Structural determination of 3beta-stearyloxy-urs-12-ene from Maytenus salicifolia by 1D and 2D NMR and quantitative 13C NMR spectroscopy

Phytochemical, Antiplasmodial, and Cytotoxic Investigation of Euclea natalensis A.DC. subsp. natalensis Leaves

Previous research shows that the root and bark extracts of Euclea natalensis have antiplasmodial activity, but the leaves have not been examined yet. This study investigated the phytochemical, antiplasmodial, and cytotoxic properties of the plant leaves. The activity against 3D7 Plasmodium falciparum was determined using the parasite lactate dehydrogenase assay, and the cytotoxicity against Vero and HeLa cells was evaluated using the MTT and resazurin assays, respectively. The bioactive compounds were isolated by chromatography, and their structures were established with spectroscopic and spectrometric techniques. The extract showed antiplasmodial activity (IC₅₀ =25.6 μg/mL) and was not cytotoxic against Vero cells (IC₅₀ =403.7 μg/mL). Purification of the extract afforded six flavonoid glycosides, four triterpenoids, and a coumarin. The glycosides showed antiplasmodial and cytotoxic activities, against HeLa cells, at 50 μg/mL, but the activity was reduced at 10 μg/mL. Naphthoquinones, which are among the predominant phytochemicals in the root and root bark of E. natalensis, were not detected in the leaves.

Pentacyclic Triterpenoids Isolated from Celastraceae: A Focus in the 13C-NMR Data

The Celastraceae family comprises about 96 genera and more than 1.350 species, occurring mainly in tropical and subtropical regions of the world. The species of this family stand out as important plant sources of triterpenes, both in terms of abundance and structural diversity. Triterpenoids found in Celastraceae species display mainly lupane, ursane, oleanane, and friedelane skeletons, exhibiting a wide range of biological activities such as antiviral, antimicrobial, analgesic, anti-inflammatory, and cytotoxic against various tumor cell lines. This review aimed to document all triterpenes isolated from different botanical parts of species of the Celastraceae family covering 2001 to 2021. Furthermore, a compilation of their ¹³C-NMR data was carried out to help characterize compounds in future investigations. A total of 504 pentacyclic triterpenes were compiled and distinguished as 29 aromatic, 50 dimers, 103 friedelanes, 89 lupanes, 102 oleananes, 22 quinonemethides, 88 ursanes and 21 classified as others.

A Review on Phytochemicals of the Genus Maytenus and Their Bioactive Studies

The genus Maytenus is a member of the Celastraceae family, of which several species have long been used in traditional medicine. Between 1976 and 2021, nearly 270 new compounds have been isolated and elucidated from the genus Maytenus. Among these, maytansine and its homologues are extremely rare in nature. Owing to its unique skeleton and remarkable bioactivities, maytansine has attracted many synthetic endeavors in order to construct its core structure. In this paper, the current status of the past 45 years of research on Maytenus, with respect to its chemical and biological activities are discussed. The chemical research includes its structural classification into triterpenoids, sesquiterpenes and alkaloids, along with several chemical synthesis methods of maytansine or maytansine fragments. The biological activity research includes activities, such as anti-tumor, anti-bacterial and anti-inflammatory activities, as well as HIV inhibition, which can provide a theoretical basis for the better development and utilization of the Maytenus.

Cytotoxic Activity of Triterpenoids from Cheiloclinium cognatum Branches against Chronic and Acute Leukemia Cell Lines

Cheiloclinium cognatum (Miers) A.C.Sm. is an endemic species of Brazilian Cerrado that belongs to Celastraceae family. The phytochemical study of C. cognatum branches led to the identification of ten triterpenoids (TPs), 3β-acyloxyurs-12-ene (1), friedelin (2), β-friedelinol (3), glut-5-en-3β-ol (4), α-amyrin (5), β-amyrin (6), β-sitosterol (7), canophyllol (8), 29-hydroxyfriedelan-3-one (9) and friedelane-3β,29-diol (10). TPs 4, 5 and 6 are described for the first Cheiloclinium genus and TPs 8 and 9 were isolated in expressive amounts. Their cytotoxic activities were evaluated against THP-1 and K562 leukemia cell lines. TPs 3 and 5 were the most active, exhibiting lower or similar IC₅₀ against both cell lines when compared to the controls. Their mechanisms of action were investigated suggesting an intrinsic mitochondrial pathway of apoptosis evidenced by up-regulation of BAK mRNA expression. Chemometric studies indicated that their activities may be related to their molecular size and shape as well as electronic interactions of C-3 hydroxy group with molecular targets.

Melissa officinalis ssp. altissima extracts: A therapeutic approach targeting psoriasis in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Melissa officinalis L., commonly known as lemon balm, is one of the most well known edible and medicinal plants of the Lamiaceae family. It is quoted in almost all known medical treatises, from Antiquity up to modern era, such as Corpus Hippocraticum, Dioscorides' De Materia Medica and later on in medieval medical manuscripts and Pharmacopoeias. Actually, it is widely used as herbal medicine for the relief of mild symptoms of mental stress, to aid sleep and for symptomatic treatment of mild gastrointestinal complaints including bloating and flatulence. In Greece, the empirical physicians "vikoyiatroi" recommended the decoction of dry flowers and leaves to treat tracheobronchitis, hysteria, epilepsy, heart arrhythmias, as hypnotic and against skin disorders.

AIM OF THE STUDY

The present study was conducted to investigate the potential beneficial effects in psoriasis in mice of M. officinalis ssp. altissima and to carry out the chemical analysis in order to reveal its main bioactive secondary metabolites.

