Chemical and Pharmacological Potential of Coccoloba cowellii, an Endemic Endangered Plant from Cuba

Abstract

Coccoloba cowellii Britton (Polygonaceae) is an endemic and critically endangered plant that only grows in Camagüey, a province of Cuba. In this study, a total of 13 compounds were identified in a methanolic leaf extract, employing a dereplication of the UHPLC-HRMS data by means of feature-based molecular networking (FBMN) analysis in the Global Natural Products Social Molecular Network (GNPS), together with the interpretation of the MS/MS data and comparison with the literature. The major constituents were glucuronides and glycosides of myricetin and quercetin, as well as epichatechin-3-O-gallate, catechin, epicatechin and gallic acid, all of them being reported for the first time in C. cowellii leaves. The leaf extract was also tested against various microorganisms, and it showed a strong antifungal effect against Candida albicans ATCC B59630 (azole-resistant) (IC50 2.1 µg/mL) and Cryptococcus neoformans ATCC B66663 (IC50 4.1 µg/mL) with no cytotoxicity (CC50 > 64.0 µg/mL) on MRC-5 SV2 cells, determined by the resazurin assay. Additionally, the extract strongly inhibited COX-1 and COX-2 enzyme activity using a cell-free experiment in a dose-dependent manner, being significantly more active on COX-1 (IC50 4.9 µg/mL) than on COX-2 (IC50 10.4 µg/mL). The constituents identified as well as the pharmacological activities measured highlight the potential of C. cowellii leaves, increasing the interest in the implementation of conservation strategies for this species.

Antifungal Activity of Extracts, Fractions, and Constituents from Coccoloba cowellii Leaves

“…The total methanolic extract from C. cowellii leaves (hereafter referred to as total extract) was subjected to bioassay-guided fractionation following the scheme shown in Figure 1 . Given the promising results obtained for the total extract [ 8 ], the antifungal activity was employed as a guide for the fractionation and isolation of active compounds. Table 1 shows the results of the in vitro antifungal bioassays performed on the total extract and its fractions.…”

“…Flavonoid glycosides and glucuronides with quercetin and myricetin aglycon moiety have already been reported in relatively high concentrations in the total extract of C. cowellii leaves [ 8 ] and in other species of the genus [ 14 ]. In fact, compounds 1 – 3 from this study matched the ones previously identified in the total extract [ 8 ]. The other compounds identified in the methanol 90% fraction were reported in this species for the first time.…”

“…According to the previous analysis, flavonoid glycosides or glucuronides as well as proanthocyanidins are the main compounds of the total extract of C. cowellii leaves [ 8 ]. These compounds have a broad spectrum of biological activities, including antifungal activity [ 45 , 46 ].…”

“…In a recent study, the total methanolic extract from the leaves of Coccoloba cowellii showed promissory antifungal activity against C. albicans and Cryptococcus neoformans , with IC 50 values of 2.1 µg/mL and 4.1 µg/mL, respectively [ 8 ]. The major constituents of the aforementioned extract were glucuronides and glycosides of myricetin and quercetin; proanthocyanidins (tentatively characterized through HRMS); and epichatechin-3- O -gallate, catechin, epicatechin, and gallic acid (tentatively characterized using HRMS and authentic standards) [ 8 ].…”

“…In a recent study, the total methanolic extract from the leaves of Coccoloba cowellii showed promissory antifungal activity against C. albicans and Cryptococcus neoformans , with IC 50 values of 2.1 µg/mL and 4.1 µg/mL, respectively [ 8 ]. The major constituents of the aforementioned extract were glucuronides and glycosides of myricetin and quercetin; proanthocyanidins (tentatively characterized through HRMS); and epichatechin-3- O -gallate, catechin, epicatechin, and gallic acid (tentatively characterized using HRMS and authentic standards) [ 8 ]. The abundance of polyphenols in C. cowellii leaves and their recognised activity against fungi were the elements that allowed us to hypothesise that a bioassay-guided fractionation process could be a useful strategy to explore the potential of extracts, fractions, and constituents derived from this plant against a panel of Candida spp.…”