Comparative antioxidant and antiplasmodial activities of 11-O-galloylbergenin and bergenin isolated from Bergenia ligulata.

In the present study, the antioxidant and antiplasmodial activities of bergenin was compared with its natural derivative 11-O-galloylbergenin for the first time. Both compounds were isolated from Bergenia ligulata. 11-O-galloylbergenin was found to be very active in in-vitro antioxidant assay as compared to bergenin, which was found to be almost inactive. The EC50 values of 11-O-galloylbergenin were 7.45±0.2 µg/mL and 5.39±0.28 µg/mL in DPPH antioxidant assay and reducing power assay respectively, while IC50 value for antiplasmodial assay of both compounds were less than 2.5 µM. Interestingly, in the total antioxidant phosphomolybdate assay, 11-O-galloylbergenin was found more potent (CAHT: 940.04±115.30) as compared to α-tocopherol (CAHT: 552.4±27.91).

Antimycobacterial activity of flavonoids from Lantana camara Linn.

Linaroside (1) and lantanoside (2), two flavonoids isolated from Lantana camara and their common acetyl derivative (3) were examined for antimycobacterial activity against Mycobacterium tuberculosis, strain H(37)Rv. These compounds exhibited 30, 37 and 98% inhibition, respectively at 6.25 microg mL(-1) concentration. Among these flavonoids acetylated compound was found to be the most active.

Chemical constituents of Centella asiatica.

Studies on the chemical constituents of the aerial part of Centella asiatica have led to the isolation of three new compounds, named centellin (1), asiaticin (2), and centellicin (3). Their structures have been elucidated through spectral studies including 2D NMR experiments (HMQC, HMBC, (1)H-(1)H COSY, NOESY and J resolved).

A new triterpenoid, madhunolic acid, from the seeds of Madhuca latifolia.

A new triterpenoid, madhunolic acid, along with the three known constituents stigmasterol, 4-hydroxymethyl benzoate, and hydroquinone were isolated from the fruit seeds of Madhuca latifolia. The structure of the new compound was elucidated as 2beta,3beta,23-trihydroxyurs-5,12,20-trien-28-oic acid (1) on the basis of spectral data and chemical evidence.

Nematicidal natural products from the aerial parts of Lantana camara Linn.

Lantanilic acid, camaric acid and oleanolic acid possessing nematicidal activity were isolated from the methanolic extract of the aerial parts of Lantana camara Linn. through bio-assay guided fractionation. These compounds exhibited 98%, 95% and 70% mortality respectively against root-knot nematode Meloidogyne incognita at 0.5% concentration. Conventional nematicide furadan showed 100% mortality at this concentration.

Hypotensive effect of chemical constituents from Aloe barbadensis.

Hypotensive effects of aloeemodin, aloin A, elgonica dimer A and bisbenzopyran from Aloe barbadensis have been studied. Aloeemodin has emerged as a potent hypotensive agent in current pharmacological investigations and caused 26 %, 52 %, and 79 % falls in mean arterial blood pressure at the corresponding doses of 0.5, 1, and 3 mg/kg in rats. The paper also describes the absolute configuration of elgonica dimer A (1).

Triterpenoids from Lawsonia alba.

Two pentacyclic triterpenoids have been isolated from the aerial parts of Lawsonia alba. The structures of the new constituents, named as lawsonic acid and lawsonin have been elucidated as 3 alpha-E-ferulyloxy-lup-20(29)-en-28-oic acid and 3 alpha-E-ferulyloxy-urs-11-en-13 beta-ol respectively through spectroscopic studies.

Further constituents from the bark of Holarrhena pubescens.

Three compounds, pubadysone [11 alpha-hydroxy-18,20-oxido-3-oxo-pregna-1,4,17(20)-triene] (1), puboestrene [3-acetoxy-17-oxo-1,3,5(10)-estratriene] (2) and pubamide [3,18-dioxo-11 alpha-hydroxycona-1,4-diene] (3), have been isolated from the bark of Holarrhena pubescens. Their structures have been established through spectroscopic studies.

An isopyoverdin from Pseudomonas putida CFML 90-44.

From Pseudomonas putida CFML 90-44 an isopyoverdin was isolated. Its structure could be elucidated by chemical degradation and spectroscopic data.

Triterpenoidal constituents from Eucalyptus camaldulensis var. obtusa leaves.

