Natural Products Journal, The - Volume 12, Issue 6, 2022

Since the initial outbreak in December 2019, the COVID-19 pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to more than 3 million deaths worldwide. There is an urgent need for developing a potential therapy against SARS-CoV-2. Exploring the potentials of phytochemicals towards inhibition of SARS-CoV-2 proteins remains of significant scientific interest. The therapeutic values of phytochemicals in the treatment of diseases, such as viral infections, are known for a long time. In this review, we present a brief overview of the past experimental and computational efforts on evaluating phytochemicals against SARS coronaviruses, an earlier coronavirus strain. We discuss natural metabolites of different structural and chemical scaffolds, including polyphenols, flavonoids, and phytosterols, which can be promising compounds for screening against the currently evolving SARS-CoV-2 virus.

Background: Medicinal plants have been used in medicine for the treatment of numerous diseases due to their medicinal properties and pharmacological activities. The popularity of herbal- based drugs in the health sector has been increasing due to patient compliance and cost-effectiveness. Herbal drugs derived from plant and animal sources have been used in the Ayurvedic, Homeopathic, and Naturopathic systems of medicine. Medicinal plants have been used as fuel, clothing, shelter, and food material worldwide since a very early age. Phytoconstituents are pure plant chemicals found in different parts of the plant material. Flavonoids are an important class of phytochemicals found in medicinal plants and their derived products. Methods: In order to understand the biological significance of tricetin, the present study collected and analyzed scientific data on tricetin medicinal importance and pharmacological activities. Literature databases such as Google, PubMed, Science Direct, and Scopus have been searched using terms tricetin and flavonoid. All the scientific information has been collected from these databases to know the biological importance of tricetin. Analytical data of tricetin have also been collected and analyzed in the present work to know the isolation, separation, and identification procedure of tricetin. Results: Scientific data analysis of different research work revealed the presence of tricetin in Triticum dicoccum, Lathyrus pratensis, Eucalyptus globules, Thuja occidentalis, and Metasequoia glyptostroboides. Scientific data analysis signified the biological importance of tricetin against different forms of cancerous disorders, human osteosarcoma, glioblastoma multiforme, human breast adenocarcinoma, human non-small cell lung cancer, and liver cancer. Scientific data analysis also signified the biological potential of tricetin against inflammation, neurodegenerative diseases, atherosclerosis, diabetes, and respiratory syncytial virus infection. Scientific data analysis revealed the biological importance of tricetin against multidrug resistance and free radicals. Conclusion: Scientific data analysis revealed the biological importance and pharmacological activities of tricetin against various forms of human disorders, including cancer, inflammation, neurodegeneration, atherosclerosis, and diabetes.

The Amazon rainforest has wide and unique biodiversity, which is an important source of natural products for the development of drugs. Neglected tropical diseases (NTDs) represent a major health problem as they affect over 1 billion people, especially vulnerable populations living in tropical and subtropical regions. Currently available drugs are generally inadequate for the majority of these diseases, thus, there is an urgent need for new treatments. The present review aims to summarize upto- date and comprehensive information on the efficacy of the Amazon plants, in treating certainneglected tropical diseases. According to the literature information, several compounds (phenolics, alkaloids, terpenoids and steroids, among others) which were isolated from plants of the Amazon forest showed in vtro activity against Leishmania sp., Trypanosoma cruzi, the parasites responsible for leishmaniasis and Chagas disease, respectively. Moreover, extracts and essential oil from certain plants were reported to have mosquito repellent and insecticidal activities against Aedes aegypti, the vector of dengue, and chikungunya. This review demonstrated that the Amazonian rainforest is endowed with pharmacologically active plants which can be used as a starting point for the development of new drugs against NTDs, such as leishmaniasis, Chagas disease, dengue, and chikungunya.

