Bioactive saponins from Swartzia schomburgkii from the suriname rainforest

Unveiling foliar secreting sites and secretion composition in the legume tree Swartzia flaemingii Raddi

Secretory structures in plants play a crucial role in producing bioactive compounds. Despite the potential of the Swartzia genus, comprehensive studies in this context are still scarce. Swartzia is a legume tree (Fabaceae) that occurs in the Brazilian Atlantic Forest, a biodiversity hotspot, and includes species such as Swartzia flaemingii. Therefore, we aim to achieve: (1) identify and characterize the key secretory sites responsible for saponin production in S. flaemingii leaflets; (2) confirm the presence of saponins in S. flaemingii leaves by comparing them with known chemical profiles of other Swartzia species; (3) assess the potential hemolytic and cytotoxic effects of crude leaf extracts. Our investigation unveils the presence of phenolic idioblasts, mucilage cells, and articulate laticifers, which play pivotal roles in defense and adaptation. Notably, we report the first-ever ultrastructural details of laticifers in a legume species. Additionally, oleanane-type saponins were identified in the leaves, giving insights into the chemotaxonomic profile of Swartzia. The crude extracts show low cytotoxicity levels, showcasing as a promising alternative source of saponins. This investigation reinforces the importance of conserving plants in threatened regions like the Atlantic Forest, a global biodiversity hotspot facing substantial anthropogenic pressures.

My 60-Year Love Affair with Natural Products

The author describes his 60-year career in studying the chemistry of natural products, which includes structural, synthetic, and biosynthetic studies of natural products ranging from insect pigments, antibiotics, and fecal mutagens to taxol and other anticancer natural products as well as antimalarial natural products. One of the compounds discussed, napabucasin, is now an anticancer drug in phase III clinical trials.

Bloodwood: the composition and secreting-site of the characteristic red exudate that gives the name to the Swartzia species (Fabaceae)

The Swartzia species are commonly known as bloodwood due to the red exudate released from the stem after injury. This exudate has aroused great interest, and an integrative study is essential to describe it in detail. Thus, this work aimed to identify the red exudate's secreting-site in S. flaemingii and S. langsdorffii, and determine if it is a latex or a resin. Samples of the stem bark and the secondary xylem were prepared for histological analysis. Fresh exudates were dissolved in deuterated methanol and analyzed by ¹H-NMR; other samples were resuspended in MeOH:H₂O (9:1), partitioned with organic solvents and analyzed by direct infusion mass spectrometry. Total phenolic and total flavonoid contents were determined spectrophotometrically, and antioxidant capacity was determined using ferric reducing antioxidant power assay. The results showed that the exudate is a red latex produced by articulated laticifers located among the phloem cells. The latex is composed of sucrose, catechin glucosides, chlorophyll derivatives, and hederagenin-type saponins. Both samples of S. flaemingii and S. langsdorffii presented high amounts of phenolics and flavonoids, as well as a strong antioxidant capacity. The anatomical study showed that the secreting-site of the Swartzia red exudates were laticifers. This finding allows us to exclude other substances such as resin or oleoresin, generally produced by secretory cavities or ducts. Furthermore, since laticifers are rare in Fabaceae, this finding is significant, and represents an essential taxonomic feature. The showy red color is due to the large amounts of flavonoids. This latex probably has a protective role against microorganisms and photodamage. The bioactive potential of this exudate inspires further studies, which may boost the economic importance of Swartzia.

Characterization, crystal structure and cytotoxic activity of a rare iridoid glycoside from Lonicera saccata

A new iridoid glycoside, methyl (3R,4R,4aS,7S,7aR)-3-hydroxy-7-methyl-5-oxooctahydrocyclopenta[c]pyran-4-carboxylate-3-O-β-D-(1'S,2'R,3'S,4'S,5'R)-glucopyranoside, named loniceroside A, C₁₇H₂₆O₁₀, (1), was obtained from the aerial parts of Lonicera saccata. Its structure was established based on an analysis of spectroscopic data, including 1D NMR, 2D NMR and HRESIMS, and the configurations of the chiral C atoms were determined by X-ray crystallographic analysis. The single-crystal structure reveals that the cyclopenta[c]pyran scaffold is formed from a five-membered ring and a chair-like six-membered ring connected through two bridgehead chiral C atoms. In the solid state, the glucose group of (1) plays an important role in constructing an unusual supramolecular motif. The structure analysis revealed adjacent molecules linked together through intermolecular O-H...O hydrogen bonds to generate a banded structure. Furthermore, the banded structures are linked into a three-dimensional network by interesting hydrogen bonds. Biogenetically, compound (1) carries a glucopyranosyloxy moiety at the C-3 position, representing a rare structural feature for naturally occurring iridoid glycosides. The growth inhibitory effects against human cervical carcinoma cells (Hela), human lung adenocarcinoma cells (A549), human acute mononuclear granulocyte leukaemia (THP-1) and the human liver hepatocellular carcinoma cell line (HepG2) were evaluated by the MTT method.

