Phytochemicals for the prevention and treatment of pancreatic cancer: Current progress and future prospects

Pancreatic cancer is the third leading cause of cancer-related deaths in the United States, owing to its aggressive nature and suboptimal treatment options, emphasizing the need for novel therapeutic approaches. Emerging studies have exhibited promising results regarding the therapeutic utility of plant-derived compounds (phytochemicals) in pancreatic cancer. The purpose of this review is to evaluate the potential of phytochemicals in the treatment and prevention of pancreatic cancer. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses was applied to collect articles for this review. Scholarly databases, including PubMed, Scopus and ScienceDirect, were queried for relevant studies using the following keywords: phytochemicals, phenolics, terpenoids, alkaloids, sulfur-containing compounds, in vitro, in vivo, clinical studies, pancreatic cancer, tumour, treatment and prevention. Aggregate results pooled from qualified studies indicate phytochemicals can inhibit pancreatic cancer cell growth or decrease tumour size and volume in animal models. These effects have been attributed to various mechanisms, such as increasing proapoptotic factors, decreasing antiapoptotic factors, or inducing cell death and cell cycle arrest. Notable signalling pathways modulated by phytochemicals include the rat sarcoma/mitogen activated protein kinase, wingless-related integration site/β-catenin and phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin signal transduction pathways. Clinically, phytochemicals have been found to increase survival while being well-tolerated and safe, though research is scarce. While these promising results have produced great interest in this field, further in-depth studies are required to characterize the anticancer activities of phytochemicals before they can be utilized to prevent or treat pancreatic cancer in clinical practice.

Comparative study among Avicennia marina, Phragmites australis, and Moringa oleifera based ethanolic-extracts for their antimicrobial, antioxidant, and cytotoxic activities

Microbial resistance and other emerging health risk problems related to the side effects of synthetic drugs are the major factors that result in the research regarding natural products. Fruits, leaves, seeds, and oils-based phyto-constituents are the most important source of pharmaceutical products. Plant extract chemistry depends largely on species, plant components, solvent utilized, and extraction technique. This study was aimed to compare the ethanolic extracts of a mangrove plant, i.e., Avicennia marina (1E: Lower half of A. marina‘s pneumatophores, 2E: A. marina‘s leaves, 3E: Upper half of A. marina‘s pneumatophores, and 4E: A. marina‘s shoots), with non-mangrove plants, i.e., Phragmites australis (5E: P. australis‘s shoot), and Moringa oleifera (6E: M. oleifera‘s leaves) for their antimicrobial activities, total phenolic contents, antioxidant activity, and cytotoxicity potential. The antimicrobial activity assays were performed on gram-positive bacteria (i.e., Bacillus subtilis and Staphylococcus aureus), gram-negative bacteria (i.e., Escherichia coli, and Pseudomonas aeruginosa), and fungi (i.e., Aspergillus niger, Candida albicans, and Rhizopus spp.). We estimated antioxidant activity by TAC, DPPH, and FRAP assays, and the cytotoxicity was evaluated by MTT assay. The results of antimicrobial activities revealed that B. subtilis was the most sensitive to the tested plant extracts compared to S. aureus, while it only showed sensitivity to 6E and Imipenem. 5E and 6E showed statistically similar results against P. aeruginosa as compared to Ceftazidime. E. coli was the most resistant bacteria against tested plant extracts. Among the tested plant extracts, maximum inhibition activity was observed by 6E against A. niger (22 ± 0.57 mm), which was statistically similar to the response of 6E against C. albicans and 3E against Rhizopus spp. 2E did not show any activity against tested fungi. We found that 6E (208.54 ± 1.92 mg g⁻¹) contains maximum phenolic contents followed by 1E (159.42 ± 3.22 mg g⁻¹), 5E (131.08 ± 3.10 mg g⁻¹), 4E (i.e., 72.41 ± 2.96 mg g⁻¹), 3E (67.41 ± 1.68 mg g⁻¹), and 2E (48.72 ± 1.71 mg g⁻¹). The results depict a significant positive correlation between the phenolic contents and the antioxidant activities. As a result, phenolic content may be a natural antioxidant source.

