Fucoidans are marine sulfated biopolysaccharides that have heterogenous and complicated chemical structures. Various sugar monomers, glycosidic linkages, molecular masses, branching sites, and sulfate ester pattern and content are involved within their backbones. Additionally, sources, downstream processes, and geographical and seasonal factors show potential effects on fucoidan structural characteristics. These characteristics are documented to be highly related to fucoidan potential activities. Therefore, numerous chemical qualitative and quantitative determinations and structural elucidation methods are conducted to characterize fucoidans regarding their physicochemical and chemical features. Characterization of fucoidan polymers is considered a bottleneck for further biological and industrial applications. Consequently, the obtained results may be related to different activities, which could be improved afterward by further functional modifications. The current article highlights the different spectrometric and nonspectrometric methods applied for the characterization of native fucoidans, including degree of purity, sugar monomeric composition, sulfation pattern and content, molecular mass, and glycosidic linkages.

The vast spread of multidrug-resistant bacteria has encouraged researchers to explore new antimicrobial compounds. This study aimed to investigate the phytochemistry and antibacterial activity of Cycas thouarsii R.Br. leaves extract against Klebsiella pneumoniae clinical isolates. The minimum inhibitory concentration (MIC) values of C. thouarsii extract ranged from 4 to 32 µg/mL. The impact of the treatment of the isolates with sub-inhibitory concentrations of C. thouarsii extract was investigated on the bacterial growth, membrane integrity, inner and outer membrane permeability, membrane depolarization, and bacterial morphology using a scanning electron microscope (SEM) and on the efflux activity using qRT-PCR. Interestingly, most K. pneumoniae isolates treated with C. thouarsii extract showed growth inhibition—a decrease in membrane integrity. In addition, we observed various morphological changes, a significant increase in inner and outer membrane permeability, a non-significant change in membrane depolarization, and a decrease in efflux activity after treatment. The phytochemical investigation of C. thouarsii extract revealed the isolation of one new biflavonoid, 5,7,7″,4‴-tetra-O-methyl-hinokiflavone (3), and five known compounds, stigmasterol (1), naringenin (2), 2,3-dihydrobilobetin (4), 4′,4‴-O-dimethyl amentoflavone (5), and hinokiflavone (6), for the first time. Moreover, the pure compounds′ MICs′ ranged from 0.25 to 2 µg/mL. Thus, C. thouarsii could be a potential source for new antimicrobials.

Fucoidans encompass versatile and heterogeneous sulfated biopolysaccharides of marine origin, specifically brown algae and marine invertebrates. Their chemistry and bioactivities have been extensively investigated in the last few decades. The reported studies revealed diverse chemical skeletons in which l-fucose is the main sugar monomer. However, other sugars, i.e., galactose, mannose, etc., have been identified to be interspersed, forming several heteropolymers, including galactofucans/fucogalactans (G-fucoidans). Particularly, sulfated galactofucans are associated with rich chemistry contributing to more promising bioactivities than fucans and other marine polysaccharides. The previous reports in the last 20 years showed that G-fucoidans derived from Undaria pinnatifida were the most studied; 21 bioactivities were investigated, especially antitumor and antiviral activities, and unique biomedical applications compared to other marine polysaccharides were demonstrated. Hence, the current article specifically reviews the biogenic sources, chemistry, and outstanding bioactivities of G-fucoidans providing the opportunity to discover novel drug candidates.