An investigation on the constituents of the fresh, uncrushed leaves of Ecalyptus camaldulensis var. obtusa has led to the isolation of the triterpenoid amirinic acid and four known triterpenoids ursolic acid lactone, betulinic acid, oleanolic acid and ursolic acid. Amirinic acid transformed into amirolide in deuterated chloroform at room temperature. The new products were characterized by exhaustive spectroscopic studies as 2alpha,3beta,7beta-trihydroxy-11alpha-methoxyurs -12-en-28-oic acid and 2alpha,3beta,7beta-trihydroxyurs-11-en-28,13beta -olide.

A pyoverdine from Pseudomonas putida CFML 90-51 with a Lys epsilon-amino link in the peptide chain.

From Pseudomonas putida CFML 90-51--a hospital isolate--a pyoverdine was obtained which is characterized by the unusual linkage by the epsilon--rather than the alpha-amino group of Lys in the peptide chain. The structure elucidation by spectroscopic methods and degradation reactions is reported.

Spasmolytic constituents from Eucalyptus camaldulensis var. obtusa leaves.

Phytochemical studies on the leaves of Eucalyptus camaldulensis var. obtusa have resulted in the isolation of a new triterpenoid camaldulin (3beta-formyloxyurs-11-en-28,13beta-olide) (1) along with ursolic acid lactone acetate (2), ursolic acid lactone (3), betulinic acid (4), and beta-sitosterol 3-O-beta-D-glucopyranoside (5). The structures were assigned on the basis of 1D and 2D NMR studies. Compounds 1-3 were tested for spasmolytic activity and were found to possess calcium antagonist activity.

Ethnopharmacological evaluation of the anticonvulsant, sedative and antispasmodic activities of Lavandula stoechas L.

Lavandula stoechas L. (Lamiaceae) has been used for a long time in traditional medicine as an anticonvulsant and antispasmodic. The aqueous-methanolic extract of L. stoechas flowers (LS) was studied for its possible anticonvulsant and antispasmodic activities. When tested in mice, LS (600 mg/kg) significantly reduced the severity and increased the latency of convulsions induced by pentylene tetrazole (PTZ). LS likewise reduced PTZ's lethality. LS up to a dose of 600 mg/kg was found devoid of any hypnotic effect in mice, however, animals were found to be dull, calm and relaxed. The sedative effect of the plant extract was confirmed, as it prolonged the pentobarbital sleeping time in mice similar to that of diazepam. In isolated rabbit jejunum preparations, LS caused a dose-dependent (0.1-1.0 mg/ml) relaxation of spontaneous contractions. LS also inhibited K(+)-induced contractions in a similar dose range, thereby suggesting calcium channel blockade. This effect was confirmed when pretreatment of the jejunum preparation with LS produced a dose-dependent shift of the Ca(2+) dose-response curve to the right, similar to the effect of verapamil, a standard calcium channel blocker. These data indicate that the plant extract exhibits anticonvulsant and antispasmodic activities. Its calcium channel blocking property may be mechanistically related to these activities. Its usefulness in folk medicine appears thus to be based on a sound mechanistic background.

Nematicidal constituents of the aerial parts of Lantana camara.

Two new constituents, lantanoside (1) and lantanone (2), and the known compounds linaroside (3) and camarinic acid (4) were isolated from the aerial parts of Lantana camara. Compounds 1, 3, and 4 were tested for nematicidal activity against root-knot nematode Meloidogyne incognita and showed 90, 85, and 100% mortality, respectively, at 1.0% concentration. The results were comparable to those obtained with the conventional nematicide furadan (100% mortality at 1.0% concentration). Structures of the new compounds were elucidated by spectroscopic and chemical techniques.

Two insecticidal tetranortriterpenoids from Azadirachta indica.

Two new triterpenoids, 6 alpha-O-acetyl-7-deacetylnimocinol [24,25,26,27-tetra-norapotirucalla-(apoeupha)-6 alpha-acetoxy-7 alpha-hydroxy-1,14,20,22-tetraen-21,23-epoxy-3-one] (1) and meliacinol [24,25,26,27-tetranorapotirucalla-(apoeupha)-1 alpha-trimethylacryloxy-21,23-6 alpha,28-diepoxy-16-oxo-17-oxa-14,20,22-trien-3 alpha,7 alpha-diol] (2) were isolated from the methanolic extract of the fresh leaves of Azadirachta indica (neem). Their structures have been elucidated through spectral studies, including 2D-NMR (COSY-45, NOESY, HMQC and HMBC). The bioactivity of these as well as of nimocinol, reported earlier from the same source, is reported. The first compound and nimocinol showed toxicity on fourth instar larvae of mosquitoes (Aedes aegypti) with LC50 values of 21 and 83 ppm, respectively. The second compound had no effect upto 100 ppm.

