Antimicrobial, Anticancer, and Antioxidant Activities of Maize and Clover Pollen Grains Extracts: A Comparative Study with Phytochemical Characterizations

The failure to treat infectious diseases due to the continual emergence of drug-resistant microbes poses a huge and serious challenge for human health globally. Currently, the discovery and development of natural therapeutic compounds are attracting considerable attention from researchers worldwide. In this project, two types of pollen grains (maize and clover) were evaluated for potential antimicrobial activities. Extracts of both pollen grains were purified using HPLC, which has been shown to have numerous phenolic and flavonoid compounds. Pyro catechol and methyl gallate were detected in high concentrations (1145.56 and 1056.57 µg/mL, respectively) in the maize extract, while caffeic acid, quercetin, and kaempferol (464.73, 393.05, and 390.93 µg/mL, respectively) were among the compounds observed at high concentrations in the clover pollen grains extract. Staphylococcus aureus, Escherichia coli, Salmonella typhi, and Candida albicans were more sensitive to the clover pollen grains extract with inhibition zones of 22 ± 0.2, 18 ± 0.1, 29 ± 0.3, and 42 ± 0.4 mm compared to the size of the inhibitory zones caused by the maize pollen grains extract (19 ± 0.3, 15 ± 0.4, 27 ± 0.1, and 22 ± 0.4 mm, respectively). Moreover, lower MIC values for the clover pollen grains extract were recorded against C. albicans (1.97 ± 0.04 µg/mL), S. aureus (62.5 ± 1.00 µg/mL), and E. coli (62.5 ± 0.07 µg/mL) than the MICs caused by the maize pollen grains extract. The use of a transmission electron microscope revealed that the E. coli that had been treated with the clover pollen grains extract showed changes in its cell walls compared to that treated with the maize pollen grains extract. The clover pollen grains extract exhibited a stronger antioxidant potential, with an IC50 value of 22.18 µg/mL, compared to an IC50 value of 54.85 µg/mL for the maize pollen grains extract, via a DPPH scavenging assay. Regarding anticancer activity, the maize pollen grains extract was revealed to be more effective in terms of inhibiting the human colon cancer cell line HCT-116, with an IC50 value of 67.02 ± 1.37 µg/mL, compared with the observed toxicity caused by the clover extract, with an IC50 value of 75.03 ± 1.02 µg/mL. Overall, the clover pollen grains extract demonstrated potent antibacterial and antioxidant activities, but not anticancer activity, when compared to the maize grains extract. Thus, the current findings related to both types of pollen grains (clover and maize) highlight their potential therapeutic applications for the treatment of certain infectious diseases and malignancies.

Chemical Properties and Biological Activity of Bee Pollen

Pollen, a remarkably versatile natural compound collected by bees for its abundant source of proteins and nutrients, represents a rich reservoir of diverse bioactive compounds with noteworthy chemical and therapeutic potential. Its extensive biological effects have been known and exploited since ancient times. Today, there is an increased interest in finding natural compounds against oxidative stress, a factor that contributes to various diseases. Recent research has unraveled a multitude of biological activities associated with bee pollen, ranging from antioxidant, anti-inflammatory, antimicrobial, and antifungal properties to potential antiviral and anticancer applications. Comprehending the extensive repertoire of biological properties across various pollen sources remains challenging. By investigating a spectrum of pollen types and their chemical composition, this review produces an updated analysis of the bioactive constituents and the therapeutic prospects they offer. This review emphasizes the necessity for further exploration and standardization of diverse pollen sources and bioactive compounds that could contribute to the development of innovative therapies.

The Influence of Enzymatic Hydrolysis on Bee Pollen Antioxidant and Antibacterial Activities

Bee pollen is one of the most valuable apitherapeutic products with high nutritional value. To obtain a higher diversity of compounds, higher bioactivity, and improve the release of nutrients from bee pollen, additional processing of the raw material may be applied: fermentation using microorganisms or hydrolysis using selective enzymes. This research aimed to determine the impact of enzymatic hydrolysis on the antioxidant and antibacterial activities of bee pollen. Bee pollen samples from Sweden, Spain, Netherlands, Italy, Poland, Denmark, Slovakia, Malta, and Lithuania were hydrolyzed using pure enzymes, including lipase, cellulase, protease, and amyloglucosidase, as well as enzyme mixtures such as Viscozyme® L and Clara-diastase. Total phenolic content, total flavonoid content, and antioxidant activity were analyzed spectrophotometrically. Antibacterial activity against Staphylococcus aureus, Listeria monocytogenes, Staphylococcus enteritidis, and Salmonella typhimurium was evaluated using the agar well diffusion assay. Obtained results revealed a positive effect of enzymatic hydrolysis on biologically active compound content and activity: total phenolic content increased by 1.1 to 2.5 times, total flavonoid content by 1.1 to 3.0 times, radical scavenging activity by 1.1-3.5 times, and antibacterial activity by 1.1 to 3.3 times. K-means clustering analysis grouped samples into 5-9 clusters and was dependent on the measured characteristic used as an input-total phenolic compounds content, total flavonoid content, antioxidant activity, and antibacterial activity against four different bacteria. Chemometrics showed, that the enzyme used for the hydrolysis had a higher impact on clustering results than the geographical origin of the samples.

