Lawrence A. D. Williams

A critical review of the therapeutic potential of dibenzyl trisulphide isolated from Petiveria alliacea L (guinea hen weed, anamu)

The data compiled in the present review on dibenzyl trisulphide (DTS) isolated from Petiveria alliacea L (the guinea hen weed or anamu) revealed that the compound and its derivatives could be of tremendous pharmaceutical interest. The mode of action elucidated for DTS revealed that it is a mitogen activated protein extracellular regulated kinases 1 and 2 (MAPKinases erk1 and erk 2) signal transduction molecule. Dibenzyl trisulphide caused hyper-phosphorylation of growth factor induced MAPKinases (erk 1 and erk 2) phosphorylation, a process critical for the improvement of long term memory, and is implicated in neuronal growth. Dibenzyl trisulphide and its derivatives exhibited potent anti-proliferation/cytotoxic activity on a wide range of cancer cell lines. The cytotoxic activity of DTS was increased by 70-1000 fold when bound to albumin in vitro. Dibenzyl trisulphide seems to have a cytokine switching mechanism in which it down regulates cytokines from the Type I helper cells (Th -1 cell) pathway which contained several pro-inflammatory cytokines and up-regulates those on the Type 2 helper cells (Th-2) pathway. The trisulphide up-regulates some reticuloendothelial system parameters eg granulocyte counts and increased thymic and Peyers patches masses via cell proliferation processes which are known to be regulated via the MAPKinase signal transduction pathway. When the zygotes ofAsternia pectinifera (Starfish) were exposed to DTS at concentration of 10 mM, a dose lethal to all cancer cells tested, it was observed that the sensitive process of protein biosynthesis was not affected Similarly, the proliferation of the HOFA human fibroblast, a noncancerous cell line, was not severely affected by DTS at 8.9 microM over seven days, a concentration also lethal to most cancer cell lines tested The implications of the findings will be highlighted in the present review.

Acaricidal and insecticidal activities of cadina-4,10 (15)-dien-3-one

The novel assignment of 13C and 1H NMR data for cadina-4,10(15)-dien-3-one obtained from Hyptis verticillata is presented. The study revealed that cadina-4,10(15)-dien-3-one possesses chemosterilant activities against the economically important cattle tick, Boophilus microplus, and toxic action against adult Cylas formicarius the most destructive pest of sweet potato (I pomoea sp.).

Biotransformation of cadinane sesquiterpenes by Beauveria bassiana ATCC 7159

Incubation of cadina-4,10(15)-dien-3-one with Beauveria bassiana ATCC 7159 has resulted in the production of nine novel sesquiterpenes. These metabolites were identified as (4S)-cadin-10(15)-en-3-one, (4S)-3 alpha-hydroxycadin-10(15)-ene, (4R)-3 alpha-hydroxycadin-10(15)-ene, (4S)-3 beta-hydroxycadin-10(15)-ene, (4S)-3 beta-hydroxycadina-10(15),12(14)-diene, (4S)-13-hydroxycadin-10(15)-en-3-one, (4S)-12-hydroxycadin-10(15)-en-3-one, (4R)-3 beta, 14-dihydroxycadin-10(15)-ene and 3 alpha-hydroxycadina-4,10(15)-diene. The allylic alcohol 3 alpha-hydroxycadina-4,10(15)-diene was also biotransformed to afford cadina-4,10(15)-dien-3-one, (4S)-cadin-10(15)-en-3-one and (4S)-12-hydroxycadin-10(15)-en-3-one. The insecticidal potential and phytotoxicity of the isolated metabolites have been evaluated.

Adverse effects of extracts of Artocarpus altilis Park, and Azadirachta indica (A. Juss) on the reproductive physiology of the adult female tick, Boophilus microplus (Canest.)

Summary Adverse effects of extracts from the plants Artocarpus altilis and Azadirachta indica on egg laying and hatching in the tick Boophilus microplus were quantified. A 50% inhibition of egg laying was achieved by a dose of 0.54 and 0.46 μg crude ethanol extract per tick, respectively. These doses also caused a 65% and 80% hatching failure, respectively. Extracts, particularly those of A. indica, inhibit protein and lipid sequestration by ovaries and oocytes. GC-MS analyses revealed reductions in the quantities of four methyl esters sequestered from the ovaries into the oocytes oviposited on the 12th day of engorgement by the treated ticks in the order of (A. indica effects are in parentheses): undecanoic acid 10-methyl-,methyl ester 40% (100%); tetradecanoic acid, methyl ester 100% (100%); tetradecanoic acid, 12-methyl-,methyl ester 100% (100%) and pentadecanoic acid, 14-methyl-,methyl ester 30% (75%).

