Radhakrishnan Srivedavyasasri

Phytochemical and biological evaluation of Salvia apiana

Abstract Salvia apiana (white sage, Lamiaceae family) plant is native to southern California and parts of Mexico. Some Native American tribes local to this region consider S. apiana to be sacred and burn the leaves as incense for purification ceremonies. The plant has been used to treat sore throats, coughs, chest colds, upper respiratory infections and poison oak rashes. The aqueous ethanolic extract of S. apiana showed moderate CB1 activity (58.3% displacement). Chromatographic purification of the ethanolic extract on silica gel column led to isolation of nine compounds: rosmadial (I), carnosol (II), 16-hydroxycarnosol (III), sageone (IV), cirsimaritin (V), salvigenin (VI), oleanolic acid (VII), 3β,28-dihydroxy-urs-12-ene (VIII), and ursolic acid (IX). The structures of the isolated compounds were determined by their 1D, 2D NMR and MS spectral data. All the fractions and isolated compounds were tested for cannabinoid and opioid receptor binding.

Chemical and biological studies on Bridelia ferruginea grown in Nigeria

Abstract Phytochemical investigation of the methanolic extract of dried leaves of Bridelia ferruginea led to the isolation and identification of fourteen compounds (1–14): compound 1 [mixture of palmitic, stearic and oleic acids], stearyl monoester of 2-O-β-ᴅ-glucosylglycerol (2), 6β-hydroxy-(20R)-24-ethylcholest-4-en-3-one (3a), 6β-hydroxy-(20R)-24-ethylcholest-4,22-dien-3-one (3b), lutein (4), vomifoliol (5), corilagin (6), kaempferide-3-O-β-ᴅ-glucoside (7), myricetin (8), isomericitrin (9), isoquercetin (10), myricitrin (11), quercitrin (12), rutin (13), and β-sitosterol glucoside (14). The total extract exhibited moderate activity towards CB2 receptor and 90% inhibition against leishmanial pathogen Trypanosoma brucei. Compound 4 exhibited 73% displacement in CB2 receptor with IC50 56.47 μM, and 93% inhibition towards T. brucei with IC50 4.16 μM. Compound 11 showed 99% inhibition towards Escherichia coli with IC50 1.123 μM.

Isolation and Biological Evaluation of Prenylated Flavonoids from Maclura pomifera

Phytochemical analysis of the ethanolic extract of Maclura pomifera fruits yielded four new compounds (I–IV) along with eleven known compounds (V–XV). The crude extract exhibited significant activity towards cannabinoid receptors (CB1: 103.4% displacement; CB2: 68.8% displacement) and possibly allosteric interaction with δ and μ opioid receptors (−49.7 and −53.8% displacement, resp.). Compound I was found to be possibly allosteric for κ and μ opioid receptors (−88.4 and −27.2% displacement, resp.) and showed moderate activity (60.5% displacement) towards CB1 receptor. Compound II exhibited moderate activity towards cannabinoid receptors CB1 and CB2 (47.9 and 42.3% displacement, resp.). The known compounds (V–VIII) exhibited prominent activity towards cannabinoid receptors: pomiferin (V) (IC50 of 2.110 and 1.318 μM for CB1 and CB2, resp.), auriculasin (VI) (IC50 of 8.923 μM for CB1), warangalone (VII) (IC50 of 1.670 and 4.438 μM for CB1 and CB2, resp.), and osajin (VIII) (IC50 of 3.859 and 7.646 μM for CB1 and CB2, resp.). The isolated compounds were also tested for inhibition of human monoamine oxidase-A and monoamine oxidase-B enzymes activities, where all the tested compounds showed fewer inhibitory effects on MAO-A compared to MAO-B activities: auriculasin (VI) (IC50 of 1.91 and 45.98 μM for MAO-B and MAO-A, resp.).

Phytochemical constituents and antioxidant activity of Echinops albicaulis

Abstract Two thiophenes; 5-(3-buten-1-ynyl)-2,2′-bithiophene (2) and α-tertthienyl (9), two alkaloids; echinopsine (10) and echinorine (11), three flavonoids; genkwanin (5), apigenin (6), and rutin (7), two triterpenoids; lupeol acetate (1) and lupeol linoleate (4), together with 2,6,10-trimethyldodeca-2,6,10-triene (4) and β-sitosterol glucoside (8) were isolated from the aerial parts of Echinops albicaulis. Antioxidant, antimicrobial and antiprotozoal activities were evaluated. E. albicaulis aqueous methanolic extract (50, 10, and 1 mg/mL) showed significant antioxidant activity comparable to the potent antioxidant, N-acetyl cysteine, moreover, the aqueous methanolic extract (1 mg/mL) significantly reduced intracellular reactive oxygen species in active cell cultures of human peripheral blood mononuclear cells under oxidative stress more than the reference antioxidant N-acetyl cysteine. None of the isolated compounds showed antimicrobial or antiprotozoal activities at concentration up to 20 μg/mL.

