Antitrypanosomal activity of new semi-synthetic bergenin derivatives

Bergenin and 11-O-(4'-O-methyl galloyl)-bergenin, previously isolated from Crassula capitella extract, were used as starting materials for the synthesis of eight derivatives; four derivatives 2a-2d were synthesized from bergenin through the formation of ester derivatives and four alkyl derivatives 4a-4d were synthesized from 11-O-(4'-O-methyl galloyl)-bergenin. The structures of the synthesized analogues were confirmed upon ¹ H and ¹³ C NMR spectroscopic elucidation. Antileishmanial and antitrypanosomal activities of the synthesized derivatives were evaluated, compounds 11-O-(3',5' di-benzyl, 4'-O-methyl galloyl)-8,10-di-O-benzyl-bergenin (4c) and 11-O-(3',5'di-4-chlorobenzyl,4'-O-methyl galloyl)-8,10di-O-4-chlorobenzyl bergenin (4d) showed potent antitrypanosomal activity with IC₅₀ values of 0.52 and 0.5 μM, respectively and IC₉₀  values of 0.66 μM against T. brucei compared with IC₅₀ and IC₉₀ values of 21.7 and 50.3 μM for the positive control difluoromethylornithine.

Antioxidant, Antimicrobial, Antidiabetic and Cytotoxic Activity of Crocus sativus L. Petals

The purpose of this research is to examine in vitro antioxidant, antimicrobial, antidiabetic and cytotoxic efficacy of different extracts of Crocus sativus L. petals. Antioxidant activity of extracts was assessed by DPPH and ABTS (2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) assay. Among all extracts, ethanol (SPE) had the maximum radical scavenging activity with IC50 values 86.63 ± 7.53 μg/mL. The antimicrobial activity was determined by the evaluation of the minimum inhibitory concentration using the agar well plate procedure. The most effective extract was SPE with a minimum inhibitory concentration varying between 500 µg/mL, 250 µg/mL, 125 µg/mL, 62.5 µg/mL, 31.25 µg/mL, 15.63 µg/mL. Cytotoxic activity was tested against MDA-MB-231 cell lines using the MTT method whereas, antidiabetic activity was evaluated using an alpha-glucosidase inhibition assay. All extracts were found to have significant antidiabetic activity.

New Polyisoprenylated Polycyclic Phloroglucines from Clusia gundlachii

A bioassay-guided fractionation yielded five new polycyclic phloroglucines derivatives, namely, gundlachiione A (1), gundlachiione B (2), gundlachiione C (3), gundlachiione D (4) and gundlachiione E (5) from the fruits of Clusia gundlachii, collected in Puerto Rico, USA. Their structures were determined by full spectroscopic data, including 2D NMR COSY, HMQC, HMBC, and NOESY experiments, and HRESIMS. Compounds 1 and 3 demonstrated activities against Leishmania donovani intracellular macrophage amastigotes in THP1 cultures, comparable to those observed for the standard drug pentamidine (IC50 and IC90 values 0.84 and 6.13 μg/mL, 2.32 and 3.01 μg/mL, 0.77 and 2.99 μg/mL, respectively). Both compounds, 1 and 3, also showed weak activities against L. donovani promastogotes and absence of cytotoxicity against transformed THP 1 cells.