Triterpenoid saponin anthranilates from Albizia grandibracteata leaves ingested by primates in Uganda

A review of structural modification and biological activities of oleanolic acid

Oleanolic acid (OA), a pentacyclic triterpenoid, exhibits a broad spectrum of biological activities, including antitumor, antiviral, antibacterial, anti-inflammatory, hepatoprotective, hypoglycemic, and hypolipidemic effects. Since its initial isolation and identification, numerous studies have reported on the structural modifications and pharmacological activities of OA and its derivatives. Despite this, there has been a dearth of comprehensive reviews in the past two decades, leading to challenges in subsequent research on OA. Based on the main biological activities of OA, this paper comprehensively summarized the modification strategies and structure-activity relationships (SARs) of OA and its derivatives to provide valuable reference for future investigations into OA.

A New Triterpenoid Saponin from Albizia zygia Induced Apoptosis by Reduction of Mitochondrial Potential Status in Malignant Melanoma Cells

In our ongoing research program on the proapoptotic function of saponins, two previously undescribed saponins, named zygiaosides E (1: ) and F (2: ), were isolated from the leaves of Albizia zygia. Their structures were established based on extensive analysis of 1D and 2D NMR data, HR-ESI-MS analysis, and by chemical degradation. The proapoptotic effect of zygiaoside E (1: ) was evaluated on human malignant melanoma (A375), human epidermoid cancer (A431), and normal Homo sapiens skin tissue (TE 353.SK.) cell lines by cytometric analysis. Zygiaoside E (1: ) induced apoptosis of the two human cancer cell lines (A375 and A431) in a dose-dependent manner at 1 µM but did not induce apoptosis in noncancerous skin cells (TE 353.Sk), even when treated with concentrations up to 15 µM. The underlying mechanism of the apoptosis induction activity of zygiaoside E (1: ) on the mitochondrial membrane potential status in A375 cells was further assessed by monitoring the uptake rate of DiOC6, a mitochondrial specific and voltage-dependent fluorescent dye. The number of malignant melanoma cells emitting high fluorescence levels was decreased when cells were treated with 3 or 5 µM of zygiaoside E (1: ) during either 12 or 24 h, thereby revealing a drop of mitochondrial membrane potential in A375 cells upon treatment, which indicated mitochondrial perturbation.

Oleanane-type saponins and prosapogenins from Albizia julibrissin and their cytotoxic activities

Two undescribed oleanane-type saponins, julibrosides K-L, along with three undescribed oleanane-type prosapogenins, julibrosides M-O, were isolated from the stem bark of Albizia julibrissin Durazz. and the mild alkaline hydrolysate of the total saponin, respectively. Their structures were established by extensive analysis of 1D and 2D NMR experiments (COSY, TOCSY, HSQC, HMBC, and HSQC-TOCSY) and mass spectrometry. Furthermore, the cytotoxic activities of the isolated compounds against BGC-823, A549, HCT-116, and HepG2 cell lines were evaluated, and julibroside L showed significant cytotoxic activities against the four cancer cell lines with IC₅₀ values of 5.77, 4.80, 4.26, and 4.93 μM, respectively.

Synthesis of MeON-Glycoside Derivatives of Oleanolic Acid by Neoglycosylation and Evaluation of Their Cytotoxicity Against Selected Cancer Cell Lines

A series of C-3 and C-28 MeON-neoglycosides of oleanolic acid were designed and synthesized by neoglycosylation as potential antiproliferative agents. Their cytotoxicity was evaluated in vitro against five human cancer cell lines: human non-small cell lung cancer cell line (A549), human melanoma cell line (A375), human colon cancer cell line (HCT116), human liver carcinoma cell line (HepG2), human breast adenocarcinoma cell line (MCF-7) by the Cell Counting Kit-8 (CCK-8) assay. Most of C-3 and C-28 MeON-neoglycosides of oleanolic acid exhibited notably inhibitory effects against the tested cancer cells and more sensitive to HepG2 cells than 5-Fluorouracil (5-FU). Structure-activities relationship (SAR) analysis revealed that sugar types and the d/l configuration of sugars would significantly affect their antiproliferative activities of neoglycosides. Among them, compound 8a (28-N-methoxyaminooleanane-β-d-glucoside) exhibited the most potent antiproliferative activities against HepG2 cells with IC₅₀ values of 2.1 µM. Further pharmacological experiments revealed that compound 8a could cause morphological changes and cell cycle arrest at G0/G1 phase and induce apoptosis in HepG2 cells. These results suggested that neoglycosylation could provide a rapid strategy for the discovery of potential antiproliferative agents and their possible pharmacological mechanisms need more further research.

