Pancreatic lipase inhibition activity of trilactone terpenes of Ginkgo biloba

The prevalence of obesity is increasing at an alarming rate, but, unfortunately, only a few drugs are currently available on the market. In the present study, the methanolic extract of Ginkgo biloba L. (Ginkgoaceae) was investigated as an inhibitor of pancreatic lipase (PL) in an attempt to explain its hypolipidaemic activity. In vitro assay of G. biloba leaves extract revealed a substantial PL inhibition activity (IC(50)?=?16.5 μg/mL). Further investigation was performed by employing theoretical docking simulations and experimental testing to uncover the active constituents responsible for G. biloba anti-lipase activity. Virtually, terpene trilactones, including ginkgolides and bilobalide, were found to fit within the binding pocket of PL via several attractive interactions with key amino acids. Experimentally, ginkgolides A, B, and bilobalide were found to inhibit PL significantly (IC(50)?=?22.9, 90.0, and 60.1 μg/mL, respectively). Our findings demonstrated that the hypolipidaemic effects of G. biloba extract can be attributed to the inhibition of PL by, at least in part, terpene trilactones. In conclusion, this work can be considered a new step towards the discovery of new natural safe hypolipidaemic PL inhibitors.     

Effect of n-3 and n-6 polyunsaturated fatty acids on lymphocyte proliferation, interleukin production and phospholipid fatty acids composition in type 2 diabetic and healthy subjects in Jordan people

Dietary lipid manipulation may affect a great number of immune parameters, such as lymphocyte proliferation, cytokine synthesis. In this study, lymphocytes of diabetic type 2 were incubated with different polyunsaturated fatty acid (docosahexaenoic, eicosapentaenoic, arachidonic acid) for investigated their effect on lymphoproliferation response, the concentration of interleukin 2 produced in each essay and phospholipid fatty acid composition of lymphocyte membrane. Our results found that the concanavalin A and insulin increase significantly the proliferative response while eicosapentaenoic, arachidonic and docosahexaenoic acid inhibited that by different degrees: 47%, 37% and 19%, respectively, for healthy subjects and 39%, 29% and 13% for diabetes. However, the concentration of IL-2 produced in presence of either docosahexaenoic, eicosapentaenoic or arachidonic acid was significantly reduced by 36%, 32% and 39%, respectively, in controls while 16%, 15% and 23%, respectively, in diabetics. On the other hand, the tested fatty acids demonstrated a major impact on the fatty acid composition of different phospholipid fractions of lymphocyte membrane but these fractions were different in their response to each fatty acid examined. For instance, the addition of docosahexaenoic acid to culture media was accompanied with a predominant composition of docosahexaenoic acid in phospholipid fractions. Also, our results showed a notable increased proportion of arachidonic, eicosapentaenoic and docosahexaenoic acids in control phospholipid fractions than those of diabetic.     

Efficacy of artificial seeds in the delivery of bioactive compounds to the seed dwelling larvae of Callosobruchus maculatus (Coleoptera: Bruchidae)

Artificial seeds offer an important method to assay the bioactivity of natural and synthetic compounds against insect larvae that develop within the cotyledons of seeds. Here, the efficacy of artificial seeds as a mechanism to deliver bioactive compounds to larvae of the bruchid beetle, Callosobruchus maculatus, was compared to that of black-eyed beans that had been imbibed with the same bioactive compounds: malachite green or the methanolic extract of neem (Azadirachta indica). Females laid an equivalent number of eggs on control artificial seeds in comparison with black-eyed beans, although egg-to-adult survival on artificial seeds was reduced. Manipulation of the hardness of artificial seeds influenced female oviposition decisions, with more eggs laid on the harder seeds, although seed hardness had no effect on egg-to-adult survival. Incorporation of neem extract or malachite green into the artificial seeds resulted in 100 % larval mortality, while larval mortality on seeds imbibed with neem extract or malachite green was between 50 and 70 %. This suggests incorporation of toxins into artificial seeds, produces a more sensitive assay of compound toxicity in comparison with the method of imbibing seeds and offers a useful method to study of seed–arthropod interactions.     

Effect of seed moisture content and d‐limonene on oviposition decisions of the seed beetle Callosobruchus maculatus

Callosobruchus maculatus (Fabricius) (Coleoptera: Bruchidae) is a cosmopolitan pest of stored pulses and legumes. Under legume storage conditions neither adults nor larvae drink, with larvae obtaining their hydration from metabolic water. However, lack of water limits female fecundity and longevity, thus females might be expected to preferentially oviposit on seeds with high moisture content so as to minimize water stress on their offspring. This was tested by offering females a choice of seeds that differed in relation to their level of water content. After controlling for differences in seed size, females were found to preferentially oviposit on the driest seeds. Offspring size and larval survival were equivalent on seeds that differed in moisture content, which in combination with the preference to lay on the driest seeds would indicate that the egg laying decisions of C. maculatus females do not function to minimize larval water stress. Analysis of the chemical volatiles released by seeds that differed in their moisture content revealed a greater level of d ‐limonene in the environment surrounding high moisture seeds. d ‐limonene has known anti‐herbivory properties, thus we suggest the observed female preference for dry seeds may be related to the observed difference in the level of d ‐limonene in the immediate vicinity of beans that differ with respect to their moisture content.