Comparative antioxidant and antimicrobial activities of the peels, rind, pulp and seeds of watermelon (Citrullus lanatus) fruit

Phytochemical fingerprint revealing antibacterial and antioxidant activities of endemic banana cultivars in Southeast Asia

This study explores the bioactive secondary metabolite profiles of the peels of three major cultivars of bananas (Musa acuminata and Musa balbisiana). These cultivars are primarily grown in Southeast Asia and are widely consumed due to their rich nutritional and fiber content. The research utilizes advanced analytical techniques, specifically HPLC-DAD-q-TOF-MS/MS, in conjunction with both univariate and multivariate statistical analyses, to analyze the ethanolic extracts of the banana peels. This study identifies phenolic acids, flavonoids, and proanthocyanidins as significant contributors to the differentiation of the cultivars. The secondary metabolites rutin, chlorogenic acid, and gentisic acid are pinpointed as the key discriminants. Moreover, the research demonstrates a synergistic contribution of certain phytochemicals to the antioxidant and antibacterial properties of the banana peel extracts. The fingerprint profiling tools introduced in this study offer a reliable method for identifying metabolite biomarkers for the discrimination of banana cultivars.

Antioxidant and Antibacterial Activities Evaluation, Phytochemical Characterisation of Rhizome from Angiopteris helferiana and Barks from Saurauia fasciculata in Nepal

Ethnomedicinally, more than 2000 plants were found to be used in Nepal. Among them, the red colored rhizome of Angiopteris helferiana and the bark of Saurauia fasciculata have been used widely to treat muscle fatigue, bone pain, fever, postpartum hemorrhage, and thirst by healers in Kaski and Tanahun districts, Nepal. However, scientific evidence towards their traditional uses is lacking till December, 2023. Therefore, we report the phytochemicals, total phenolic content (TPC), total flavonoid content (TFC), total carbohydrate content (TCC), antioxidant and antibacterial activities of A. helferiana and S. fasciculata extracts. Phytochemical analysis indicated that A. helferiana and S. fasciculata extracts were potential sources of chemicals such as phenols, flavonoids, tannins, terpenoids, saponins, and carbohydrates. The TPC, TFC, and TCC of extracts were determined by using an ultraviolet visible spectrophotometer. Among the extracts tested, A. helferiana extracts showed the highest phenolic and carbohydrate contents of 208.33 ± 12.96 mg of gallic acid equivalent/g and 564.16 ± 2.92 mg of D-glucose equivalent/g of dry extract, respectively. Similarly, S. fasciculata revealed the highest flavonoid content of 30.35 ± 0.1 mg quercetin equivalent/g of dry extract. The extract of A. helferiana and S. fasciculata exhibited potent antioxidant activity by scavenging 2,2-diphenyl-1-picrylhydrazyl radicals with an IC50 of 25.9 µg/ml and 31.07 µg/ml, respectively. The antibacterial activity of the A. helferiana and S. fasciculata extract against Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli was determined using an agar-well diffusion protocol that revealed the potential antibacterial activity of A. helferiana against E. coli. The present study will help validate the traditional uses of A. helferiana rhizomes and S. fasciculata barks as a healing medicine and inspire the researcher towards further research, development, and formulation.

Nutritional aphrodisiacs: Biochemistry and Pharmacology

In 2022, the global prevalence of erectile dysfunction (ED) was estimated to be at least 150 million cases. This number is greatly suspected to be underestimate as most men withhold information about ED. Also, about 15% of world population have infertility troubles, and male factors are responsible for almost half of these cases. Studies have shown that the quality of semen has decreased in the past several decades owing to various health factors and environmental toxicants. The current medical interventions involve the inhibition of phosphodiesterase 5 which suffer from serious side effects and costly. One of the popular and most sought interventions are the natural and nutritional remedies as they are foods in essence and potentially with no harm to the body. Therefore, the goal of this paper is to provide a review of the most common nutritional aphrodisiacs with increasing libido and fertility highlighting the potential active constituents as well as the underlying mechanisms.

Phytochemicals and UHPLC-QTOF-HRMS characterisation of bioactives of butterfly pea (Clitoria ternatea L.) seeds and their antioxidant potentials

Clitoria ternatea Linn. (Fabaceae) is a medicinal and ornamental plant, widely used in Ayurvedic and Chinese medicine. There is no strong scientific evidence on the consumption of the tender fruits/seeds of blue- and white-flower plants as vegetables. Analysis of the nutrient composition revealed that the total carbohydrate, protein, and lipid were highest in the mature-stage seeds of both varieties. UHPLC analysis revealed the presence of rutin (1.66 mg%) as the major compound. LC-HRMS confirmed the presence of other bioactives, such as sinapic acid (m/z 223), catechin derivatives (m/z 305 and m/z 153), quercetin (m/z 463), etc., as well. The ascorbic acid content was found to be highest in blue-flowered plant seeds (18.10 mg/100 g). Analysis of antioxidant activity displayed the superiority of immature seeds over mature seeds. The research shows that these seeds are rich in nutrients and bioactives, which may have use in the food and pharmaceutical industries.