The ethnopharmacology, phytochemistry, pharmacology and toxicology of genus Albizia: A review

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Albizia (Leguminosae) comprises about 150 species and some species have been used for the treatment of rheumatism, stomachache, cough, diarrhea, and wounds in traditional and local medicine. The aim of the review: This review article documents and critically assesses the current status of the traditional uses, phytochemistry, pharmacology, and toxicology of the Albizia species.

MATERIALS AND METHODS

All provided literatures on the Albizia species were searched using the electronic databases (e.g. Web of Science, Elsevier, Springer, PubMed, ACS, CNKI, Google Scholar, and Baidu Scholar), books, and theses with keywords of 'Albizia' and 'Albizzia'.

RESULTS

Albizia species have been used for melancholia, insomnia, wounds, fever, abscesses, diabetes, headache, stomachache, diarrhea, cough, rheumatism, snake bite, malaria, and parasitic infection in traditional and local medicine. These plants mainly contain triterpenoid saponins, flavonoids, lignanoids, alkaloids, phenolic glycosides, etc. Albizia species have been demonstrated to possess various pharmacological activities. Among them, the antidiabetic, anti-inflammatory, antifertility, antianxiety, antidepressant, and anti-fever properties are consistent with the traditional and local applications of the Albizia species.

CONCLUSIONS

The traditional and local uses of Albizia species have been partially demonstrated by the pharmacological investigation. However, some traditional applications have not been assessed scientifically due to incomplete methodologies and ambiguous findings. Moreover, no clinical evidences support the health benefits of these plants. The systematic and comprehensive preclinical studies and clinical trials are still required to verify the pharmacological activities, clinical efficacy, and safety of Albizia species.

Structural characterization of a complex triterpenoid saponin from Albizia lebbeck and investigation of its permeability property and supramolecular interactions with membrane constituents

As part of the ongoing efforts in discovering potentially bioactive natural products from medicinal plants, the present study was conducted to isolate a new complex triterpenoid saponin from the barks of Albizia lebbeck. It was isolated by using chromatographic methods and its structural elucidation was performed using detailed analyses of ¹H and ¹³C NMR spectra including 2D-NMR (COSY, TOCSY, HSQC and HMBC) spectroscopic techniques, high-resolution electrospray ionization mass spectrometry (HRESIMS) analysis and chemical conversions. Its structure was established as 21-[[(2E,6S)-6-[6-deoxy-4-O-[(2E,6S)-6-hydroxy-2-(hydroxymethyl)-6-methyl-1-oxo-2,7-octadienyl]-[(β-d-glucopyranosyl)oxy]-2-(hydroxymethyl)-6-methyl-1-oxo-2,7-octadienyl]-[(β-d-glucopyranosyl)oxy]-2,6-dimethyl-1-oxo-2,7-octadienyl]oxy]-16-hydroxy-3-[[O-β-d-xylopyranosyl-(1 → 2)-O-α-l-arabinopyranosyl-(1 → 6)-2-(acetylamino)-2-deoxy-β-d-glucopyranosyl]oxy]-(3β,16α,21β)-olean-12-en-28-oic acid O-α-l-arabinofuranosyl-(1 → 4)-O-[β-d-glucopyranosyl-(1 → 3)]-O-6-deoxy-α-l-mannopyranosyl-(1 → 2)-β-d-glucopyranosyl ester (1). Additionally, this study aimed to investigate the permeability property of 1, its activity on membrane integrity and supramolecular interactions with cellular constituents using in vitro experimental models.

Nitric oxide-donating derivatives of hederacolchiside A1: Synthesis and biological evaluation in vitro and in vivo as potential anticancer agents

A series of nitric oxide (NO) donating derivatives of hederacolchiside A₁ bearing triterpenoid saponin motif were designed, synthesized and evaluated for their anticancer activity. All of the tested furoxan-based NO releasing compounds showed significant proliferation inhibitory activities. Especially compound 6a exhibited strong cytotoxicity (IC₅₀=1.6-6.5μM) against four human tumor cell lines (SMMC-7721, NCI-H460, U251, HCT-116) in vitro and the highest level of NO releasing. Furthermore, compound 6a was revealed low acute toxicity to mice and weak haemolytic activity with potent tumor growth inhibition against mice H22 hepatocellular cells in vivo (51.5%).

