Dennis D. Raga

Bioactive triterpenes from Diospyros blancoi.

The ethyl acetate extract of the air-dried leaves of Diospyros blancoi afforded isoarborinol methyl ether (1), a mixture of α-amyrin palmitate, α-amyrin palmitoleate, β-amyrin palmitate and β-amyrin palmitoleate (2) in a 13 : 4 : 3 : 1 ratio, and squalene. The structures of 1, 2 and squalene were elucidated by extensive 1D and 2D NMR spectroscopy. Compounds 1 and 2 exhibited antimicrobial activity against Escherichia coli, Pseudomonas aeruginosa, Candida albicans, Staphylococcus aureus and Trichophyton mentagrophytes, and were found inactive against Bacillus subtilis and Aspergillus niger. Sample 2 exhibited significant analgaesic and anti-inflammatory activities.

Hypoglycaemic effects of tea extracts and ent-kaurenoic acid from Smallanthus sonchifolius

Hypoglycaemic activity was observed in normoglycaemic mice orally administered with the aqueous Smallanthus sonchifolius leaf tea extract, alloxan-induced diabetic mice orally administered with ent-kaurenoic acid (1), and normoglycaemic mice intraperitoneally administered with 1 from S. sonchifolius leaves. A single dose administration of 50 mg kg−1 BW yacon leaf tea extract demonstrated immediate but relatively short hypoglycaemic activity, with significant effects observed during 1–2 h. Similarly, administration with 100 mg kg−1 BW yacon leaf tea extract obtained by heavy stirring in hot water demonstrated a more potent activity compared to the positive control at 1.5–2.0 h. Oral administration of 1 did not affect the blood glucose level of the alloxan-induced diabetic mice, but a single intraperitonial injection of 10 mg kg−1 BW in normoglycaemic mice had consistent percent blood glucose reduction persisting from 1 to 2 h observation periods.

TERPENOIDS FROM Ardisia squamulosa

The genus Ardisia Swartz belongs to the family Myrsinaceae. Ardisia has 68 recorded species in the Philippines [1], 60 of which are endemic. The hexane extract from A. squamulosa was reported to have a significant effect on sperm count but has a negligible effect on sperm morphology and viability [2]. No chemical study of A. squamulosa has been reported. However, we earlier studied a congener of this plant, Ardisia pyramidalis, which afforded spinasterol, spinasteryl acetate, a mixture of -amyrin, -amyrin and bauerenol, squalene, lutein, and triglycerides from the dichloromethane (DCM) extract of the leaves. Spinasterol was found to exhibit anti-angiogenic potential [3]. This study was conducted as part of our research on the chemical constituents of Ardisia species found in the Philippines. We report herein the chemical constituents of the DCM extract of the leaves of A. squamulosa. Fresh leaves of Ardisia squamulosa were collected from Kanawan, Morong Bataan, Philippines in 2010 by Ramon Bandong. The sample was authenticated by the Jose Vera Herbarium Collection at the Institute of Biology of the University of the Philippines-Diliman and the Philippine National Museum, Manila. The DCM extracts of the air-dried leaves of A. squamulosa afforded terpenoids by silica gel chromatography. These compounds were identified by comparison of their 13C NMR data with those of -caryophyllene (1) [4], squalene (2) [5], bauerenone (3a) [6], ursenone (3b) [7], oleanone (3c) [7], bauerenol (4a) [6], -amyrin (4b) [8], -amyrin (4c) [8], and lutein (5) [9] reported in the literature. Air-dried leaves of Ardisia squamulosa (1 kg) were ground in an Osterizer and then soaked in DCM for three days and filtered. The filtrate was concentrated in vacuo to afford a crude extract (55 g), which was chromatographed in increasing proportions of acetone in dichloromethane at 10% increment. The DCM fraction was rechromatographed (6 ) in petroleum ether to afford 1 (5 mg) and 2 (20 mg). The 10% acetone in DCM and 20% acetone in DCM fractions were combined and rechromatographed (4 ) with 2.5% ethyl acetate in petroleum ether as eluent to afford a mixture of 3a–3c (12 mg). The 30% acetone in DCM fraction was rechromatographed (5 ) using 5% ethyl acetate in petroleum ether to afford a mixture of 4a–4c (15 mg). The 40% acetone in DCM and 50% acetone in DCM fractions were combined and rechromatographed (3 ) with DCM–diethyl ether–acetonitrile (9:0.5:0.5) as eluent to afford 5 (18 mg) after washing with diethyl ether.

