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ContextIxora megalophyllaChamch. (Rubiaceae) is a new plant species recently found in southern Thailand. Ethyl acetate extracts of its leaves and stems showed antimicrobial activities. ObjectivesTo isolate and identify the antimicrobial compounds fromI. megalophyllaleaves and stems. Materials and methodsThe dried leaves (1.7 kg) and stems (3.5 kg) were consecutively extracted with petroleum ether (5 L × 4), ethyl acetate (5 L × 3) and ethanol (5 L × 4) under reflux conditions. The ethyl acetate extract was subjected to an antimicrobial assay guided isolation withCandida albicansandStreptococcus mutans. Compounds1–10were identified by1H NMR,13C NMR and EI-MS. Minimal lethal concentration (MLC) againstC. albicansandStreptococcusspp. was determined using a broth microdilution method for 48 and 24 h, respectively. Results and discussionOn the basis of the antimicrobial assay guided isolation, 10 known compounds, including vanillic acid (1), syringic acid (2), 4-hydroxy benzaldehyde (3), scopoletin (4), loliolide (5), syringaldehyde (6), sinapaldehyde (7), coniferaldehyde (8), syringaresinol (9) and 2,2′-dithiodipyridine (10), were identified. Compounds1–5were purified from the ethyl acetate extract of the leaves, while6–9and10were from the ethyl acetate and ethanol extracts of the stems, respectively. Among these isolates,10showed the strongest antibacterial activities againstS. mutansandStreptococcus mitis, with minimum inhibitory concentrations (MICs) of 2–4 μg/mL, and MLC of 4 μg/mL, as well as having a weak antifungal activity againstC. albicans(MIC of 125 μg/mL). This is the first report of the antimicrobial activities of10. [ABSTRACT FROM PUBLISHER]

Context: Medicinal plants involved in traditional Thai longevity formulations are potential sources of antimicrobial compounds. Objective: To evaluate the antimicrobial activities of some extracts from medicinal plants used in traditional Thai longevity formulations against some oral pathogens, including Streptococcus pyogenes, Streptococcus mitis, Streptococcus mutans, and Candida albicans. An extract that possessed the strongest antimicrobial activity was fractionated to isolate and identify the active compounds. Materials and methods: Methanol and ethyl acetate extracts of 25 medicinal plants used as Thai longevity formulations were evaluated for their antimicrobial activity using disc diffusion (5 mg/disc) and broth microdilution (1.2-2500 µg/mL) methods. The ethyl acetate extract of Ficus foveolata Wall. (Moraceae) stems that exhibited the strongest antibacterial activity was fractionated to isolate the active compounds by an antibacterial assay-guided isolation process. Results and discussion: The ethyl acetate extract of F. foveolata showed the strongest antibacterial activity with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of 19.5-39.0 and 39.0-156.2 µg/mL, respectively. On the basis of an antibacterial assay-guided isolation, seven antibacterial compounds, including 2,6-dimethoxy-1,4-benzoquinone ( 1), syringaldehyde ( 2), sinapaldehyde ( 3), coniferaldehyde ( 4), 3β-hydroxystigmast-5-en-7-one ( 5), umbelliferone ( 6), and scopoletin ( 7), were purified. Among these isolated compounds, 2,6-dimethoxy-1,4-benzoquinone ( 1) exhibited the strongest antibacterial activities against S. pyogenes, S. mitis, and S. mutans with MIC values of 7.8, 7.8, and 15.6 µg/mL, and MBC values of 7.8, 7.8, and 31.2 µg/mL, respectively. In addition, this is the first report of these antibacterial compounds in the stems of F. foveolata. [ABSTRACT FROM AUTHOR]

Context: Integrase (IN) is one of the three human immunodeficiency virus type 1 (HIV-1) enzymes that, together with a reverse transcriptase and protease, allow the virus to reproduce itself after infecting the host cells. Any new knowledge on inhibitors of this enzyme could provide essential clues for the development of anti-HIV drugs. Objective: To evaluate the anti-HIV-1 IN activity of some Thai medicinal plant extracts, and to isolate the active compounds from the extract that possessed the strongest anti-HIV-1 IN activity. Materials and methods: Ethanol extracts of eight Thai medicinal plants (10-100 µg/mL) were evaluated for their inhibitory effect against HIV-1 IN. An extract of Mimusops elengi L. (Sapotaceae) leaves that possessed the strongest anti-HIV-1 IN activity was fractionated to isolate the active compounds by an anti-HIV-1 IN assay-guided isolation process. Results and discussion: The leaf extract from M. elengi had the strongest anti-HIV-1 IN activity with an IC50 value of 62.1 µg/mL. A bioassay-guided isolation of the active compounds from M. elengi leaf extract resulted in the isolation of active compounds, identified as a mixture of gallocatechin and epigallocatechin. This mixture of gallocatechin and epigallocatechin showed satisfactory anti-HIV-1 IN activity with an IC50 value of 35.0 µM. A flavanol glycoside, mearnsitrin was also isolated but was inactive at a concentration of 100 µM. [ABSTRACT FROM AUTHOR]

