Potato Disc Assay Research Articles

Determination of the Anti-bacterial potency of Allium sativum (Garlic) extract against Agrobacterium tumefaciens causing Crown Gall Disease

The isolated crown galls (a bacterial plant disease) from Pongamia pinnata leaf were investigated to identify the causative agent. The SEM analysis revealed that the causative agent in crown gall appeared to be a slender, pink and rod-shaped bacterium. The morphological, cultural, biochemical and tumorogenesis analyses were performed to identify causative organisms in the crown gall disease. The isolate was negative for Indole, MR and VP tests, but positive for Citrate, TSI, Urease, Catalase and Oxidase tests. The causative organism also developed a tumor-like sport during the potato disc assay after 3rd week of incubation. The causative agent in crown gall was identified as Agrobacterium tumefaciens. The ethanolic extract of Allium sativum produced an inhibitory zone of 15 mm against this isolate. The current study proved that ethanolic extract of garlic can be effectively used to treat crown gall disease in the economically valuable dicot plant of Pongamia pinnata.

Anticancer L-Asparaginase and Phytoactive Compounds From Plant Solanum nigrum Against MDR (Methicillindrug resistant) Staphylococcus aureus and Fungal Isolates.

L-asparaginase is used in chemotherapy for acute lymphoblastic leukemia and other cancers. L-asparaginase derived from bacterial source triggers immune responses. The current study investigates Solanum nigrum as a novel and latent source of L-asparaginase to minimize immunological reactions. The antitumor activity of SN methanol extract was determined using the potato disc assay. InterPro Chimera and InterPro were used to predict the amino acid sequence of L-asparaginase and its anticancer activity. Purification of the enzyme was carried out to homogeneity of 1.51-fold with a recovery of 61.99%. At optimal conditions of 36.5°C, pH 8.6, and 8.5 g/mL substrate, fruit (crude extract) revealed an L-asparaginase titer of 48.23 U/mL. The molecular weight of the enzyme was calculated to be 32 ± 5 kDa using SDS PAGE. The fruit’s total flavonoids and phenolic contents are 0.42 ± .030 g/mL and 94 ± 1.9 mg CAE, respectively. Anti-tumorigenic efficacy was determined to be 66% against Agrobacterium tumefaciens. Additionally, the extract possesses potent antifungal and antibacterial properties. Molecular docking provided the structural motifs and underlying interactions between L-asparaginase, N-acetylglucosamine, murine, and chitin. SN contains high levels of the enzyme L-asparaginase and phytochemicals, making it a potential source of anticancer drugs.

Phytochemical investigation and effective therapeutic potential of plants extracts against breast and ovarian cancer cell lines: compounds from zizyphus mauritiana and triticum aestivum.

ancer is the leading cause of death, accounting for approximately one out of six people dying with this disease worldwide. Among all, the breast and ovarian cancers are top-ranked causes of women mortalities compared to other disorders. Although, there is advancement in technologies, but still, there are unresolved concerns to overcome the global disease burden. Currently, plants are being explored as a natural remedy to cure disorders. This research was planned to explore phytochemicals in methanolic extracts of Zizyphus mauritiana and Triticum aestivum, and their pharmacological activities were studied through Agrobacterium tumefaciens bacteria, in vitro breast cancer cell line and ovarian cancer cell line to find out novel candidates in disease control and prevention. Eleven different types of bioactive compounds were analysed in the tested extracts. The highest crude extracts percentage (75±0.02) was observed with Z. mauritiana. The extracts showed promising cell growth inhibition and tumor initiation inhibition in potato disc assay. MTT assay and Incucytes imaging analysis revealed that Z. mauritiana extract had a higher anticancer potential with 40 ± 0.92 cell viability against breast cancer cells (SKBR3) and 45 ±0.29 against ovarian cancer cells (SKOV3). In conclusion, these extracts could be used as chemotherapeutics owing to their cheapness, and easy availability. While detailed study is required for further purification and characterization of bioactives/target compounds and in-vivo activity confirmations.