The insecticidal and acaricidal actions of compounds fromAzadirachta indica (A. Juss.) and their use in tropical pest management

The pest control potential demonstrated by various extracts and compounds isolated from the kernels and leaves of the neem plant (Azadirachta indica) A. Juss. (Meliaceae) seem to be of tremendous importance for agriculture in developing countries. Laboratory and field trial data have revealed that neem extracts are toxic to over 400 species of insect pests some of which have developed resistance to conventional pesticides, e.g. sweet potato whitefly (Bemisia tabaci Genn. Diptera: Aleyrodidae), the diamond back moth (Plutella xylostella L. Lepidoptera: Plutellidae) and cattle ticks (Amblyomma cajennense F. Acarina: Ixodidae andBoophilus microplus Canestrini. Acarina: Ixodidae). The compounds isolated from the neem plant manifest their effects on the test organisms in many ways, e.g. as antifeedants, growth regulators, repellents, toxicants and chemosterilants. This review strives to assess critically the pest control potential of neem extracts and compounds for their use in the tropics. This assessment is based on the information available on the wide range of pests against which neem extracts and compounds have proven to be toxic, toxicity to non-target organisms, e.g. parasitoids, pollinators, mammals and fish, formulations, stability and phytotoxicity.

An Insecticidal and Acaricidal Polysulfide Metabolite from the Roots of Petiveria alliacea

The present study reports on the insecticidal and acaricidal potentials of dibenzyltrisulfide (DBTS) isolated from the roots of Petiveria alliacea L. using thin layer and high performance liquid chromatography. The 96-h LD50 value (μg per tick) obtained for adult Boophilus microplus (Canestrini) topically treated with DBTS was 0·920. The LD50 values obtained for three commercial acaricides dimethoate, lindane and carbaryl were 4·6, 9·3 and 6·9 μg per tick respectively. The IOD50 and IHD50 (concentrations inhibiting egg laying and hatching by 50% respectively) in μg per tick doses for DBTS were 0·22 and 0·24 respectively. The 24-h LD50 dose (μg per insect) obtained for DBTS on adult Cylas formicarius elegantulus (Summer) was 0·193 μg per insect. The vapour from a stock solution of 5 g litre-1 of DBTS was highly toxic to adult Hypothenemus hampei Ferr. inside coffee berries, inflicting 89% mortality within 24 h.

Rhizophora mangle (Rhizophoraceae) Triterpenoids with Insecticidal Activity

Cells of human buccal epithelium were irradiated in vitro by laser light at a wavelength of 632.8 nm and and an intensity of 1 mW/cm. The irradiation induced changes in the chromatin condensation state. The effect of irradiation depends on exposure time, and cells of different donors reveal varying sensitivity to laser light. In some donors 1 s exposure induced decondensation, but 2.5 min and 5 min condensation of chromatin in all donors. He-Ne laser light is widely used in a variety of technical devices, both in everyday life and in medical treatment. The use of lasers in surgical practice has a number of advantages due to the specific nature of the effect that laser irradiation exerts on biological tissues. Low-power laser therapy is used as an effective medical agent in treating a wide range of degenerative and dystrophic diseases; it stimulates healing processes, improves the microcirculation in tissues, and leads to an anesthetic outcome (Kozlov 1997). Thus the possible benefits of applying laser light are relatively high. In this connection the biological effects of low-intensity laser light re of special interest. The main effects on cultured cells include the following: The proliferation of mammalian cells increases after irradiation; increased [H]thymidine incorporation is caused by the enhanced DNA synthesis in S-phase cells due to an increased number of S-phase cells. Irradiation increases the growth of relatively slowly proliferating subpopulations and can increase the cellular ATP level and increase or decrease the cellular AMP level (Karn 1997). As is known, the state of chromatin depends closely on its genetic activity. The content of interphase cell nucleus, chromatin, may be in a more of less condensed state: heterochromatin and euchromatin. Heterochromatic sites, called also chromocenters, consist of functionally inactivated, condensed chromatin. An increase in heterochromatinization is evidence of decreased chromatin genetic activity (Therman and Susman 1993). We therefore hypothesized that such an active external factor as laser light can induce changes in the state of chromatin in human cells. Cells of human buccal epithelium were investigated from five female donors (aged: A, 18; B, 19; C, 28; D, 53; and E, 78 years). Cells were obtained from the inner surface of donor’s cheek by light scraping with sterile spatula. This operation is absolutely bloodless and painless. Cells were suspended in 25 ml of solution containing 2.89 mM calcium chloride, and 3.03 mM phosphate buffer (pHp7.0). The cells were placed on the cover slide and irradiated by laser light of wavelength 632.8 nm and intensity 1 mW/cm for 1–300 s. 5 min after irradiation cells were stained with 2% orsein solution in 45% acetic acid (Darlington and LaCour 1976). After 1 h cells were investigated at a magnification of !700. The typical images of heterohromatin granules staining at this magnification are presented in Fig. 1. The heterochromatin granules quantity (HGQ) was estimated in interphase nuclei in 30 nuclei, and the mean HGQ value was calculated; the standard error never exceeded 5% of the measured value. The quantity of cell nuclei analyzed in each of these experiments seemed to be near optimal, because increasing the number of analyzed nuclei to 60 did not significantly decrease the standard error. The HGQ is a highly reproducible characteristic of cell nuclei. For instance, three independent experiments carried out in a single day (3 March 1999) in cells of donor D revealed the following values of HGQ: 27.4B0.5; 27.2B0.7; 26.9B0.7 (means BSE of 30 determinations). HGQ may change over time, however; for instance, the value in donor D on 28 May 1998 was 18.3B0.6.