A pair of new enantiomers of xanthones from the stems and leaves of Cratoxylum cochinchinense

Background

The simple and caged xanthones from Clusiaceae showed significant antineoplastic activity. This study aims to identify structural diverse xanthones and search for novel antitumor natural products from this family plants.

Methods

The structures of new compounds 1a and 1b were elucidated mainly through comprehensive NMR and MS spectroscopic data, and their absolute configurations were determined by the comparison of the experimental and calculated electronic circular dichroism.

Results

A pair of new xanthone enantiomers, (+)- and (-)-cracochinxanthone A (1a and 1b), along with thirty known analogues (2-31), were isolated from extracts of the stems and leaves of C. cochinchinense. Preliminary biological assay of some isolates against HL-60, PC-3, and MDA-MB-231 cancer cell lines.

Conclusion

Some isolated xanthones exhibited high sensitivity against three human malignant cell lines and the structure-activity relationship study showed that the prenyl and geranyl units may play an important role in antitumor activity.

Potential of Central, Eastern and Western Africa Medicinal Plants for Cancer Therapy: Spotlight on Resistant Cells and Molecular Targets

Cancer remains a major health hurdle worldwide and has moved from the third leading cause of death in the year 1990 to second place after cardiovascular disease since 2013. Chemotherapy is one of the most widely used treatment modes; however, its efficiency is limited due to the resistance of cancer cells to cytotoxic agents. The present overview deals with the potential of the flora of Central, Eastern and Western African (CEWA) regions as resource for anticancer drug discovery. It also reviews the molecular targets of phytochemicals of these plants such as ABC transporters, namely P-glycoprotein (P-gp), multi drug-resistance-related proteins (MRPs), breast cancer resistance protein (BCRP, ABCG2) as well as the epidermal growth factor receptor (EGFR/ErbB-1/HER1), human tumor suppressor protein p53, caspases, mitochondria, angiogenesis, and components of MAP kinase signaling pathways. Plants with the ability to preferentially kills resistant cancer cells were also reported. Data compiled in the present document were retrieved from scientific websites such as PubMed, Scopus, Sciencedirect, Web-of-Science, and Scholar Google. In summary, plant extracts from CEWA and isolated compounds thereof exert cytotoxic effects by several modes of action including caspases activation, alteration of mitochondrial membrane potential (MMP), induction of reactive oxygen species (ROS) in cancer cells and inhibition of angiogenesis. Ten strongest cytotoxic plants from CEWA recorded following in vitro screening assays are: Beilschmiedia acuta Kosterm, Echinops giganteus var. lelyi (C. D. Adams) A. Rich., Erythrina sigmoidea Hua (Fabaceae), Imperata cylindrical Beauv. var. koenigii Durand et Schinz, Nauclea pobeguinii (Pobég. ex Pellegr.) Merr. ex E.M.A., Piper capense L.f., Polyscias fulva (Hiern) Harms., Uapaca togoensis Pax., Vepris soyauxii Engl. and Xylopia aethiopica (Dunal) A. Rich. Prominent antiproliferative compounds include: isoquinoline alkaloid isotetrandrine (51), two benzophenones: guttiferone E (26) and isoxanthochymol (30), the isoflavonoid 6α-hydroxyphaseollidin (9), the naphthyl butenone guieranone A (25), two naphthoquinones: 2-acetylfuro-1,4-naphthoquinone (4) and plumbagin (37) and xanthone V1 (46). However, only few research activities in the African continent focus on cytotoxic drug discovery from botanicals. The present review is expected to stimulate further scientific efforts to better valorize the African flora.

Anti-inflammatory activity of Vismia guianensis (Aubl.) Pers. extracts and antifungal activity against Sporothrix schenckii

ETHNOPHARMACOLOGICAL RELEVANCE

Vismia guianensis (Aubl.) Pers. is traditionally used in North and Northeast of Brazil for the treatment of dermatomycoses. Since the strategy associating immunomodulators with antifungal drugs seems to be promissory to improve the treatment efficacy in fungal infections, we aimed to investigate the antifungal activity of V. guianensis ethanolic extract of leaves (VGL) and bark (VGB) against Sporothrix schenckii ATCC 16345 and their antinflammatory activities.

