Development and Applications of Water‐based Extraction Methods in Natural Products Isolation Chemistry

Plant-derived bioactive compounds as key players in the modulation of immune-related conditions

The immune system is a complex and fundamental network for organism protection. A minimal unbalance in the host defense system homeostasis can originate severe repercussions in human health. Fundamentally, immune-related diseases can arise from its compromise (immunodeficiency diseases), overactivation against itself (autoimmune diseases) or harmless substances (allergies), and failure of eliminating the harmful agent (chronic inflammation). The notable advances and achievements in the immune system diseases pathophysiology have been allowing for a dramatic improvement of the available treatments. Nevertheless, they present some drawbacks, including the inappropriate benefit/risk ratio. Therefore, there is a strong and urgent need to develop effective therapeutic strategies. Nature is a valuable source of bioactive compounds that can be explored for the development of new drugs. Particularly, plants produce a broad spectrum of secondary metabolites that can be potential prototypes for innovative therapeutic agents. This review describes the immune system and the inflammatory response and examines the current knowledge of eight plants traditionally used as immunomodulatory medicines (Boswellia serrata, Echinacea purpurea, Laurus nobilis, Lavandula angustifolia, Olea europaea, Salvia officinalis, Salvia rosmarinus, and Taraxacum officinale). Moreover, the issues responsible for possible biologic readout inconsistencies (plant species, age, selected organ, developmental stage, growth conditions, geographical location, drying methods, storage conditions, solvent of extraction, and extraction method) will also be discussed. Furthermore, a detailed list of the chemical composition and the immunomodulatory mechanism of action of the bioactive compounds of the selected plant extracts are presented. This review also includes future perspectives and proposes potential new avenues for further investigation.

Distinctive Arbutin-Containing Markers: Chemotaxonomic Significance and Insights into the Evolution of Proteaceae Phytochemistry

Natural products isolation studies of eight endemic Tasmanian Proteaceae species - Agastachys odorata, Persoonia juniperina, Hakea megadenia, Hakea epiglottis, Orites diversifolius, Orites acicularis, Orites revolutus, and Telopea truncata - and three endemic Australian Proteaceae species Banksia serrata, Banksia praemorsa, and Banksia marginata were undertaken. Two previously unreported glycoside-derived natural products were identified, in addition to four other tremendously rare arbutin esters. The results of this study provide further evidence consistent with the proposal that these distinctive arbutin esters represent markers that can provide valuable insights into the chemical evolution of plant species within the family Proteaceae.

Furanosesquiterpenes and Related Natural Products from Myoporum Species: Isolation and Semisynthesis

Myoporum species are recognized as toxic plants. Essential oils from the leaves of these species contain furanosesquiterpenes, which comprise the active toxins. In this report, natural products isolation studies of three Myoporum species (M. insulare, M. parvifolium, and M. montanum) afforded two previously unreported furanosesquiterpenes (24 and 25) and three unprecedented γ-lactone-containing analogues (26-28), along with nine previously reported furanosesquiterpenes and five other natural products. Among the 14 furanosesquiterpenes and related compounds isolated in this study, we observed three distinct types of furanosesquiterpene structures isolated from each of these Myoporum species. Semisyntheses of four sesquiterpene natural products were completed from (-)-ngaione over two steps in each case. This included the synthesis of the lactam-containing sesquiterpene myoporumine A.

Recent bioanalytical methods for the isolation of bioactive natural products from genus Codonopsis

INTRODUCTION

Chromatography and spectroscopy are nowadays well-validated techniques allowing to isolate and purify different class of natural products from the genus Codonopsis. Several categories of phytochemicals with drug like properties have been selectively extracted, isolated, characterised by this methodology.

OBJECTIVES

The present review aims to provide up-to-date and comprehensive information on the chromatography, phytochemistry and pharmacology of natural products of Codonopsis with an emphasis on the search for natural products having various biological activities and the semi-synthetic derivatives of bioactive ones and to highlight current gaps in knowledge.

MATERIALS AND METHODS

A literature search was performed in the SciFinder Scholar, PubMed, Medline, and Scopus databases.

RESULTS

During the period covered in this review, several classes of compounds have been reported from genus Codonopsis. Codonopsis pilosula and Codonopsis lanceolata are the most popular in the genus especially as per phytochemical and bioactive studies. Phytochemical investigation demonstrates that Codonopsis species contain mainly xanthones, flavonoids, alkaloids, polyacetylenes, phenylpropanoids, triterpenoids and polysaccharides, which contribute to numerous bioactivities. The major bioactive compounds isolated were used for semi-synthetic modification to increase the chance to discover lead compound.

CONCLUSIONS

It can be concluded that genus Codonopsis has been used as traditional medicines and food materials around the world over years due to chemical constituents with diverse structural types, exhibiting extensive pharmacological activities in immune system, blood system, cardiovascular system, central nervous system, digestive system, and so forth, with almost no obvious toxicity and side effect. Therefore, Codonopsis can be used as a promising ethnopharmacological plant source.

Natural products isolation studies of the paleoendemic plant species Nothofagus gunnii and Nothofagus cunninghamii

The first natural product isolation studies of Nothofagus gunnii (Hook.f.) Oerst and Nothofagus cunninghamii (Hook.f.) Oerst have been undertaken. A previously unreported stilbene derivative, pinosylvin monoacetate, was isolated from the leaves of N. gunnii, in addition to 14 known compounds; including the flavonoids galangin, pinobanksin, catechin and quercetin; sesquiterpenoids such as, ilicol and (+)-β-costol acetate; 2,4-dihydroxy-6-methoxychalcone and pinosylvin. Four known flavonoid natural products, catechin, quercetin, ayanin, and avicularin were isolated from the leaves of N. cunninghamii. This study reveals that N. gunnii is a rich source of flavonoid, chalcone and stilbene compounds, while primarily hydroxyflavonoid compounds are found in N. cunninghamii. The isolated phytochemicals are consistent with the evolutionary relationships suggested to exist among Nothofagus species.

The isolation of water-soluble natural products - challenges, strategies and perspectives

Covering period: up to 2019Water-soluble natural products constitute a relevant group of secondary metabolites notably known for presenting potent biological activities. Examples are aminoglycosides, β-lactam antibiotics, saponins of both terrestrial and marine origin, and marine toxins. Although extensively investigated in the past, particularly during the golden age of antibiotics, hydrophilic fractions have been less scrutinized during the last few decades. This review addresses the possible reasons on why water-soluble metabolites are now under investigated and describes approaches and strategies for the isolation of these natural compounds. It presents examples of several classes of hydrosoluble natural products and how they have been isolated. Novel stationary phases and chromatography techniques are also reviewed, providing a perspective towards a renaissance in the investigation of water-soluble natural products.