Changes in the Contents of Oleoresin and Pungent Bioactive Principles of Jamaican Ginger (Zingiber officinale Roscoe.) during Maturation

Changes in the yields of the oleoresin and content of pungent bioactive principles: [6], [8], [10] gingerols and [6] shogaol of Jamaican ginger ( Zingiber officinale) were investigated during different stages of maturity (7-9 months). Ethanolic oleoresin extracts were prepared (95%, w/w) by cold maceration of dried ginger powder, and their percentage yields were calculated (w/w). The pungent bioactive principles in the ginger oleoresin were extracted with methanol and quantitatively analyzed by high performance liquid chromatography (HPLC). Ginger harvested at 8 months from Bourbon, Portland had the highest oleoresin yield (8.46 +/- 0.46%). [6] Gingerol was found to be the most abundant pungent bioactive principle in all the oleoresin samples investigated, with the 9 months sample from Bourbon, Portland containing the highest level (28.94 +/- 0.39%). The content of [6] gingerols was also found to be consistently high (7-9 months) in oleoresin samples from Johnson Mountain, St. Thomas (15.12 +/- 0.39 to 16.02 +/- 0.95%). The results suggest that Bourbon in Portland may be the most ideal location for cultivating ginger for high yields and quality, however, Johnson Mountain in St. Thomas could prove to be the least restrictive location, allowing for harvesting of good quality material throughout the maturity period (7-9 months).

Extraction, Processing, and Storage Effects on Curcuminoids and Oleoresin Yields from Curcuma longa L. Grown in Jamaica

Aromatic diarylheptanoid compounds from Curcuma longa Linn grown in Jamaica were quantified by UV-vis spectrophotometry and high-performance liquid chromatographic (HPLC) analyses. The oleoresin yields from ethanolic extracts were quantified and evaluated with regard to the effects of the type of postharvesting process and the type of extraction method conducted on the plant material. Fresh samples that were hot solvent extracted provided the highest oleoresin yields of 15.7% +/- 0.4 ( n = 3), and the lowest oleoresin yields of 7.8% +/- 0.2 ( n = 3) were from the dried milled samples that were cold solvent extracted. Data from the ASTA spectrophotometer assay confirmed that dried samples contained the highest curcuminoid content of 55.5% +/- 2.2 ( n = 6) at the fifth month of storage, and the fresh samples showed a curcuminoid content of 47.1% +/- 6.4 ( n = 6) at the third month of storage. A modified HPLC analysis was used to quantify curcumin content. Data from the HPLC analysis confirmed that the dried treated, hot extracted, room temperature stored samples had the highest curcumin content of 24.3%. A novel high-performance thin layer chromatography (HPTLC) method provided a chemical fingerprint of the C. longa with the use of a commercial curcumin standard.

An insecticidal diterpene from Croton linearis

Abstract A novel insecticidal diterpene was isolated from Croton linearis and its structure determined by spectroscopic methods. Its 72 hr LD50 on Cylas formicarius elegantulus (summer) was 0.32 μg insect −1 .