In-Vitro Studies on Antitumour and Antimicrobial Activities of Methanolic Kernel Extract of Mangifera Indica L. Cultivar Banganapalli

Mangifera indica L. belongs to the family Anacardiaceae and is considered as “King of all Fruits”. Mango kernels are discarded as waste after the industrial processing and it has several proven medicinal benefits. Attempts were made to study its antitumour and antimicrobial activities. In the current research work, 15 local cultivars of Mangifera indica L. were collected with a motto to screen the best cultivar having high total phenolic content, flavonoid content, antitumour property and antimicrobial activity. Banganapalli cultivar of mango showed high total phenolic content and total flavonoid content i.e. 63.5±1.1 mg GAE/g and 16.7±0.5 mg quercetin/g followed by Royal special cultivar (TPC-58.7±0.6 mg GAE/g TFC-16.2±0.6 mg quercetin/g). Mangifera indica L. cultivar Banganapalli which showed highest total phenolic content and total flavonoid content was screened for its antitumour and antimicrobial properties. Antitumour property was tested by using potato disc assay which recorded 40.12% tumour inhibition percentage. Antimicrobial activity was assessed by agar diffusion method by taking 3 test microorganisms viz. Bacillus subtilis subsp. subtilis DSM 10, Staphylococcus aureus MTCC 737 and Escherichia coli MTCC 46. The measured area of inhibition is around Staphylococcus aureus MTCC 737 in 8.5±0.3 mm followed by E.coli MTCC 46 (8.2±0.3 mm) and Bacillus subtilis sub subtilis (6.6±0.5 mm). The present study showed that the mango kernels which were generally discarded as waste has antitumour and antibacterial properties and further studies need to be carried out.

Chemical composition, antioxidant, antitumor, anticancer and cytotoxic effects of Psidium guajava leaf extracts

Context Psidium guajava L. (Myrtaceae) leaves are used in traditional medicines for the treatment of cancer, inflammation and other ailments.Objective The current study explores scientific validation for this traditional medication.Materials and methods We used ferric-reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picryl hydrazil (DPPH) assays to estimate antioxidant activity of P. guajava leaf extracts (methanol, hexane and chloroform). Antitumour and in vivo cytotoxic activities were determined using potato disc assay (PDA) and brine shrimp lethality assay, respectively. Three human carcinoma cell lines (KBM5, SCC4 and U266) were incubated with different doses (10–100 μg/mL) of extracts and the anticancer activity was estimated by MTT assay. NF-κB suppressing activity was determined using electrophoretic mobility shift assay (EMSA). Chemical composition of the three extracts was identified by GC-MS. Total phenolic and flavonoid contents were measured by colorimetric assays.Results and discussions The order of antioxidant activity of three extracts was methanol > chloroform > hexane. The IC50 values ranged from 22.73 to 51.65 μg/mL for KBM5; 22.82 to 70.25 μg/mL for SCC4 and 20.97 to 89.55 μg/mL for U266 cells. The hexane extract exhibited potent antitumour (IC50 value = 65.02 μg/mL) and cytotoxic (LC50 value = 32.18 μg/mL) activities. This extract also completely inhibited the TNF-α induced NF-κB activation in KBM5 cells. GC-MS results showed that pyrogallol, palmitic acid and vitamin E were the major components of methanol, chloroform and hexane extracts. We observed significant (p < 0.05) difference in total phenolic and flavonoid contents of different solvent extracts.Conclusion The present study demonstrates that P. guajava leaf extracts play a substantial role against cancer and down-modulate inflammatory nuclear factor kB.

Evaluation of phytochemical content, antimicrobial, cytotoxic and antitumor activities of extract from Rumex hastatus D. Don roots.

BackgroundBeing a part of Chinese as well as ayurdic herbal system, roots of Rumex hastatus D. Don (RH) is highly medicinal, used to regulated blood pressure. It is also reported that the plant is diuretic, laxative, tonic, used against microbial skin diseases, bilious complaints and jaundice. The present study is conducted to evaluate phytochemical, antimicrobial, antitumor and cytotoxic activities of extract obtained from R. hastatus roots.MethodsRH roots were powdered and extracted with methanol to get crude extract. Crude extract was further fractioned on the basis of increasing polarity, with n-hexane (HRR), chloroform (CRR), ethyl acetate (ERR), n-butanol (BRR) and residual aqueous fraction (ARR). Methanol extract and its derived fractions were subjected to phytochemical screening and assayed for antibacterial activities via agar well diffusion method. Antifungal activities were checked through agar tube dilution method whereas potato disc assay was employed for the determination of antitumor activity. On the other hand cytotoxic activities were conducted using brine shrimps procedures.ResultsThe results obtained from phytochemical analysis indicate the presence of alkaloids, anthraquinones, flavonoids and saponins in all the fractions. Most of the plant fractions showed substantial antimicrobial activities, which is in accordance with the spacious use of tested plant samples in primary healthcare center. Fractions of R. hastatus roots for cytotoxicity were tested as an effective cytotoxic was found as BRR > MRR > CRR > ARR > ERR > HRR. Ranking order of fractions of R. hastatus roots for effective antitumor screening was found as MRR > BRR > ARR > CRR > ERR > HRR.ConclusionsThese results showed that R. hastatus appeared as an important source for the discovery of new antimicrobial drugs and antitumor agents; verify its traditional uses and its exploitation as therapeutic agent.