Context: Plumbagin is a major active constituent of Plumbago indica L. (Plumbaginaceae). It possesses various pharmacological activities that have been shown to assist in the treatment of various diseases. Objectives: This work is focused on increasing the production of plumbagin in P. indica root cultures using low doses of gamma ray irradiation as an elicitor. Materials and methods: The effect of low doses of gamma ray irradiation (0, 5, 10, 15, 20, 25 Gy) and ages of the root cultures (0, 5, 10, 15, 20 days) for elicitation of plumbagin production was determined. The stability of the elicited root cultures to produce plumbagin was also determined during three cycles of subculture. Results and discussion: Treatment of the root cultures with a low dose of gamma ray at 20 Gy gave the highest level of plumbagin production (1.04 mg/g DW) when compared to all other treated groups. The appropriate age of the root cultures for maximum production of plumbagin was found to be 10 days. However, treatment of 5-day-old root cultures resulted in a significant increase of dried root biomass that also had a high plumbagin production. Based on the total biomass per culture flask, the amounts of plumbagin produced by the 5- and 10-day-old treated roots were 0.59 and 0.37 mg/250 mL flask, respectively, which were 4.2- and 2.6-fold higher than the level in the control. Subculturing the root cultures until the third generation still showed an increase in plumbagin production without any effects on their growth. [ABSTRACT FROM AUTHOR]

Context: Lawsone, lawsone methyl ether and 3,3′-methylelnebislawsone are the main active compounds of Impatiens balsamina L. (Balsaminaceae). These compounds possess various pharmacological activities that have been shown to assist with the treatment of skin diseases. Objective: This work focused on increased naphthoquinone production in I. basamina root cultures using methionine feeding. Materials and methods: I. balsamina root cultures were maintained in liquid Gamborg's B5 medium supplemented with 0.1 mg/L α-naphthalene acetic acid, 0.1 mg/L kinetin, 1.0 mg/L 6-benzyladenine and 20 g/L sucrose. The effect of methionine concentration (50, 100, 300, 500 and 1000 mg/L) on naphthoquinone production of I. basamina root cultures was determined. Isolation of secondary metabolites from I. balsamina root cultures was also carried out. Results and discussion: Feeding of 300 mg/L methionine to the root cultures at the beginning of the growth cycle increased the production of 3,3′-methylelnebislawsone almost two-fold (0.63 mg/g dry weight, compared to the control group 0.32 mg/g dry weight). Optimization of the feeding conditions showed that adding 500 mg/L methionine to a 21-day old root cultures increased production of lawsone methyl ether and 3,3′-methylenebislawsone up to 2.6- and 3.1-fold higher, respectively, compared to the controls. In addition, various pharmacologically interesting secondary metabolites were isolated from I. balsamina root cultures, such as a flavonoid, luteolin, a naphthoquinone, 2,3-dihydroxy-1,4-naphthoquinone, and a triterpenoid, echinocystic acid. This is the first report of the occurrence of these compounds in this plant. [ABSTRACT FROM AUTHOR]

Context: Pentacyclic triterpenes, mainly, asiatic acid, madecassic acid, asiaticoside, and madecassoside are the active constituents of Centella asitica (L.) Urban. (Apiaceae). These compounds possess various pharmacological activities that have been shown to assist with wound healing and brain enrichment. Objective: Determination of these active pentacyclic triterpenes in extracts from the various parts of C. asiatica plants harvested at different times of the year and grown in different environments. Materials and methods: The separate plant parts selected were leaves, stolons, petioles, flowers, fruits, and nodes with roots. Dried powder from each part was extracted with ethanol by microwave-assisted extraction and subjected to determination of their content of the four pentacyclic triterpenes using a HPLC method. The effects of the places of cultivation as well as harvesting periods on the content of the four pentacyclic triterpenes in the extracts were also determined. Results and discussion: Among the various parts of C. asiatica, the leaves contained the highest amount of pentacyclic triterpenes with a total content of pentacyclic triterpenes of 19.5 mg/g dry powder. However, the contents of the pentacyclic triterpenes in C. asiatica varied according to the place of cultivation and the harvesting period . C. asiatica collected from Trang, Thailand gave the highest content of total pentacyclic triterpenes (37.2 mg/g dry powder) when harvested in March, while those collected from Songkhla, Thailand gave the highest value (37.4 mg/g dry powder) when collected in December. C. asiatica collected from Nakornsrithammarat and Ratchaburi, Thailand gave the lowest content of total pentacyclic triterpenes in all experimental harvesting periods. [ABSTRACT FROM AUTHOR]

