Munawwer Rasheed

Chemical composition and mechanisms underlying the spasmolytic and bronchodilatory properties of the essential oil of Nepeta cataria L.

AIM OF THE STUDY The study was aimed to investigate the chemical composition and pharmacological basis for traditional use of essential oil of Nepeta cataria L. (Limiaceae) (Nc.Oil) in gastrointestinal and respiratory disorders. MATERIALS AND METHODS Chemical analysis was carried out through GC-EIMS, 13C NMR and Kovats Retention Indices while pharmacological study was carried out in isolated tissues preparations. RESULTS Four major components; 1,8-cineol (21.00%), alpha-humulene (14.44%), alpha-pinene (10.43%) and geranyl acetate (8.21%) were identified among the 27 compounds in Nc.Oil. In isolated rabbit jejunum, Nc.Oil, papaverine and verapamil inhibited spontaneous and high K+(80 mM) precontractions, as well as shifted the Ca++ concentration-response curves (CRCs) to right, indicating calcium channel blocking activity. In isolated guinea-pig trachea, Nc.Oil and papaverine inhibited carbachol (1 microM) and K+ precontractions with similar potency, while verapamil was more potent against K+. Nc.Oil also potentiated isoprenaline inhibitory CRCs, similar to papaverine, indicating papaverine-like PDE inhibitor activity. In isolated guinea-pig atria, Nc.Oil caused cardiodepression at around 25-80 times higher concentrations, similar to papaverine. CONCLUSIONS These data indicate that Nepeta cataria possesses spasmolytic and myorelaxant activities mediated possibly through dual inhibition of calcium channels and PDE, which may explain its traditional use in colic, diarrhea, cough and asthma.

Phytochemical studies on the seed extract of Piper nigrum Linn.

The petroleum ether extract of dried ground seeds of Piper nigrum Linn. and some column fractions of this extract were subjected to GC and GC-MS analysis, resulting in the identification of fourteen compounds (1–14) by using NIST Mass spectral search program 1998 and the Kovats retention indices. Ten of the compounds (1, 2, 4–12) are reported for the first time from this plant. All the fractions showed insecticidal activity against the fourth instar larvae of Aedes aegypti and against the fourth instar larvae of Anopheles stephensi Liston, determined by the WHO method.

Studies on the Chemical Composition and Possible Mechanisms Underlying the Antispasmodic and Bronchodilatory Activities of the Essential Oil of Artemisia maritima L.

This study describes the chemical composition of the essential oil of Artemisia maritima (Am.Oil) and the pharmacological basis for its medicinal use in gut and airways disorders. Twenty five compounds, composing 93.7% of the oil, were identified; among these, chrysanthenyl propionate and elixene were identified for the first time from any Artemisia species. The Am.Oil (0.3–1.0 mg/mL) suppressed spontaneous and high K+ (80 mM)-induced contractions in isolated rabbit jejunum, suggestive of an antispasmodic effect mediated possibly through calcium channel blockade. The calcium channel blockade activity was confirmed when pre-treatment of the tissue with Am.Oil (0.01–0.03 mg/mL) shifted the Ca++ concentration-response curves to the right, similar to verapamil and papaverine. In isolated tracheal strips, Am.Oil inhibited carbachol (CCh; 1 μM)-induced contractions more than that induced by K+ and shifted the isoprenaline-induced inhibitory CRCs to the left, similar to papaverine, suggestive of potentiation, while, verapamil was more potent against K+ than CCh-induced contractions and had no potentiating effect on isoprenaline-induced inhibitory CRCs. These data indicate that the Am.Oil exhibited spasmolytic and bronchodilator activities mediated possibly through dual blockade of calcium channels and phosphodiesterase, which provides the pharmacological basis to the medicinal use of Artemisia maritima in colic, diarrhea and possibly asthma.

GC-based analysis of insecticidal constituents of the flowers of Azadirachta indica A. Juss.

The present article describes the analysis of an n-hexane soluble fraction of fresh flowers of Azadirachta indica A. Juss (Neem), possessing larvicidal activity against Anopheles stephensi Liston, a vector of malarial parasite. Forty-one compounds were identified in non-polar to less-polar fraction as well as in essential oil. These identifications were basically made through GC-EIMS. Thus 5 sesquiterpenes, 3 aromatics, 17 fatty acids, 5 fatty acid esters, three steroids and 8 hydrocarbons were identified. The compounds 1–5, 10, 14–17, 21a and 36–38 were reported previously from different parts of the tree including flowers. The rest of the compounds are reported for the first time from flowers.

Analysis of Insecticidal Azadirachta indica A. Juss. Fractions

As a result of chemical investigation on the ethanolic extract of fresh fruit coatings of Azadirachta indica A. Juss. (neem), twenty-seven compounds were identified in non-polar to less polar fractions which showed pesticidal activity determined by WHO method against Anopheles stephensi Liston. These identifications were basically made through GC-EIMS and were further supported by other spectroscopic techniques, including 13C NMR, UV and FTIR as well as retention indices. Thus sixteen n-alkanes, 1-16; three aromatics 2,6-bis-(1,1- dimethylethyl)-4-methyl phenol (17), 2-(phenylmethylene)-octanal (20), 1,2,4-trimethoxy-5- (1Z-propenyl)-benzene (27); three benzopyranoids 3,4-dihydro-4,4,5,8-tetramethylcoumarin (18), 3,4-dihydro-4,4,7,8-tetramethylcoumarin-6-ol (19), 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethyl- cyclopenta[g]-2-benzopyran (22); one sesquiterpene methyl-3,7,11-trimethyl-2E,- 6E,10-dodecatrienoate (21); three esters of fatty acids methyl 14-methyl-pentadecanoate (23), ethyl hexadecanoate (24), ethyl 9Z-octadecenoate (25) and one monoterpene 3,7-dimethyl- 1-octen-7-ol (26) were identified. Except 6, 8, 24 and 25 all these compounds were identified for the first time from the pericarp and fifteen of these, 1-3, 7, 9, 10, 17-23, 26, 27, are hitherto unreported previously from any part of the tree. Although this tree is a rich source of various natural products, it is the first report of identification of mono- and sesquiterpenes 26 and 21 and a potent antioxidant, 17.

