Pregnane glycosides from Stapelia variegata

Orbea variegata (L.) Haw in skin carcinogenesis: insights from an in vivo male Swiss mouse model study

Skin cancer is the most widespread type of malignant tumor representing a major public health concern. Considering the numerous side effects associated with conventional treatments, phytotherapy may be regarded as a viable medicinal alternative. This study aimed to investigate the therapeutic potential of Orbea variegata (L.) Haw, an ornamental plant, in treating skin cancer using an animal model induced by a combination of ultraviolet (UV) irradiation and sulfuric acid treatment. The hydroethanolic extract of Orbea variegata underwent phytochemical characterization, identifying the presence of reducing sugars, coumarins, alkaloids, flavonoids, tannins, and saponins through qualitative screening. Quantitative analysis demonstrated significant amounts of phenolic compounds (29.435 ± 0.571 mg GAE/g of dry extract), flavonoids (6.711 ± 0.272 mg QE/g of dry extract), and tannins (274.037 ± 11.3 mg CE/g of dry extract). The administration the hydroethanolic extract in two concentrations (1 or 2 g/kg) to male Swiss mice exhibited no marked adverse effects, as evidenced by serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) enzyme activity levels. In addition, the extract significantly reduced skin hyperplasia and inflammation induced by UV/sulfuric acid treatment as noted in tissue analyses and decreased protein expression of nuclear proliferation marker (Ki-67). This improvement was associated with a marked decrease in oxidative stress, as indicated by diminished lipid peroxidation levels, and restoration of the activity of endogenous antioxidant enzyme catalase (CAT) to control levels. Our findings demonstrated the potential of Orbea variegata hydroethanolic extract to be considered as a treatment for skin cancer, exhibiting its apparent safety and efficacy in reducing inflammation and carcinogenesis in a UV/sulfuric acid-induced Swiss mouse model, attributed to its phytochemical content and associated antioxidant activities.

Pregnane glycosides from the leaves of Dregea volubilis and their α-glucosidase and α-amylase inhibitory activities

Three new pregnane glycosides, drevoluosides O-Q (1-3) along with five known volubiloside C (4), dreageoside A11 (5), 17β-marsdenin (6), stavaroside H (7), and hoyacarnoside G (8) were isolated from the methanol extract of the Dregea volubilis leaves. Their structures were elucidated by chemical and spectroscopic methods. Compounds 6-8 showed significant anti α-glucosidase activity with the inhibitory percentages ranging from 32.6 to 47.1% at the concentration of 200 μM. Compound 3 showed significant inhibitory α-amylase activity with IC₅₀ value of 51.3 ± 2.1 μM.

Acylated pregnane glycosides from Caralluma sinaica

Caralluma sinaica is sold on local markets of Saudi Arabia for various health benefits however no phytochemical study has specifically been performed on this species. NMR and UHPLC-ESI-TOF-MS profilings of the ethanolic extract of the whole plant reveal a very complex phytochemical composition dominated by pregnanes. Detailed information on its constituents was obtained after isolation. Six pregnane glycosides were obtained and characterized based on the extensive spectroscopic analysis (including IR, ¹H NMR, ¹³C NMR and MS data), in addition to ten known compounds (seven pregnanes and three flavonoids). The compounds were identified as 12β-O-benzoyl-20-O-acetyl boucerin-3-O-6-deoxy-3-O-methyl-β-D-glucopyranosyl-(1-->4)-β-D-cymaropyranosyl-(1-->4)-β-D-cymaropyranoside, 12β-O-tigloyl-20-O-acetyl boucerin-3-O-β-D-glucopyranosyl-(1-->4)-β-D-cymaropyranoside, 12β-O-benzoyl-20-O-acetyl boucerin-3-O-β-D-glucopyranosyl-(1-->4)-β-D-digitalopyranosyl-(1-->4)-β-D-cymaropyranosyl-(1-->4)-β-D-cymaropyranoside, 12β-O-benzoyl-20-O-acetyl boucerin-3-O-β-D-glucopyranosyl-(1-->4)-hevetopyranosyl-(1-->4)-β-D-cymaropyranosyl-(1-->4)-β-D-cymaropyranoside, 12β-O-benzoyl-20-O-tigloyl boucerin-3-O-β-D-glucopyranosyl-(1-->4)-β-D-cymaropyranoside, 12β-20-O-dibenzoyl boucerin-3-O-β-D-glucopyranosyl-(1-->4)-β-D-cymaropyranosyl-(1-->4)-β-D-cymaropyranoside. Finally, the isolated compounds were evaluated for their quinone reductase induction.

Activity-guided isolation of cytotoxic constituents from the bark of Aglaia crassinervia collected in Indonesia

Activity-guided fractionation of a CHCl(3)-soluble partition of the MeOH extract of the bark of Aglaia crassinervia collected in Indonesia led to the isolation of three new glabretal-type triterpenoids, aglaiaglabretols A-C (1-3), as well as nine known compounds, 3-epi-cabraleahydroxylactone (4), cabraleahydroxylactone (5), rocaglaol (6), 2beta,3beta-dihydroxy-5alpha-pregn-17(20)-(E)-16-one, scopoletin, and mixtures of cabraleadiol and epicotillol and of beta-sitosterol and stigmasterol. The structures of compounds 1-3 were determined on the basis of spectroscopic and chemical methods. The structure of aglaiaglabretol A (1) was confirmed by single-crystal X-ray analysis, and the absolute stereochemistry of this isolate was established by the Mosher ester method. The cytotoxic activity of all isolates and several chemical transformation products obtained in the present study was evaluated. The known cyclopenta[b]benzofuran, rocaglaol (6), was found to be significantly active and comparable in potency to the positive controls, paclitaxel and camptothecin. Aglaiaglabretol B (2) was further tested in an in vivo hollow fiber model.

