A Study of the Effects of Azadirachtin on Specific Tissues in the Locust, Schistocerca gregaria

Azadirachtin was isolated from the seeds of the neem tree (Azadirachta indica) by solvent extraction and flash column chromatography. The recrystallised material was characterised by chromatography, NMR and melting point, and was found to have a purity of >95%. The yield, from Sri Lankan neem seeds, was 0.065% w/w. The pure compound was used to prepare the reduced derivative (22,23) dihydroazadirachtin and (22,23-3H2)- dihydroazadirachtin was also commercially prepared for tracer and metabolic studies. The radiolabelled tracer was used to follow tissue uptake, metabolism and excretion in the locust Schistocerca gregaria. It was found that an injected dose of the tracer was removed with great speed from the haemolymph, apparently by carrier-mediated specific mechanisms, into many of the locust tissues. Unlabelled analogues, injected in large excess, inhibited the clearance of the tracer to different extents and the results suggested that azadirachtin and its dihydro derivative have different affinities for the uptake mechanism. Radio-labelled dihydroazadirachtin applied topically to the locusts was shown to penetrate the insect to only a limited extent. A large fraction of the tracer was absorbed into the fat body as well as into gut, Malpighian tubules and nervous tissue. Binding of the dihydroazadirachtin was persistent and not easily displaced. There was no evidence of active excretion of dihydroazadirachtin by the Malpighian tubules. Metabolism of the dihydroazadirachtin was slow, and largely restricted to fat body and crop. Attempts, in vivo and in vitro, to show an effect of azadirachtin on Malpighian tubule function in a) water secretion and b) clearance of the sulphonic acid dye, amaranth, were unsuccessful. 3H-glycine and 35S-cysteine were used as tracers to examine the effects of azadirachtin on the incorporation of these amino acids into the protein and peptides in various tissues both in vivo and in vitro. The tissues examined were fat body, ovary, gut, brain and corpus cardiacum. It was found that the terpenoid eliminated the stimulatory effects of crude neurohormonal extracts from corpus cardiacum on protein synthesis in fat body and ovary, but had no effect on basal, unstimulated synthesis. On the other hand, the azadirachtin did not inhibit the stimulation of protein synthesis in the fat body due to application of pure juvenile hormone, suggesting that the effects on protein synthesis were differential. Azadirachtin appeared to have a direct inhibitory effect on protein biosynthesis in the mid-gut, and this could partly account for observed secondary antifeedant effects. Incorporation of 35S-cysteine into the polypeptides, including glutathione, synthesised in both brain and corpus cardiacum was strongly inhibited by azadirachtin. This suggested that many of the biological effects of the terpenoid are due to interference with neuroendocrine processes, most of which are mediated by peptide hormones

Medicinal plants commonly used against cancer in traditional medicine formulae in Sri Lanka

Cancer is a global burden. In low- and middle-income countries around 70% of deaths are due to cancer. For a number of years natural products have been a good source of agents for combatting cancer and plants have played a huge role in anti-cancer product development. For many centuries, indigenous cultures around the world have used traditional herbal medicine to treat a myriad of diseases including cancer. In Sri Lanka, a number of plants have been reported to have anti-cancer properties and some of the commonly used plants are described in this review with an account of their compounds and modes of action. Only a small number of the plants in Sri Lanka have been tested for their bioactivity and more research is required to determine their medicinal activity with the aim of developing novel drugs to fight this disease. Keywords: Plants with anti-cancer properties, Traditional medicine, Cance

Natural Antibrowning Agents against Polyphenol Oxidase Activity in Annona muricata and Musa acuminata