Given the lack of adequate research on Dioon spinulosum (D. spinulosum) Dyer Ex Eichler, this study was conducted focusing on different biological activities and phytochemical investigation of D. spinulosum for the first time. D. spinulosum showed strong protective activity against DNA damage and potent activity against VERO cell line. It also presented antimicrobial and hepatoprotective activity. Phytochemical investigation of the leaves resulted in isolation of two new flavonoids, apigenin 7-O-α-d-glucopyranoside (15) and amentoflavone 7-O-α-l-rhamnopyranoside (16), in addition to fifteen known compounds: phytone (1), trans-phytol (2), β-sitosterol (3), stigmasterol (4), oliveriflavone (5), 7,4′,7″,4″′-tetramethylamentoflavone (6), 7,4',7''-trimethylamentoflavone (7), scaidopitysin (8), bilobetin (9), isoginkgetin (10), aromadendrin (11), sotusflavone (12), engeletin (14) and eriocitrin (17) for the first time together with amentoflavone (13). Compounds (11) and (13) displayed very strong cytotoxic activity and showed the highest protective activity against DNA damage.

Candida albicans can cause various infections, especially in immunocompromised patients. Its ability to develop resistance to the current antifungal drugs as well as its multiple virulence factors have rendered the problem even more complicated. Thus, in the present investigation, we elucidated an in vitro and in vivo antifungal activity of Encephalartos laurentianus methanol extract (ELME) against C. albicans clinical isolates for the first time. A phytochemical identification of 64 compounds was conducted in ELME using LC-MS/MS. Interestingly, ELME exhibited antifungal activity with MIC values that ranged from 32–256 µg/mL. Furthermore, we investigated the antibiofilm activity of ELME against the biofilms formed by C. albicans isolates. ELME displayed antibiofilm activity using a crystal violet assay as it decreased the percentages of cells, moderately and strongly forming biofilms from 62.5% to 25%. Moreover, the antibiofilm impact of ELME was elucidated using SEM and fluorescent microscope. A significant reduction in the biofilm formation by C. albicans isolates was observed. In addition, we observed that ELME resulted in the downregulation of the biofilm-related tested genes (ALS1, BCR1, PLB2, and SAP5) in 37.5% of the isolates using qRT-PCR. Besides, the in vivo antifungal activity of ELME on the kidney tissues of rats infected with C. albicans was investigated using histological and immunohistochemical studies. ELME was found to protect against C. albicans induced renal damage, decrease desmin and inducible nitric oxide synthase, increase alkaline phosphatase, and increase infected rats’ survival rate. Additionally, the cytotoxicity of ELME was elucidated on Human Skin Fibroblast normal cells using MTT assay. ELME had an IC₅₀ of 31.26 µg/mL. Thus, we can conclude that ELME might be a promising future source for antifungal compounds.

The rising prevalence of non-alcoholic fatty liver disease NAFLD has strained the healthcare system. Natural products could solve this problem, so the current study focused on the impact of G. thunbergia Thunb. against this ailment. LC–ESI–MS/MS revealed the phytochemical profile of the methanol extract from Gardenia thunbergia leaves (GME). Forty-eight compounds were tentatively identified, and stigmasterol, fucosterol, ursolic acid, and rutin were isolated. The separation of the last three compounds from this plant had not before been achieved. The anti-NAFLD effect of the methanol extract of the leaves of G. thunbergia, and its major metabolite, rutin, was assessed in mice against high-fructose diet (HFD)-induced obesity. Male mice were allocated into nine groups: (1) saline (control), (2) 30% fructose (diseased group), (3) HFD, and 10 mg/kg of simvastatin. Groups 4–6 were administered HFD and rutin 50, 75, and 100 mg/kg. Groups (7–9) were administered HFD and methanol extract of leaves 100, 200, and 300 mg/kg. Methanol extract of G. thunbergia leaves at 200 mg/kg, and rutin at 75 mg/kg significantly reduced HFD-induced increments in mice weight and hepatic damage indicators (AST and ALT), steatosis, and hypertrophy. The levels of total cholesterol, LDL–C, and triglycerides in the blood decreased. In addition, the expressions of CYP2E1, JNK1, and iNOS in the diseased mice were downregulated. This study found that GME and rutin could ameliorate NAFLD in HFD-fed mice, with results comparable to simvastatin, validating G. thunbergia’s hepatoprotective effects.