In order to evaluate the therapeutic potential of polyphenolic extracts from root bark of M. arboreus, we have determined the content of various polyphenols in aqueous and ethanol (EtOH) extract as well as two sub-fractions of the latter: ethyl acetate (EAc) and hexane (Hex). The total phenols, flavonoids, hydroxycinnamic acids and proanthocyanidins have been determined for all studied extracts/fractions by spectrophotometric methods. Both TP content (331.5 ± 2.5 mg GAE/g) and HCA content (201 ± 1.5 mg CAE/g) were determined to be the highest in EAc fraction of EtOH extract. All studied extracts were however determined to have a low content in flavonoids. The determination of antioxidant capacities of the studied extracts has also been performed by the following in vitro antioxidant tests: DPPH scavenging, phosphomolybdenum method and oxygen radical absorbance (ORACFl and ORACPRG) assay. The results of the DPPH free radical and ORACFl assays showed that there is no significant difference between the EAc fraction and Oligopin®, but the EAc fraction exhibited the highest antioxidant capacity as determined by the phosphomolybdenium method. In addition, the EtOH extract was determined to have the same antioxidant efficiency as the synthetic antioxidant BHT or commercial extract Oligopin® by phosphomolybdenum method. On the other hand, a positive correlation (r < 0.6) was found between different classes of polyphenols and the results of the phosphomolybdenum method, ORACFl as well as ORACPRG, except for the DPPH assay, for which a negative correlation was indicated (r < 0.62). Interestingly, it seems that the content in hydroxycinnamic acids played a big role in all assays with r < 0.9. According to the present study, EAc fraction and EtOH extract should be further studied for the potential use in the pharmaceutical and food industry.
Background: We have determined previously that the water extract of sugar maple bark contained an important quantity of a complex sugar. In this study, we investigated the organosolv pulping of pre-extracted bark to follow the acid conversion of sugars into major products, furfural and 5-hydroxymethyl-2-furfural (HMF), while comparing the structures of organosolv lignins. Methods: The bark particles were pre-extracted with an ethanol–water mixture or water only. The extractives-free barks were then converted into cellulosic pulp and lignin by a patented organosolv process. The composition of residual liquor was determined by using HPLC-UV. Results: The pre-extraction with water was more efficient for complex sugars recovery than with the ethanol–water system. HMF was determined to be more abundant in residual liquor than furfural after ethanol–water pre-extraction while their quantities were comparable in the residual liquor after water pre-extraction. The higher yield of HMF from ethanol–water pre-extracted bark (1.18%) than from water pre-extracted (0.69%) could be related to the efficiency of complex sugar removal during the pre-extraction step. Conclusions: The pre-extraction before pulping affected, at least in part, the composition of residual liquor in terms of HMF production. These results demonstrate how the bark can be converted into valuable products and intermediates for organic synthesis.
Due to its nature and structure, lignin is a very difficult
polymer
to electrospin without any additives as only a few studies reported
on the successful electrospinning of lignins in general and even more
limited for softwood lignins to date. This paper highlights the possibility
to use softwood organosolv lignin as a precursor for fiber electrospinning
without any polymer addition. We have successfully electrospun pure
organosolv softwood lignin into uniform, bead-free fibers. A concentration
of 57 wt % of lignin in dimethyl formamide was determined as optimal,
while other processing parameters (voltage, needle–collector
distance, flow rate, and humidity) were studied to improve the fiber
uniformity. We also studied the effects of minimum FeCl3 addition and demonstrated its efficiency in improving the processability.
Thus, the addition of 2 wt % FeCl3 allowed decreasing the
minimum fiber diameter from 400 to 200 nm. The addition of FeCl3 also resolved the problem of fiber fusion on the collector,
and it also allowed increasing the glass transition temperature of
lignin fibers. These results open a way to new applications of lignin,
such as 100% biosourced carbon fiber since no petroleum-sourced molecules
were used in this study.
Four new Δ12 ursene-type
pentacyclic triterpenes
containing the trans-feruloyl moiety (1–4), along with ursolic acid (5),
were isolated from a Myrianthus arboreus root bark
ethanol extract, after bioassay-guided subfractionation of its hexane
fraction. The structures of 1–4 were
established on the basis of the results of standard spectroscopic
analytical methods (IR, HRESIMS, GC-MS, 1D and 2D NMR). The compounds
3β-O-trans-feruloyl-2α,19α-dihydroxyurs-12-en-28-oic
acid (1), 2α-acetoxy-3β-O-trans-feruloyl-19α-hydroxyurs-12-en-28-oic
acid (3), and 5 were determined to decrease
the activity of hepatocellular glucose-6-phosphatase (G6Pase) and
to activate glycogen synthase (GS). Their action on G6Pase activity
implicated both Akt and AMPK activation. In addition, these compounds
were determined to stimulate GS via the phosphorylation of glycogen
synthase kinase-3. Compound 3 showed the most potent
effect in modulating glucose homeostasis in liver cells. This is the
first comprehensive report on novel phytochemical components of the
root bark extract of M. arboreus based on the isolation
of the principles responsible for its antidiabetic effects.
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