New Insecticidal Amides from Petroleum Ether Extract of Dried Piper nigrum L. Whole Fruits

1 H and 13 C NMR data, occurrence, biosynthesis, and biological activity of Piper amides

Alkamides are the major and characteristic chemical compounds of the plants belonging to the Piper genus. These compounds are responsible for the flavor of pepper spices and for its broad use in cuisine across many regions of the world. Humans are in contact every day with these substances, which additionally show a broad variety of pharmacological activities, making them an important research target. A large amount of NMR data for these natural products is dispersed throughout literature. Its organization will help those research groups interested in their identification and structural elucidation. This review summarizes the ¹ H and ¹³ C NMR data of 268 Piper amides in a systematic and orderly way, with a discussion on their biological activities, biosynthetic aspects, and NMR analysis of typical and relevant aspects of this information.

Phytochemical Profiling and Larval Control of Erythrina variegata Methanol Fraction against Malarial and Filarial Vector

Erythrina variegata (E. variegata) bioactive chemical has been the potential to be utilized as a good, eco-friendly approach for the control of mosquito population. In the present investigation, methanol extract using insecticidal compounds isolated against mosquito larvae kill assay was carried out. Secondary metabolism was characterized by thin layer chromatography, column chromatography, Fourier transform-infrared spectroscopy, gas chromatography-mass spectral, and identification of compound. Mosquito immature third instar larval, Anopheles stephensi, and Culex quinquefasciatus have been exposed to different concentrations of 50-250 µg/ml. Totally, larvae were death rate 98.2% (significant value 0.001b) from methanol extract and it is significant toxicity against larvae of An. stephensi and Cx. quinquefasciatus with LC50/LC99 values were 157.69/339.55 µg/ml and 137.67/297.33 µg/ml, respectively. FT-IR analysis in the functional groups such as alcohol, amines, amides, alkenes, 1⁎ amines, aromatic amines, aliphatic amines, 1⁎,2⁎ amines, and alkyl halides searched the identity of secondary metabolites, which may act as 12-Octadecenoic acid, methyl ester compound and clearly indicates being phytochemical. Chemical constituents of twenty-five compounds were identified in the methanol extract. The major components were 12-Octadecenoic acid and methyl ester (37.31%). Compound molecules consist of carbon 19 atoms (gray), hydrogen 36 atoms (greenish blue), and oxygen 2 atoms (red), indicated by the different colors. The results were obtained suggesting that, in addition to their pharmaceutical and medicine sources, 12-Octadecenoic acid, methyl ester compound can also serve as a natural mosquito control.

A systematic review on black pepper (Piper nigrum L.): from folk uses to pharmacological applications

Considered as the "King of spices", black pepper (Piper nigrum L.) is a widely used spice which adds flavor of its own to dishes, and also enhances the taste of other ingredients. Piper nigrum has also been extensively explored for its biological properties and its bioactive phyto-compounds. There is, however, no updated compilation of these available data to provide a complete profile of the medicinal aspects of P. nigrum. This study endeavors to systematically review scientific data on the traditional uses, phytochemical composition, and pharmacological properties of P. nigrum. Information was obtained using a combination of keywords via recognized electronic databases (e.g., Science Direct and Google Scholar). Google search was also used. Books and online materials were also considered, and the literature search was restricted to the English language. The country with the highest number of traditional reports of P. nigrum for both human and veterinary medicine was India, mostly for menstrual and ear-nose-throat disorders in human and gastrointestinal disorders in livestock. The seeds and fruits were mostly used, and the preferred mode of preparation was in powdered form, pills or tablets, and paste. Piper nigrum and its bioactive compounds were also found to possess important pharmacological properties. Antimicrobial activity was recorded against a wide range of pathogens via inhibition of biofilm, bacterial efflux pumps, bacterial swarming, and swimming motilities. Studies also reported its antioxidant effects against a series of reactive oxygen and nitrogen species including the scavenging of superoxide anion, hydrogen peroxide, nitric oxide, DPPH, ABTS, and reducing effect against ferric and molybdenum (VI). Improvement of antioxidant enzymes in vivo has also been reported. Piper nigrum also exhibited anticancer effect against a number of cell lines from breast, colon, cervical, and prostate through different mechanisms including cytotoxicity, apoptosis, autophagy, and interference with signaling pathways. Its antidiabetic property has also been confirmed in vivo as well as hypolipidemic activity as evidenced by decrease in the level of cholesterol, triglycerides, and low-density lipoprotein and increase in high-density lipoprotein. Piper nigrum also has anti-inflammatory, analgesic, anticonvulsant, and neuroprotective effects. The major bioactive compound identified in P. nigrum is piperine although other compounds are also present including piperic acid, piperlonguminine, pellitorine, piperolein B, piperamide, piperettine, and (-)-kusunokinin, which also showed biological potency. Most pharmacological studies were conducted in vitro (n = 60) while only 21 in vivo and 1 clinical trial were performed. Hence, more in vivo experiments using a pharmacokinetic and pharmacokinetic approach would be beneficial. As a conclusive remark, P. nigrum should not only be regarded as "King of spices" but can also be considered as part of the kingdom of medicinal agents, comprising a panoply of bioactive compounds with potential nutraceutical and pharmaceutical applications.

