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Comparative phytochemical composition, antibacterial activity, cytotoxicity and antioxidant potentiality of seven brinjal cultivars Solanum melongena L. were determined. Strong presence of carbohydrates, phenolic glycosides and weak presence of alkaloids, falvonoids, tannins, terpenoids, steroids and saponins were recorded in all the brinjal varieties. Antibacterial assay of brinjal extracts showed varying degree of sensitivity against both gram-positive and gramnegative bacteria. In cytotoxicity assay, the LC 50 values ranged between 59.91 to 216.45 mg/ml after 6 hours was an indication of poor cytotoxic potential of brinjal cultivars. The DPPH free radical scavenging activity ranged between 80.79% to 87.64 although the phenolic content was found between 6.082 to 9.292 mg GAE/g among the brinjal cultivars.

As part of the search for new sources of mental health supplements, alcohol extracts of 11 Bangladeshi medicinal fruits and plants were investigated for neuropharmacological effects in mice and on ionotropic γ-aminobutyric acid receptors (GABA A receptors). The extracts of S. caseolaris, T. bellirica, S. cumini, and T. arjuna significantly potentiated the GABA-induced response of GABA A receptors expressed in Xenopus oocytes, though the extracts alone induced no response. In mice, administration of these extracts prolonged pentobarbital-induced sleeping time. Potentiation of GABA A receptor response reportedly generates anxiolytic, sedative, sleep-inducing and anesthetic activities in the human brain. Thus, these extracts may have potential regarding the development of a supplement with tranquilizing and sleepinducing effects that is beneficial for mental health.Keywords: Bangladeshi fruit, GABA A receptor, mangrove tree, pentobarbital-induced sleeping time, tranquilizer *To whom correspondence should be addressed. E-mail: aoshima@yamaguchi-u.ac.jp IntroductionAs society ages and the amount of lifestyle-related stress increases, there is increasing demand for the development of supplements which improve physical and mental health. Therefore, it is important to find new botanical resources for use as active ingredients for supplements or drugs.Over 1000 of the estimated 5000 species of phanerogams found in Bangladesh, Southeast Asia are regarded as having useful chemical constituents (Goni, 2003). A variety of these plants have been used traditionally as astringents, antiseptics, tonics, febrifuges and fish poison as they possess active compounds such as alkaloids, polyphenols, saponins, tanic acids, resins, waxes and fragrant compounds (Goni, 2003). However, despite the consumption and use of these herbs and fruits, little scientific data clarifying their physiological activities are available. There is some information available relating to their chemical constituents (Goni, 2003;Sadhu, et al., 2006) and biological properties (Scartezzini et al., 2005;Abdille et al., 2004; Lee et al., 2005). Our laboratory has recently reported the antioxidative, antiamylase, antiglucosidase and antihistamine release activities of some Bangladeshi fruits (Hossain et al., 2008).Various neurotransmitter receptors are involved in defining mental state, particularly the ionotropic γ-aminobutyric acid receptors (GABA A receptors), which are the main inhibitory neurotransmitter receptors in the human brain (Hossain et al., 2007). These heteropentamers composed of various α, β, γ, δ and ε subunits were found to be expressed in Xenopus laevis oocytes (Trauner et al., 2008). The potentiation of the response of these receptors by drugs such as benzodiazepine, pentobarbital and anesthetics induces tranquilizing, sleepinducing or anesthetic responses in humans (Nicholls, 1994;Chebib & Johnston, 2000;Harrison et al., 2000). It was found that fragrant compounds such as terpinen-4-ol, 1-octen-3-ol, and linalool potentiated the response of GAB...

The distribution and abundance of Azotobacter as well as heterotrophic bacteria in root, rhizosphere soil and non-rhizosphere soil samples from various wheat fields of four different areas under three districts were investigated in this study. The potential for nitrogen-fixation of five Azotobacter isolates was also detected. All samples tested were positive in their capacity to harbouring Azotobacter with a range of 26-100%. The population of heterotrophic bacteria ranged from 2.1 x 107 to 1.2 x 108 cfu/g sample. Ranges of total number of Azotobacter in different samples were 5.2 x 104 to 7.2 x 104 cfu/g, 17.2 x 104 to 25.5 x 104 cfu/g, and 12.4 x 104 to 16.7 x 104 cfu/g respectively for root, rhizosphere soil and non-rhizosphere soil. A positive correlation was found in Azotobacter colonization between root and rhizosphere, but it was negative in case of the population between heterotrophic bacteria and Azotobacter in rhizosphere. The highest amount of N was found to be fixed by the isolate M1 and the lowest by the isolate M4 and it was respectively 9.26 and 5.45 mg N/g substrate. In terms of the capacity to fix nitrogen in laboratory condition the five isolates of Azotobacter could be arranged as M1> M3 > M5 > M4 > M2. Keywords: Azotobacter, Wheat field, Nitrogen fixing potentialDOI: http://dx.doi.org/10.3329/bjm.v24i2.1262

Blumea lacera collected from JU campus and the Sundarbans showed strong presence of carbohydrates, flavonoids, trace amount of alkaloids, weak presence of some glucosides, terpenoids and steroids following preliminary phytochemical screening. DPPH free radical scavenging activity increased with the increase of concentration of methanol, ethyl acetate and n-hexane fractions of both the samples. Methanol and ethyl acetate fractions of JU sample showed strong scavenging activity of DPPH free radical. Concentration dependent increment in percent mortality of brine shrimp nauplii was observed in all the fractions of both the samples. Ethyl acetate and methanol fractions of JU sample showed less cytotoxicity than that of Sundarbans samples. Therefore, methanol and ethyl acetate fractions of JU sample should be the choice to identify new bioactive compound(s) in the future.