MATERIAL AND METHODS

The extracts were analyzed by HPLC-DAD-IT MS/MS for in situ identification of major compounds. Antifungal activity was evaluated in vitro (microdilution test) and in vivo using a murine model of S. schenckii infection. The production of TNF-α, IFN-γ, IL-4, IL-10 and IL-12 by measured by ELISA, as well as measured the production and inhibition of the NO after treatment with the plant extracts or itraconazole (ITR).

RESULTS

Two O-glucosyl-flavonoids and 16 prenylated benzophenone derivatives already described for Vismia were detected. Both VGL and VGB showed significant antifungal activity either in in vitro assay of microdilution (MIC=3.9µg/mL) and in vivo model of infection with reduction of S. schenckii load in spleen. It was also observed a predominance of reduction in the production of NO and the proinflammatory cytokines evaluated except TNFα, but with stimulation of IL-10, as evidence of a potential anti-inflammatory effect associated.

CONCLUSION

The results showed that both VGL and VGB have a significant antifungal against S. schenckii and an anti-inflammatory activity. These results can support the use of these extracts for alternative treatment of sporotrichosis.

Stem bark and flower extracts of Vismia cauliflora are highly effective antioxidants to human blood cells by preventing oxidative burst in neutrophils and oxidative damage in erythrocytes

CONTEXT

Vismia cauliflora A.C.Sm. [Hypericaceae (Clusiaceae)] is an Amazonian plant traditionally used by indigenous population to treat dermatosis and inflammatory processes of the skin. Previous research on V. cauliflora extracts suggests its potential to neutralize cellular oxidative damages related to the production of reactive oxygen and nitrogen species.

OBJECTIVE

To determine the activity of stem bark and flower extracts of V. cauliflora on the modulation of oxidative burst in human neutrophils, as well as its potential to inhibit oxidative damage in human erythrocytes.

MATERIALS AND METHODS

The modulation of neutrophil's oxidative burst by the ethanolic extracts (0.3-1000 µg/mL) was determined by the oxidation of specific probes by reactive species. Additionally, the potential of these extracts to inhibit oxidative damage in human erythrocytes was evaluated by monitoring its biomarkers of oxidative stress.

RESULTS

Vismia cauliflora extracts presented remarkable capacity to prevent the oxidative burst in activated human neutrophils (IC50 < 15 µg/mL). However, the maximum percentage of inhibition achieved against hydrogen peroxide was 45%. Concerning the oxidative damage in human erythrocytes, the extracts were able to minimize the tert-butyl hydroperoxide-induced hemoglobin oxidation and lipid peroxidation in a very low concentration range (2.7-18 μg/mL). Furthermore, only stem bark extract (100 µg/mL) was able to inhibit the depletion of glutathione (13%).

DISCUSSION AND CONCLUSION

These results reinforce the therapeutic potential of stem bark and flower extracts of V. cauliflora to heal topical skin disease, namely in the treatment of neutrophil-related dermatosis and skin conditions related to oxidative stress, including skin aging.

Essential Oil Composition and Antimicrobial Activity of Vismia macrophylla Leaves and Fruits Collected in Táchira-Venezuela

Hydrodistillation of Vismia macrophylla Kunth (Hypericaceae) leaves (L) and fruits (F) yielded 1.3%, v/w, and 5.6%, v/w, of essential oil, respectively. GC and GC-MS analyses showed the presence of twenty-four (96.4%, L) and thirty-one (96.6%, F) components, respectively. Major compounds identified in the leaf oil were γ-bisabolene (44.4%) and β-bisabolol (14.9%), while those in the fruit oil were germacrene-D (12.1%), δ-cadinene (10.7%) and γ-bisabolene (22.3 %). Oil obtained from the fruits of V. macrophylla showed antibacterial activity against Gram-positive (S. aureus ATCC 25923 and E. faecalis ATCC 29212) as well as Gram-negative bacteria (E. coli ATCC 25922), with MIC values ranging from 150 μL/mL to 740 μLmL. Oil obtained from leaves were active only on the Gram-positive bacteria S. aureus (100 μLmL) and E. faecalis (500 μLmL), but also showed antiyeast activity against Candida albicans CDC-B385 and C krusei ATCC 6258 (600 μL/mL, each).