A Survey of the Chemical Compounds of Piper spp. (Piperaceae) and Their Biological Activities

The genus Piper is one of the largest genera in the Piperaceae, with most species widely distributed globally, covering all continents. To date, many Piper species have been scientifically investigated for their chemical diversities and interesting broad spectrum of bioactivities, including central nervous system (CNS), pesticidal, antifungal and antibacterial effects. This review systematically summarizes the scaffolds of the alkaloids reported, the major chemicals isolated from Piper spp., and their biological activities. Besides the alkaloids, some neolignans with rearranged skeletons show structural diversities, while the chalcones, flavonoids and kava-pyrones have some potential activities. Herein, the sesquiterpenes and phenolic compounds from Piper species and their bioactivities are also surveyed.

Physiological and biochemical effects of botanical extract from Piper nigrum Linn (Piperaceae) against the dengue vector Aedes aegypti Liston (Diptera: Culicidae)

The leaves of Piper nigrum L. (Piperaceae) were evaluated for chemical constituents and mosquito larvicidal activity against the larvae of Aedes aegypti. GC and GC-MS analyses revealed that the crude extracts contain 16 compounds. Thymol (20.77%) and ç-elemene (10.42%) were identified as the major constituents followed by cyclohexene, 4-ethenyl-4-methyl-3-(1-methylethenyl)-1-(1 methylethyl)-, (3R-trans) (7.58%), 4,6-octadienoic acid, 2-acetyl-2-methyl-, ethyl ester (6.98), 2(3H)-furanone, 3,4-bis(1,3-benzodioxol-5-ylmethyl) dihydro-, (3R-trans) (6.95%), 1-naphthalenol, 1,2,3,4,4a,7,8,8a-octahydro-1,6-dimethyl-4-(1-methylethyl)-, [1R-(1à,4á,4aá,8aá)]-(Cedreanol) (5.30%), trans-2-undecen-1-ol (4.48%), phytol (4.22%), 1,6-cyclodecadiene, 1-methyl-5-methylene-8-(1-methylethyl)-,[s-(E,E)] (3.78%) and 2,6-dimethyl-3,5,7-octatriene-2-ol, Z,Z (2.39%). Larval mortality was observed after 3 h of exposure period. The crude extract showed remarkable larvicidal activity against Ae. aegypti (LC50 = 34.97). The larvae of Ae. aegypti exposed to the P. nigrum, significantly reduced the activities of α- and β-carboxylesterases and superdioxide. Further, P. nigrum extract was severely affecting the mosquito gut cellular organelles. Based on the results, the chemical constituents of crude extracts of P. nigrum can be considered as a new source of larvicide for the control of Ae. aegypti.

