Antineoplastic agents. 558. Ampelocissus sp. cancer cell growth inhibitory constituents

Evaluation of Antioxidant, Antimicrobial, and Cytotoxic Activities and Correlation with Phytoconstituents in Some Medicinal Plants of Nepal

Traditional herbal medicines have been consumed in Nepal and other parts of the eastern hemisphere since ancient times. Many of these plants reportedly have been effective against ailments as well. This study aims to analyze the phytochemical constituents from the extracts of ten such plants and evaluate their antimicrobial, cytotoxicity, and antioxidant properties. In addition, the study aims to study the correlation of cytotoxicity and antioxidant activities with the total phenolic, flavonoid, and tannin contents. The plants investigated were Oroxylum indicum, Kalanchoe pinnata, Phragmites vallatoria, Ehretia acuminata, Cirsium wallichii, Ampelocissus tomentosa, Dichrocephala integrifolia, Boenninghausenia albiflora, Cynoglossum zeylanicum, and Clerodendrum serratum. Phytochemical analyses were performed to evaluate secondary metabolites, such as glycosides, flavonoids, terpenoids, saponins, alkaloids, and fats. The total phenolic contents of the extracts ranged from 14.94 to 229.89 mg GAE/g, the total flavonoid contents varied from 66.67 to 900 mg QE/g, and the total tannin contents were 42 to 168 mg GAE/g. The results of the antioxidant studies showed that the highest antioxidant activity was exhibited by the extract of A. tomentosa (IC50 = 7.89 µg/mL) followed by E. acuminata (IC50 = 24.82 µg/mL) and C. serratum (IC50 = 32.91 µg/mL). The extracts from P. vallatoria and A. tomentosa exhibited substantial antimicrobial activity. The extracts of A. tomentosa and B. albiflora showed lethality against brine shrimp with LC50 values of 33.11 µg/mL.

Acetogenins from Annonaceae family. Their potential biological applications

The aim of this contribution has been to continue with the knowledge about newly isolated acetogenins from Annonaceae family for the last fifteen years. This review will report classification, extraction, isolation, elucidation of the structure, biological activities and mechanism of action of such interesting natural products. In fact, out of the 532 compounds reviewed, 115 previously non-described annonaceous acetogenins have been added to the list of isolated compounds from 2005 to May 2019.

Antibacterial, Antifungal, Antiviral, and Anthelmintic Activities of Medicinal Plants of Nepal Selected Based on Ethnobotanical Evidence

BACKGROUND

Infections by microbes (viruses, bacteria, and fungi) and parasites can cause serious diseases in both humans and animals. Heavy use of antimicrobials has created selective pressure and caused resistance to currently available antibiotics, hence the need for finding new and better antibiotics. Natural products, especially from plants, are known for their medicinal properties, including antimicrobial and anthelmintic activities. Geoclimatic variation, together with diversity in ethnomedicinal traditions, has made the Himalayas of Nepal an invaluable repository of traditional medicinal plants. We studied antiviral, antibacterial, antifungal, and anthelmintic activities of medicinal plants, selected based upon ethnobotanical evidence.

METHODS

Ethanolic and methanolic extracts were tested (1) on a panel of microbes: two Gram-positive bacteria (Staphylococcus aureus and Listeria innocua), four Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica, and Shigella sonnei), and one fungal species: Candida albicans; (2) against three different viruses: yellow fever, chikungunya, and enterovirus; and (3) on the nematode Caenorhabditis elegans. Also, cytotoxicity was assessed on human hepatoma (Huh), rhabdosarcoma (RD), and Vero (VC) cell lines.

