Natural Products Journal, The - Volume 1, Issue 2, 2011

Phytochemical analyses have revealed the genus Lonchocarpus to be a rich source of many different classes of polyphenolic compounds. These classes include aurones, chalcones, dibenzoylmethane derivatives, pterocarpans, rotenoids, flavanones, flavanols, flavans, flavones, flavonols, and isoflavones. This review presents a summary of polyphenolic compounds found in Lonchocarpus species as well as activities of some of those compounds.

Since most of the pathogenic microbes have developed resistance against chemical drug derivatives therefore need of the hour is to formulate plant based natural medicines. These formulations with no or least toxicity can prove better alternative of synthetic drugs. Ethnopharmacologists, botanists, microbiologists, and natural-products chemists are combing the earth for phytochemicals and “leads” which could be developed for the treatment of infectious diseases. While, 25 to 50% of current pharmaceuticals are derived from plants, none are used as antimicrobials. Traditional healers have long used plants to prevent or cure infectious conditions; western medicine is trying to duplicate their successes. Plants are rich in a wide variety of secondary metabolites, such as tannins, terpenoids, alkaloids, and flavonoids, which have been found in vitro to have antimicrobial properties. The present review mainly discusses exploitation of plant secondary compounds as antimicrobial agents. Mode of action of some agents was also addressed. Since many of these compounds are currently available as unregulated botanical preparations and their use by the public is increasing rapidly, clinicians need to consider the consequences of patients self-medicating with these preparations.

Phytochemical evaluation of Terminalia brownii extracts led to the isolation of five compounds namely β- sitosterol, stigmasterol, monogynol A, betulinic acid and arjungenin. Their structures were established by spectroscopic and physical methods as well as by comparison with literature data. The in vitro antimicrobial activities of the extracts and isolates were investigated against fungi and bacteria which infect sweet potato. Ethyl acetate extract exhibited the highest (p ≤ 0.05) antifungal and antibacterial activities compared to n-hexane and methanol ones. Streptomyces ipomoeae was more susceptible to ethyl acetate extract (inhibition zone, 18.6 mm) than streptocycline used as a positive control. The minimum inhibitory concentration (MIC) for the isolates ranged between 50 and 200 μg/ml with the lowest MIC value of 50 μg/ml being observed with betulinic acid against Aspergillus niger and S. ipomoea.

Three acridone alkaloids, 1-hydroxy-3-methoxy-9-acridone 1, 1-hydroxy-3,4-dimethoxy-10-methyl-9-acridone 2, and 1-hydroxy-3-methoxy-10-methyl-9-acridone 3 were isolated from the plant Zanthoxylum leprieurii (Rutaceae) and evaluated for mosquito larvicidal activity against the malaria vector Anopheles gambiae. The mortalities of the larvae were determined after 24 hours. The results of the larvicidal tests demonstrated that compound 1 was the most potent with LC50 and LC90 values of 39.61 and 77.53 ppm, respectively. Compound 2 produced over 75% mortality at a concentration of 250 ppm and had LC50 and LC90 values of 189.76 and 475.41 ppm, respectively. Compound 3 was less potent and achieved only 33% mortality at a concentration of 1000 ppm. Compounds 1 and 2 showed a mortality of up to 100% of the larvae population tested and this can certainly help reduce the mosquito population drastically. Considering that a large proportion of the human population living in malaria prone areas suffer from varying degrees of poverty, the discovery of compounds from plant extracts that may control the mosquito population could be of great value.

The essential oils obtained by hydrodistillation of unripe galls of Pistacia atlantica and collected from both male and female trees yielded 0.53% and 0.46% v/w, respectively. The essential oils were analyzed by GC and GC-MS showing the occurrence of a new Δ3-carene rich chemotype showing a content of 75.34%. The second is the well known chemotype α-pinene/β-pinene, which is rich in &α-pinene (59.01%) and β-pinene (13.26%).