Fresh-cut fruits and vegetables emerge as popular food for consumers in retail markets. However, a loss of millions of dollars yearly to the food industry has been due to discoloration of fruits and vegetables caused by a pronounced reaction called enzymatic browning, which is caused by the activity of the polyphenol oxidase enzyme present in most of the fruits and vegetables. The main objective of this study was to investigate the natural antibrowning effects of the aqueous extract of ginger and essential oil of cinnamon bark on PPO enzymatic activity in Annona muricata (katu anoda) and Musa acuminata (ash plantains), which are considered to be widely consumable by Sri Lankans due to its respective health benefits. The antibrowning activity analyzed using a UV-visible spectrophotometer at a wavelength of 525 nm showed that cinnamon bark oil of 0.0035 g/mL had a % inhibitory activity of 51.97 percent on PPO activity in Annona muricata and 49.51 percent on PPO activity in Musa acuminata, while the aqueous extract of ginger of 0.091 g/mL had a % inhibitory activity of 60.90 percent on PPO activity in Annona muricata and 48.10 percent on PPO activity in Musa acuminata, respectively. This study shows that cinnamon bark oil and ginger can be used as effective, natural, nontoxic antibrowning agents that can inhibit the activity of the PPO enzyme, thereby preventing the essence and nutritional benefits of fruits and vegetables

Molecular phylogeny and bioprospecting of Endolichenic Fungi (ELF) inhabiting in the lichens collected from a mangrove ecosystem in Sri Lanka.

Endolichenic fungi (ELF) are unexplored group of organisms as a source for the production of bioactive secondary metabolites with radical scavenging activity, antilipase and amylase inhibitory activities. Endolichenic fungi in lichens collected from mangrove or mangrove associated plants are least known for their fungal diversity and potential to produce bioactive compounds. A total of 171 ELF strains were isolated from the lichens collected from mangrove and mangrove associated plants in Puttalam lagoon. Out of this collection, 70 isolates were identified using rDNA-ITS region sequence homology to the GenBank accessions and a phylogenetic analysis was performed. Commonly isolated genera of ELF from lichens were Aspergillus, Byssochlamys, Talaromyces, Diaporthe, Phomopsis, Endomelanconiopsis, Schizophyllum, Cerrena, Trichoderma, Xylaria, Hypoxylon, Daldinia, Preussia, Sordaria, Neurospora, and Lasiodiplodia. In the present study, the effectiveness of ethyl acetate extracts of the ELF isolates were investigated against antioxidant activity, antilipase activity and α-amylase inhibition activity in in-vitro conditions. The results revealed that the extracts of Daldinia eschscholtzii, Diaporthe musigena and Sordaria sp. had the highest radical scavenging activity with smaller IC50 values (25 μg/mL to 31 μg/mL) compared to the IC50 values of BHT (76.50±1.47 μg/mL). Antilipase assay revealed that 13 extracts from ELF showed promising antiobesity activity ranged between 25% to 40%. Amylase inhibitory assay indicated that the test extracts do not contain antidiabetic secondary metabolites

Apoferritin and Dps as drug delivery vehicles: Some selected examples in oncology

Background: The ideal nanoparticle should be able to encapsulate either pharmaceutical agents or imaging probes so that it could treat or image clinical tumours by targeting the cancer site efficiently. Further, it would be an added advantage if it demonstrates: small size, built in targeting, biocompatibility and biodegradability. Ferritin, which is an endogenous self-assembling protein, stores iron and plays a role in iron homeostasis. When iron atoms are removed apoferritin (AFt) is formed which consists of a hollow shell where it can be used to load guest molecules. Due to its unique architecture, AFt has been investigated as a versatile carrier for tumour theranostic applications. DNA-binding protein from starved cells (Dps), which also belongs to the ferritin family, is a protein found only in prokaryotes. It is used to store iron and protect chromosomes from oxidative damage; because of its architecture, Dps could also be used as a delivery vehicle. Conclusions: Both these nano particles are promising in the field of oncology, especially due to their stability, solubility and biocompatibility features. Further their exterior surface can be modified for better tumour-targeting ability. More studies, are warranted to determine the immunogenicity, biodistribution, and clearance from the body. General perspective: This review discusses a few selected examples of the remarkable in vitro and in vivo studies that have been carried out in the recent past with the use of AFt and Dps in targeting and delivery of various pharmaceutical agents, natural products and imaging probes in the field of oncology