Sickness behaviour associated with non-lethal infections in wild primates

Non-lethal parasite infections are common in wildlife, but there is little information on their clinical consequences. Here, we pair infection data from a ubiquitous soil-transmitted helminth, the whipworm (genus Trichuris), with activity data from a habituated group of wild red colobus monkeys (Procolobus rufomitratus tephrosceles) in Kibale National Park, Uganda. We use mixed-effect models to examine the relationship between non-lethal parasitism and red colobus behaviour. Our results indicate that red colobus increased resting and decreased more energetically costly behaviours when shedding whipworm eggs in faeces. Temporal patterns of behaviour also changed, with individuals switching behaviour less frequently when whipworm-positive. Feeding frequency did not differ, but red colobus consumption of bark and two plant species from the genus Albizia, which are used locally in traditional medicines, significantly increased when animals were shedding whipworm eggs. These results suggest self-medicative plant use, although additional work is needed to verify this conclusion. Our results indicate sickness behaviours, which are considered an adaptive response by hosts during infection. Induction of sickness behaviour in turn suggests that these primates are clinically sensitive to non-lethal parasite infections.

Natural product-based design, synthesis and biological evaluation of Albiziabioside A derivatives that selectively induce HCT116 cell death

A series of Albiziabioside A coupled substituents of cinnamoyl derivatives were designed and synthesized. The synthesized compounds were screened for anticancer activity against a panel of six human cancer cell lines using a MTT assay. Synthetic derivatives showed excellent selectivity, as they were toxic against only HCT116 cell line. Some compounds exhibited better anti-cancer activity against HCT116 compared to positive controls, such as 5-fluorouracil and Albiziabioside A. Compound 8n was the most active derivative. Importantly, it was also found that the anti-proliferative activity of 8n could be attributed to the induction of cell cycle arrest and apoptosis in HCT116 cells.

The Influence of Seasonal Frugivory on Nutrient and Energy Intake in Wild Western Gorillas

The daily energy requirements of animals are determined by a combination of physical and physiological factors, but food availability may challenge the capacity to meet nutritional needs. Western gorillas (Gorilla gorilla) are an interesting model for investigating this topic because they are folivore-frugivores that adjust their diet and activities to seasonal variation in fruit availability. Observations of one habituated group of western gorillas in Bai-Hokou, Central African Republic (December 2004-December 2005) were used to examine seasonal variation in diet quality and nutritional intake. We tested if during the high fruit season the food consumed by western gorillas was higher in quality (higher in energy, sugar, fat but lower in fibre and antifeedants) than during the low fruit season. Food consumed during the high fruit season was higher in digestible energy, but not any other macronutrients. Second, we investigated whether the gorillas increased their daily intake of carbohydrates, metabolizable energy (KCal/g OM), or other nutrients during the high fruit season. Intake of dry matter, fibers, fat, protein and the majority of minerals and phenols decreased with increased frugivory and there was some indication of seasonal variation in intake of energy (KCal/g OM), tannins, protein/fiber ratio, and iron. Intake of non-structural carbohydrates and sugars was not influenced by fruit availability. Gorillas are probably able to extract large quantities of energy via fermentation since they rely on proteinaceous leaves during the low fruit season. Macronutrients and micronutrients, but not digestible energy, may be limited for them during times of low fruit availability because they are hind-gut fermenters. We discuss the advantages of seasonal frugivores having large dietary breath and flexibility, significant characteristics to consider in the conservation strategies of endangered species.