Ethnopharmacological relevance: Oroxylum indicum Vent. (Bignoniaceae), popularly known as the tree of Damocles, has been traditionally used as wound healing agent. Objective: To investigate in vivo wound healing and antimicrobial properties of methanolic extract of Oroxylum indicum. Material and methods: Partial thickness burn wounds were inflicted upon 5 groups of six animals each. Group I was assigned as control, Group II received the plain ointment base. Groups III and IV were given ointment containing 1% and 2.5% methanolic extract of Oroxylum indicum, respectively. Group-V received the standard drug silver sulphadiazine and chlorhexidine gluconate cream. The parameters observed were rate of wound contraction, epithelization time and hydroxyproline content. Histological study of the granulation tissue was carried out to know the extent of collagen formation in the wound tissue. The antimicrobial activity of extract was studied against the bacterial and fungal strain using agar dilution method. Results: The result showed that Oroxylum indicum root bark extract had significant wound healing activity as evident from the rate of wound contraction. Highly significant wound contraction was observed from day 20 onward in groups III, IV and V. The period of epithelization also decreased significantly in groups IV and V. Higher hydroxyproline content in treated groups suggested higher collagen re-deposition than the control group. Finally, histopathology studies conformed wound-healing activity of Oroxylum indicum. Methanolic extract also exhibited antimicrobial activity against all tested microorganisms. Conclusion: The present study provides a scientific rationale for the traditional use of Oroxylum indicum in the management of wounds.

A novel technique in mass spectrometry, mass defect filter (MDF), has recently been developed and widely employed in metabolite screening and profiling. This approach depends on the elemental constituents but not the molecular weight or mass fragmentation, which can serve as a useful tool for the screening for natural products. We explored the potential of this technique in the screening and dereplication of natural products and generating natural product profiles. The sensitivity, selectivity, and effectiveness of this technique was determined by the screening of steroidal alkaloids from a methanolic extract of Fritillaria thunbergii, glycyrrhizin analogs, coumarin and flavonoid analogs from a methanolic extract of Radix glycyrrhizae. The capability of this technique to remove matrix or interference ions from a crude extract of Fritillaria thunbergii was examined using peimine as a template. The ion signals of the peimine analogs were buried in the total ion chromatogram before mass defect filter processing. Importantly, after the mass defect filtering processing, the alkaloid analogs were easily identified with a much cleaner ion chromatogram. The major alkaloid analogs that have been previously isolated from Fritillaria thunbergii could be identified as well as some minor alkaloids in the filtered chromatogram, confirming the sensitivity and specificity of this technique. The application of mass defect filter in natural product screening and dereplication was also demonstrated by analyzing glycyrrhizin analogs and coumarin or flavonoid analogs from the extract of Radix glycyrrhizae. The total ion chromatograms after mass defect filtering represent the profiles of individual classes of natural products, which are the best finger-prints of traditional Chinese medicines.

A high performance liquid chromatography (HPLC) method for the determination of the monosaccharide compositions and molar ratio of polysaccharide in quince has been established. The quince polysaccharides were derivatized with 1-phenyl-3-methyl-5- pyrazolone (PMP) after hydrolyzed into monosaccharides with 2 M sulfuric acid. Monosaccharide derivatives were separated by a reversed phase C18 column and monitored by UV at 250 nm. Analysis of monosaccharides of quince polysaccharides sample by HPLC indicated the presence of mannose, rhamnose, glucose, galactose, and arabinose with the molar ratio of 0.10, 0.72, 1.12, 4.23, and 4.73, respectively. It could be applied for the quality control of quince polysaccharides. Moreover, quince polysaccharide shows the inhibitory activity of protein tyrosine phosphatase- 1B (PTP1B) with IC50 value of 2.07 μg/mL.

Crocus sativus stigmas (saffron) are most commonly used as spice, coloring, and flavoring agent in the preparation of various foods. The effect of saffron on the cell mediated immune system was evaluated by using different experimental animal models such as carbon clearance test; cyclophosphamide induced neutropenia, neutrophil adhesion test, whereas humoral mediated immunity was analysed by its effect on serum immunoglobulins, mice lethality test, and indirect hemagglutination test. Saffron was orally administered as suspension at doses of 50 and 100 mg/kg; Ocimum sanctum L. extract (100 mg/kg p.o) was used as a reference drug. Saffron significantly increased the level of serum immunoglobulins and circulating antibody titre, prevented the mortality in mice when challenged with lethal Pasteurella multocida toxin suggesting an increase in overall humoral mediated immunity. Also, there was a significant increase in the neutrophil adhesion to nylon fibers. Saffron was not effective in preventing cyclophosphamide-induced neutropenia. However in carbon clearance test, only the low dose was effective in producing a significant increase in the phagocytic index with the high dose failing to do so. The results from the present investigation indicate that C. sativus at low doses posses humoral and cell mediated immunity, thus substantiating its traditional claim as a potential immunostimulant and as an anticancer agent.