Anticancer and antimicrobial activities of some antioxidant-rich cameroonian medicinal plants

Traditional remedies have a long-standing history in Cameroon and continue to provide useful and applicable tools for treating ailments. Here, the anticancer, antimicrobial and antioxidant activities of ten antioxidant-rich Cameroonian medicinal plants and of some of their isolated compounds are evaluated.The plant extracts were prepared by maceration in organic solvents. Fractionation of plant extract was performed by column chromatography and the structures of isolated compounds (emodin, 3-geranyloxyemodin, 2-geranylemodin) were confirmed spectroscopically. The antioxidant activity (AOA) was determined using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) bleaching method, the trolox equivalent antioxidant capacity (TEAC), and the hemoglobin ascorbate peroxidase activity inhibition (HAPX) assays. The anticancer activity was evaluated against A431 squamous epidermal carcinoma, WM35 melanoma, A2780 ovary carcinoma and cisplatin-resistant A2780cis cells, using a direct colorimetric assay. The total phenolic content in the extracts was determined spectrophotometrically by the Folin–Ciocalteu method. Rumex abyssinicus showed the best AOA among the three assays employed. The AOA of emodin was significantly higher than that of 3-geranyloxyemodin and 2-geranylemodin for both TEAC and HAPX methods. The lowest IC₅₀ values (i.e., highest cytotoxicity) were found for the extracts of Vismia laurentii, Psorospermum febrifugum, Pentadesma butyracea and Ficus asperifolia. The Ficus asperifolia and Psorospermum febrifugum extracts are selective against A2780cis ovary cells, a cell line which is resistant to the standard anticancer drug cisplatin. Emodin is more toxic compared to the whole extract, 3-geranyloxyemodin and 2-geranylemodin. Its selectivity against the platinum-resistant A2780cis cell line is highest. All of the extracts display antimicrobial activity, in some cases comparable to that of gentamycin.

Chemistry and biology of genus Vismia

CONTEXT

Many herbal remedies have been employed in the treatment and management of various human ailments since the beginning of human civilization. Vismia is an extensive genus of the family Hypericaceae and consists of small trees inhabiting the tropical and subtropical regions of South and Central America. Within the framework of an International Cooperative Biodiversity Groups project, three Vismia species were studied for their potential anticancer activity.

OBJECTIVES

This review is an extensive study of the available scientific literature published and comprises of the ethnopharmacological, phytochemical and therapeutic potential of genus of plants under the umbrella Vismia.

METHODS

The present review includes 134 natural products with 47 references compiled from the major databases, viz., Chemical Abstracts, Science Direct, SciFinder, PubMed, Dr. Dukes Phytochemical and Ethnobotany, CIMER, and InteliHealth.

RESULTS

An exhaustive survey of the accessed literature revealed that flavonoids, flavanols, xanthones, anthraones, anthraquinones, benzophenones, lignans, steroids, monoterpenes and triterpenes constituted the major classes of phytoconstituents of this genus. Pharmacological reports revealed that it is used for skin diseases such as dermatitis, leprosy, syphilis, herpes, scabies and eczemas, and as an anticancer for human breast, CNS, and lung cancer cell lines.

CONCLUSION

Genus Vismia plants seem to hold great potential for an in-depth investigation towards discovering biological activities, especially for the treatment of cancers affecting our society. Through this review, the authors hope to attract the attention of natural product researchers throughout the world to focus on the unexplored potential of Vismia plants, with the view of developing new formulations with an improved therapeutic value.