Chemical composition and in vitro antioxidant and antitumor activities of Eucalyptus camaldulensis Dehn. leaves

Euclayptus camaldulensis leaves have been widely used in folk medicines for treatment of various ailments. In current study an effort was made to explore chemical composition and biological (in vitro antioxidant and antitumor) potentials of three different solvent (methanol, chloroform and hexane) extracts of E. camaldulensis leaves. For this purpose, different solvent extracts of E. camaldulensis leaves were characterized by GC–MS and polyphenolic (phenolic acids and flavonoids) compounds in them were quantified by HPLC. Total phenolic and total flavonoid contents of each extract were explored by colorimetric assays. Antioxidant activity and total antioxidant contents of different extracts were determined by free radical (DPPH) scavenging and ferric reducing antioxidant power (FRAP) assays, respectively. Potato disc assay was used to estimate antitumor potential of each extract. GC/MS analysis led to identification of eucalyptol as major constituent of methanol (31.86%) and chloroform (45.94%) extracts. Palmitic acid (31.06%) was the dominating component of hexane extract. Different phenolic acids (gallic acid, p-hydroxybenzoic acid, syringic acid and vanillic acid) and flavonoids (catechin and quercetin) were highly abundant in methanol extract. The hierarchy of antioxidant activity for three extracts was: methanol (IC50=89.11μg/mL)>chloroform (IC50=154.8μg/mL)>hexane (IC50=532.9μg/mL). Similar order of extracts was observed for antitumor and colorimetric assays. Hexane extract of E. camaldulensis exhibited the maximum amount of total antioxidant contents (34.81±0.67mgGAE/g of plant extract). These results demonstrate E. camaldulensis leaf extracts as potential source of bioactive compounds and exhibit remarkable antioxidant and antitumor activities.

Comparative antitumor and anti-proliferative activities of Hippophae rhamnoides L. leaves extracts

Objective: To evaluate the antitumor and anti-proliferative activities of methanol, aqueous, acetone, ethyl acetate, ethanol, chloroform and n-hexane extracts of Hippophae rhamnoides leaves. Methods: Antitumor activities were evaluated by using the antitumor potato disc assay by using inoculums (Agrobacterium tumefaciens) with three different concentrations of test samples (10, 100 and 1 000 mg/L). Anti-proliferative activity was evaluated by the given method of methyl thiazolyl tetrazolium assay. The concentrations of the extract ranging from 0.039 to 10 mg/mL were tested against HeLa cells. Results: Highest tumors inhibition activity (60.9% and 55.8%) was shown by methanol and ethanol extracts, with EC50 values of 424.41 and 434.61 mg/L respectively. At 10 mg/mL, The highest cell inhibition 75.61% was observed in methanol extract and the lowest 36.59% were calculated in n-hexane extract. The difference in tumor and cell inhibition (%) may be due to the different concentration of active compounds responsible for antitumor and anti-proliferative activities. All extracts have considerable level of tumor and cell inhibitiory effect in a dose dependent manner. Conclusions: Our finding showed that Hippophae rhamnoides leaves are a potent natural source of antitumor and antiproliferative agent.

Antioxidant, antimicrobial, antitumor, and cytotoxic activities of an important medicinal plant (Euphorbia royleana) from Pakistan

