanocrystalline cellulose from the production waste of rubber-wood and kenaf-bast fibers

In the present study, nanocrystalline cellulose (NCC) was successfully prepared from raw rubberwood fiber (RRaw) and raw Kenaf-bast fiber (KRaw) via a series of multi-step chemical-mechanical purification techniques, namely, alkalization treatment, hydrogen peroxide bleaching and acid hydrolysis. The obtained nanocellulose yields were 27.51% and 32.53% for RRaw and KRaw, respectively. The crystallinity index of the RRaw and KRaw based nanocellulose increased from 61.21% to 74.34% and 54.12% to 73.19%, respectively, after acid hydrolysis. Morphological characterization by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) clearly showed the formation of rod-shaped NCC with an average diameter of 5.14 ± 1.91 nm and 5.27 ± 2.38 nm for RRaw and KRaw, respectively. Their size distributions significantly reduced compared to raw cellulose biomass fiber and extracted cellulose (EC). Furthermore, changes in the Fourier transform-infrared (FTIR) peaks showed that amorphous regions (e.g. hemicelluloses and lignin) were successfully removed from the fibre surface. The thermogravimetric analysis (TGA) of as-synthesized NCC confirmed its thermostability. Cytotoxicity tests demonstrated that NCC did not exhibit cellular toxicity upon exposure to macrophages (RAW 264.7) and HaCaT cells up to 700 µg mL−1. © 2019 Elsevier Lt