Chemical profile and antiacetylcholinesterase, antityrosinase, antioxidant and α-glucosidase inhibitory activity of Cynometra cauliflora L. leaves.

BACKGROUND: The aim of the current study was (i) to evaluate the bioactive potential of the leaf methanolic extract of Cynometra cauliflora L., along with its respective hexane, dichloromethane, ethyl acetate (EtOAc), n-butanol (n-BuOH) and aqueous fractions, in inhibiting the enzymes α-glucosidase, acetylcholinesterase (AChE) and tyrosinase as well as evaluating their antioxidant activities. (ii) In addition, in view of the limited published information regarding the metabolite profile of C. cauliflora, we further characterized the profiles of the EtOAc and n-BuOH fractions using liquid chromatography-diode array detection-electrospray ionization-tandem mass spectrometry. RESULTS: The leaf methanolic extract of C. cauliflora exhibited potent inhibition of all three enzymes and high antioxidant activity. The bioactivity was found to be concentrated in the EtOAc and n-BuOH fractions. A total of 18 compounds were identified in these bioactive fractions, comprising a procyanidin trimer, procyanidin tetramer, procyanidin hexamer, taxifolin pentoside, catechin, vitexin, isovitexin, kaempferol hexoside, quercetin pentoside, quercetin hexoside, apigenin-6-C-glucoside-8-C-glucoside, kaempferol-coumaroyl hexoside and isorhamnetin hexoside. CONCLUSION: The results indicated that C. cauliflora, the leaves in particular, is a rich source of bioactive compounds and could be beneficial for further development of high-value phytomedicinal preparations and functional food products.

Anti- and pro-lipase activity of selected medicinal, herbal and aquatic plants, and structure elucidation of an anti-lipase compound.

Plants that help in slowing down the digestion of triacylglycerols (TAGs) in the pancreas and small intestine of humans play an important role in the reduction of obesity. On the other hand, there may be plants or plant parts that stimulate intestinal lipolytic activity, thus contributing to greater TAG assimilation. The aim of this study was to evaluate the aqueous methanolic extracts of ninety eight (98) medicinal, herbal and aquatic plant materials from Malaysia for their effect on porcine pancreatic lipase (PPL) activity and to identify the structure of an anti-lipase compound from one of the sources. The degree of inhibition was also quantified as relative to orlistat activity against PPL (orlistat equivalents). Results revealed that while 19.4% of the extracts were found to have anti-lipase activity ≥80%, 12% were actually found to promote PPL activity. Twenty two percent (22.4%) exhibited moderate inhibition (41%-80%) and 2% were neutral toward PPL activity. The ripe fruit of Averrhoa carambola and the leaves of Archidendron jiringa (Jack) I.C Nielsen L. (jering), Cynometra cauliflora (nam-nam) and Aleurites moluccana (L.) Willd (candle nut/buah keras) had the highest (100%) anti-lipase activity and are equivalent to 0.11 µg orlistat/mL. Plants that stimulated lipase activity included Pimpinella anisum L. (aniseed/jintan manis), activating the enzyme by 186.5%. Kaempferol 3-O-rhamnoside was isolated from the ethyl acetate fraction of C. cauliflora leaves and found to be an active lipase inhibitor. The structure was elucidated using 1H-NMR, 13C-NMR and 2D-NMR analyses.

Use of two vertical injectors in place of a horizontal injector to improve the efficiency and stability of THAI in situ combustion process for producing heavy oils.