The aim of present study was to evaluate antioxidant, antimicrobial, and antitumor activities of methanol, hexane, and aqueous extracts of fresh Euphorbia royleana. Total phenolic and flavonoid contents were estimated as gallic acid and querectin equivalents, respectively. Antioxidant activity was assessed by scavenging of free 2,2′- diphenyl-1-picrylhydrazyl radicals and reduction of ferric ions, and it was observed that inhibition values increase linearly with increase in concentration of extract. The results of ferric reducing antioxidant power assay showed that hexane extract has maximum ferric reducing power (12.70 ± 0.49 mg gallic acid equivalents/g of plant extract). Maximum phenolic (47.47 ± 0.71 μg gallic acid equivalents/mg of plant extract) and flavonoid (63.68 ± 0.43 μg querectin equivalents/mg of plant extract) contents were also found in the hexane extract. Furthermore, we examined antimicrobial activity of the three extracts (methanol, hexane, aqueous) against a panel of microorganisms (Escherichia coli, Bacillus subtillis, Pasteurella multocida, Aspergillus niger, and Fusarium solani) by disc-diffusion assay, and found the hexane extract to be the best antimicrobial agent. Hexane extract was also observed as to be most effective in a potato disc assay. As hexane extract showed potent activity in all the investigated assays, it was targeted for cytotoxic assessment. Maximum cytotoxicity (61.66%) by hexane extract was found at 800 μg/mL. It is concluded that investigated extracts have potential for isolation of antioxidant and antimicrobial compounds for the pharmaceutical industry.

English

In this study, four plants [Chrozophora hierosolymitana Spreng (Euphorbiaceae), Ephedra gerardiana Wall. ex Stapf (Ephedraceae), Chrysanthemum leucanthemum L. (Astraceae),and Quercus dilatata L. (Fegaceae)] collected from different regions of Pakistan were screened to identify any chemotherapeutic agents present in them. Seven methanol extracts of these plants (leaf, stem, and root extracts of C. hierosolymitana; stem and root extracts of E. gerardiana; aerial parts of C. leucanthemum, and aerial parts of Q. dilatata) were examined for cytotoxicity using brine shrimp assay, antitumor activity using potato disc assay, and phytotoxicity activity using radish seed bioassay. Two methanol plant extracts, that is, leaf extract of C. hierosolymitana and root extract of E. gerardiana showed significant brine shrimp cytotoxicity activity ranging from 171.55 to 523.8 ppm. Six of the seven extracts exhibited tumor inhibition at all the three concentrations tested, ranging from 10 to 80%. All extracts showed growth and seed germination inhibition at high concentration against radish seeds, while two extracts (root extract of C. hierosolymitana and aerial parts of Q. dilatata) showed growth stimulating effects at lower concentrations. Phytochemical tests showed the presence of alkaloids, saponins, anthraquinones, terpenoids, flavonoids, flavones, tannins, phlobatannins, and cardiac glycosides in different concentrations in these extracts. Key words: Antitumor, cytotoxicity, plant extracts, plant growth regulatory factors, phytochemical constituents.

Potential antitumor activity of two Polygonum species

Two Bangladeshi Polygonum species, P. barbatum (L.) Hara var. barbata (common name ?bekhanjabaj?) and P. stagninum Buch.-Ham. ex Meissn. (common name ?ratooti sag? or ?bara bishkatali?), are perennial herbs of the family Polygonaceae. The genus Polygonum L. is well-known for its use in oriental traditional medicine systems for the treatment of various ailments including fever, pain, inflammation, infections, cancer and tumors. The extracts of P. barbatum var. barbata and P. stagninum were assessed for potential antitumor properties using the potato disc assay. All extracts showed a considerable level of potential antitumor activity. The petroleum ether extract of P. barbatum var. barbata and the n-hexane and ethyl acetate extracts of P. stagninum, having IC50 values of 290, 200 and 180 ?g/disc, respectively, were the most active among the extracts. The methanol extracts of both plants were the least active and had an IC50 value of &gt;400 ?g/disc. Overall, the extracts of P. stagninum showed better antitumor activity potential than the extracts of P. barbatum var. barbata.

Structure elucidation and inhibitory effects of self-assembled organotin(IV) esters of p-tolyl acetic acid on bacterial, fungal, brine shrimp, and potato tumor cells

Biologically active new organotin(IV) acetates (1–6) of p-tolyl acetic acid have been synthesized and characterized by multinuclear nuclear magnetic resonance (1H, 13C) and mass spectrometry. The X-ray crystallographic data of compounds (3 and 4) were also collected. These studies show that in diorganotin(IV) compounds (compounds 1, 2, 3, and 6), tin exists in skew trapezoidal geometry with four strong and two weaker bonds, whereas triorganotin(IV) carboxylates (compounds 4 and 5) have four and five coordinated geometries in solution and solid form, respectively. These compounds were screened for a range of biological activities. Antibacterial activities were determined against six pathogenic bacterial strains, three Gram-positive and three Gram-negative; the activities were measured in terms of inhibition zones (mm). Antifungal activities were determined against six pathogenic fungal strains, cytotoxicity by the brine shrimp lethality assay, and antitumor activities by the crown gall tumor inhibition (potato disc) assay.