Triterpenoid saponins from Albizia lebbeck (L.) Benth and their inhibitory effect on the survival of high grade human brain tumor cells

As part of our search of new bioactive triterpenoid saponins from Cameroonian Mimosaceae plants, phytochemical investigation of the roots of Albizia lebbeck led to the isolation of two new oleanane-type saponins, named lebbeckosides A-B (1-2). Their structures were established on the basis of extensive 1D and 2D NMR ((1)H, (13)C NMR, DEPT, COSY, TOCSY, ROESY, HSQC, and HMBC) and HRESIMS studies, and by chemical evidence. Compounds 1-2 were evaluated for their inhibitory effect on the metabolism of high grade human brain tumor cells, the human glioblastoma U-87 MG cell lines and the glioblastoma stem-like TG1 cells isolated from a patient tumor, and known to be particularly resistant to standard therapies. The isolated saponins showed significant cytotoxic activity against U-87 MG and TG1 cancer cells with IC50 values of 3.46 μM and 1.36 μM for 1, and 2.10 μM and 2.24 μM for 2, respectively.

Synthesis and anti-cancer activity of a glycosyl library of N-acetylglucosamine-bearing oleanolic acid

N-Acetylglucosamine-bearing triterpenoid saponins (GNTS) were reported to be a unique type of saponins with potent anti-tumor activity. In order to study the structure-activity relationship of GNTS, 24 oleanolic acid saponins with (1 --> 3)-linked, (1 --> 4)-linked, (1 --> 6)-linked N-acetylglucosamine oligosaccharide residues were synthesized in a combinatorial and concise method. The cytotoxicity of these compounds toward the leukemia cell line HL-60 and the colorectal cancer cell line HT-29 could not be improved. Half maximal inhibition below 10 μM was achieved in one single case. The study revealed that the activity decreased following the order of 3' > 4' > 6' glycosyl modifications. GNTS that incorporated (D/L)-xylose and L-arabinose at positions 3' and 4' were more potent than those bearing other sugars.

Seasonal effects on great ape health: a case study of wild chimpanzees and Western gorillas

Among factors affecting animal health, environmental influences may directly or indirectly impact host nutritional condition, fecundity, and their degree of parasitism. Our closest relatives, the great apes, are all endangered and particularly sensitive to infectious diseases. Both chimpanzees and western gorillas experience large seasonal variations in fruit availability but only western gorillas accordingly show large changes in their degree of frugivory. The aim of this study is to investigate and compare factors affecting health (through records of clinical signs, urine, and faecal samples) of habituated wild ape populations: a community (N = 46 individuals) of chimpanzees (Pan troglodytes) in Kanyawara, Kibale National Park (Uganda), and a western gorilla (G. gorilla) group (N = 13) in Bai Hokou in the Dzanga-Ndoki National Park (Central African Republic). Ape health monitoring was carried out in the wet and dry seasons (chimpanzees: July-December 2006; gorillas: April-July 2008 and December 2008-February 2009). Compared to chimpanzees, western gorillas were shown to have marginally greater parasite diversity, higher prevalence and intensity of both parasite and urine infections, and lower occurrence of diarrhea and wounds. Parasite infections (prevalence and load), but not abnormal urine parameters, were significantly higher during the dry season of the study period for western gorillas, who thus appeared more affected by the large temporal changes in the environment in comparison to chimpanzees. Infant gorillas were the most susceptible among all the age/sex classes (of both apes) having much more intense infections and urine blood concentrations, again during the dry season. Long term studies are needed to confirm the influence of seasonal factors on health and parasitism of these great apes. However, this study suggest climate change and forest fragmentation leading to potentially larger seasonal fluctuations of the environment may affect patterns of ape parasitism and further exacerbate health impacts on great ape populations that live in highly seasonal habitats.

Unusual feeding behavior in wild great apes, a window to understand origins of self-medication in humans: role of sociality and physiology on learning process

Certain toxic plants are beneficial for health if small amounts are ingested infrequently and in a specific context of illness. Among our closest living relatives, chimpanzees are found to consume plants with pharmacological properties. Providing insight on the origins of human self-medication, this study investigates the role social systems and physiology (namely gut specialization) play on learning mechanisms involved in the consumption of unusual and potentially bioactive foods by two great ape species. We collected data from a community of 41-44 wild chimpanzees in Uganda (11 months, 2008), and a group of 11-13 wild western gorillas in Central African Republic (10 months, 2008-2009). During feeding, we recorded food consumed, its availability, and social interactions (including observers watching conspecifics and the observers' subsequent activity). Unusual food consumption in chimpanzees was twice higher than in gorillas. Additionally chimpanzees relied more on social information with vertical knowledge transmission on unusual foods by continually acquiring information during their life through mostly observing the fittest (pre-senescent) adults. In contrast, in gorillas observational learning primarily occurred between related immatures, showing instead the importance of horizontal knowledge transmission. As chimpanzees' guts are physiologically less specialized than gorillas (more capable of detoxifying harmful compounds), unusual-food consumption may be more risky for chimpanzees and linked to reasons other than nutrition (like self-medication). Our results show that differences in sociality and physiology between the two species may influence mechanisms that discriminate between plants for nutrition and plants with potential therapeutic dietary components. We conclude that self-medication may have appeared in our ancestors in association with high social tolerance and lack of herbivorous gut specialization.

