Chemical Constituents and Anti-ulcer Activity of Propolis from the North-West Region of Cameroon

Chemical Composition of Mexicali Propolis and Its Effect on Gastric Repair in an Indomethacin-Induced Gastric Injury Murine Model

Propolis is a resinous substance produced by bees that has several biomedical properties that could contribute to the repair process of the gastric mucosa, such as antioxidant, anti-inflammatory, healing, and gastroprotective properties. Thus, this study aimed to determine the chemical composition of Mexicali propolis, its antioxidant capacity, and its effect on gastric repair. Three polarity-directed extracts were obtained: the ethanolic extract, the ethyl acetate extract, and the hexane extract. The antioxidant activity, total phenolic content (TPC), and flavone/flavonol content were determined for each extract. The chemical composition was analysed using HPLC-TOF-MS (High-Performance Liquid Chromatography-Time-Of-Flight Mass Spectrometry) and GC-MS (Gas Chromatography-Mass Spectrometry), and a total of 52 compounds were identified. The results revealed that the ethanolic extract had the greatest effect on free radical scavenging and the content of bioactive compounds. On the basis of these results, the effect of the Mexicali ethanolic extract of propolis (MeEEP) on gastric repair was subsequently evaluated. Prior to the evaluation, MeEEP was found to exhibit low oral toxicity, as determined under the Organisation for Economic Co-operation and Development (OECD) 425 guidelines. Gastric injury was induced in male C57BL/6 mice by intragastric administration of indomethacin (10 mg/kg). MeEEP (300 mg/kg) was administered 6 h after the induction of injury using indomethacin and daily thereafter. The mice were sacrificed at 12, 24, and 48 h to assess the effect. As a result, MeEEP enhanced the repair of the gastric lesion by decreasing the percentage of the bleeding area and attenuating the severity of histological damage, as demonstrated by H&E staining. This effect was associated with a reduction in MPO enzyme activity and in the levels of the proinflammatory cytokines TNF-α, IL-1β, and IL-6, maintaining controlled inflammation in gastric tissue. Furthermore, the administration of the extract increased SOD enzymatic activity and GSH levels, reducing the degree of oxidative damage in the gastric tissue, as demonstrated by low MDA levels. Finally, after evaluating the effect on apoptosis via immunohistochemistry, MeEEP was shown to reduce the expression of the proapoptotic marker Bax and increase the expression of the antiapoptotic marker Bcl-2. In conclusion, these findings suggest that MeEEP may enhance gastric repair through a cytoprotective mechanism by controlling inflammation exacerbation, reducing oxidative stress, and regulating apoptosis. These mechanisms are primarily attributed to the presence of pinocembrin, tectochrysin, chrysin, apigenin, naringenin, acacetin, genistein, and kaempferol. It is important to highlight that this study provides a preliminary exploration of the reparative effect of Mexican propolis, describing the potential mechanisms of action of the compounds present in Mexicali propolis.

Evaluation of the gastroprotective effects of Chihuahua propolis on indomethacin- induced gastric ulcers in mouse

The aim of this work was to evaluate the gastroprotective activity of a Mexican propolis on indomethacin-induced gastric ulcers in a mouse model. The following contents of the ethanolic extract of propolis of Chihuahua (EEPCh) were determined: antioxidant activity (SA50), total phenolic content (TPC), total flavonoid content (TFC), and chemical composition by HPLC-DAD and HPLC-MS, as well as acute toxicity by OECD Guideline 423. Gastric lesions were induced by intragastric indomethacin treatment in male ICR mice. As the positive control, omeprazole was administered, and three doses of EEPCh were evaluated (50, 150 and 300 mg/kg). Gastric mucosal injury, histological changes and mucosal content were evaluated by means of H&E and PAS staining. For homogenized gastric tissues, the following were evaluated: TBARS, MPO, and PGE2 levels; SOD and GPx antioxidant enzymatic activity; and the concentrations of the proinflammatory cytokines, TNF-α, IL-1β and IL-6. EEPCh had a significant SA50 of 41.55 µg/mL. The TPC of EEPCh was 860 mg GAE/g, and its TFC was 49.58 mg QE/g. Different phenolic compounds were identified in the extract and were not toxic. The EEPCh doses decreased mucosal damage and histological injuries, maintained the mucosal content and reduced the TBARS, MPO and concentrations of proinflammatory cytokines in gastric ulcer tissues. The 150 and 300 mg/kg doses increased the SOD activity and maintained the PGE2 content. Only the 300 mg/kg dose increased the GPx activity. The results of this study suggest that EEPCh displays gastroprotective effects by means of its antioxidant activity and anti-inflammatory effects and promotes ulcer protection through the maintenance of mucosal content and PGE2 levels.

Metabolomics Reveals Discrimination of Chinese Propolis from Different Climatic Regions

The chemical profiles of propolis vary greatly due to the botanic sources and geographic origins, which limit its standardization for modern usages. Here, we proposed a reliable ¹H NMR-based metabolomic approach, to discriminate the function and quality of Chinese propolis. A total 63 Chinese propolis samples from different temperate regions were collected and extracted for NMR analysis. Twenty-one compositions in ethanol extracts were assigned based on characteristic chemical shifts and previous literature reports. Significant geographic indicators were identified after the PCA and orthogonal partial least squares discriminant analysis (OPLS-DA) analysis of the obtained ¹H NMR data. It was found that the composition discriminations arose from long-term acclimation of the different climates of botanic origin and caused the differences in the biological activities. This study provides us a reasonable instruction for the quality control of Chinese propolis.