Anti-Candida Cassane-Type Diterpenoids from the Root Bark of Swartzia simplex

A dichloromethane extract of the roots from the Panamanian plant Swartzia simplex exhibited a strong antifungal activity in a bioautography assay against a genetically modified hypersusceptible strain of Candida albicans. At-line HPLC activity based profiling of the crude extract enabled a precise localization of the antifungal compounds, and dereplication by UHPLC-HRESIMS indicated the presence of potentially new metabolites. Transposition of the HPLC reversed-phase analytical conditions to medium-pressure liquid chromatography (MPLC) allowed an efficient isolation of the major constituents. Minor compounds of interest were isolated from the MPLC fractions using semipreparative HPLC. Using this strategy, 14 diterpenes (1-14) were isolated, with seven (5-10, 14) being new antifungal natural products. The new structures were elucidated using NMR spectroscopy and HRESIMS analysis. The absolute configurations of some of the compounds were elucidated by electronic circular dichroism spectroscopy. The antifungal properties of these compounds were evaluated as their minimum inhibitory concentrations in a dilution assay against both hypersusceptible and wild-type strains of C. albicans and by assessment of their antibiofilm activities. The potential cytological effects on the ultrastructure of C. albicans of the antifungal compounds isolated were evaluated on thin sections by transmission electron microscopy.

Two antiproliferative triterpene saponins from Nematostylis anthophylla from the highlands of Central Madagascar

Investigation of the endemic Madagascan plant Nematostylis anthophylla (Rubiaceae) for antiproliferative activity against the A2780 ovarian cancer cell line led to the isolation of the known triterpene saponin randianin (1), and the two new bioactive triterpene saponins 2"-O-acetylrandianin (2) and 6"-O-acetylrandianin (3). The structures of the two new compounds were elucidated based on analysis of their 1D- and 2D-NMR spectra, and mass spectrometric data. The three isolated triterpene saponins displayed moderate but selective antiproliferative activities, with IC(50) values of 1.2, 1.7, and 2.2 μM, respectively, against the A2780 ovarian cancer, but only weak inhibitions of the proliferation of A2058 melanoma and the H522 lung cancer cell lines.

Studies on cytotoxic triterpene saponins from the leaves of Aralia elata

Aralia elata has long been used as a tonic, anticancer and antidiabetic agent in China and Japan, and is widely consumed as food. Phytochemical investigation of the leaves of A. elata has led to the isolation of four new compounds, 3-O-[β-D-glucopyranosyl(1 → 3)-β-D-glucopyranosyl] echinocystic acid 28-O-β-D-glucopyranosyl ester (congmuyenoside I, 1), 3-O-[β-D-glucopyranosyl(1 → 2)-β-D-glucopyranosyl] hederagenin 28-O-β-D-glucopyranosyl ester (congmuyenoside II, 2), 3-O-{[β-D-glucopyranosyl(1 → 2)]-[β-D-glucopyranosyl(1 → 3)-β-D-glucopyranosyl(1 → 3)]-β-D-glucopyranosyl} echinocystic acid 28-O-β-D-glucopyranosyl ester (congmuyenoside III, 3) and 3-O-β-D-glucopyranosyl caulophyllogenin 28-O-β-D-glucopyranosyl ester (congmuyenoside IV, 4), and eight known triterpene saponins (5-12). The structural determination was accomplished with spectroscopic analysis, in particularly (13)C NMR, 2D NMR and HR-ESI-MS techniques. In addition, compounds 5–10 were found for the first time in the genus Aralia. Compounds 1-12 were tested for their inhibition of the growth of HL60, A549 and DU145 cancer cells. In addition, compound 8 showed significant cytotoxic activities against HL60, A549 and DU145 cancer cells with IC(50) values of 15.62, 11.25 and 7.59 μM, respectively.

Biotransformation of oleanolic acid by Alternaria longipes and Penicillium adametzi

Microbial transformation of oleanolic acid (1) was carried out. Six transformed products (2-7) from 1 by Alternaria longipes and three transformed products (8-10) from 1 by Penicillium adametzi were isolated. Their structures were elucidated as 2α,3α,19α-trihydroxy-ursolic acid-28-O-β-d-glucopyranoside (2), 2α,3β,19α-trihydroxy-ursolic acid-28-O-β-d-glucopyranoside (3), oleanolic acid 28-O-β-d-glucopyranosyl ester (4), oleanolic acid-3-O-β-d-glucopyranoside (5), 3-O-(β-d-glucopyranosyl)-oleanolic acid-28-O-β-d-glucopyranoside (6), 2α,3β,19a-trihydroxy-oleanolic acid-28-O-β-d-glucopyranoside (7), 21β-hydroxyl oleanolic acid-28-O-β-d-glucopyranoside (8), 21β-hydroxyl oleanolic acid (9), and 7α,21β-dihydroxyl oleanolic acid (10) based on the extensive NMR studies. Among them, 10 was a new compound and compounds 5 and 8-10 had stronger cytotoxic activities against Hela cell lines than the substrate. At the same time, it was reported for the first time in this paper that the skeletons of compounds 2 and 3 were changed from oleanane to uranane and seven glycosidation products were obtained by biotransformation.