Three New Triterpenoids from Azadirachta indica

by Bina S. Siddiqui* and Munawwer RasheedH.E.J. Research Institute of Chemistry, International Centre for Chemical Sciences, University of Karachi,Karachi-75270, PakistanA new trinortriterpene, meliacinolactol (1), and two new tetranortriterpenes, limocin C (2) and limocin D(3), along with a known constituent, azadiradionolide, were isolated from the fresh fruit coats of Azadirachtaindica and were characterized by chemical transformation and spectroscopic experiments, including 2D-NMRtechniques.

Simple Method for the Preparation of Symmetrical Alkyl and Aryl Disulfides with Alkyl Sulfonyl Halides in Nitrogenous Base

Abstract In the present study, the reaction of thiols with alkyl sulfonyl halides was carried out in a nitrogenous base to compare the reactivity of ‐SH with that of ‐OH, which, however, led to the formation of disulfides. The reaction achieved as a result offers the use of an inexpensive reagent, quantitative yields of the product, and simplicity for the formation of the S‐S bond.

GC-MS profile of antimicrobial and antioxidant fractions from Cordia rothii roots.

Abstract Context: An ethnobotanical survey of Cordia rothii Roem. & Schult. (Boraginaceae) reveals it as a medicinal plant. Objective: Antimicrobial and antioxidant potential evaluation and identification of chemical constituents via GC-MS of C. rothii roots fractions. To the best of our knowledge, this is the first systematic investigation of the roots exploiting GC-MS. Materials and methods: Extraction and fractionation of C. rothii roots furnished various fractions using solvents of varying polarity, i.e., n-hexane, chloroform, ethyl acetate, acetone and methanol. In vitro antimicrobial and antioxidant screening was performed using disk diffusion and DPPH methods, respectively. MIC of active fractions was also determined using disk diffusion method. GC-MS was used to identify constituents which may be responsible for these activities. Results: Among various fractions from C. rothii roots, fraction KA-C showed strong antibacterial activity against 17 microorganisms tested, with MIC ranging from 250–31.25 μg/mL. Fractions KA-A, KM and KM-A exhibited significant antioxidant potential with EC50 46.875 μg/mL, while fractions KEA-PE, KM-PE and KM-M were good with EC50 93.750 μg/mL. Forty-five phytochemicals were identified in GC-MS studies including eight hydrocarbons, six free fatty acids, 11 fatty acids esters, two phenylpropanoids, four aromatics, four terpenoid quinones/hydroquinones, three triterpenes, four phytosterols, two hexose metabolites and a DNA base. Of these, 32 constituents have been reported for the first time from C. rothii, 24 from genus Cordia and 15 from Boraginaceae. Discussion and conclusion: Strong antibacterial and antioxidant potential of C. rothii roots may be due to the contribution of phytoconstituents identified through GC-MS studies.

Antibacterial activity of flower of Melia azedarach Linn. and identification of its metabolites

Constituents of eight different extracts and fractions, obtained from flowers of Melia azedarach, were identified by gas chromatography–mass spectrometry and mass spectral library search. Altogether, 38 phytochemicals were identified, all for the first time from the flowers. Only 14 of these were known from parts of M. azedarach other than flowers, while 24 are reported for the first time from any part of the plant. These metabolites included branched and n-hydrocarbons, aromatics, a polyisoprenoid, fatty acids, fatty acid methyl esters, and fatty alcohols, which were found to be different from its essential oil constituents. One major constituent 4-hydroxybenzoic acid (4) was not only identified but also isolated as a pure compound from ethyl acetate extract. Extracts, compound 4 and its derivatives gallic acid and methyl gallate were tested for antimicrobial potential. Gallic acid and methyl gallate exhibited antibacterial activity against Staphylococcus saprophyticus. Methyl gallate also showed some activity against Corynebacterium diphtheriae and Corynebacterium. hofmannii. Among the extracts, only methanol extract exhibited activity against Pseudomonas sp. The extracts only inhibited the growth of dermatophytic fungi.

Brauhenefloroside E and F; acylated flavonol glycosides from Stocksia brauhica Linn

Two new acylated flavonol glycosides, 3‐O‐{[2‐O‐β‐D‐glucopyranosyl]‐3‐[O‐β‐D‐glucopyranosyl]‐4‐[(6‐O‐p‐coumaroyl)‐O‐β‐D‐glucopyranosyl]}‐α‐L‐rhamnopyranosyl‐kaempferol 7‐O‐α‐L‐rhamnopyranoside and 3‐O‐{2‐[(6‐O‐p‐coumaroyl)‐O‐β‐D‐glucopyranosyl]‐3‐[O‐β‐D‐glucopyranosyl]‐4‐[(6‐O‐p‐coumaroyl)‐O‐β‐D‐glucopyranosyl]}‐α‐L‐rhamnopyranosyl‐kaempferol 7‐O‐α‐L‐rhamnopyranoside, trivially named as brauhenefloroside E (1) and F (2), respectively, were isolated from the fruits of Stocksia brauhica and their structures were elucidated using spectroscopic methods, including 2D NMR experiments. Copyright