The current commercial technologies used to produce heavy oils and bitumen are carbon-, energy-, and wastewater-intensive. These make them to be out of line with the global efforts of decarbonisation. Alternative processes such as the toe-to-heel air injection (THAI) that works as an in situ combustion process that uses horizontal producer well to recover partially upgraded oil from heavy oils and bitumen reservoirs are needed. However, THAI is yet to be technically and economically well proven despite pilot and semi-commercial operations. Some studies concluded using field data that THAI is a low-oil-production-rate process. However, no study has thoroughly investigated the simultaneous effects of start-up methods and wells configuration on both the short and long terms stability, sustainability, and profitability of the process. Using THAI validated model, three models having a horizontal producer well arranged in staggered line drive with the injector wells are simulated using CMG STARS. Model A has two vertical injectors via which steam was used for pre-ignition heating, and models B and C each has a horizontal injector via which electrical heater and steam were respectively used for pre-ignition heating. It is found that during start-up, ultimately, steam injection instead of electrical heating should be used for the pre-ignition heating. Clearly, it is shown that model A has higher oil production rates after the increase in air flux and also has a higher cumulative oil recovery of 2350 cm3 which is greater than those of models B and C by 9.6% and 4.3% respectively. Thus, it can be concluded that for long-term projects, model A settings and wells configuration should be used. Although it is now discovered that the peak temperature cannot in all settings tell how healthy a combustion front is, it has revealed that model A does indeed have far more stable, safer, and efficient combustion front burning quality and propagation due to the maintenance of very high peak temperatures of mostly greater than 600 °C and very low concentrations of produced oxygen of lower than 0.4 mol% compared to up to 2.75 mol% in model C and 1 mol% in model B. Conclusively, since drilling of, and achieving uniform air distribution in horizontal injector (HI) well in actual field reservoir are costly and impracticable at the moment, and that electrical heating will require unphysically long time before mobilised fluids reach the HP well as heat transfer is mainly by conduction, these findings have shown decisively that the easy-and-cheaper-to-drill two vertical injector wells configured in a staggered line drive pattern with the horizontal producer should be used, and steam is thus to be used for pre-ignition heating.

Detailed investigations of the influence of catalyst packing porosity on the performance of THAI-CAPRI process for in situ catalytic upgrading of heavy oil and bitumen.

Heavy oils and bitumen are indispensable resources for a turbulent-free transition to a decarbonized global energy and economic system. This is because according to the analysis of the International Energy Agency's 2020 estimates, the world requires up to 770 billion barrels of oil from now to year 2040. However, BP's 2020 statistical review of world energy has shown that the global total reserves of the cheap-to-produce conventional oil are roughly only 520.2 billion barrels. This implies that the huge reserves of the practically unexploited difficult-and-costly-to-upgrade-and-produce heavy oils and bitumen must be immediately developed using advanced upgrading and extraction technologies which have greener credentials. Furthermore, in accordance with climate change mitigation strategies and to efficiently develop the heavy oils and bitumen resources, producers would like to maximize their upgrading within the reservoirs by using energy-efficient and environmentally friendly technologies such as the yet-to-be-fully-understood THAI-CAPRI process. The THAI-CAPRI process uses in situ combustion and in situ catalytic reactions to produce high-quality oil from heavy oils and bitumen reservoirs. However, prolonging catalyst life and effectiveness and maximizing catalytic reactions are a major challenge in the THAI-CAPRI process. Therefore, in this work, the first ever-detailed investigations of the effects of alumina-supported cobalt oxide-molybdenum oxide (CoMo/γ-Al2O3) catalyst packing porosity on the performance of the THAI-CAPRI process are performed through numerical simulations using CMG STARS. The key findings in this study include: the larger the catalyst packing porosity, the higher the accessible surface area for the mobilized oil to reach the inner coke-uncoated catalysts and thus the higher the API gravity and quality of the produced oil, which clearly indicated that sulphur and nitrogen heteroatoms were catalytically removed and replaced with hydrogen. Over the 290 min of combustion period, slightly more oil (i.e. an additional 0.43% oil originally in place (OOIP)) is recovered in the model which has the higher catalyst packing porosity. In other words, there is a cumulative oil production of 2330 cm3 when the catalyst packing porosity is 56% versus a cumulative oil production of 2300 cm3 in the model whose catalyst packing porosity is 45%. The larger the catalyst packing porosity, the lower the mass and thus cost of the catalyst required per m3 of annular space around the horizontal producer well. The peak temperature and the very small amount of produced oxygen are only marginally affected by the catalyst packing porosity, thereby implying that the extents of the combustion and thermal cracking reactions are respectively the same in both models. Thus, the higher upgrading achieved in the model whose catalyst packing porosity is 56% is purely due to the fact that the extent of the catalytic reactions in the model is larger than those in the model whose catalyst packing porosity is 45%.