Antimicrobial and antioxidant activities of the extracts and compounds from the leaves of Psorospermum aurantiacum Engl. and Hypericum lanceolatum Lam

Background

Psorospermun aurantiacum and Hypericum lanceolatum are plants locally used in Cameroon and other parts of Africa for the treatment of gastrointestinal and urinary tract infections, skin infections, venereal diseases, gastrointestinal disorder, infertility, epilepsy as well as microbial infections. The present study was designed in order to investigate the in vitro antimicrobial and radical scavenging activities of the extracts and isolated compounds from the leaves of these plants.

Methods

The plant extract was prepared by maceration in ethyl acetate and methanol and fractionated by column chromatography. The structures of isolated compounds were elucidated by spectroscopic analyses in conjunction with literature data. The broth microdilution method was used to evaluate the in vitro antimicrobial activity against bacteria, yeasts and dermatophytes. The antioxidant potentials of the extracts and their isolated compounds were evaluated using the DPPH radical scavenging method.

Results

Five known compounds: physcion (1), 1,8-dihydroxy-3-geranyloxy-6-methylanthraquinone (2), kenganthranol B (3), vismiaquinone (4), and octacosanol (5) were isolated from the leaves of P. aurantiacum while six compounds including friedelin (6), betulinic acid (7), 2,2’,5,6’-tetrahydroxybenzophenone (8), allanxanthone A (9), 1,3,6- trihydroxyxanthone (10) and isogarcinol (11) were isolated from H. lanceolatum. Compound 8 and 4 exhibited the highest antibacterial and antifungal activities with MIC ranges of 2–8 μg/ml and 4–32 μg/ml respectively. P. aurantiacum crude extract (Rsa50 = 6.359 ± 0.101) showed greater radical scavenging activity compared with H. lanceolatum extract (Rsa50 = 30.996 ± 0.879). Compound 11 showed the highest radical scavenging activity (RSa₅₀ = 1.012 ± 0.247) among the isolated compounds, comparable to that of L-arscobic acid (RSa50 = 0.0809 ± 0.045).

Conclusions

The experimental findings show that the ethyl acetate and methanol extracts and isolated compounds from P. aurantiacum and H. lanceolatum stem bark possess significant antimicrobial and antioxidant activities justifying the use of these plants in traditional medicine, which may be developed as phytomedicines.

Antibacterial and Antioxidant Properties of the Methanolic Extract of the Stem Bark of Pteleopsis hylodendron (Combretaceae)

Pteleopsis hylodendron (Combretaceae) is used in Cameroon and West Africa folk medicine for the treatment of various microbial infections (measles, chickenpox, and sexually transmitted diseases). The antibacterial properties of the methanolic extract and fractions from stem bark of Pteleopsis hylodendron were tested against three Gram-positive bacteria and eight Gram-negative bacteria using Agar-well diffusion and Broth microdilution methods. Antioxidant activities of the crude extract and fractions were investigated by DPPH radical scavenging activity and β-carotene-linoleic acid assays. The methanolic extract and some fractions exhibited antibacterial activities that varied between the bacterial species (ID = 0.00–25.00 mm; MIC = 781–12500 μg/mL and 0.24–1000 μg/mL). The activity of the crude extract is, however, very weak compared to the reference antibiotics (MIC = 0.125–128 μg/mL). Two fractions (F_E and F_F) showed significant activity (MIC = 0.97 μg/mL) while S. aureus ATCC 25922 was almost resistant to all the tested fractions. In addition, the crude extract and some fractions showed good antioxidant potential with inhibition values ranging from 17.53 to 98.79%. These results provide promising baseline information for the potential use of this plant as well as some of the fractions in the treatment of infectious diseases and oxidative stress.

Anticancer activities of six selected natural compounds of some Cameroonian medicinal plants

BACKGROUND

Natural products are well recognized as sources of drugs in several human ailments. In the present work, we carried out a preliminary screening of six natural compounds, xanthone V(1) (1); 2-acetylfuro-1,4-naphthoquinone (2); physcion (3); bisvismiaquinone (4); vismiaquinone (5); 1,8-dihydroxy-3-geranyloxy-6-methylanthraquinone (6) against MiaPaCa-2 pancreatic and CCRF-CEM leukemia cells and their multidrug-resistant subline, CEM/ADR5000. Compounds 1 and 2 were then tested in several other cancer cells and their possible mode of action were investigated.