HYPOGLYCEMIC POTENTIAL OF TRITERPENES FROM ALSTONIA SCHOLARIS

A dichloromethane extract of air-dry leaves of Alstonia scholaris (L.) R. Br. contains a mixture of cycloeucalenol (1a), cycloartanol (1b) and lupeol (1c); lupeol acetate (2); and betulin (3). The structures of these triterpenes were elucidated by extensive 1D and 2D NMR spectroscopy and confirmed by comparison of their 13C NMR data to those reported in the literature. A previous study reported that the powdered leaves of Alstonia scholaris produced a highly significant decrease in blood glucose and a mechanism of this action was upon insulin triggering and direct insulin-like effects. Betulin and lupeol acetate were reported to exhibit hypoglycemic activity. Thus, only a mixture of 1a – 1c was tested for hypoglycemic potential using the oral glucose tolerance test (OGTT). A possible hypoglycemic activity was observed for a mixture of 1a – 1c at a dose of 25 mg/kg BW administered orally to normoglycemic mice.

Erratum to: Hypoglycemic Potential of Triterpenes from Alstonia scholaris

This article was unintentionally published twice in this journal by the same authors. The following should be considered the version of record and used for citation purposes: “Consolacion Y. Ragasa, Kosta Fremmielle Lim, Chien-Chang Shen, and Dennis D. Raga, Hypoglycemic Potential of Triterpenes from Alstonia scholaris, Pharmaceutical Chemistry Journal, Vol. 47, No. 1, pp. 54-57, DOI 10.1007/s11094-013-0896-3.”

A New Triterpene from Atalantia retusa Merr.

Atalantia retusa Merr. is a rare Philippine endemic shrub which was reported to exhibit high antinociceptive and anti-inflammatory activities. The dichloromethane extract of the air-dried leaves of A. retusa afforded a new triterpene, retusenol (1), and friedelin (2), dischidiol (3), 5,7-dimethoxy-8- (3-methyl-2-oxybutyl)coumarin (4), humulene (5), and β-caryophyllene (6). The structures of 1 - 4 were elucidated by extensive 1D and 2D NMR experiments. Friedelin, a known analgesic and antiinflammatory drug, is an active principle of the shrub. Compounds 1 - 4 were tested for cytotoxicity against the human cancer lung adenocarcinoma A549, colon carcinoma HCT116 and the non-cancer Chinese hamster ovary AA8 using the MTT assay. Triterpenes 1 - 3 had no linear interpolation with HCT 116 and A549, thus the IC50 value could not be computed. This implied that these compounds did not exhibit any cytotoxic effect against these cell lines. Meanwhile, 4 exhibited moderate cytoxicity against A549, HCT 116 and AA8 with IC50 values of 47.5634, 42.4338 and 46:2751 μ g mL-1, respectively. Compounds 1, 2 and 4 were tested for their antimicrobial properties against seven microorganisms and exhibited the highest activity against B. subtilis, even surpassing the activity of the standard antibiotic Chloramphenicol. They also exhibited antimicrobial activities against P. aeruginosa, S. aureus, C. albicans, and T. mentagrophytes, but were inactive against A. niger and E. coli. Graphical Abstract A New Triterpene from Atalantia retusa Merr.

Anti-nociceptive and anti-inflammatory activities of Atalantia retusa Merr.

Atalantia retusa is an endemic medicinal plant used in the Philippines. Hexane extract from leaves were orally administered on rats and mice and tested using rat paw edema, formalin and writhing assays. Increased pain tolerance was observed in animals administered with the median dose (1.43 mg/Kg BW) in both somatic (P<0.05) and visceral (P<0.01) models by 6.05% and 55.48% better compared to the positive control. The degree of swelling was also reduced by the administration of 1.43 mg/Kg BW at 0.5 to 3.0h after carrageenan injection suggesting a high impact analgesic and anti-inflammatory effects of A. retusa hexane extract.