Antidiabetic Activity of Momordica charantia L. and Mechanism of Insulin Secretion of 1-Butanol Soluble Part on Type 2 Diabetic Model Rats

The in vivo effects of fruit pulp juice (MC-PJ) of Momordica charantia and its 1-butanol soluble part (MC-BP) and aqueous soluble part (MC-AP) on blood glucose of type 2 diabetic rats were studied. In vitro insulin secretion in response to MC-BP and MC-AP from whole perfused pancreas was measured. For elucidating the mechanism of insulinotropic action, the insulin secretory activity of MC-BP in the presence of 11 mM glucose, 50 μM verapamil (Ca++ channel blocker), 8 mM diazoxide (K+ ATP channel opener) and 10 mM theophylline (cAMP phosphodiesterase inhibitor) were studied. Serum glucose was measured by glucose oxidase-peroxidase method and rat insulin was assayed by specific ELISA. In the in vivo study, MC-BP significantly opposed the rise of serum glucose compared to control at 105 min (p<0.05). Although the MC-AP and MC-PJ lowered the serum glucose both at 60 and 105 min, these were not statistically significant. In the in vitro study, only MC-BP produced 22-fold increase in insulin secretion from the perfused pancreas at nonstimulatory glucose level, which was significant (basal vs. MC-BP, 0.071±0.009 vs. 1.563±0.150 ng/ml, p<0.001). The MC-BP also enhanced the insulin secretion from the glucose-stimulated pancreas (p<0.001). The MC-BP induced insulin secretion was not affected in presence of diazoxide and verapamil. The obtained results also showed that MC-BP enhanced the insulin secretory effect of theophylline (p<0.001). The findings indicate that MC-BP has stimulatory effects on physiological pathways of insulin secretion which may underlie its reported antidiabetic action. Dhaka Univ. J. Pharm. Sci. 19(2): 111-117, 2020 (December)

Verbascum sinaiticum: A Rich Source of Antioxidant Phenylethanoid Glycosides

Background: The genus Verbascum is well documented for its antioxidant potential but Verbascum sinaiticum is comparatively less studied plant. The current study was carried out to search for antioxidant nutraceuticals from this species. Objective: To explore the antioxidant potential of Verbascum sinaiticum and to identify its active constituents. Methods: The methanolic extract of air-dried aerial part of the Verbascum sinaiticum was partitioned with hexane, chloroform and ethyl acetate. The water-soluble part of ethyl acetate afforded six phenylethanoid glycosides by repeated chromatography over Sephadex LH-20, silica gel and ODS columns. Antioxidant activity of solvent extracts and isolated constituents were evaluated by DPPH, ABTS and FRAP assays. Results: Six phenylethanoid glycosides was isolated and characterized as Verbascoside, Eukovoside, Martynoside, Jionoside D, Campneoside I and Campneoside II, from the most active fraction. Conclusion: Verbascum sinaiticum demonstrated prospective antioxidant activity. The watersoluble part of EtOAc (WSEAE) was found the most active extract whereas Verbascoside was identified as the most potent constituent. All isolated compounds exhibited significant antioxidant activity whereas their synergistic effect was found prominent in the parent fraction.

Biomass Characteristics and Their Effect on Membrane Bioreactor Fouling

Biomass characteristics are regarded as particularly influential for fouling in Membrane Bio-Reactors (MBRs). They primarily include the Mixed Liquor Suspended Solids (MLSS), the colloids and the Extracellular Polymeric Substances (EPS). Among them, the soluble part of EPS, which is also known as Soluble Microbial Products (SMP), is the most significant foulant, i.e., it is principally responsible for membrane fouling and affects all fundamental fouling indices, such as the Trans-Membrane Pressure (TMP) and the membrane resistance and permeability. Recent research in the field of MBRs, tends to consider the carbohydrate fraction of SMP (SMPc) the most important characteristic for fouling, mainly due to the hydrophilic and gelling properties, which are exhibited by polysaccharides and allow them to be easily attached on the membrane surface. Other wastewater and biomass characteristics, which affect indirectly membrane fouling, include temperature, viscosity, dissolved oxygen (DO), foaming, hydrophobicity and surface charge. The main methods employed for the characterization and assessment of biomass quality, in terms of filterability and fouling potential, can be divided into direct (such as FDT, SFI, TTF100, MFI, DFCM) or indirect (such as CST, TOC, PSA, RH) methods, and they are shortly presented in this review.