Background: Clusia nemorosa, popularly known as pororoca, is used in folk medicine to treat inflammation. Objective: The current study was conducted to isolate and identify bioactive compounds from C. nemorosa fruits and to investigate their antimicrobial and antioxidant activities. Methods: The isolation and structural elucidation of the substances were carried out by usual chromatographic techniques and spectroscopic methods, respectively. The antioxidant activity of extracts of C. nemorosa fruits was measured by DPPH assay and antimicrobial activity was evaluated against the microorganisms Staphylococcus aureus, Candida albicans, Cryptococcus neoformans, and Rhizopus oryzae. Results: The chemical investigation of the fruit extract of C. nemorosa led to the identification of two phenolic acids, protocatechuic acid (1) and coumaric acid (6), a flavonoid apigenin (7), glycosyl-β- sitosterol (4), glycosyl-stigmasterol (5), citric acid (3), and the trimethyl citrate ester (2). The fraction in AcOET showed the best scavenging activity of the DPPH radical, with IC50 = 23.50±1.7 μg. mL^-1. The extracts were inactive against the tested microorganisms up to 2500 μg. mL^-1. Conclusion: With the exception of the steroid glycosyl-β-sitosterol, the substances are described for the first time in the species, and, in addition, we report the promising free radical scavenging activity showing its potential in the treatment of diseases related to oxidative stress.

Background: The Coussapoa genus (Urticaceae, tribe Cecropieae) contains 50 species mainly distributed throughout the Neotropical region. Although some genera belonging to the Cecropieae tribe have been well-assessed, the chemical profile of Coussapoa members has not yet been investigated. Objective: In this context, the aim of the present study was to characterize phenolic substances present in a methanol extract obtained from Coussapoa microcarpa leaves employing UPLC-DAD-ESI-MS analyses. Methods: Several condensed tannins (epi-afzelechin-epi-catechin, B-type and C-type procyanidins), flavan-3-ols ((+) -catechin and (-) - epicatechin), phenolic acid (O-caffeoylquinic acid) and C-glycosyl flavones (orientin, isoorientin, vitexin, isovitexin, isoorientin-2″-O-rhamnoside, vitexin-2″-Ohexoside, vitexin-2″-O-xyloside and isovitexin-2″-O-xyloside) were identified. Results: The determined chemical profile observed for C. microcarpa exhibits chemo-taxonomic significance compared to other neotropical genera. Conclusion: Structural variability of the identified secondary metabolites is of significant value for chemosystematic studies concerning the Coussapoa genus and the Cecropieae tribe, both still unexplored with respect to their chemodiversity.

Background: The composition and bioactivity of natural plant extract strongly depend on the extraction technique employed. Clinacanthus nutans Lindau (C. nutans) is a well-known medicinal plant in South-East Asia that has been traditionally used for the treatment of various diseases. Several conventional methods have been using for the extraction of bioactive compounds from C. nutans. However, extraction of fatty acids using supercritical carbon dioxide was not reported yet from this medicinal herbs. Objective: The main objective of the study is to examine the potential of supercritical carbon dioxide (scCO2) extraction of fatty acids from leaves and stems of C. nutans. Method: Fatty acid compositions were determined from leaves and stems of C. nutans oil extracted by scCO2 (temperature 45-65 °C, pressure 25-35 MPa) and compared to the results of Soxhlet extraction. Results: Supercritical CO2 extraction shows the highest oil recovery in both leaves (3.7%) and stems (1.6%) at pressure 35 MPa, temperature 65°C and 2 ml/min flow rate, which was closer to the yield of Soxhlet. The scCO2 yields presented a higher percentage of polyunsaturated fatty acids (PUFA), especially linoleic acid (C18:2n-6). Palmitic acid ranging from 42%- 47% in leaves and stems of C. nutans was found dominant saturated fatty acids (SFA) in both scCO2 and Soxhlet method. Conclusion: The current results indicate that leaves and stems of C. nutans could be a potential source of fatty acids, especially biologically active compounds.

Aim: Herein, we determined the anti-amoebic properties of propolis collected from different regions in Iran against Naegleria fowleri and Balamuthia mandrillaris. Background: Natural products remain a valuable source of compounds that are biologically active. Approximately one-third of well-known therapeutic drugs worldwide are derived from natural products. Objectives: Considering the use of propolis in folk medicine, here, for the first time, we evaluated anti-amoebic properties of propolis against free-living pathogenic amoebae, B. mandrillaris and N. fowleri. Methods: Propolis was collected from different regions of Iran and ethanolic extracts were prepared. Amoebicidal and cysticidal assays were accomplished to determine the effects of propolis against N. fowleri and B. mandrillaris. In vitro cytotoxicity assays were carried out to establish propolis effects on host cell damage. Finally, propolis metabolites were determined using spectrometric methods. Results: It was observed that propolis exhibited potent antiamoebic effects against trophozoites and cysts of both N. fowleri and B. mandrillaris at μg concentrations. When tested against cysts of both amoebae, only selected propolis exhibited cysticidal properties. The best activity was observed by propolis from the Kermanshah region, which depicted more than 95% amoebicidal activity and more than 60% cysticidal activity against both amoebae, respectively. Liquid chromatography- tandem mass spectrometry revealed that each extract is comprised of various components. Conclusion: For the first time, we showed that propolis has amoebicidal activity against both amoebae tested. Investigation into the individual activity of the components of propolis extracts and their mechanism of action against the aforementioned parasites might lead to the discovery of novel anti-amoebic compounds.

