A new 9,10-dihydrophenanthrene and cell proliferative 3,4-δ-dehydrotocopherols from Stemona tuberosa

Dihydrophenanthrenes from a Sicilian Accession of Himantoglossum robertianum (Loisel.) P. Delforge Showed Antioxidant, Antimicrobial, and Antiproliferative Activities

The peculiar aspect that emerges from the study of Orchidaceae is the presence of various molecules, which are particularly interesting for pharmaceutical chemistry due to their wide range of biological resources. The aim of our study was to investigate the properties of two dihydrophenanthrenes, isolated, for the first time, from Himantoglossum robertianum (Loisel.) P. Delforge (Orchidaceae) bulbs and roots. Chemical and spectroscopic study of the bulbs and roots of Himantoglossumrobertianum (Loisel.) P. Delforge resulted in the isolation of two known dihydrophenanthrenes-loroglossol and hircinol-never isolated from this plant species. The structures were evaluated based on ¹H-NMR, ¹³C-NMR, and two-dimensional spectra, and by comparison with the literature. These two molecules have been tested for their possible antioxidant, antimicrobial, antiproliferative, and proapoptotic activities. In particular, it has been shown that these molecules cause an increase in the activity of superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST) in polymorphonuclear leukocytes (PMN); show antimicrobial activity against Escherichia coli and Staphylococcus aureus, and have anti-proliferative effects on gastric cancer cell lines, inducing apoptosis effects. Therefore, these two molecules could be considered promising candidates for pharmaceutical and nutraceutical preparations.

The traditional uses, phytochemistry, and pharmacology of Stemona species: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Plants of genus Stemona (Stemonaceae) have been long used locally and traditionally in many South and East Asian counties to relieve cough, dispel phlegm, prevent asthma, control pests, diminish inflammation, decrease pain, and treat some cutaneous diseases.

AIM OF STUDY

This review provided comprehensive and up-to-date information about botanic characterization and distribution, ethnopharmacology, secondary metabolites, pharmacological activities, and toxicology of plants of genus Stemona to explore the scientific potential and future therapeutic potential of the plants.

MATERIALS AND METHODS

This article conducted a literature review on information about the Stemona species in multiple electronic databases, including PubMed, Web of Science, Wiley, Science Direct, Elsevier, Google Scholar, ACS publications, SpringerLink, and China National Knowledge Internet. Information was also derived from other literature sources (e.g. Chinese Pharmacopoeia, 2015 edition, Chinese herbal classic books, PhD and MSc thesis). Plant names were validated by "The Plant List" (www.theplantlist.org). All studies of the genus Stemona were included in this review until March 2020.

RESULTS

Our comprehensive analysis of the scientific literatures indicated that many Stemona species are popular and valuable herbal medicines with therapeutic potentials to treat various ailments. Phytochemical analyses identified alkaloids and stilbenoids as the major bioactive substances of Stemona species. Numerous studies have shown that the extracts and secondary metabolites isolated from these plants have a wide range of pharmacological activities, including insecticidal and antifeedant, antitussive, anti-inflammatory, anticancer, antimicrobial, and antivirus activities.

CONCLUSION

Though plants of genus Stemona have been put to enormous traditional uses, the pharmacological studies conducted were insufficient. Therefore, more secondary metabolites need to be studied for more detailed pharmacological studies. Further studies are also required to establish the mechanisms which mediate the plants' bioactivities in relation to the medicinal uses as well as investigate any potential toxicity for future clinical studies.

Wound Healing and the Use of Medicinal Plants

Cutaneous wound healing is the process by which skin repairs itself. It is generally accepted that cutaneous wound healing can be divided into 4 phases: haemostasis, inflammation, proliferation, and remodelling. In humans, keratinocytes re-form a functional epidermis (reepithelialization) as rapidly as possible, closing the wound and reestablishing tissue homeostasis. Dermal fibroblasts migrate into the wound bed and proliferate, creating “granulation tissue” rich in extracellular matrix proteins and supporting the growth of new blood vessels. Ultimately, this is remodelled over an extended period, returning the injured tissue to a state similar to that before injury. Dysregulation in any phase of the wound healing cascade delays healing and may result in various skin pathologies, including nonhealing, or chronic ulceration. Indigenous and traditional medicines make extensive use of natural products and derivatives of natural products and provide more than half of all medicines consumed today throughout the world. Recognising the important role traditional medicine continues to play, we have undertaken an extensive survey of literature reporting the use of medical plants and plant-based products for cutaneous wounds. We describe the active ingredients, bioactivities, clinical uses, formulations, methods of preparation, and clinical value of 36 medical plant species. Several species stand out, including Centella asiatica, Curcuma longa, and Paeonia suffruticosa, which are popular wound healing products used by several cultures and ethnic groups. The popularity and evidence of continued use clearly indicates that there are still lessons to be learned from traditional practices. Hidden in the myriad of natural products and derivatives from natural products are undescribed reagents, unexplored combinations, and adjunct compounds that could have a place in the contemporary therapeutic inventory.