A New fatty acid and some triterpenoids from propolis of Nkambe (North-West Region, Cameroon) and evaluation of the antiradical scavenging activity of their extracts

The aim of this work was to evaluate in vitro antiradical scavenging activity of propolis from Nkambe (North-West, Cameroon). The polyphenol content of the acetone extract was evaluated using the Folin-Ciocalteu reagent as 0.166±0.008 gGAE/100 gRM. Antiradical scavenging activity of hexane and acetone extracts was carried out on DPPH using ascorbic acid as standard. The results showed that the extracts possess antiradical activity with IC50 of 141 μg/mL and 267 μg/mL for acetone and hexane extracts, respectively. The column chromatography separation on silica gel of the hexane fractionyielded compounds 1 to 3. The structures of these compounds were elucidated by NMR and mass spectrometry data as Lupenone (1), a mixture of α and ß-Amyrin (2) and lastly Hexatriacontanoic acid (3) which was described for the first time from propolis.

A new isoflavonol and other constituents from Cameroonian propolis and evaluation of their anti-inflammatory, antifungal and antioxidant potential

Propolis is rich in diverse bioactive compounds. Propolis samples were collected from three localities of Cameroon and used in the study. Column chromatography separation of propolis MeOH:DCM (50:50) extracts yielded a new isoflavonol, 2-hydroxy-8-prenylbiochanin A (1) alongside 2',3'-dihydroxypropyltetraeicosanoate (2) and triacontyl p-coumarate (3) isolated from propolis for first time together with seven compounds: β-amyrine (4), oleanolic acid (5), β-amyrine acetate (6), lupeol (7), betulinic acid (8), lupeol acetate (9) and lupenone (10). These compounds were tested for their inhibitory effect on oxidative burst where intracellular reactive oxygen species (ROS) were produced from zymosan stimulated human whole blood phagocytes and on production of nitric oxide (NO) from lipopolysaccharide (LPS) stimulated J774.2 mouse macrophages. The cytotoxicity of these compounds was evaluated on NIH-3 T3 normal mouse fibroblast cells, antiradical potential on 2,2-diphenyl-1-picrylhydrazylhydrazyl (DPPH·) as well as their anti-yeast potential on four selected candida species. Compound 1 showed higher NO inhibition (IC₅₀ = 23.3 ± 0.3 µg/mL) than standard compound L-NMMA (IC₅₀ = 24.2 ± 0.8 µg/mL). Higher ROS inhibition was shown by compounds 6 (IC₅₀ = 4.3 ± 0.3 µg/mL) and 9 (IC₅₀ = 1.1 ± 0.1 µg/mL) than Ibuprofen (IC₅₀ = 11.2 ± 1.9 µg/mL). Furthermore, compound 1 displayed moderate level of cytotoxicity on NIH-3 T3 cells, with IC₅₀ = 5.8 ± 0.3 µg/mL compared to the cyclohexamide IC₅₀ = 0.13 ± 0.02 µg/mL. Compound 3 showed lower antifungal activity on Candida krusei and Candida glabrata, MIC of 125 μg/mL on each strain compared to 50 μg/mL for fuconazole. The extracts showed low antifungal activities ranging from 250 to 500 μg/mL on C. albicans, C. krusei and C. glabrata and the values of MIC on Candida parapsilosis were 500 μg/mL and above. DPPH* scavenging activity was exhibited by compounds 1 (IC₅₀ = 15.653 ± 0.335 μg/mL) and 3 (IC₅₀ = 89.077 ± 24.875 μg/mL) compared to Vitamin C (IC₅₀ = 3.343 ± 0.271 μg/mL) while extracts showed moderate antiradical activities with IC₅₀ values ranging from 309.31 ± 2.465 to 635.52 ± 11.05 µg/mL. These results indicate that compounds 1, 6 and 9 are potent anti-inflammatory drug candidates while 1 and 3 could be potent antioxidant drugs.

Propolis Exerts an Anti-Inflammatory Effect on PMA-Differentiated THP-1 Cells via Inhibition of Purine Nucleoside Phosphorylase

Previous research has shown that propolis has immunomodulatory activity. Propolis extracts from different geographic origins were assessed for their anti-inflammatory activities by investigating their ability to alter the production of tumour necrosis factor-α (TNF-α) and the cytokines interleukin-1β (IL-1β), IL-6 and IL-10 in THP-1-derived macrophage cells co-stimulated with lipopolysaccharide (LPS). All the propolis extracts suppressed the TNF-α and IL-6 LPS-stimulated levels. Similar suppression effects were detected for IL-1β, but the release of this cytokine was synergised by propolis samples from Ghana and Indonesia when compared with LPS. Overall, the Cameroonian propolis extract (P-C) was the most active and this was evaluated for its effects on the metabolic profile of unstimulated macrophages or macrophages activated by LPS. The levels of 81 polar metabolites were identified by liquid chromatography (LC) coupled with mass spectrometry (MS) on a ZIC-pHILIC column. LPS altered the energy, amino acid and nucleotide metabolism in THP-1 cells, and interpretation of the metabolic pathways showed that P-C reversed some of the effects of LPS. Overall, the results showed that propolis extracts exert an anti-inflammatory effect by inhibition of pro-inflammatory cytokines and by metabolic reprogramming of LPS activity in macrophage cells, suggesting an immunomodulatory effect.