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2′,4′-dihydroxy-6′-methoxy-3′,5′-dimethylchalcone (DMC) is a major compound in Cleistocalyx nervosum seed extract (CSE), which has been reported to have various biological activities, including anti-cancer activity. Therefore, this study attempted to evaluate whether DMC is a chemopreventive compound in CSE. Moreover, the preventive mechanisms of CSE and DMC in the DEN-induced early stages of hepatocarcinogenesis in rats were investigated. Male Wistar rats were intraperitoneally injected with DEN 50 mg/kg bw once a week for 8 weeks. Rats received CSE and DMC orally throughout the experiment. The number of glutathione S-transferase placental form (GST-P)-positive foci in the liver was measured. Furthermore, the preventive mechanisms of CSE and DMC on DEN-induced HCC, including cell proliferation and apoptosis, were investigated. Administering CSE at a dosage of 400 mg/kg bw and DMC at a dosage of 10 mg/kg bw significantly decreased the number and size of GST-P-positive foci and GST-P expression. In addition, DMC inhibited the development of preneoplastic lesions by decreasing cell proliferation and causing cell apoptosis; however, CSE inhibited the development of preneoplastic lesions by inducing cell apoptosis. In conclusion, DMC exhibited a cancer chemopreventive effect on the early stages of hepatocarcinogenesis by increasing cell apoptosis and reducing cell proliferation. [ABSTRACT FROM AUTHOR]

Garcinia schomburgkiana (locally known as Ma-dan) was studied to determine their phytochemical constituents by using gas chromatography-mass spectrometry. To obtain 12 extracts with a variety of nutrients and bioactive compounds, 4 parts (leaves, twigs, branches and roots) of Ma-dan were extracted with 3 different polarity solvents (CH2Cl2, Acetone and MeOH). According to the GC-MS analysis with both original and TMS-derivatized extracts, 51 known compounds (23 volatile compounds from original extracts and 28 non-volatile compounds from TMS-derivatized extracts) were detected. In addition, many beneficial compounds for the food and pharmaceutical industry such as benzoic acid, vanillin, citric acid, linoleic acid, oleic acid, protocatechuic acid, catechol, and phloroglucinol were found. [ABSTRACT FROM AUTHOR]

The Lewis acid organocatalytic system of lithium tetramethylene-tethered bis [ N -( N '-butylimidazol-2-ylidene)] N -heterocyclic carbene (1,4- bis NHC) including lithium benzyloxide and benzyl alcohol has been successfully utilized in the ring-opening polymerization (ROP) of ε-caprolactone (CL) for the first time. The catalytic performance of this organic catalyst in the synthesis of high-molecular-weight polymers was investigated via bulk polymerization using different combinations of tetramethylene-tethered bis [ N -( N '-butylimidazolium)] hexafluorophosphate (1,4- bis [Bim][PF 6 ]), benzyl alcohol (BnOH), and n -butyl lithium ( n BuLi) ([1,4- bis [Bim][PF 6 ]]/[BnOH]/[ n BuLi]) with the molar ratios of 0:2:2, 1:1:3, 1:2:3, and 1:2:4. The results showed that the molar ratio of 1:2:3 efficiently and rapidly initiated the bulk ROP of CL at room temperature with a high molar ratio of CL to 1,4- bis [Bim][PF 6 ] of 3000/1 and produced the highest number of average-molecular-weight ( M n ) poly(ε-caprolactone) (103,057 g mol -1 ) with the dispersity ( D̵ ) and %conversion of 1.73 and 98% in a short period of time (152 s). From comparative studies, the relative polymerization rates of the bulk ROP of CL with different [1,4- bis [Bim][PF 6 ]]/[BnOH]/[ n BuLi] molar ratios was determined in the following order: 1:2:4 > 1:1:3 > 1:2:3 > 0:2:2. For mechanistic investigation, the bulk ROP mechanism of CL with our organic catalyst was proposed through the intramolecular bis -lithium-carbene interaction pathway for 1,4- bis NHC 1,1,3 , 1,4- bis NHC 1,2,3 , and 1,4- bis NHC 1,2,4 systems.