A pyoverdin from Pseudomonas sp. CFML 95-275.

From Pseudomonas sp. CFML 95-275 a pyoverdin was isolated with a cyclopeptidic substructure. It could be shown that this pyoverdin is identical with one obtained from Pseudomonas fluorescens BTP 7 for which a lactone structure had been deduced from the interpretation of a FAB spectrum. The elucidation of the correct structure of the pyoverdin is described.

Bio-active cardenolides from the leaves of Nerium oleander.

A bioactivity directed isolation of the methanolic extract of the fresh, uncrushed leaves of Nerium oleander showing a central nervous system (CNS) depressant effect in mice has been undertaken. As a result, four CNS depressant cardenolides including a new cardenolide, neridiginoside and three known constituents, nerizoside, neritaloside and odoroside-H, have been isolated which exhibited CNS depressant activity in mice at a dose of 25 mg/kg. The structure of neridiginoside was elucidated as 3 beta-O-(D-diginosyl)-5 beta, 14 beta-dihydroxy-card-20(22)-enolide, using spectroscopic methods including one-dimensional and two-dimensional NMR (COSY-45, NOESY, J-resolved, HMQC and HMBC). The known compounds have been indentified through spectral studies and comparison of data with those reported in the literature.

Hypotensive constituents from the pods of Moringa oleifera.

Hypotensive activity of the ethanolic and aqueous extracts of Moringa oleifera whole pods and their parts, namely, coat, pulp, and seed was investigated. The activity of the ethanolic extract of both the pods and the seeds was equivalent at the dose of 30 mg/kg. The ethyl acetate phase of the ethanolic extract of pods was found to be the most potent fraction at the same dose. Its bioassay-directed fractionation led to the isolation of thiocarbamate and isothiocyanate glycosides which were also the hypotensive principles of the pods as observed in case of Moringa leaves. Two new compounds, O-[2'-hydroxy-3'-(2"-heptenyloxy)]-propyl undecanoate (1) and O-ethyl-4-[(alpha-L-rhamnosyloxy)-benzyl] carbamate (2) along with the known substances methyl p-hydroxybenzoate (3) and beta-sitosterol have also been isolated in the present studies. The latter two compounds and p-hydroxybenzaldehyde showed promising hypotensive activity. Structures of all these compounds have been deduced by spectroscopy and chemical reactions.

Acetates and benzoates of alkyl catechols and evaluation of their antibacterial activity.

Potential biologically active alkyl catechol esters were prepared and their antibacterial activity was determined against 12 Gram-positive and 16 Gram-negative bacteria. Esterification (acetylation and benzoylation) of mono-, di- and tetra- substituted alkyl catechols afforded the di-acetyl and di-benzoyl derivatives in each case. In the primary screening it was observed that the substitution of hydroxyl group in alkyl catechol with an acyl group generally resulted in a decrease of antibacterial activity. A number of acetyl and benzoyl derivatives inhibited the growth of Salmonella typhi. In case of Gram-positive bacteria only di-O-benzoyl-3,5,6,-tetra-(3-hexyl) catechol (26) showed a significant activity.

Cardenolides from the methanolic extract of Nerium oleander leaves possessing central nervous system depressant activity in mice.

Two new cardenolides, 3 beta-O-(D-2-O-methyldigitalosyl)-14 beta-hydroxy-5 beta-carda-16,20(22)-dienolide (1) and 3 beta-hydroxy-8,14-epoxy-5 beta-carda-16,20(22)-dienolide (2), and two known cardenolides, 3 beta-O-(D-digitalosyl)-14 beta-hydroxy-16 beta-acetoxy-5 beta-card-20(22)-enolide (3) and 3 beta-O-(D-digitalosyl)-14 beta-hydroxy-5 beta-card-20(22)-enolide (4), have been isolated from the leaves of Nerium oleander following a bioactivity-directed isolation of the MeOH extract, which showed central nervous system (CNS) depressant activity in mice at a dosage of 50 mg/kg i.p. Their structures were established on the basis of chemical and spectral data. Compounds 1, 3, and 4 were found to exhibit sedation in mice at a dosage of 25 mg/kg, although 2 had no effect on the CNS of mice at a dosage of up to 50 mg/kg.