Marsdenosides A-H, polyoxypregnane glycosides from Marsdenia tenacissima

Eight polyoxypregnane glycosides, marsdenosides A-H, were isolated from the CHCl(3)-soluble fraction of the ethanolic extract of the stem of Marsdenia tenacissima, along with six known glycosides and two known polyoxypregnane aglycones. Three polyoxypregnanes, 12beta-O-2-methylbutyryl-tenacigenin A, 11alpha,12beta-di-O-acetyltenacigenin B, and 11alpha-O-tigloyltenacigenin B were also obtained. Their structures were established on the basis of spectroscopic analysis and chemical evidence.

Microbial and chemical transformation studies of the bioactive marine sesquiterpenes (S)-(+)-curcuphenol and -curcudiol isolated from a deep reef collection of the Jamaican sponge Didiscus oxeata

Microbial and chemical transformation studies of the marine sesquiterpene phenols (S)-(+)-curcuphenol (1) and (S)-(+)-curcudiol (2), isolated from the Jamaican sponge Didiscus oxeata, were accomplished. Preparative-scale fermentation of 1 with Kluyveromyces marxianus var. lactis (ATCC 2628) has resulted in the isolation of six new metabolites: (S)-(+)-15-hydroxycurcuphenol (3), (S)-(+)-12-hydroxycurcuphenol (4), (S)-(+)-12,15-dihydroxycurcuphenol (5), (S)-(+)-15-hydroxycurcuphenol-12-al (6), (S)-(+)-12-carboxy-10,11-dihydrocurcuphenol (7), and (S)-(+)-12-hydroxy-10,11-dihydrocurcuphenol (8). Fourteen-days incubation of 1 with Aspergillus alliaceus (NRRL 315) afforded the new compounds (S)-(+)-10beta-hydroxycurcudiol (9), (S)-(+)-curcudiol-10-one (10), and (S)-(+)-4-[1-(2-hydroxy-4-methyl)phenyl)]pentanoic acid (11). Rhizopus arrhizus (ATCC 11145) and Rhodotorula glutinus (ATCC 15125) afforded (S)-curcuphenol-1alpha-D-glucopyranoside (12) and (S)-curcudiol-1alpha-D-glucopyranoside (13) when incubated for 6 and 8 days with 1 and 2, respectively. The absolute configuration of C(10) and C(11) of metabolites 7-9 was established by optical rotation computations. Reaction of 1 with NaNO(2) and HCl afforded (S)-(+)-4-nitrocurcuphenol (14) and (S)-(+)-2-nitrocurcuphenol (15) in a 2:1 ratio. Acylation of 1 and 2 with isonicotinoyl chloride afforded the expected esters (S)-(+)-curcuphenol-1-O-isonicotinate (16) and (S)-(+)-curcudiol-1-O-isonicotinate (17), respectively. Curcuphenol (1) shows potent antimicrobial activity against Candida albicans, Cryptococcus neoformans, methicillin-resistant Staphylococcus aureus, and S. aureus with MIC and MFC/MBC ranges of 7.5-25 and 12.5-50 microg/mL, respectively. Compounds 1 and 3 also display in vitro antimalarial activity against Palsmodium falciparium (D6 clone) with MIC values of 3600 and 3800 ng/mL, respectively (selectivity index >1.3). Both compounds were also active against P. falciparium (W2 clone) with MIC values of 1800 (S.I. >2.6) and 2900 (S.I. >1.6) ng/mL, respectively. Compound 14 shows anti-hepatitis B virus activity with an EC(50) of 61 microg/mL.

Penicillosides A-C, C-15 oxypregnane glycosides from Caralluma penicillata

The chloroform fraction of the defatted ethanol extract from the aerial parts of Caralluma penicillata yielded three C-15 oxypregnane glycosides, penicillosides A-C. Their structures were established by a combination of spectroscopic methods.

Pregnane glycosides from Caralluma russeliana

The aerial parts of Caralluma russeliana yielded four new pregnane glycosides, russeliosides A-D (1-4), in addition to a known flavone glycoside, luteolin 4'-O-beta-D-neohesperidoside. The structures of compounds 1-4 were elucidated using a combination of spectroscopic methods.

Analysis of taxol and major taxoids in Himalayan yew, Taxus wallichiana

A reversed-phase column liquid chromatography method for the analysis of taxol, 10-deacetylbaccatin III, baccatin IV, 1-hydroxybaccatin I, 2-acetoxybrevifoliol, brevifoliol, 2'-deacetoxydecinnamoyltaxinine J and 2'-deacetoxytaxinine J in yew needles has been developed using a Nova-Pak Phenyl column and a binary gradient profile. The various aspects of analysis such as extraction efficiency, detection limits, reproducibility and peak purity were validated using UV-Vis as well as photodiode array detection.