Watermelon (Citrullus lanatus) rind flour: Development and characterization of a novel watermelon byproduct

Watermelon (Citrullus lanatus) is a fruit widely consumed by the Brazilian population; however, its rind is usually discarded, despite its nutritional value. This work aimed to develop a watermelon rind flour (WRF) and a fiber-rich bread. The WRF was submitted to microbiological analysis, proximate composition, antioxidant activity, and a profile of phenolic compounds. Six types of bread were developed: three using WRF (20%, 30%, and 40% of wheat flour replacement) and three control samples (only wheat flour), which were submitted to the same analysis, in addition to colorimetric properties, instrumental texture profile, and sensory evaluation (check-all-that-apply, purchase intent, and acceptance test). A high fiber content was observed in WRF (27.15%). The total concentration of phenolic compounds was 2.38 ± 0.20 mg of gallic acid equivalent per g and benzoic acid was the main compound found (73.50 mg/100 g WRF). The results of the antioxidant capacity through the DPPH method indicated a 30% reduction. The WRF 40% bread had 3.06 g of insoluble fiber, characterizing itself as a source of fiber. In the instrumental texture analysis, it was observed that bread hardness increased significantly as the WRF content increased. The formulation of the bread containing WRF is an alternative for the use of waste, favoring the development of a fiber-source product, with a functional food claim.

Evaluation of physicochemical, antioxidant, antibacterial activity, and sensory properties of watermelon rind candy

Watermelon (Citrullus lanatus) is consumed all over the world that contains a large number of seeds and rind, which is discarded. These by-products contain phytochemical compounds with great nutritional potential. This study aims to evaluate physicochemical properties and sensory values of watermelon rind candy. In this study in order to make the waste of watermelon a more sustainable and value-added food product, the watermelon rind was dried using an osmotic dehydration technique which comprises gradual impregnation of syrup (50 and 70% w/w - 1 to 5 h) before drying at 40 and 60 °C in 8 and 10 h. Various variables such as moisture content, chemical composition, water loss, solid gain, rehydration water, acidity, pH, antioxidant activity, antibacterial activity, residual toxins, phenolic and flavonoid contents during osmotic dehydration of watermelon were investigated. Results showed by rising temperatures, dehydration becomes more severe. Increasing the temperature in both osmotic samples in a concentrated solution (70%) and in osmotic samples with a dilute solution (50%) can enhance the mass transfer, water loss, solid absorption, as well as dehydration intensity. However, antioxidant activity, phenolic and flavonoid content significantly decreased after osmotic dehydration. TPC decreased from 35.83 mg/100 g to 27.45 mg/100 g and TFC of the watermelon rind (8.71 ± 0.01 mg/100 g) decreased to 2.63 ± 0.02 mg/100 g and also antioxidant activity after the osmotic process decreased from 61% to 40%. Also, osmotic dehydration had no significant impact on acidity and pH. The watermelon rind dehydrated sample (osmosis temperature: 40 °C, osmotic solution concentration: 70%, immersion duration: 5 h) was the best choice of panelists due to the highest score in the sensory evaluation including taste, texture, and overall acceptability. By determining the hardness of the watermelon rind candy and comparing it with the results of texture analysis of other dried products, it can be concluded that this product can be used as a healthy snack with longer shelf life properties.

Bacterial Communities Associated with Crude Oil Bioremediation through Composting Approaches with Indigenous Bacterial Isolate

In this study, we aim to investigate the efficiency of crude oil bioremediation through composting and culture-assisted composting. First, forty-eight bacteria were isolated from a crude oil-contaminated soil, and the isolate with the highest crude oil degradation activity, identified as Pseudomonas aeruginosa, was selected. The bioremediation was then investigated and compared between crude oil-contaminated soil (S), the contaminated soil composted with fruit-based waste (SW), and the contaminated soil composted with the same waste with the addition of the selected bacterium (SWB). Both compost-based methods showed high efficiencies of crude oil bioremediation (78.1% and 83.84% for SW and SWB, respectively). However, only a slight difference between the treatments without and with the addition of P. aeruginosa was observed. To make a clear understanding of this point, bacterial communities throughout the 4-week bioremediation period were analyzed. It was found that the community dynamics between both composted treatments were similar, which corresponds with their similar bioremediation efficiencies. Interestingly, Pseudomonas disappeared from the system after one week, which suggests that this genus was not the key degrader or only involved in the early stage of the process. Altogether, our results elaborate that fruit-based composting is an effective approach for crude oil bioremediation.