Cytotoxicity of piperamides towards Aedes aegypti (Diptera: Culicidae)

The effectiveness of the amides piplartine and piperlonguminine isolated from Piper species for controlling L3 and L4 of Aedes aegypti (L.) was assessed through bioassays at concentrations ranging from 1 to 300 g/l ml. Piplartine reduced the mosquito development period and caused larval mortality only at concentrations > 100 microg/ml, whereas piperlonguminine resulted in an extended period of mosquito development (10 microg/ml) and caused 100% larval mortality (30 microg/ml) within 24 h. The toxicity and cytotoxic effects of piperlonguminine on epithelial cells of the digestive system of Ae. aegypti were viewed using transmission electron microscopy, which indicated vacuolization of cytoplasm, mitochondrial swelling and leaking of nuclear material. Piperlonguminine was the more effective amide, showing toxic activity with LD50 of approximately 12 microg/ml against the larvae of Ae. aegypti.

Mosquito larvicidal activity of methyl-p-hydroxybenzoate isolated from the leaves of Vitex trifolia Linn

The vector-borne diseases caused by mosquitoes are one of the major health problems in many countries especially in tropical and sub-tropical countries. The resistance of mosquitoes to synthetic chemicals and environmental toxicity created by the chemicals raised the demand for finding of alternate natural molecules that control mosquito. In the present study, a crystalline compound methyl-p-hydroxybenzoate was isolated from the methanol extract of Vitex trifolia leaves and it was identified by (1)H and (13)C NMR and single crystal X-ray diffractometer. The larvicidal potential of the isolated compound was evaluated against early 4th instar larvae of Culex quinquefasciatus and Aedes aegypti. The compound exhibited 100% larval mortality of both the mosquitoes at 20 ppm with LC(50) values of 5.77 and 4.74 ppm against C. quinquefasciatus and A. aegypti, respectively. The methyl-p-hydroxybenzoate, which is reported for the first time to our best of knowledge from V. trifolia can be better explored for the control of mosquito population.

Amides from Piper nigrum L. with dissimilar effects on melanocyte proliferation in-vitro

Melanocyte proliferation stimulants are of interest as potential treatments for the depigmentary skin disorder, vitiligo. Piper nigrum L. (Piperaceae) fruit (black pepper) water extract and its main alkaloid, piperine (1), promote melanocyte proliferation in-vitro. A crude chloroform extract of P. nigrum containing piperine was more stimulatory than an equivalent concentration of the pure compound, suggesting the presence of other active components. Piperine (1), guineensine (2), pipericide (3), N-feruloyltyramine (4) and N-isobutyl-2E, 4E-dodecadienamide (5) were isolated from the chloroform extract. Their activity was compared with piperine and with commercial piperlongumine (6) and safrole (7), and synthetically prepared piperettine (8), piperlonguminine (9) and 1-(3, 4-methylenedioxyphenyl)-decane (10). Compounds 6–10 either occur in P. nigrum or are structurally related. Compounds 1, 2, 3, 8 and 9 stimulated melanocyte proliferation, whereas 4, 5, 6, 7 and 10 did not. Comparison of structures suggests that the methylenedioxyphenyl function is essential for melanocyte stimulatory activity. Only those compounds also possessing an amide group were active, although the amino component of the amide group and chain linking it to the methylenedioxyphenyl group can vary. P. nigrum, therefore, contains several amides with the ability to stimulate melanocyte proliferation. This finding supports the traditional use of P. nigrum extracts in vitiligo and provides new lead compounds for drug development for this disease.

Bioactive constituents of the stem bark of Beilschmiedia zenkeri

Phytochemical investigation of the stem bark of Beilschmiedia zenkeri led to the isolation of four new methoxylated flavonoid derivatives, (2S,4R)-5,6,7-trimethoxyflavan-4-ol (1), (2S,4R)-4,5,6,7-tetramethoxyflavan (2), beilschmieflavonoid A (3), and beilschmieflavonoid B (4), together with seven known compounds. The structures of 1-4 were established by spectroscopic methods, and their relative configurations confirmed by X-ray crystallographic and CD analysis. The isolated compounds were evaluated in vitro for their antibacterial activity against three strains of bacteria, Pseudomonas agarici, Bacillus subtilis, and Streptococcus minor, and for their antiplasmodial activity against Plasmodium falciparum, chloroquine-resistant strain W2.