Potential anti-inflammatory constituents of the stems of Gordonia chrysandra

Eight new oleanane-type triterpenoid glycosides, gordonosides I-P (1-8), and two new phenolic glycosides (9 and 10) were isolated from the stems of Gordonia chrysandra. Their structures were elucidated by spectroscopic and chemical methods. In an in vitro bioassay, compound 1 showed a strong inhibitory effect on nitric oxide production in LPS-activated macrophages with an IC50 value of 0.14 μM.

Neophobia and learning mechanisms: how captive orangutans discover medicinal plants

Great apes sometimes feed on items of low nutritional value with bioactive secondary compounds. These molecules may be toxic and neophobia is presumed to be an essential factor in avoiding the ingestion of noxious items. The aim of this study is to investigate, in captive orangutans, individual and social learning involved in the discovery and ingestion of new items. We presented novel aromatic plants - 11 fresh plants and 4 infused plants - to 4 captive weaned Bornean orangutans, both under isolated and group conditions, and recorded their behaviour and interactions between group members. All animals tasted by nibbling or ingested most of the plants presented. Regardless of the experimental condition, individual responses did not vary visibly across the sessions, despite numerous close observations, and food transfers between individuals were observed. Our results suggest that a low level of neophobia and a strong propensity to look to conspecifics for information allow Bornean orangutans to expand their diet after weaning. Our results also provide some evidence that olfaction is a key sense in determining food edibility based on previous experience.

Cytotoxic oleanane-type saponins from Albizia inundata

Bioassay-guided fractionation of a CH(2)Cl(2)-MeOH extract of the aerial parts of Albizia inundata resulted in the isolation of two new natural oleanane-type triterpene saponins {3-O-[α-L-arabinopyranosyl(1→6)]-2-acetamido-2-deoxy-β-D-glucopyranosyl oleanolic acid (1) and 3-O-[α-L-arabinopyranosyl(1→2)-α-L-arabinopyranosyl(1→6)]-2-acetamido-2-deoxy-β-D-glucopyranosyl acacic acid lactone (2)} along with seven known saponins {3-O-[α-L-arabinopyranosyl(1→6)]-2-acetamido-2-deoxy-β-D-glucopyranosyl echinocystic acid (3), 3-O-[β-D-xylopyranosyl (l→2)-α-L-arabinopyranosyl(l→6)]-2-acetamido-2-deoxy-β-D-glucopyranosyl acacic acid lactone (concinnoside D) (4), 3-O-[β-D-glucopyranosyl(l→2)]-β-D-glucopyranosyl oleanolic acid (5), 3-O-[α-L-arabinopyranosyl(1→2)-α-L-arabinopyranosyl(l→6)]-β-D-glucopyranosyl oleanolic acid (6), 3-O-[β-D-xylopyranosyl(1→2)-α-L-arabinopyranosyl(l→6)]-β-D-glucopyranosyl oleanolic acid (7), 3-O-[α-L-arabinopyranosyl(l→2)-α-L-arabinopyranosyl(1→6)-[β-D-glucopyranosyl(l→2)]-β-D-glucopyranoside echinocystic acid (8), and 3-O-[β-D-xylopyranosyl(l→2)-α-L-arabinopyranosyl(1→6)-[β-D-glucopyranosyl(l→2)]-β-D-glucopyranoside echinocystic acid (9)}. The structures of 1 and 2 were established on the basis of extensive 2D NMR ((1)H-(1)H COSY or DQF-COSY, HSQC, HMBC, TOCSY, and HSQC-TOCSY) spectroscopic, ESIMS, and chemical methods. Saponins 1, 3, 6, and 7 showed cytotoxicity against human head and neck squamous cells (JMAR, MDA1986) and melanoma cells (B16F10, SKMEL28) with IC(50) values in the range 1.8-12.4 μM, using the MTS assay.