HEALTH BENEFITS OF SOME VIABLE AND NONVIABLE MICROORGANISMS

In Vitro Cholesterol reducing ability, β- galactosidase, antioxidant, antitumor and antibacterial activity of L. acidophilus La-5,L. casei - 01, L. helveticus Lh. B 02, B. bifidum Bb-12, K. lactis NRRL Y- 8279 and Sacch. cerevisiae DSMZ 70 449 were investigated.Results obtained showed that all strains were able to reduce cholesterol and had β- galactosidase activity especially yeast strains and the viable form (free and microencapsulated) of all microbial stains had higher cholesterol reducing ability and β- galactosidase activity than nonviable form.Howeverthe nonviable form of all tested microorganisms had the highest antioxidant power compared with the others. The yeast strains had higher antioxidant activity than bacterial strains in the different forms. All strains in different forms exhibited antitumor activity by using potato disc assay. Antibacterial activity was observed in lactobacilli and Bifidobacterium strains against spoilage and pathogenic bacteria.

Di‐ and Triorganotin(IV) Esters of 3,4‐Methylenedioxyphenylpropenoic Acid: Synthesis, Spectroscopic Characterization and Biological Screening for Antimicrobial, Cytotoxic and Antitumor Activities

Nine biologically significant organotin(IV) esters of 3,4-Methylenedioxyphenylpropenoic acid (L) were synthesized with the general formulae [R2SnL2], where R includes Me(1), Et(3), But(4), Oct(5), Ph(8), and [R3SnL], in which R is Me(2), Cy(6), Ph(7), and But(9). The acid and its compounds were characterized by basic analytical techniques comprising elemental analysis, FTIR and mass spectrometry in solid state and by Multinuclear (1H, 13C and 119Sn) NMR in solution form, which provides some important information about the different coordination behaviors of metal in both solid and solution. Methylenedioxy moiety in these compounds enhances the biological activity of these compounds. These compounds were screened for a range of biological activities. Antibacterial activities were determined against six pathogenic bacterial strains, three gram-positive and three gram-negative, the activities were measured in terms of inhibition zones (mm). Results demonstrate that diorganotin derivatives are more active than triorganotin derivatives and ligand acid. Antifungal activity was determined against six pathogenic fungal strains, cytotoxicity by the brine shrimp lethality assay, and antitumor activity by crown gall tumor inhibition (potato disc) assay. Results for antifungal activity, cytotoxicity, and antitumor activity of these compounds demonstrate that triorganotin derivatives are more active than diorganotin derivatives and ligand. Finally, the results were compared with similar reports in the literature.

Synthesis, Chemical Characterization and Biological Screening for Cytotoxicity and Antitumor Activity of Organotin (IV) Derivatives of 3,4-Methylenedioxy 6-nitrophenylpropenoic Acid

A series of mono-, di- and triorganotin compounds with general formulae [RSnL(2)Cl], R = Bu (compound 3), [R(2)SnL(2)], where R = Me, Et, Bu, Oct (compounds 1, 2, 4 and 6) and [R(3)SnL], where R = Bu, Cy and Ph (compounds 5, 7 and 8) and where L = 3,4-methylenedioxy-6-nitrophenylpropenoic acid have been prepared and characterized by elemental analysis, multinuclear ((1)H-, (13)C- and (119)Sn-) NMR and mass spectrometry. The ligand and its respective organotin complexes were screened for cytotoxicity using the brine shrimp lethality assay and for antitumor activity using the crown gall tumor inhibition (potato disc) assay. The bioassay results support the conclusion that the biological activities of these synthetic compounds are in the following order: [RSnL(2)Cl] < [R(2)SnL(2)] < [R(3)SnL].

Combinatorial Synthesis, Lead Identification, and Antitumor Study of a Chalcone‐Based Positional‐Scanning Library

A 175-member chalcone library was designed and synthesized from seven differently substituted acetophenones (A(1)-A(7)) and 25 differently substituted aryl or heteroaryl aldehydes (B(1)-B(25)). Potential lead compounds were identified by deconvolution of a two-dimensional library matrix via positional scanning, and the members of the most-active sub-libraries were synthesized and screened against crown-gall tumors with the aid of the potato-disc assay. The resulting hits gave rise to significant antitumor activities, with no antibacterial effect on the tumor-producing bacterium Agrobacterium tumefaciens. Two identified lead structures, (2E)-3-(2-chlorophenyl)-1-phenylprop-2-en-1-one (A(1)B(9)) and the hydroxy analogue (2E)-3-(2-chlorophenyl)-1-(2-hydroxyphenyl)prop-2-en-1-one (A(2)B(9)), are promising candidates to be developed into highly effective anticancer chemotherapeutics.