Biodiversity conservation and drug discovery: Can they be combined? The Suriname and Madagascar experiences

The approach to new drugs through natural products has proved to be the single most successful strategy for the discovery of new drugs, but in recent years its use has been deemphasized by many pharmaceutical companies in favor of approaches based on combinatorial chemistry and genomics, among others.Drug discovery from natural sources requires continued access to plant, marine, and microbial biomass, and so the preservation of tropical rainforests is an important part of our drug discovery program. Sadly, many of the tropical forests of the world are under severe environmental pressure, and deforestation is a serious problem in most tropical countries. One way to combat this loss is to demonstrate their value as potential sources of new pharmaceutical or agrochemical products.As part of an effort to integrate biodiversity conservation and drug discovery with economic development, we initiated an International Cooperative biodiversity Group (ICBG) to discover potential pharmaceuticals from the plant biodiversity of Suriname and Madagascar. The Group, established with funding from agencies of the United States government, involved participants from the USA, Suriname, and Madagascar. The basic approach was to search for bioactive plants in the Suriname and Malagasy flora, and to isolate their bioactive constituents by the best available methods, but the work included capacity building as well as research. Progress on this project will be reported, drawing on results obtained from the isolation of bioactive natural products from Suriname and Madagascar. The benefits of this general approach to biodiversity and drug discovery will also be discussed.

Biological activities and distribution of plant saponins

Plant saponins are widely distributed amongst plants and have a wide range of biological properties. The more recent investigations and findings into their biological activities were summarized. Isolation studies of saponins were examined to determine which are the more commonly studied plant families and in which families saponins have been identified.

Oleanolic glycosides from Pometia ridleyi

Six triterpenoid saponins were isolated from the stem bark of Pometia ridleyi along with two known saponins, acutoside A and calenduloside C. Their structures were established using one- and two-dimensional NMR and mass spectrometry as 3-O-beta-D-apiofuranosyl-(1-->3)-[beta-D-glucopyranosyl-(1-->2)]-beta-D-glucopyranosyl-, 3-O-beta-D-apiofuranosyl-(1-->3)-alpha-L-arabinopyranosyl-(1-->3)-[beta-D-glucopyranosyl-(1-->2)]-beta-D-glucopyranosyl-, 3-O-beta-D-apiofuranosyl-(1-->3)-beta-D-galactopyranosyl-(1-->3)-[beta-D-glucopyranosyl-(1-->2)]-beta-D-glucopyranosyl-, 3-O-alpha-L-arabinopyranosyl-(1-->3)-[beta-D-glucopyranosyl-(1-->2)]-alpha-L-arabinopyranosyl-, 3-O-beta-D-galactopyranosyl-(1-->3)-[beta-D-glucopyranosyl-(1-->2)]-alpha-L-arabinopyranosyl-, 3-O-beta-D-apiofuranosyl-(1-->3)-beta-D-galactopyranosyl-(1-->3)-[beta-D-glucopyranosyl-(1-->2)]-alpha-L-arabinopyranosyl-oleanolic acid. The EtOH and EtOAc extracts of the stem bark showed no cytotoxic activity. At a concentration of 23 microg/ml, the saponin mixture showed haemolytic activity and caused 50% haemolysis of a 10% suspension of sheep erythrocytes.

Saponins from Swartzia langsdorffii: biological activities

The presence of saponins and the molluscicidal activity of the roots, leaves, seeds and fruits of Swartzia langsdorffii Raddi (Leguminosae) against Biomphalaria glabrata adults and eggs were investigated. The roots, seeds and fruits were macerated in 95% ethanol. These extracts exerted a significant molluscicidal activity against B. glabrata, up to a dilution of 100 mg/l. Four mixtures (A2, B2, C and D) of triterpenoid oleanane type saponins were chromatographically isolated from the seed and fruit extracts. Two known saponins (1 and 2) were identified as beta-D-glucopyranosyl-[alpha-L-rhamnopyranosyl-(1->3)- beta-D-glucuronopyranosyl-(1->3)]-3beta-hydroxyolean-12-ene-28 -oate, and beta-D-glucopyranosyl-(1->3)-beta-D-glucuronopyranosyl-(1 ->3)]-3beta-hydroxyolean-12-ene-28-oate, respectively. These two saponins were present in all the mixtures, together with other triterpenoid oleane type saponins, which were shown to be less polar, by reversed-phase HPLC. The saponin identifications were based on spectral evidence, including H- H two-dimensional correlation spectroscopy, nuclear Overhauser and exchange spectroscopy, heteronuclear multiple quantum coherence, and heteronuclear multiple-bond connectivity experiments. The toxicity of S. langsdorffii saponins to non-target organisms was prescreened by the brine shrimp lethality test.