Antiplasmodial and cytotoxic activities of medicinal plants traditionally used in the village of Kiohima, Uganda

AIM OF THE STUDY

In Uganda, malaria is the most common disease and Ugandan people largely rely on traditional medicine. In this context, we carried out an ethnobotanical study on the Kiohima village, located close to the Kibale National Park in South-Western Uganda and investigated in vitro the antiplasmodial and cytotoxic activities of selected medicinal plants.

MATERIALS AND METHODS

Seventy-five plants-using adults (men and women) were interviewed to find out their plant use. From these information, 48 plants used in traditional medicine were identified and according to their reported uses and to bibliographic data, several parts of 28 plants (leaves, barks, roots), were selected and collected for biological evaluations. These samples were dried, extracted with ethyl acetate and the crude extracts were assayed for in vitro antiplasmodial and cytotoxic activities at 10 μg/mL.

RESULTS

One third of the screened plants showed a significant antiplasmodial activity with inhibition greater than 50% at 10 μg/mL.

CONCLUSION

These results may indicate a possible explanation of the use of some medicinal plant against malaria in the village of Kiohima and have also allowed to highlight a plant with potent antimalarial activity: Citropsis articulata root barks.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: an update for the period 2005-2006

This review is the fourth update of the original review, published in 1999, on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2006. The review covers fundamental studies, fragmentation of carbohydrate ions, method developments, and applications of the technique to the analysis of different types of carbohydrate. Specific compound classes that are covered include carbohydrate polymers from plants, N- and O-linked glycans from glycoproteins, glycated proteins, glycolipids from bacteria, glycosides, and various other natural products. There is a short section on the use of MALDI-TOF mass spectrometry for the study of enzymes involved in glycan processing, a section on industrial processes, particularly the development of biopharmaceuticals and a section on the use of MALDI-MS to monitor products of chemical synthesis of carbohydrates. Large carbohydrate-protein complexes and glycodendrimers are highlighted in this final section.

Structure elucidation of new acacic acid-type saponins from Albizia coriaria

Three new acacic acid derivatives, named coriariosides C, D, and E (1-3) were isolated from the roots of Albizia coriaria. Their structures were elucidated on the basis of extensive 1D- and 2D-NMR studies and mass spectrometry as 3-O-[β-D-xylopyranosyl-(1 → 2)-β-D-fucopyranosyl-(1 → 6)-2-(acetamido)-2-deoxy-β-D-glucopyranosyl]-21-O-{(2E,6S)-6-O-{4-O-[(2E,6S)-2,6-dimethyl- 6-O-(β-D-quinovopyranosyl)octa-2,7-dienoyl]-4-O-[(2E,6S)-2,6-dimethyl-6-O-(β-D-quinovopyranosyl)octa-2,7-dienoyl]-β-D-quinovopyranosyl}-2,6-dimethylocta-2,7-dienoyl}acacic acid 28-O-β-D-xylopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 2)-β-D-glucopyranosyl ester (1), 3-O-{β-D-fucopyranosyl-(1 → 6)-[β-D-glucopyranosyl-(1 → 2)]-β-D-glucopyranosyl}-21-O-{(2E,6S)-6-O-{4-O-[(2E,6S)-2,6-dimethyl-6-O-(β-D-quinovopyranosyl)octa-2,7-dienoyl]-4-O-[(2E,6S)-2,6-dimethyl-6-O-(β-D-quinovopyranosyl)octa-2,7-dienoyl]-β-D-quinovopyranosyl}-2,6-dimethylocta-2,7-dienoyl}acacic acid 28-O-α-L-rhamno pyranosyl-(1 → 2)-β-D-glucopyranosyl ester (2), and 3-O-[β-D-fucopyranosyl-(1 → 6)-β-D-glucopyranosyl]-21-O-{(2E,6S)-6-O-{4-O-[(2E,6S)-2,6-dimethyl-6-O-(β-D-quinovopyranosyl)octa-2,7-dienoyl)-β-D-quinovopyranosyl]octa-2,7-dienoyl}acacic acid 28-O-β-D-glucopyranosyl ester (3).