Valorization of Agro-Industrial Wastes by Ultrasound-Assisted Extraction as a Source of Proteins, Antioxidants and Cutin: A Cascade Approach

The use of agro-industrial wastes to obtain compounds with a high added-value is increasing in the last few years in accordance with the circular economy concept. In this work, a cascade extraction approach was developed based on ultrasound-assisted extraction (UAE) for tomato, watermelon, and apple peel wastes. The protein and antioxidant compounds were obtained during the first extraction step (NaOH 3 wt.%, 98.6 W, 100% amplitude, 6.48 W/cm², 6 min). The watermelon peels (WP) showed higher proteins and total phenolic contents (857 ± 1 mg BSA/g extract and 107.2 ± 0.2 mg GAE/100 g dm, respectively), whereas the highest antioxidant activity was obtained for apple peels (1559 ± 20 µmol TE/100 g dm, 1767 ± 5 µmol TE/100 g dm, and 902 ± 16 µmol TE/100 g dm for ABTS, FRAP and DPPH assays, respectively). The remaining residue obtained from the first extraction was subsequently extracted to obtain cutin (ethanol 40 wt.%, 58 W, 100% amplitude, 2 W/cm², 17 min, 1/80 g/mL, pH 2.5). The morphological studies confirmed the great efficiency of UAE in damaging the vegetal cell walls. WP showed a higher non-hydrolysable cutin content (55 wt.% of the initial cutin). A different monomers’ profile was obtained for the cutin composition by GC-MS, with the cutin from tomato and apple peels being rich in polyhydroxy fatty acids whereas the cutin extracted from WP was mainly based on unsaturated fatty acids. All of the cutin samples showed an initial degradation temperature higher than 200 °C, presenting an excellent thermal stability. The strategy followed in this work has proved to be an effective valorization methodology with a high scaling-up potential for applications in the food, pharmaceutical, nutraceutical, cosmetics and biopolymer sectors.

Active Thermoplastic Starch Film with Watermelon Rind Extract for Future Biodegradable Food Packaging

Petrochemical plastic wastes generate serious environmental problems because they are resistant to natural decomposition. The aim of this study was to develop a biodegradable active thermoplastic film composed of polyvinyl alcohol (PVA), corn starch (ST), glycerol, and the active compounds from watermelon rind extract (WMRE), or PVA/ST/WMRE, using the casting technique. The film was examined for its mechanical, antioxidant, and functional properties against selected foodborne pathogens. The results showed that the addition of 10% v/v of watermelon rind extract to the film formulation significantly increased the tensile strength from 19.44 ± 0.84 MPa to 33.67 ± 4.38 MPa and slightly increased the percent elongation at break (% EAB) from 35.04 ± 0.96% to 35.16 ± 1.08%. The antioxidant property of PVA/ST/WMRE film was analyzed based on the DPPH scavenging activity assay, which significantly increased from 29.21 ± 0.24% to 63.37 ± 4.27%. The minimum inhibitory concentration (MIC) of watermelon rind extract was analyzed for the growth inhibition of Bacillus cereus ATCC 11778, Escherichia coli ATCC 8739, and Salmonella enterica subsp. enterica serovar Typhimurium ATCC 13311, with 10% (v/v) found as an optimal concentration against B. cereus. Wrapping fresh-cut purple cabbage with PVA/ST/WMRE film significantly reduced the microbial load after 3 days of storage, in comparison to commercial packaging (PET) and thermoplastic control film. Consumer testing of the packaging film indicated that user acceptance of the product was favorable. Therefore, we suggest that this newly developed film can be used as a biodegradable food packaging item that will lead to enhanced food safety, food quality, prolonged shelf life, and consumer acceptance for further food applications.

Watermelon (Citrullus lanatus) leaf extract attenuates biochemical and histological parameters in high-fat diet/streptozotocin-induced diabetic rats

The present research aimed to investigate the attenuative effects of watermelon (Citrullus lanatus) leaf extract on biochemical and histological parameters in a high-fat diet combined with a low-dose streptozotocin (HFD/STZ)-induced type 2 diabetes mellitus. Forty male Sprague Dawley rats were divided into five groups, including three supplemented groups: 10 mg metformin/kg BW (HFD/STZ +M), 200 mg watermelon leaf extract /kg BW (HFD/STZ + LD), and 400 mg watermelon leaf extract /kg BW (HFD/STZ + HD). The efficacy of the 6-week intervention was evaluated by measuring body weight, fasting blood sugar, serum insulin, lipid profile, superoxide dismutase, catalase, malondialdehyde, and serum liver markers. Kidneys and liver structure were defined by histopathological examination. Results revealed that intervention with watermelon leaf extract attenuated the biochemical parameters and the structural changes in kidneys and liver. In brief, the watermelon leaf extract treatment could effectively decrease complications associated with diabetes better than metformin, and that the treatment with 400 mg/kg BW is the most potent. PRACTICAL APPLICATIONS: This was the first study to investigate the antidiabetic potential of watermelon leaf extract in obese diabetic rats. Data revealed that the watermelon leaf extract significantly attenuated the HFD/STZ-induced diabetes changes, as evidenced by the biochemical and histological data. Hence, watermelon leaf could be an excellent candidate to be developed as a functional food ingredients or nutraceuticals for holistic management of diabetes mellitus and its complications.