Isolation and Characterization of Two Cucurbitane Type Triterpenoid Glycocide from 1-Butanol Soluble Part of Momordica charantia Fruit Pulp Juice

Momordica charantia is a member of the Cucurbitaceae family having diverse biological activities. Two cucurbitane type triterpene glycoside have been isolated from 1-butanol soluble part of clear juice of M. charantia fruit pulp through column chromatography and HPLC. The isolated compounds were characterized as compound MC1 (3β, 7-O-β-glucopyranosyl-25-methoxy cucurbita –5-en-19-al) and compound MC2 (5β, 19-epoxy- 3- O-glucopyranosyl-25 methoxy cucurbita-6, 23-dien) with the help of UV Spectroscopy, Thin Layer Chromatography, IR Spectroscopy, 1H, 13C and dept-135 NMR. The proposed structures of the compounds were further confirmed by comparing the 13C-NMR values of the compounds with previous reported data. Dhaka Univ. J. Sci. 66(2): 145-149, 2018 (July)

Formiside and seco-formiside: lignin glycosides from leaves of Clerodendrum formicarum Gürke (Lamiaceae) from Cameroon

The ethanol soluble part of the leaves of Clerodendrum formicarum, a Lameacious plant of Cameroon, afforded two new lignin glycosides named formiside and seco-formiside. Structures of both the isolated constituents have been elucidated with the aid of 1D and 2D NMR spectroscopic techniques.

Characterization of styrene butadiene rubber and microwave devulcanized ground tire rubber composites

Ground tire rubber (GTR) was devulcanized by microwaves at the same heating rate (constant power) and different times of exposure. The devulcanized rubber (DV-R) and untreated GTR were characterized physically and thermally. Composite materials were prepared from different proportions of the GTR, which was used as a filler, and the DV-R, which was used as part of the styrene butadiene rubber (SBR) matrix, and by varying the exposure time of the microwave power. These composites were compared with a control sample that was prepared from virgin SBR. The sol content (soluble part) and Fourier transform infrared spectroscopy (FTIR) analyses of the devulcanized samples were examined to define the efficiency of devulcanization. The cure characteristics and tensile properties of the SBR composites were researched. In this study, it was found that using DV-R as part of the rubber matrix produced much better properties than using GTR as a filler, thereby showing the significant benefits of microwave devulcanization. At the DV-R content of 50 phr, the elongation at break of the DV-R 5 min/SBR composites increased to 445.06% from 217.25% for the GTR/SBR composites, i.e., the elongation at break was enhanced by 105% by the devulcanization of GTR. Scanning electron microscopy (SEM) photographs displayed a better interface coherence between the DV-R 5 min and SBR matrix than the GTR/SBR composites.

Water-soluble Constituents of the Heartwood of Streblus asper

A new lignan, (7′ R,8′ R)- threo-strebluslignanol-2- O-β-D-glucopyranoside, along with 8 known compounds (2–9) were isolated from the water-soluble part of the MeOH extract of the heartwood of Streblus asper. Their structures were elucidated through various spectroscopic methods, including 1D NMR (1H NMR, 13C NMR), 2D NMR (HMQC, HMBC, and NOESY), and HRMS. The stereochemistry at the chiral centers was determined using the CD spectrum, as well as analyses of coupling constants and optical rotation data. In the preliminary bioassay, the isolated compounds did not show anti-HBV activities in vitro using the HBV transfected HepG2.2.15 cell line.