Background: Saline stress is an important environmental factor that limits the productivity of numerous agricultural crops, such as onion (Allium cepa L.), a vegetable present in gardens and used in various ways. Pulegone has been identified as a component that has a large number of biological functions. Objective: The aim of this study was to investigate the effect of pulegone (100 and 500 μg/mL) on the morphological and biochemical changes to onions induced by stressing seeds with NaCl. Methods: Soil composition, emergence percentage and its inhibition, emergence speed index (ESI), leaf and root parameters, malondialdehyde (MDA) content, free iron content and chelation/oxidation capacity (Fe²⁺) were measured following 120 days of treatment. Results: Pulegone was able to significantly improve the changes in ESI caused by saline stress, not restoring other emergence parameters. The leaf size was also improved by the pulegone, which did not affect the morphological changes of the roots. Conclusion: Our results suggest that the use of pulegone is a viable treatment to mitigate the effects of salt stress on A. cepa seeds.

Aim: Spirulina is a microalga that is widely used as a food supplement and is regarded as having performance-enhancing and health-promoting properties. We conducted a preliminary evaluation of the possible anti-depressant, anti-anxiety, pro-socialization and cognition-enhancing effects of Spirulina in mouse models. Methods: Sixty male BalbC mice aged 3 weeks were administered with phycocyanin-rich Spirulina extract [PRSE, 545 mg/kg], fluoxetine [20 mg/kg] or water orally for 5 weeks. During the last 2 weeks of the experiment, a series of behavioral-cognitive tests were performed to evaluate motor activity, anti-depressant and anti-anxiety effects, socialization and cognitive effects. Effects of PRSE and fluoxetine were compared to those of water. Results: There was a significant effect of PRSE in the activity domain, manifesting as an increase in velocity in the open field [p=0.0007 vs. water]. Fluoxetine significantly enhanced immobility in the tail suspension test and the forced swim test reflecting the known anti-depressant effect of this compound, but not PRSE. There were no significant effects of PRSE found in the tests of anxiety, socialization or cognition. Conclusion: The most striking observation in this study was that PRSE significantly enhanced activity in the open field test. Further studies are indicated to confirm and extend this finding and investigate the possible mechanisms of action. The results of the current study do not support sporadic reports of possible anti-depressant or cognition-enhancing effects of PRSE. Nevertheless, additional studies are indicated using depression models rather than naïve mice, alternative mouse strains, using additional cognitive tests, and administering higher PRSE doses.

Background: Ferns are underestimated as medicinal plants and their use in traditional medicine is limited despite their diversity. Most of the research on their healing properties and phytochemical composition related to their biological activity has been focused on the secondary metabolites synthesized by ferns. Objective: In this study, we aimed to make an in-depth chemical characterization of three ferns widely spread in Bulgaria - Asplenium ceterach L., Asplenium scolopendrium L. and Asplenium trichomanes L. Methods: Micro elemental analysis was carried out using ICP-MS. Standard laboratory methods were used to determine the content of proteins, fats and fatty acids. Chromatographic methods were applied to quantify some secondary metabolites. Two antioxidant methods and two antimicrobial tests were used to evaluate the biological properties of the ferns tested. Results: Micro elemental analysis showed that these ferns could be useful source of zinc and iron. Protein content slightly varied among the species (13.6% - 18.4% of the dried plant weight). Negligible was the variation in oil content (3.1% - 4.0%, dry weight base); oil composition was dominated by saturated fatty acids. Some principal classes secondary metabolites, individual phenolic acids and flavonoids were quantified. The extract obtained from Asplenium ceterach L. demonstrated the highest antioxidant capacity. Fern extracts showed moderate antimicrobial activity against six of the 14 microorganisms tested. Conclusion: The results obtained may reveal new areas of application for ferns and are a solid basis for comparison with the same species growing in other geographical and climatic conditions, which may affect their healing properties.