Acetylcholinesterase and α-glucosidase inhibitory compounds from Callicarpa maingayi.

Phytochemical investigation on the soluble fractions of n-hexane and dichloromethane of methanolic leaves extract of the Callicarpa maingayi K. & G. led to the isolation of three triterpenoids [euscaphic acid (1), arjunic acid (2), and ursolic acid (3)] together with two flavones [apigenin (4) and acacetin (5)], two phytosterols [stigmasterol 3-O-ß-glycopyranoside (6) and sitosterol 3-O-ß-glycopyranoside (7)], and a fatty acid [n-hexacosanoic acid (8)]. Six (6) compounds (1, 2, 3, 4, 5, and 8) are reported for the first time from this species. Their structures were elucidated and identified by extensive NMR techniques, GC-MS and comparison with the previously reported literature. Compound 3 was found to displayed good inhibition against acetylcholinesterase with an IC50 value of 21.5 ± 0.022 µM, while 1 and 2 exhibited pronounced α-glucosidase inhibitory activity with IC50 values of 22.4 ± 0.016 µM and 24.9 ± 0.012 µM, respectively.

Impacts of Kinetics Scheme Used To Simulate Toe-to-Heel Air Injection (THAI) in Situ Combustion Method for Heavy Oil Upgrading and Production.

While simulating toe-to-heel air injection (THAI), which is a variant of conventional in situ combustion that uses a horizontal producer well to recover mobilized partially upgraded heavy oil, the chemical kinetics is one of the main sources of uncertainty because the hydrocarbon must be represented by the use of oil pseudo-components. There is, however, no study comparing the predictive capability of the different kinetics schemes used to simulate the THAI process. From the literature, it was determined that the thermal cracking kinetics schemes can be broadly divided into two: split and direct conversion schemes. Unlike the former, the latter does not depend on the selected stoichiometric coefficients of the products. It is concluded that by using a direct conversion scheme, the extent of uncertainty imposed by the kinetics is reduced as the stoichiometric coefficients of the products are known with certainty. Three models, P, G, and B, each with their own different kinetics schemes, were successfully validated against a three-dimensional combustion cell experiment. In models P and G, which do not take low-temperature oxidation (LTO) into account, the effect of oil pseudo-component combustion reactions is insignificant. For model B, which included LTO reactions, LTO was also found to be insignificant because only a small fraction of oxygen bypassed the combustion front and the combustion zone was maintained at temperatures of over 600°C. Therefore, in all the models, it is observed that coke deposition was due to the thermal cracking taking place ahead of the combustion zone. During the first phase of the combustion, peak temperature curves of models P, G, and B closely matched the experimental curve, albeit with some deviations by up to 100°C between 90 and 120 min. After the increase in the air injection flux, only the model P curve overlapped the experimental curve. The model P cumulative oil production curve deviated from the experimental one by only a relative error of 4.0% compared to deviations in models G and B by relative errors of 6.0 and 8.3%, respectively. Consequently, it follows that model P provided better predictions of the peak temperature and cumulative oil production. The same conclusion can be drawn with regard to the produced oxygen concentration and combustion front velocity. With regard to American Petroleum Institute (API) gravity, it is found that all the three models predicted very similar trends to the experiment, just like in the case of the oil production rate curves, and therefore, no model, in these two cases, can be singled out as the best. Also, all the models' predictions of the produced CO X concentration prior to the increase in the air flux closely match the experimental curve. There are, however, serious differences, especially by model P, from the reported experimental curve by up to 15% after the increase in the air flux.