Assessment of Cucurbita spp. Peel Extracts as Potential Sources of Active Substances for Skin Care and Dermatology

Essential oil from Citrus depressa peel exhibits antimicrobial, antioxidant and cancer chemopreventive effects

BACKGROUND

Many diseases may be caused by pathogens and oxidative stress resulting from carcinogens. Earlier studies have highlighted the antimicrobial and antioxidant effects of plant essential oils (EO). It is crucial to effectively utilize agricultural waste to achieve a sustainable agricultural economy and protect the environment. The present study aimed to evaluate the potential benefits of EO extracted from the discarded peels of Citrus depressa Hayata (CD) and Citrus microcarpa Bunge (CM), synonyms of Citrus deliciosa Ten and Citrus japonica Thunb, respectively.

RESULTS

Gas chromatography-mass spectrometry analysis revealed that the main compounds in CD-EO were (R)-(+)-limonene (38.97%), γ-terpinene (24.39%) and linalool (6.22%), whereas, in CM-EO, the main compounds were (R)-(+)-limonene (48.00%), β-pinene (13.60%) and γ-terpinene (12.07%). CD-EO exhibited inhibitory effects on the growth of common microorganisms, including Candida albicans, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. However, CM-EO showed only inhibitory effects on E. coli. Furthermore, CD-EO exhibited superior antioxidant potential, as demonstrated by its ability to eliminate 1,1-diphenyl-2-picrylhydrazyl and 2,2'-azinobis-3-ethylbenzthiazoline-6-sulfonate free radicals. Furthermore, CD-EO at a concentration of 100 μg mL-1 significantly inhibited 12-O-tetradecanoylphorbol-13-acetate-induced cancer transformation in mouse epidermal JB6 P+ cells (P < 0.05), possibly by up-regulating protein expression of nuclear factor erythroid 2-related factor 2 and its downstream antioxidant enzymes, such as NAD(P)H:quinone oxidoreductase 1, heme oxygenase-1 and UGT1A.

CONCLUSION

These findings suggest that CD-EO exhibits inhibitory effects on pathogenic microorganisms, possesses antioxidant properties and has cancer chemopreventive potential. © 2024 Society of Chemical Industry.

Pulp or Peel? Comparative Analysis of the Phytochemical Content and Selected Cosmetic-Related Properties of Annona cherimola L., Diospyros kaki Thumb., Cydonia oblonga Mill. and Fortunella margarita Swingle Pulp and Peel Extracts

Fruit peels might be a valuable source of active ingredients for cosmetics, leading to more sustainable usage of plant by-products. The aim of the study was to evaluate the phytochemical content and selected biological properties of hydroglycolic extracts from peels and pulps of Annona cherimola, Diospyros kaki, Cydonia oblonga, and Fortunella margarita as potential cosmetic ingredients. Peel and pulp extracts were compared for their antiradical activity (using DPPH and ABTS radical scavenging assays), skin-lightening potential (tyrosinase inhibitory assay), sun protection factor (SPF), and cytotoxicity toward human fibroblast, keratinocyte, and melanoma cell lines. The total content of polyphenols and/or flavonoids was significantly higher in peel than in pulp extracts, and the composition of particular active compounds was also markedly different. The HPLC-MS fingerprinting revealed the presence of catechin, epicatechin and rutoside in the peel of D. kaki, whereas kaempferol glucoside and procyanidin A were present only in the pulp. In A. cherimola, catechin, epicatechin and rutoside were identified only in the peel of the fruit, whereas procyanidins were traced only in the pulp extracts. Quercetin and luteolinidin were found to be characteristic compounds of F. margarita peel extract. Naringenin and hesperidin were found only in the pulp of F. margarita. The most significant compositional variety between the peel and pulp extracts was observed for C. oblonga: Peel extracts contained a higher number of active components (e.g., vicenin-2, kaempferol rutinoside, or kaempferol galactoside) than pulp extract. The radical scavenging potential of peel extracts was higher than of the pulp extracts. D. kaki and F. margarita peel and pulp extracts inhibited mushroom and murine tyrosinases at comparable levels. The C. oblonga pulp extract was a more potent mushroom tyrosinase inhibitor than the peel extract. Peel extract of A. cherimola inhibited mushroom tyrosinase but activated the murine enzyme. F. margarita pulp and peel extracts showed the highest in vitro SPF. A. cherimola, D. kaki, and F. margarita extracts were not cytotoxic for fibroblasts and keratinocytes up to a concentration of 2% (v/v) and the peel extracts were cytotoxic for A375 melanoma cells. To summarize, peel extracts from all analyzed fruit showed comparable or better cosmetic-related properties than pulp extracts and might be considered multifunctional active ingredients of skin lightening, anti-aging, and protective cosmetics.

Valorization of Pumpkin Byproducts: Antioxidant Activity and Carotenoid Characterization of Extracts from Peel and Filaments

Pumpkin (Cucurbita sp.) represents an unquestionable source of valuable nutrients and bioactive compounds having a broad spectrum of health-promoting effects. The goal of this work was to characterize the byproducts (peels and filaments) of different pumpkin varieties belonging to C. moschata (Butternut, Lunga di Napoli, Moscata di Provenza, and Violina rugosa) and C. maxima (Delica, Delica vanity, Hokkaido, and Mantovana) species in terms of total carotenoid content, antioxidant activity, and carotenoid profiling. The research revealed that peels and filaments were a good source of β-carotene and other non-esterified carotenoids, as well as esterified carotenoids. Considering the growing market demand for safe and healthy food products, pumpkin byproducts, having also an interesting antioxidant bioactivity, could be useful in the development of novel functional products.

Biological Activities of Natural Products III

The search for natural products that display biological activity is invariably an attractive research area for scientific centers and teams from around the world [...].