RESULTS

Of 18 plants studied, Ampelocissus tomentosa and Aleuritopteris anceps inhibited S. aureus (MIC 35 μg/mL and 649 μg/mL, respectively) and Pseudomonas aeruginosa (MIC 15 μg/mL and 38 μg/mL, respectively). Rhododendron arboreum and Adhatoda vasica inhibited S. enterica (MIC 285 μg/mL and 326 μg/mL, respectively). Kalanchoe pinnata, Ampelocissus tomentosa, and Paris polyphylla were active against chikungunya virus, and Clerodendrum serratum was active against yellow fever virus (EC50 15.9 μg/mL); Terminalia chebula was active against enterovirus (EC50 10.6 μg/mL). Ampelocissus tomentosa, Boenninghausenia albiflora, Dichrocephala integrifolia, and Kalanchoe pinnata significantly reduced C. elegans motility, comparable to levamisole.

CONCLUSIONS

In countries like Nepal, with a high burden of infectious and parasitic diseases, and a current health system unable to combat the burden of diseases, evaluation of local plants as a treatment or potential source of drugs can help expand treatment options. Screening plants against a broad range of pathogens (bacteria, viruses, fungi, and parasites) will support bioprospecting in Nepal, which may eventually lead to new drug development.

Acetogenins from Annonaceae

In recent decades, annonaceous acetogenins have become highly studied plant secondary metabolites in terms of their isolation, structure elucidation, synthesis, biological evaluation, mechanism of action, and toxicity. The aim of the present contribution is to summarize chemical and biological reports published since 1997 on annonaceous acetogenins and synthetic acetogenin mimics. The compounds are considered biologically in terms of their cytotoxicity for cancer cell lines, neurotoxicity, pesticidal effects, and miscellaneous activities.

In vitro cytotoxic, antifungal, trypanocidal and leishmanicidal activities of acetogenins isolated from Annona cornifolia A. St. -Hil. (Annonaceae)

Annona cornifolia A. St. -Hil. is a small annual perennial tree found in the Brazilian savannah; their green fruit is popularly used in the treatment of ulcers. The acetogenins isolated from the seeds of Annona cornifolia previously showed to possess antioxidant activity. In continuation of our investigations on the biological activities of acetogenins, four binary mixtures and ten pure adjacent bis-tetrahydrofuran annonaceous acetogenins were evaluated: the cytotoxic (against three human tumor cell lines), antifungal (against Paracoccidioides brasiliensis), trypanocidal (against Trypanosoma cruzi) and leishmanicidal (against Leishmania amazonensis) activities. Acetogenins presented cytotoxic activity confirming their potential use in anti-cancer therapy. Regarding leishmanicidal and trypanocidal activities, an inhibition of 87% of L. amazonensis amastigotes and 100% of T. cruzi amastigotes and trypomastigotes was observed, when tested at the concentration of 20 µg mL–1. Moreover, six acetogenins showed more activity against all the three tested isolates of P. brasiliensis than trimethoprim-sulfamethoxazole, a drug used for treating paracoccidioidomycosis. Thus, acetogenins may be an alternative in treating a number of diseases that have a huge impact on millions of people worldwide. This paper reports for the first time the antifungal, leishmanicidal and trypanocidal activities for these acetogenins.

Total synthesis of (-)-goniotrionin

A stereoselective total synthesis of the reported structure of goniotrionin (4) has been accomplished. The key steps involved the opening of a chiral epoxide, a highly diastereoselective Mukaiyama aerobic oxidative cyclization, a selective 1,2-syn Mukaiyama aldol reaction, and a Noyori reduction.

Highly cytotoxic and neurotoxic acetogenins of the Annonaceae: new putative biological targets of squamocin detected by activity-based protein profiling

Acetogenins of the Annonaceae are strong inhibitors of mitochondrial complex I but discrepancies in the structure/activity relationships pled the search for other targets within the whole cell proteome. Combining hemisynthetic work, Cu-catalyzed Huisgen cycloaddition and proteomic techniques we have identified new putative protein targets of squamocin ruling out the previously accepted 'complex I dogma'. These results give new insights into the mechanism of action of these potent neurotoxic molecules.