METHODOLOGY/FINDINGS

The tested compounds were previously isolated from the Cameroonian medicinal plants Vismia laurentii (1, 3, 4, 5 and 6) and Newbouldia laevis (2). The preliminary cytotoxicity results allowed the selection of xanthone V(1) and 2-acetylfuro-1,4-naphthoquinone, which were then tested on a panel of cancer cell lines. The study was also extended to the analysis of cell cycle distribution, apoptosis induction, caspase 3/7 activation and the anti-angiogenic properties of xanthone V(1) and 2-acetylfuro-1,4-naphthoquinone. IC(50) values around or below 4 µg/ml were obtained on 64.29% and 78.57% of the tested cancer cell lines for xanthone V(1) and 2-acetylfuro-1,4-naphthoquinone, respectively. The most sensitive cell lines (IC(50)<1 µg/ml) were breast MCF-7 (to xanthone V(1)), cervix HeLa and Caski (to xanthone V(1) and 2-acetylfuro-1,4-naphthoquinone), leukemia PF-382 and melanoma colo-38 (to 2-acetylfuro-1,4-naphthoquinone). The two compounds showed respectively, 65.8% and 59.6% inhibition of the growth of blood capillaries on the chorioallantoic membrane of quail eggs in the anti-angiogenic assay. Upon treatment with two fold IC(50) and after 72 h, the two compounds induced cell cycle arrest in S-phase, and also significant apoptosis in CCRF-CEM leukemia cells. Caspase 3/7 was activated by xanthone V(1).

CONCLUSIONS/SIGNIFICANCE

The overall results of the present study provided evidence for the cytotoxicity of compounds xanthone V(1) and 2-acetylfuro-1,4-naphthoquinone, and bring supportive data for future investigations that will lead to their use in cancer therapy.

Essential Oil Composition of Vismia macrophylla Leaves (Guttiferae)

The essential oil from Vismia macrophylla Kunth (Guttiferae) leaves, extracted by hydrodistillation, was analyzed by GC/MS. The oil obtained (yield 0.11%) contained twenty-eight compounds, which were identified from their retention indices and by comparison of their mass spectra with those in the Wiley GC-MS Library data base. The major components were β-caryophyllene (20.1%), germacrene D (11.6%) and β-elemene (7.0%).

Antimicrobial activities of methanol extract and compounds from stem bark of Vismia rubescens

ETHNOPHARMACOLOGICAL RELEVANCE

The plant, Vismia rubescens (Guttiferae) is popularly used in Cameroon and in several parts of Africa as febrifugal and for the treatment of various microbial infections (skin diseases, diarrhoea and venereal diseases).

AIM OF THE STUDY

This study was mapped out to evaluate the antimicrobial activities of the methanol extract and compounds from the stem bark of Vismia rubescens.

MATERIALS AND METHODS

Structures of the compounds obtained after column chromatography of the methanol-soluble fraction were determined by spectroscopy and in comparison with published data. The broth micro-dilution method was used to evaluate the antimicrobial activities against three bacteria species (Salmonella typhi, Staphylococcus aureus and Pseudomonas aeruginosa) and four yeast species (Candida albicans, Candida tropicalis, Candida parapsilosis and Cryptococcus neoformans).

RESULTS

Chemical analysis of the methanol extract from the stem bark of Vismia rubescens yielded five known compounds 1,4,8-trihydroxyxanthone (1), 1,7-dihydroxyxanthone (2), physcion (3), friedelin (4) and friedelanol (5). The crude extract and compounds 1, 2 and 3 exhibited both antibacterial and antifungal activities that varied between the microbial species (MIC=3.12-1000 microg/ml). Compounds 2 and 3 were the most active (MIC=3.12-100 microg/ml) while Staphylococcus aureus and Pseudomonas aeruginosa were sensitive to all the tested compounds. The antimicrobial activity of this plant as well as that of compounds 1 and 2 is being reported here for the first time.

CONCLUSION

These results provide promising baseline information for the potential use of this plant as well as some of the isolated compounds in the treatment of skin diseases and diarrhoea.