In this work, we successfully synthesized high thermal stable 1,n- bis ( N -( N '-butylimidazolium)alkane bis hexafluorophosphates (1,n- bis [Bim][PF 6 ], n = 4, 6, 8, and 10) catalysts in 55-70% yields from imidazole which were applied as non-toxic DILs catalysts with 1-butanol as initiator for the bulk ROP of ε -caprolactone (CL) in the varied ratio of CL/ n BuOH/1,4- bis [Bim][PF 6 ] from 200/1.0/0.25-4.0 to 700/1.0/0.25-4.0 by mol%. The result found that the optimal ratio of CL/ n BuOH/1,4- bis [Bim][PF 6 ] 400/1.0/0.5 mol% at 120 °C for 72 h led to the polymerization conversions higher than 95%, with the molecular weight ( M w ) of PCL 20,130 g mol -1 ( Đ ~1.80). The polymerization rate of CL increased with the decreasing linker chain length of ionic liquids. Moreover, the mechanistic study was investigated by DFT using B3LYP (6-31G(d,p)) as basis set. The most plausible mechanism included the stepwise and coordination insertion in which the alkoxide insertion step is the rate-determining step.

The kinetics of ring-opening polymerization (ROP) of ε -caprolactone ( ε -CL) initiated by 1.0, 1.5 and 2.0 mol% of stannous(II) octoate/ n -hexanol (Sn(Oct) 2 / n -HexOH) wase successfully studied by non-isothermal differential scanning calorimetry (DSC) at heating rates of 5, 10, 15 and 20 °C/min. The DSC polymerization kinetic parameters of ε -CL were calculated using differential (Friedman) and integral isoconversional methods (Kissinger-Akahira-Sunose, KAS). The average activation energy ( E a ) values obtained from Friedman and KAS methods were in the range of 64.9-70.5 kJ/mol and 64.9-80.4 kJ/mol, respectively. The values of frequency factor ( A ) were determined from model fitting method using Avrami-Erofeev reaction model. The average values of A for the ROP of ε -CL initiated by 1.0, 1.5 and 2.0 mol% of Sn(Oct) 2 / n -HexOH (1:2) were 7.3x10 7 , 2.8x10 6 and 1.2x10 6 min -1 , respectively. From kinetics studied, the polymerization rate of ε -CL increased with increasing initiator concentration. The performance of Sn(Oct) 2 / n -HexOH in the synthesis of poly( ε -caprolactone) (PCL) was investigated by bulk polymerization at temperatures of 140, 160 and 180 °C. Sn(Oct) 2 / n -HexOH (1:2) could produce high number average molecular weight ( M n ‾ = 9.0 × 10 4 g/mol) and %yield (89%) of PCL in a short period of time at Sn(Oct) 2 concentration of 0.1 mol% and temperature of 160°C. The mechanism of the ROP of ε -CL with Sn(Oct) 2 / n -HexOH was proposed through the coordination-insertion mechanism., Competing Interests: No potential conflict of interest was reported by the authors., (© 2021 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

Garcinia schomburgkiana , locally known in Thailand as an edible fruit "Ma-dan", is a plant species of the Clusiaceae family which has been reported as sources of a variety of compounds with biological activities. In the phytochemical studies of Ma-dan, four xanthones were, for the very first time, isolated from the branch acetone extract of G. schomburgkiana . Their structures were determined through the analysis of spectroscopic data ( 1 H, 13 C-NMR, IR and MS) and the comparison with those previously reported. Dihydroosajaxanthone ( 1 ), an original synthetic xanthone, is reported herein for the first time as a naturally occurring xanthone, together with three known xanthones: xanthochymone A ( 2 ), 1,3,7-trihydroxy-2-(3-hydroxy-3-methylbutyl) xanthone ( 3 ) and 1,3,5,6-tetrahydroxyxanthone ( 4 ). These compounds, especially dihydroosajaxanthone ( 1 ), might be considered as chemotaxonomic markers of the Garcinia genus.