Monofloral Corn Poppy Bee-Collected Pollen-A Detailed Insight into Its Phytochemical Composition and Antioxidant Properties

The aim of this study was to compile a detailed phytochemical profile and assess the antioxidant properties of bee-collected pollen (PBP) obtained from corn poppy (Papaver rhoeas L.) plants. To achieve this, a lipid fraction was prepared for quantifying fatty acids using GC-FID. Extractable and alkaline-hydrolysable PBP fractions (obtained from a defatted sample) were used to determine the qualitative and quantitative profiles of phenolic compounds, phenylamides and alkaloids using UHPLC/Q-ToF-MS. Additionally, various spectrophotometric assays (TAC, FRP, CUPRAC, DPPH^⦁) were conducted to evaluate the antioxidant properties. Phenolic compounds were more present in the extractable fraction than in the alkaline-hydrolysable fraction. Luteolin was the predominant compound in the extractable fraction, followed by tricetin and various derivatives of kaempferol. This study presents one of the first reports on the quantification of tricetin aglycone outside the Myrtaceae plant family. The alkaline-hydrolysable fraction exhibited a different phenolic profile, with a significantly lower amount of phenolics. Kaempferol/derivatives, specific compounds like ferulic and 5-carboxyvanillic acids, and (epi)catechin 3-O-gallate were the predominant compounds in this fraction. Regarding phenylamides, the extractable fraction demonstrated a diverse range of these bioactive compounds, with a notable abundance of different spermine derivatives. In contrast, the hydrolysable fraction contained six spermine derivatives and one spermidine derivative. The examined fractions also revealed the presence of seventeen different alkaloids, belonging to the benzylisoquinoline, berberine and isoquinoline classes. The fatty-acid profile confirmed the prevalence of unsaturated fatty acids. Furthermore, both fractions exhibited significant antioxidant activity, with the extractable fraction showing particularly high activity. Among the assays conducted, the CUPRAC assay highlighted the exceptional ability of PBP's bioactive compounds to reduce cupric ions.

In Vitro Study of the Phytochemical Composition and Antioxidant, Immunostimulant, and Hemolytic Activities of Nigella sativa (Ranunculaceae) and Lepidium sativum Seeds

The Moroccan flora abounds and is an important reserve of medicinal plants. Nigella sativa and Lepidium sativum are plants that are widely used in traditional medicine for their multiple therapeutic properties. The current study aims to highlight the biological activities that can justify and valorize the use of these plants. Flavonoids, total phenols, condensed tannins, and sugars were determined. The biological activities tested were antioxidant by determining the IC50 (defined as the concentration of an antioxidant required to decrease the initial concentration by 50%; inversely related to the antioxidant capacity), hemagglutination, and hemolytic activities. Phytochemical quantification of the seed extracts indicated that the total phenol content was largely similar for both plants and in the order of 10 mg GAE (Gallic acid equivalent)/g. On the other hand, L. sativum seeds registered a higher content of flavonoids (3.09 ± 0.04 mg QE (quercetin equivalent)/g) as compared to Nigella saliva (0.258 ± 0.058). Concerning condensed tannins, N. saliva seeds present a higher amount with a value of 7.2 ± 0.025 mg/g as compared to L. sativum (1.4 ± 0.22 mg/g). Concerning the total sugar content, L. sativum shows a higher content (67.86 ± 0.87 mg/g) as compared to N. sativa (58.17 ± 0.42 mg/g); it is also richer in mucilage with a content of 240 mg as compared to 8.2 mg for N. saliva. Examination of the antioxidant activity using a DPPH (2.2-diphenyl 1-pycrilhydrazyl) test revealed that the EButOH (n-butanol extract) and EAE (ethyl acetate extract) extracts were the most active, with IC50 values of 48.7 and 50.65 μg/mL for the N. sativa extracts and 15.7 and 52.64 μg/mL for the L. sativum extracts, respectively. The results of the hemagglutination activity of the different extracts of the two plants prepared in the PBS (phosphate-buffered saline) medium showed significant agglutination for the L. sativum extract (1/50) compared to the N. sativa extract (1/20). An evaluation of the hemolytic effect of the crude extract of the studied seeds on erythrocytes isolated from rat blood incubated in PBS buffer compared to the total hemolysis induced by distilled water showed a hemolysis rate of 54% for Nigella sativa and 34% for L. sativum. In conclusion, the two plants studied in the current work exhibited high antioxidant potential, which could explain their beneficial properties.

Bee Bread as a Promising Source of Bioactive Molecules and Functional Properties: An Up-to-Date Review

Bee bread is a natural product obtained from the fermentation of bee pollen mixed with bee saliva and flower nectar inside the honeycomb cells of a hive. Bee bread is considered a functional product, having several nutritional virtues and various bioactive molecules with curative or preventive effects. This paper aims to review current knowledge regarding the chemical composition and medicinal properties of bee bread, evaluated in vitro and in vivo, and to highlight the benefits of the diet supplementation of bee bread for human health. Bee bread extracts (distilled water, ethanol, methanol, diethyl ether, and ethyl acetate) have been proven to have antioxidant, antifungal, antibacterial, and antitumoral activities, and they can also inhibit α-amylase and angiotensin I-converting enzyme in vitro. More than 300 compounds have been identified in bee bread from different countries around the world, such as free amino acids, sugars, fatty acids, minerals, organic acids, polyphenols, and vitamins. In vivo studies have revealed the efficiency of bee bread in relieving several pathological cases, such as hyperglycemia, hyperlipidemia, inflammation, and oxidative stress.