Echinocystic acid 3,16-O-bisglycosides from Albizia procera

Three triterpene glycosides and two known ones were isolated from the bark of Albizia procera by using chromatographic techniques. The structures of the compounds were determined to be 3-O-beta-D-xylopyranosyl-(1-->2)-beta-D-galactopyranosyl-(1-->6)-2-acetamido-2-deoxy-beta-D-glucopyranosyl echinocystic acid 16-O-beta-D-glucopyranoside, 3-O-beta-D-xylopyranosyl-(1-->2)-alpha-L-arabinopyranosyl-(1-->6)-2-acetamido-2-deoxy-beta-D-glucopyranosyl echinocystic acid 16-O-beta-D-glucopyranoside and 3-O-alpha-L-arabinopyranosyl-(1-->2)-alpha-L-arabinopyranosyl-(1-->6)-2-acetamido-2-deoxy-beta-D-glucopyranosyl echinocystic acid 16-O-beta-D-glucopyranoside. Their structures were determined by NMR techniques including HOHAHA, (1)H-(1)H COSY, ROE, HMQC and HMBC experiments together with FABMS as well as acid hydrolysis. To the best of our knowledge, the new compounds are considered the first examples of echinocystic acid 3,16-O-bisglycosides. In contrast to other cytotoxic echinocystic acid glycosides with N-acetyl glucosamine unit, the new glycosides were found inactive when assayed by MTT method for their cytotoxicities against the human tumor cell lines HEPG2, A549, HT29 and MCF7. The results showed the importance of the free hydroxyl group at the aglycone C-16 for exhibiting cytotoxic properties.

Bioactive natural products derived from the East African flora

This review describes bioactive natural products isolated from East African medicinal plants. It includes 211 bioactive compounds from 41 plant species, and cites 116 references.

Cytotoxic acacic acid glycosides from the roots of Albizia coriaria

Two new oleanane-type saponins, coriariosides A (1) and B (2), along with a known saponin, gummiferaoside C (3), were isolated from the roots of Albizia coriaria. Their structures were established by extensive analysis of 1D and 2D NMR experiments (COSY, ROESY, TOCSY, HSQC, and HMBC) and mass spectrometry. Compounds 1 and 3 when tested for cytotoxicity against two colorectal human cancer cells showed activity against the HCT 116 (IC50 4.2 microM for 1 and 2.7 microM for 3) and HT-29 (IC50 6.7 microM for 1 and 7.9 microM for 3) cell lines.

Hydroperoxy-cycloartane triterpenoids from the leaves of Markhamia lutea, a plant ingested by wild chimpanzees

In the framework of the phytochemical investigation of plant species eaten by wild chimpanzees in their natural environment in Uganda, leaf samples of Markhamia lutea were selected and collected. The crude ethyl acetate extract of M. lutea leaves exhibited significant in vitro anti-parasitic activity and low cytotoxicity against MRC5 and KB cells. Fractionation of this extract led to six cycloartane triterpenoids, musambins A-C and their 3-O-xyloside derivatives musambiosides A-C. The structures were elucidated on the basis of spectral studies including mass spectroscopy and extensive 2D NMR. Most of the compounds exhibited mild anti-leishmanial and anti-trypanosomal activities.

Concise synthesis of two natural triterpenoid saponins, oleanolic acid derivatives isolated from the roots of Pulsatilla chinensis

The first synthesis of two natural triterpenoid saponins, which were isolated from the roots of Pulsatilla chinensis and exhibited excellent in vitro cytotoxic activity against HL-60 cells, was concisely achieved in a convergent approach. We employed an odourless 2-methyl-5-tert-butylphenyl (Mbp) thioglycoside and trichloroacetimidate donors in one-pot reaction as a key step.

Cytotoxic oleanane triterpene saponins from Albizia chinensis

Three new oleanane-type triterpene saponins, albizosides A-C (1-3), were isolated from the stem bark of Albizia chinensis. Their structures were established by 1D and 2D NMR experiments and chemical methods. Compounds 1-3 showed cytotoxic activity against a small panel of human tumor cell lines as well as hemolytic activity against rabbit erythrocytes.

Triterpenoidal Saponins and Prosapogenins from Albizia Lebbeck (Leguminosae)

Four new echinocystic acid glycosides (1–4) were isolated from the dried seeds of Albizia lebbeck. The alkaline hydrolysate of the saponin fraction yielded two new prosapogenins (5–6). Their structures were determined by extensive NMR and spectroscopic analysis.