Improved microwave-mediated synthesis of 3-(3-aryl-1,2,4-oxadiazol-5-yl)propionic acids and their larvicidal and fungal growth inhibitory properties

The synthesis of 3-(3-aryl-1,2,4-oxadiazol-5-yl)propionic acids from arylamidoximes and succinic anhydride under focused microwave irradiation conditions is described. The new synthetic method furnished the desired products in 2-3 min and good yields. Furthermore, the previously complicated purification procedure has been simplified in a manner which is quick, eco-friendly and cost-effective. Larvicidal bioassay and fungal growth inhibitory tests were performed using several 3-(3-aryl-1,2,4-oxadiazol-5-yl)propionic acids. These acids presented strong larvicidal activity against L4 larvae of Aedes aegypti. The results suggest that larvicidal activity might be correlated with the presence of electron-withdrawing substituents in the para position of the phenyl ring except the fluorine atom. The alterations observed in the larvae spiracular valves of the siphon and anal papillae by 1,2,4-oxadiazoles in the larvicidal bioassay are responsible for larvae's death. Furthermore, all acids inhibited the fungal growth of five different types of fungi, viz., Fusarium solani, F. oxysporum, F. moniliforme, F. decemcellulare and F. lateritium in a preliminary evaluation. Both of these activities are being disclosed for the first time for 1,2,4-oxadiazole-5-yl ring linked at C-3 of propionic acid.

Larvicidal activity of saponin from Achyranthes aspera against Aedes aegypti and Culex quinquefasciatus (Diptera: Culicidae)

The acetone, chloroform, ethyl acetate, hexane and methanol leaf extracts of Acalypha indica, Achyranthes aspera, Leucas aspera, Morinda tinctoria and Ocimum sanctum were studied against the early fourth-instar larvae of Aedes aegypti L and Culex quinquefasciatus Say. The larval mortality was observed after 24 h exposure. All extracts showed moderate larvicidal effects; however, the highest larval mortality was found in the ethyl acetate extract of A. aspera. In the present study, bioassay-guided fractionation of A. aspera led to the separation and identification ofa saponin as a potential mosquito larvicidal compound, with LC50 value of 18.20 and 27.24 ppm against A. aegypti and C. quinquefasciatus, respectively. 1H NMR, 13C NMR and mass spectral data confirmed the identification of the active compound. This is the first report on the mosquito larvicidal activity of the saponin from the ethyl acetate extract of A. aspera. This study investigates the potential of crude extracts from commonly used medical herbs in India as an environmentally safe measure to control the vector of dengue and lymphatic filariasis.

Mosquito larvicidal activity of isolated compounds from the rhizome of Zingiber officinale

The larvicidal activity of a petroleum ether extract of Zingiber officinale Roscoe (Zingiberaceae) was evaluated against Aedes aegypti L. and Culex quinquefasciatus Say (Diptera). Bioassay-guided fractionation led to the isolation of 4-gingerol (1), (6)-dehydrogingerdione (2) and (6)-dihydrogingerdione (3); the latter has not previously been reported from Z. officinale. The structures were established from infrared (IR), ultraviolet (UV), (1)H-nuclear magnetic resonance (NMR), (13)C-NMR and mass spectral data. Following a 24 h exposure, compounds 1-3 exhibited larvicidal activities against fourth instar larvae of A. aegypti (LC(50) 4.25, 9.80, 18.20 ppm) and C. quinquefasciatus (LC50 5.52, 7.66, 27.24 ppm), respectively. The results show that the most effective compound was 4-gingerol.

Mosquito larvicidal activity of gluanol acetate, a tetracyclic triterpenes derived from Ficus racemosa Linn

The larvicidal activity of crude hexane, ethyl acetate, petroleum ether, acetone, and methanol extracts of the leaf and bark of Ficus racemosa (Moraceae) was assayed for their toxicity against the early fourth-instar larvae of Culex quinquefasciatus (Diptera: Culicidae). The larval mortality was observed after 24-h exposure. All extracts showed moderate larvicidal effects; however, the highest larval mortality was found in bark acetone extract of F. racemosa. In the present study, bioassay-guided fractionation of acetone extract led to the separation and identification of a tetracyclic triterpenes derivative; gluanol acetate was isolated and identified as new mosquito larvicidal compound. Gluanol acetate was quite potent against fourth-instar larvae of Aedes aegypti L. (LC(50) 14.55 and LC(90) 64.99 ppm), Anopheles stephensi Liston (LC(50) 28.50 and LC(90) 106.50 ppm) and C. quinquefasciatus Say (LC(50) 41.42 and LC(90) 192.77 ppm). The structure was elucidated from infrared, ultraviolet, (1)H-nuclear magnetic resonance (NMR), (13)C-NMR, and mass spectral data. This is the first report on the mosquito larvicidal activity of the reported compound from F. racemosa.