MATERIALS AND METHODS

Non polar and polar extracts of M. officinalis ssp. altissima aerial parts were prepared by using dichloromethane and methanol, successively; in addition a decoction was made upon oral information by local users in Crete, where the plant was collected. All three preparations were chemically analyzed in order to isolate their main constituents. Chemical structures of all isolated compounds were determined by 1D, 2D-NMR and UV-Vis spectroscopy. Furthermore, the antioxidant potential of extracts and decoction was evaluated through DPPH radical scavenging capability. The in vivo in mice anti-psoriatic efficacy of all preparations was estimated through clinical and histopathological assessment and measurements of TEWL and hydration.

RESULTS

The dichloromethane extract yielded ursolic acid, 2α-hydroxy-ursolic acid, pomolic acid, 3β-stearyloxy-urs-12-ene, oleanolic acid, noropacursane and campesterol; the methanol extract afforded rosmarinic acid and methyl rosmarinate, while from the decoction caffeic acid, 3-(3,4-dihydroxyphenyl)lactic acid and rosmarinic acid were isolated. The psoriasis evaluation, based on PASI score, photodocumentation and histopathological estimation showed that the decoction primarily and the dichloromethane extract secondly could significantly contribute to psoriasis treatment. The decoction seems able to reestablish skin physiology by decreasing dryness and enhancing skin barrier function. Moreover, the decoction showed the best antioxidant activity, while the dichloromethane extract the weakest.

CONCLUSIONS

The triterpene derivatives of the dichloromethane extract are likely to be responsible for its anti-psoriatic activity. The abundant polyphenolic load of the decoction contributes to its high antioxidant activity and the most effective results against psoriasis. The anti-psoriatic activity of the decoction confirmed the traditional use of this plant as antioxidant, wound healing and skin barrier repair agent.

Triterpenes from Euphorbia hirta and their cytotoxicity

AIM

To investigate the chemical constituents of the stems, leaves and roots of Euphorbia hirta, and to test for the cytotoxic and antimicrobial potentials of the major constituents of the plant.

METHODS

The compounds were isolated by silica gel chromatography and their structures were elucidated by NMR spectroscopy. The cytotoxicity tests were conducted using the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, while the antimicrobial tests employed the agar well method.

RESULTS

The air-dried stems of E. hirta afforded taraxerone 1, a mixture of 25-hydroperoxycycloart-23-en-3β-ol (2a) and 24-hydroperoxycycloart-25-en-3β-ol (2b) (sample 2) in a 2 : 1 ratio, and another mixture of cycloartenol (3a), lupeol (3b), α-amyrin (3c) and β-amyrin (3d) (sample 3) in a 0.5 : 4 : 1 : 1 ratio. The air-dried leaves of E. hirta yielded sample 2 in a 3 : 2 ratio, sample 3 in a 2 : 3 : 1 : 1 ratio, phytol and phytyl fatty acid ester, while the roots afforded sample 2 in a 2 : 1 ratio, sample 3 in a 2 : 1 : 1 : 1 ratio, a mixture of cycloartenyl fatty acid ester 4a, lupeol fatty acid ester 4b, α-amyrin fatty acid ester 4c and β-amyrin fatty acid ester 4d (sample 4) in a 3 : 2 : 1 : 1 ratio, linoleic acid, β-sitosterol and squalene. Compound 1 from the stems, sample 2 from the leaves, and sample 3 from the stems were assessed for cytotoxicity against a human cancer cell line, colon carcinoma (HCT 116). Sample 2 showed good activity with an IC50 value of 4.8 μg·mL(-1), while 1 and sample 3 were inactive against HCT 116. Sample 2 was further tested for cytotoxicity against non-small cell lung adenocarcinoma (A549). It showed good activity against this cell line with an IC50 value of 4.5 μg·mL(-1). Antimicrobial assays were conducted on 1 and sample 2. Results of the study indicated that 1 was active against the bacteria: Pseudomonas aeruginosa and Staphylococcus aureus, but was inactive against Escherichia coli and Bacillus subtilis. Sample 2 was active against the bacteria: Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli and fungi: Candida albicans and Trichophyton mentagrophytes. It was inactive against Bacillus subtilis and Aspergillus niger.

CONCLUSIONS

The triterpenes: 2a, 2b, 3a, 3b, 3c and 3d were obtained from the stems, roots and leaves of E. hirta. Taraxerol (1) was only isolated from the stems, the leaves yielded phytol and phytyl fatty acid esters, while the roots afforded 4a-4d, linoleic acid, β-sitosterol, and squalene. Triterpene 1 and sample 2 were found to exhibit antimicrobial activities. Thus, these compounds are some of the active principles of E. hirta which is used in wound healing and the treatment of boils. The cytotoxic properties of sample 2 imply that triterpenes 2a and 2b contribute to the anticancer activity of E. hirta.

Lupane-type triterpenoids from Microtropis fokienensis and Perrottetia arisanensis and the apoptotic effect of 28-hydroxy-3-oxo-lup-20(29)-en-30-al

Seven new lupane triterpenoids were isolated from bioactive methanol extracts of Microtropis fokienensis (1- 4) and Perrottetia arisanensis (4-7), along with 18 known compounds. The structures of the new compounds were elucidated on the basis of spectroscopic data analysis. All triterpenoids were evaluated for their in vitro cytotoxicity toward seven human cancer cell lines. Compound 8 (28-hydroxy-3-oxo-lup-20(29)-en-30-al) was among the most cytotoxic substances obtained and was found to induce apoptosis of human leukemia HL60 cells and mediate cleavage of PARP and up-regulation of Bax proteins.