Screening of Nine Echinacea Supplements for Antitumor Activity Using the Potato Disc Bioassay

ABSTRACT To study the efficacy of commercially available Echinacea supplements, solvent fractions from nine locally purchased supplements containing Echinacea were tested in a potato disc assay for their ability to suppress formation of crown-gall tumors, a process that resembles tumor formation in animal tissues. Acetone and ethanol fractions from two supplements inhibited tumor formation and water and ethanol fractions from a third supplement suppressed tumor formation. Comparison of the bio-assay results with the supplement ingredients, as listed on the supplement label, did not reveal any correlation between quantity and suppressive activity of the listed ingredients. These results are consistent with prior investigations that noted product labels were often inaccurate and that post-harvest handling practices can be deleterious to bioactive compounds contained in Echinacea.

Biological Evaluation of Some Selected Plant Species of Pakistan

Seven methanol extracts from five different plant species [Salvia nubicola. B. (Laminiaceae), Acer oblongifolium. D. (Aceraceae), Sorbaria tomentosa. L. (Rosaceae), Hedera nepalensis. K. (Araliaceae), and Artemisia fragrans. W. (Asteraceae)] were evaluated for brine shrimp cytotoxicity, antitumor potato disc, and radish seed phytotoxicity activity. Four of the seven extracts revealed significant ED50 value ranging from 11.9 to 226.8 ppm. Inhibition of tumor formation ranged from 9 to 82.9% by all extracts in antitumor potato disc assay at three different concentrations tested (1000, 100, and 10 ppm). Growth inhibition was observed by all extracts in radish seed bioassay at high concentration (10,000 ppm). At low concentration (1000 ppm), three extracts from two plant species (leaf and flower extract of S. nubicola., stem extract of S. nubicola., and stem extract of H. nepalensis.) presented stimulation of growth ranging from 3.5 to 43.2%. A positive correlation was observed in the results of three of the described assays.

Cytotoxic and Antitumor Activities of Ethanolic Extracts of Salt Marsh Plants from the Lower Saxonian Wadden Sea, Southern North Sea

Twenty-eight plant species belonging to fifteen families were subjected to a screening for cytotoxic and antitumor activities with three test organisms in six bioassays. Freshly hatched larvae and four week old adults of Artemia salina LEACH are used for the detection of acute toxic activity after 6 h and chronic toxicity after 24 h. Adult Daphnia magna STRAUS were used to establish toxic activities of the extract after 48 h. Finally the potato disc assay with Agrobacterium tumefaciens was used to detect antitumor compounds. Of the screened plants, Limonium vulgare MILL., Artemisia maritima L. and Salicornia europaea L. showed significant cytotoxic activity against Artemia salina LEACH and Daphnia magna STRAUS. Extracts of these plants also showed anti-neoplastic activities in the potato disk assay. The extracts of Ononis spinosa L., Trifolium fragiferum L. and Trifolium repens L. showed tumor growth inhibiting activities.

Bioactive Monoterpenes from Monarda fistulosa (Lamiaceae)

Bioactivity-guided fractionation of Monarda fistulosa L. (F005), using the brine shrimp lethality test (BST) and crown gall tumor potato disc assay (PD), led to the isolation of the bioactive monoterpenes, thymoquinone (1), and thymol (2). 1, surprisingly, exhibited selective cytotoxicities against certain cell lines. Of over 60 human tumor cell lines evaluated, 1 was very selective for SF-539 (CNS) with an LC50 < 2.51 × 10−2 μg/ml. Other cell lines targeted by 1 were PC-3 (prostate), M-14 (melanoma), OVCAR-5 (ovarian), and MCF-7 (breast). The reduction of 1 to thymohydroquinone (3) resulted in a 1.7 fold decrease in the cytotoxic potency for PC-3. Thymol (2), although not significantly cytotoxic, demonstrated strong pesticidal activity, more potent than rotenone, in the yellow fever mosquito larvae assay (YFM). None of the compounds, 1–3, approached the IC50 value of rotenone in inhibiting oxygen uptake in the rat liver mitochondrial bioassay, suggesting that they must have another mode of action.