Rhinacanthus nasutus (L.) Kurz (Acanthaceae) has long been used in Thai traditional medicine for treatment of tinea versicolor, ringworm, pruritic rash, and abscess. The active constituents are known as a group of naphthoquinone esters, rhinacanthins. This work focused on establishment of R. nasutus root cultures and determination of rhinacanthin production. Induction of R. nasutus root formation was accomplished on solid Gamborg's B5 (B5) medium, supplied with 0.1 mg/L indole-3-butyric acid (IBA) and 20 g/L sucrose. The effects of explants (whole leaf explants and four-side excised leaf explants), light and medium composition on root and rhinacanthin formation were investigated. The root formation from the whole leaf explants was 10 times higher than that from the four-side excised leaf explants. In addition, light possessed an inhibitory effect on the root and rhinacanthin formation of R. nasutus. Medium manipulation found that Murashige and Skoog (MS) medium supplied with 3 mg/L IBA and 30 g/L sucrose was the most suitable for induction of the root formation. Unfortunately, the obtained root cultures produced only rhinacanthin-C in very low amount, 0.026 mg/g dry weight (DW), when they were transferred into the same MS liquid medium. With semisolid medium (4 g/L agar) of the same MS composition, however, the root cultures appeared to produce higher content of rhinacanthin-C, -D and -N (3.45, 0.07 and 0.07 mg/g DW, respectively). Our finding suggests that culturing in semisolid medium is capable of improving of rhinacanthin production in R. nasutus root cultures. [ABSTRACT FROM AUTHOR]

Ethyl acetate and methanol extracts of 18 Thai medicinal plants were investigated for their antibacterial activity against Propionibacterium acnes, Stapylococcus aureus, and S. epidermidis. Thirteen plant extracts were capable of inhibiting the growth of P. acnes and S. epidermidis, while 14 plant extracts exhibited an inhibitory effect on S. aureus. Based on the broth dilution method, the ethyl acetate extract of Alpinia galanga (L.) Wild. (Zingiberaceae) rhizome showed the strongest antibacterial effect against P. acnes, with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of 156.0 and 312.0 µg/mL, respectively. On the basis of bioassay-guided purification, the ethyl acetate extract was isolated to afford the antibacterial active compound, which was identified as 1′-acetoxychavicol acetate (1′-ACA). 1′-ACA had a strong inhibitory effect on P. acnes with MIC and MBC values of 62.0 and 250.0 µg/mL, respectively. Thus, 1′-ACA was used as an indicative marker for standardization of A. galanga extract using high performance liquid chromatography. These results suggest that A. galanga extract could be an interesting agent for further studies on an alternative treatment of acne. [ABSTRACT FROM AUTHOR]

A one-step purification of Senna alata (L.) Roxb. (Leguminosae) extract using silica gel vacuum chromatographic technique provided an anthraquinone high-yielding S. alata leaf extract. This method was capable of improving its anthraquinone content as well as antifungal activity against dermatophytes. The extract contained anthraquinone content up to 16.7% w/w, and exhibited antifungal activity against Trichophyton rubrum, T. mentagrophytes and Microsporum gypseum with minimum inhibitory concentration (MIC) values of 15.6, 62.5, and 250 μg/mL, respectively. Stability evaluations of the anthraquinone high-yielding extract in several conditions through a period of 4 months found that the extracts were stable either kept under light or protected from light. The extracts were also stable under 4 ± 2°C, 30 ± 2°C and an accelerated condition, at 45°C with 75% relative humidity. The aqueous solutions of the extracts, at pH 5.5 and 7, exhibited good stability. These results indicate that the anthraquinone high-yielding S. alata extract possessed satisfactory antifungal activity and stability for a further development of herbal medicines. [ABSTRACT FROM AUTHOR]

Root cultures of Senna alata (L.) Roxb. were established in liquid B5 medium, supplemented with 0.5 mg l -1 α-naphthalene acetic acid (NAA) and 1.0 mg l -1 kinetin. The root cultures, which were established from the high-anthraquinone-producing plants, accumulated higher amounts of emodin and chrysophanol than those established from the low-anthraquinone-producing plants and leaves and roots of the intact plants. [ABSTRACT FROM AUTHOR]

Induction of naphthoquinone formation in Impatiens balsamina cell cultures was achieved by using parent plants yielding high levels of 2-methoxy-1,4-naphthoquinone as initiated explants. The cell culture with red-yellowish color was established in B5 medium supplemented with 0.1 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D) and 1.0 mg/L 6-benzylaminopurine (BA). The cell cultures were capable of producing two naphthoquinones, lawsone, and an unknown, which was more polar than lawsone. The time-course of growth and lawsone production in I. balsamina cell culture were also established. [ABSTRACT FROM AUTHOR]