Isolation and identification of mosquito larvicidal compound from Abutilon indicum (Linn.) Sweet

Larvicidal activity of crude hexane, ethyl acetate, petroleum ether, acetone and methanol extracts of five medicinal plants, Abutilon indicum, Aegle marmelos, Euphorbia thymifolia, Jatropha gossypifolia and Solanum torvum were assayed for their toxicity against the early fourth-instar larvae of Culex quinquefasciatus. The larval mortality was observed after 24 h exposure. All extracts showed moderate larvicidal effects; however, the highest larval mortality was found in petroleum ether extract of A. indicum. In the present study, bioassay-guided fractionation of A. indicum led to the separation and identification of a beta-sitosterol as a potential new mosquito larvicidal compound with LC50 value of 11.49, 3.58 and 26.67 ppm against Aedes aegypti L, Anopheles stephensi Liston and C. quinquefasciatus Say (Diptera: Culicidae), respectively. 1H NMR, 13C NMR and mass spectral data confirmed the identification of the active compound. beta-sitosterol has been recognized as the active ingredient of many medicinal plant extracts. All the crude extracts when screened for their larvicidal activities indicated toxicity against the larvae of C. quinquefasciatus. This article reports the isolation and identification of the beta-sitosterol as well as bioassay data for the crude extracts. There are no reports of beta-sitosterol in the genus A. indicum, and their larvicidal activities are being evaluated for the first time. Results of this study show that the petroleum ether extract of A. indicum may be considered as a potent source and beta-sitosterol as a new natural mosquito larvicidal agent.

Larvicidal activity of some Euphorbiaceae plant extracts against Aedes aegypti and Culex quinquefasciatus (Diptera: Culicidae)

Larvicidal activity of ethyl acetate, butanol, and petroleum ether extracts of five species of Euphorbiaceae plants, Jatropha curcas, Pedilanthus tithymaloides, Phyllanthus amarus, Euphorbia hirta, and Euphorbia tirucalli, were tested against the early fourth instar larvae of Aedes aegypti L. and Culex quinquefasciatus (Say). The larval mortality was observed after 24 h of exposure. All extracts showed low larvicidal effects; however, the highest larval mortality was found in petroleum ether extract. The LC50 value of petroleum ether extracts of J. curcas, P. tithymaloides, P. amarus, E. hirta, and E. tirucalli were 8.79, 55.26, 90.92, 272.36, and 4.25 ppm, respectively, against A. aegypti and 11.34, 76.61, 113.40, 424.94, and 5.52 ppm, respectively, against C quinquefasciatus. Of the various ratios tested, the petroleum ether extracts of J. curcas and E. tirucalli were observed to be more efficient than the other plant extracts. It is, therefore, suggested that E. tirucalli can be applied as an ideal potential larvicide against A. aegypti and C. quinquefasciatus. This is an ideal ecofriendly approach for the control of the dengue vector, A. aegypti, and the lymphatic filariasis vector, C. quinquefasciatus.

Rapid structural determination of amides in Piper longum by high-performance liquid chromatography combined with ion trap mass spectrometry

A reversed-phase liquid chromatography/tandem multistage mass spectrometry (MS/MS) method was developed for the characterization of amides from the extracts of Piper longum. The characteristic fragmentations of the amides found in P. longum showed diagnostic structural information. Extracted ion chromatography (EIC) and constant neutral losses were used to guide the search for the amides of interest. Amides of known structures that contain four subtypes of amides were rapidly determined, and novel amides were also identified for this plant. Forty-two amides were rapidly identified, of which 22 were found in this plant for the first time and 9 were new compounds. The method is convenient and sensitive, especially for minor components in the unpurified, complex mixture; the structures of unknown constituents could be determined, in the absence of authentic sample, by comparison of the fragmentation patterns with those of homologous compounds.