Antiplasmodial Chromanes and Chromenes from the Monotypic Plant Species Koeberlinia spinosa

Nine new compounds containing either a chromane or chromene ring moiety were isolated from the monotypic plant Koeberlinia spinosa. Compounds 1-4 are chromanes with all possible E and Z isomers of the isoprenoid side chain, with compound 5 a methylated derivative of 1. Compounds 6 and 7 were assigned as diastereomeric cyclized derivatives of 2 and were probably artifacts formed during the extraction or the isolation processes. Compounds 8 and 9 were characterized as new chromenes. Structure elucidation of 1-9 was conducted via 1D and 2D NMR spectroscopic data interpretation, and absolute configurations were determined by ECD spectroscopic analysis. Compounds 2, 5, 6, and 7 had weak antiplasmodial activity, while none of the compounds exhibited antiproliferative activity. The isolation, structure elucidation, and biological evaluation of these compounds are presented.

Phenanthrenes: A Promising Group of Plant Secondary Metabolites

Although phenanthrenes are considered to constitute a relatively small group of natural products, discovering new phenanthrene derivatives and evaluating their prospective biological activities have become of great interest to many research groups worldwide. Based on 160 references, this review covers the phytochemistry and pharmacology of 213 naturally occurring phenanthrenes that have been isolated between 2008 and 2016. More than 40% of the 450 currently known naturally occurring phenanthrenes were identified during this period. The family Orchidaceae is the most abundant source of these compounds, although several new plant families and genera have been involved in the search for phenanthrenes. The presence of certain substituent patterns may be restricted to specific families; vinyl-substituted phenanthrenes were reported only from Juncaceae plants, and prenylated derivatives occur mainly in Euphorbiaceae species. Therefore, these compounds also can serve as chemotaxonomic markers. Almost all of the newly isolated compounds have been studied for their biological activities (e.g., potential cytotoxic, antimicrobial, anti-inflammatory, and antioxidant effects), and many of them showed multiple activities. According to the accumulated data, denbinobin, with a novel mechanism of action, has great potential as a lead compound for the development of a new anticancer agent.

Natural 6-hydroxy-chromanols and -chromenols: structural diversity, biosynthetic pathways and health implications

We present the first comprehensive and systematic review on the structurally diverse toco-chromanols and -chromenols found in photosynthetic organisms, including marine organisms, and as metabolic intermediates in animals. The focus of this work is on the structural diversity of chromanols and chromenols that result from various side chain modifications. We describe more than 230 structures that derive from a 6-hydroxy-chromanol- and 6-hydroxy-chromenol core, respectively, and comprise di-, sesqui-, mono- and hemiterpenes. We assort the compounds into a structure-activity relationship with special emphasis on anti-inflammatory and anti-carcinogenic activities of the congeners. This review covers the literature published from 1970 to 2017.

Morphological and chemical variation of Stemona tuberosa from southern China - Evidence for heterogeneity of this medicinal plant species

The occurrence of bioactive alkaloids and tocopherols was studied in 15 different provenances of Stemona tuberosa Lour. collected in southern China, to examine chemical variation of individuals that show notable differences in flower characteristics. Morphological variations stimulated examination of chemical characteristics of these individuals. Methanolic root extracts of 15 individuals of S. tuberosa were comparatively assessed with HPLC-UV-DAD/ELSD. Five of seven compounds were co-chromatographically identified. Two compounds were isolated and their structure elucidated using NMR and MS. Amounts of alkaloids and tocopherols were determined using HPLC-UV-DAD/ELSD with the external standard method. Five alkaloids, tuberostemonine (1), tuberostemonine A (2), neotuberostemonine (3), tuberostemonine N (4), stemoninine (5) and two 3,4-dehydrotocopherol derivatives were identified. Within S. tuberosa alkaloid accumulation tends either towards tuberostemonine (1) or stemoninine (5). All individuals show a notable co-occurrence of compounds 1 or 5 and 3,4-dehydro-δ-tocopherol (6). These results coincide with differences in flower morphology of S. tuberosa. Stemona tuberosa, as defined in the Flora of China, shows a remarkable variation in flower morphology and additionally in the accumulation of alkaloids. The obtained data show the need for future species delimitation to either species or subspecies level.

Tuberostemonine N, an active compound isolated from Stemona tuberosa, suppresses cigarette smoke-induced sub-acute lung inflammation in mice

OBJECTIVE

Our previous study demonstrated that a Stemona tuberosa extract had significant effects on cigarette smoking (CS)-induced lung inflammation in mice. The present study evaluated the potential of tuberostemonine N (T.N) to prevent airway inflammation and suppress airway responses in a CS-induced in vivo COPD model.

METHODS

T.N was isolated from the root of ST and analyzed using 1D and 2D NMR. The purity of T.N was accessed using HPLC-ELSD analysis. C57BL/6 mice in this study were whole-body exposed to mainstream CS or room air for 4 weeks, and T.N (1, 5 and 10 mg/kg body wt.) was administered to mice via intraperitoneal (i.p.) injection before CS exposure. The number of inflammatory cells, including neutrophils, macrophages and lymphocytes, and the amount of proinflammatory cytokines and chemokines were accessed from bronchoalveolar lavage fluid (BALF) to investigate the anti-inflammatory effects of T.N. Average alveoli size was also measured using histological analyses.

RESULTS

Cellular profiles and histopathological analyses revealed that the infiltration of peribronchial and perivascular inflammatory cells decreased significantly in the T.N-treated groups compared to the CS-exposed control group. T.N significantly inhibited the secretion of proinflammatory cytokines and chemokines in BALF and decreased alveoli size in lung tissue.

CONCLUSIONS

These data suggest that T.N exerts anti-inflammatory effects against airway inflammation, and T.N may be a novel therapeutic agent for lung diseases, such as COPD.