New tetranorlabdanoic acid from aerial parts of Salvia aethiopis

Abstract Salvia aethiopis is a perennial plant native to Eurasia and known by the common names Mediterranean sage or African sage. This plant has been used in Iranian medicine as a carminative and tonic. The ethanolic extract of aerial part of S. aethiopis exhibited moderate to weak activity towards delta and kappa opioid receptors (46.3 and 45.3% displacement, respectively). Chromatographic purification of the ethanolic extract on silica gel column led to isolation of one new: 3α-hydroxy-8α-acetoxy-13,14,15,16-tetranorlabdan-12-oic acid (I) and three known compounds: sesquiterpene spathulenol (II), β-sitosterol (III) and β-sitosterol-3-O-glucoside (IV). The structures of all isolated compounds were elucidated by their NMR (1D and 2D) and MS spectral data. All the fractions and isolated compounds were tested for cannabinoid and opioid receptor binding assays.

Chemical and biological studies on Cichorium intybus L.

Abstract Cichorium intybus L. (Asteraceae family) is a world-wide grown plant known as chicory. In traditional medicine, this plant is used as diuretic, anti-inflammatory, digestive, cardiotonic and liver tonic. Chromatographic purification of the supercritical fluid extract of aerial parts of C. intybus on silica gel column led to isolation of three compounds: new compound, 28β-hydroxytaraxasterol (I), and two known compounds usnic acid (II) and β-sitosterol (III). Purification of the ethanolic extract of aerial parts of this plant on silica gel column chromatography yielded four compounds: 1,3-dioleylglycerate (IV), sitoindoside II (V), 11β-13-dihydrolactucin (VI) and β-sitosterol-3-O-glucoside (VII). The structures of the isolated compounds were determined by their 1D, 2D NMR and MS spectral data. All the fractions and isolated compounds were tested for cannabinoid and opioid receptor binding, as well as antibacterial, antifungal and antimalarial activities. Compound I showed moderate activity (60.5% displacement) towards CB1 receptor.

Phytochemical study of Piliostigma thonningii, a medicinal plant grown in Nigeria

Piliostigma thonningii (Schumach.) Milne-Redhead. (Leguminosae) is used for various medicinal purposes in African countries. Phytochemical investigation of P. thonningii yielded two compounds newly isolated from natural sources, 2β-methoxyclovan-9α-ol (1), and methyl-ent-3β-hydroxylabd-8(17)-en-15-oate (2), along with 14 known compounds (3–16). Compounds 1 and 4 (alepterolic acid) showed potential selectivity towards Trypanosoma brucei brucei with IC50 7.89 and 3.42 μM, respectively. Compound 2 showed activity towards T. brucei and Leishmania donovani Amastigote with IC50 3.84 and 7.82 μM, respectively. The structure activity relationship (SAR) of the isolated metabolites suggested that hydroxylation at C-2 enhances the antiprotozoal activity towards T. brucei in sesquiterpenes 1 and 3. Similarly hydroxylation at C-3 in labdane diterpenes elevates the antiprotozoal activity towards T. brucei.

Secondary Metabolites from the Fungus Quambalaria cyanescens

A phytochemical study of the fungus Quambalaria cyanescens led to the isolation of one new natural compound (1), along with four known compounds (2–5). The structures of the isolated metabolites were elucidated based on spectroscopic and spectrometric techniques. The fatty acid composition of Q. cyanescens was determined by GC/MS and found to consist of stearic, myristic, lauric, linoleic, cis-vaccenic, oleic, and pentadecanoic acids. All the isolated compounds were evaluated for their antimicrobial, antimalarial, and antileishmanial activities.

Secondary metabolites isolated from Pinus roxburghii and interpretation of their cannabinoid and opioid binding properties by virtual screening and in vitro studies

Pinus roxburghii is highly popular as a potent analgesic and anti-inflammatory agent; however its exact mechanism of action was not fully elucidated. We aimed to interpret the analgesic and anti-inflammatory activity of the total ethanol extract of Pinus roxburghii bark (PRE) and its isolated compounds by both in silico molecular modelling and in-vitro cannabinoid and opioid binding activities evaluation for the first time. Comprehensive phytochemical investigation of PRE resulted in the isolation of sixteen compounds that were fully elucidated using 1H NMR and 13C NMR. Four of which namely 1,3,7-trihydroxyxanthone (1), 2,4,7-trihydroxyxanthone (2), isopimaric acid (9) and 3-methoxy-14-serraten-21-one (10) were first to be isolated from PRE. In silico molecular modelling was done using Accelry’s discovery studio 2.5 on the cannabinoid receptor (CB1) and the different opioid receptors (mu, kappa and delta). Results showed that the different isolated constituents exhibited variable degrees of binding with the different examined receptors that undoubtedly explained the observed analgesic and anti-inflammatory activity of PRE. Thus in vitro evaluation of cannabinoid (CB1, CB2) and opioid (μ, κ, δ) binding activities for the isolated compounds was done. PRE and ursolic acid (11) showed a good CB1 receptor binding activity with 66.8 and 48.1% binding, respectively. Isopimaric acid (9) showed good CB2 and mu receptors binding activity estimated by 58.1 and 29.1% binding, respectively. Meanwhile, querectin-3-O-rhamnoside (7) exhibited a moderate κ-opioid receptor activity showing 56.0% binding. Thus, PRE could offer a natural analgesic and anti-inflammatory candidate through the synergistic action of all its components.