Triterpenoids

This review covers the isolation and structure determination of triterpenoids including squalene derivatives, protostanes, lanostanes, holostanes, cycloartanes, dammaranes, euphanes, tirucallanes, tetranortriterpenoids, quassinoids, lupanes, oleananes, friedelanes, ursanes, hopanes, isomalabaricanes and saponins. The literature from January 2005 to December 2006 is reviewed and 478 references are cited.

In vitro antiprotozoal activities and cytotoxicity of some selected Cameroonian medicinal plants

Eight extracts from seven selected Cameroonian medicinal plants, traditionally used to treat malaria and other protozoal diseases, were tested in vitro for their antiprotozoal activities against Plasmodium falciparum K1 chloroquine-resistant strain, Leishmania donovani, Trypanosoma cruzi and Trypanosoma brucei rhodesiense, protozoa responsible for malaria, visceral leishmaniasis, Chagas disease and African trypanosomiasis, respectively. The most active extract against Plasmodium falciparum K1 strain and Trypanosoma brucei rhodesiense was the methanolic extract of Albizia zygia (Fabaceae) stem bark with IC(50) values of 1.0 microg/ml and 0.2 microg/ml, respectively. Five extracts showed IC(50) values below 5mug/ml against Leishmania donovani, with the methanolic seed extract of Harungana madagascarensis showing the highest activity, but only the methanolic extract of Albizia zygia showed activity against Trypanosoma cruzi. Cytotoxicity and selectivity indexes were estimated for the most active extracts. The best ratio of cytotoxicity to antiplasmodial activity (SI(a)=14) was established for the methanolic leaf extract of Symphonia globulifera (Clusiaceae), while the methanolic stem bark extract of Albizia zygia showed the best ratio of cytotoxicity to antitrypanosomal activity (SI(b)=22.5).

Cytotoxic triterpenoid saponins of Albizia gummifera from the Madagascar rain forest

Bioassay-guided fractionation of an EtOH extract obtained from the roots of the Madagascan plant Albizia gummifera led to the isolation of three new cytotoxic oleanane-type triterpenoid saponins, gummiferaosides A-C (1-3). The structures of these new compounds were elucidated using 1D and 2D NMR experiments and mass spectrometry. Compounds 1-3 showed cytotoxicity against the A2780 human ovarian cancer cell line with IC50 values of 0.8, 1.5, and 0.6 microg/mL, respectively.

Antiproliferative triterpene saponins from Entada africana

Nine new ester saponins (1-9) were isolated from the roots of Entada africana. Their structures were elucidated by 1D and 2D NMR experiments including 1D and 2D TOCSY, DQF-COSY, HSQC, and HMBC spectroscopy, as well as ESIMS analysis, and chemical methods. The aglycon moieties were found to be echinocystic acid for compounds 1, 2, 4-6, 8, and 9 and acacic acid for 3 and 7. All isolated compounds were tested for their antiproliferative activity against the J774.A1, HEK-293, and WEHI-164 cell lines. Moderate to high cytotoxic potency was found for almost all compounds tested.

Synthesis and antitumor activity of two natural N-acetylglucosamine-bearing triterpenoid saponins: Lotoidoside D and E

Two natural triterpenoid saponins bearing N-acetylglucosamine, lotoidoside D and lotoidoside E, which had been available only from Glinus lotoides growing in Egyptian desert, were facilely synthesized from readily available oleanolic acid. Preliminary pharmacological research showed their antitumor activity against HeLa cell.

Natural product extracts of plant and marine origin having antileukemia potential. The NCI experience

While effective treatments exist for acute lymphocytic leukemia (ALL), particularly in the case of children, and for chronic mylogenous leukemia (CML), more efficacious treatments for other forms of acute and chronic forms of the disease are still needed. The National Cancer Institute has tested over 90,000 extracts of terrestrial plants and marine plants and invertebrates in its human cancer one-dose/60-cell-line prescreen, and the results for plants and marine organisms meeting criteria established for activity against selected leukemia cell lines are presented. Taxonomic data are limited to family and genus in the case of plants, and phylum for marine organisms, and those groups of organisms exhibiting significant activity (so-called "hot" families and genera) are discussed. The "hot" terrestrial plant families Myrsinaceae and Sapindaceae have not been studied to any extent and appear to merit special attention, although leukemia cell line selectivity is also noted for other families.