Antioxidant, Cytotoxic and α-Glucosidase Inhibitory Activities of Compounds isolated from the Twig Extracts of Maclura fruticosa

Abstract

The first phytochemical investigation of the twig extracts of Maclura fruticosa led to the isolation and identification of a new xanthone, maclurafruticosone (1), together with 14 known compounds (2-15). All compounds were elucidated using spectroscopic methods as well as through comparisons made with data reported in the literature. Some isolated compounds were evaluated for their antioxidant, α-glucosidase inhibitory and cytotoxic activities. Compound 4, 6 and 7 showed significant antioxidant activity against DPPH radicals with IC 50 values ranging from 7.45-16.12 µM. Compound 4 also exhibited potent activity against ABTS + scavenging activity with an IC 50 value of 0.55 ± 0.01 µM which was better than positive control (ascorbic acid, IC 50 2.35 ± 0.17 µM). Compound 12 showed significant α-glucosidase inhibitory activity with an IC 50 value of 0.02 ± 0.37 mM. Compounds 5, 6 and 12 showed weak cytotoxic activities against a colon cancer cell line with IC 50 values ranging from 22.35-47.62 µM.

A comprehensive review on xanthone derivatives as α-glucosidase inhibitors

“…The simplest protocols involve a direct incubation of the three reactants (enzyme, inhibitor and substrate) at 37 C during 15e30 min and the absorbance is monitored during that period of time [40e44]. Nevertheless, a pre-incubation period of the enzyme and the inhibitors, before the addition of the substrate is also frequently performed, during 5 min [45], 10 min [46,47], 15 min [48e54] and 30 min [55e61]. In these cases, incubations prior the addition of substrate occur also at 37 C in periods of 5e60 min.…”

“…Oxygenated and prenylated xanthones are not restricted to the Garcinia species. A wide variety of derivatives have been isolated from other natural sources, which inhibitory effects against aglucosidase activity are depicted in Table 6 [41,43,47,50,51,53]. (Table 7).…”

“…Moreover, the inhibitory and binding mechanisms of 1,3-dihydroxyxanthone 25 and 1,3,7-trihydroxyxanthone 50 toward yeast's a-glucosidase activity were elucidated by experimental and docking studies, which indicate a noncompetitive type of inhibition for both xanthones, with loss of a-helix within the secondary structure of a-glucosidase, an important feature for the inhibitory process [58]. Furthermore, a synergistic effect of these two compounds were observed, suggesting that there may exist Table 6 Inhibitory effect of isolated xanthones 50, 65, 69, 81, 127 and 146e187 from the roots of Cudrania tricuspidata [43], stem of Securidaca inappendiculata [50], twigs of Maclura fruticosa [47], root barks of Cratoxylum cochinchinense [41], cultures of Aspergillus versicolor [53], deep-sea-derived fungus Penicillium chrysogenum SCSIO 41001 [51] on…”

“…[47]. Recently,Li et al isolated from the root barks of Cratoxylum cochinchinense a series of twelve prenyl-type polyoxygenated xanthones 65, 69, 127 and 171e179 and tested their aglucosidase inhibitory activity and kinetic profile…”

Antioxidant neolignans from the twigs and leaves of Mitrephora wangii HU

“…The determination of ABTS •+ scavenging activity was carried out using a modified literature procedure [31]. ABTS •+ were produced by reacting a 7 mM stock solution of ABTS with 2.45 mM potassium persulfate (K 2 S 2 O 8 ) and allowing the mixture to stand in the dark at room temperature for 16 h before use.…”