Novel cycloartane triterpenoids from the Nepal native plant Caragana sukiensis.

A phytochemical study on the arial part of Caragana sukiensis resulted in the isolation of three new cycloartane triterpenoids 1-3 and their structures were fully established on the basis of detailed spectroscopic (especially 2D NMR and Mass) analysis. These new compounds possessed hemiacetal fused tetrahydropyran rings at C-15/C-16, while 2 and 3 also contains d-xylose moiety.

Urease inhibitor from Datisca cannabina linn.

A new flavonoid datisdirin (1), along with eight known compounds tectochrysine, cearoin, sideroxyline, ursolic acid, corosolic acid, arjunolic acid, erythrodiol and oleanolic acid, were isolated from the ethyl acetate fraction of D. cannabina Linn. The structure of compound 1 was deduced on the basis of its spectral data. Datisdirin showed activity against the ureases enzyme.

Structure activity relationship studies on antileishmanial steroidal alkaloids from Sarcococca hookeriana.

The search for antileishmanial constituents from the medicinal plant Sarcococca hookeriana (Buxaceae) of Nepalese origin has resulted in the isolation of 17 (1-17) active steroidal alkaloids. Compounds 1, 2, and 10 were subjected to derivatization and five chemically derived derivatives (1a, 2a, 10a, 10b, 10c) were also obtained. All these natural compounds and derivatives were found to have potent to mild antileishmanial properties. The IC(50) values were found to be in the range of 0.20-61.44 microg mL(-1) (IC(50) value of standard drug amphotericin B = 0.12 microg mL(-1)). The structure activity relationship indicated that the varieties of functionalities present in ring A of the steroidal alkaloids were found to play a characteristic role to increase the antileishmanial activity.

Tyrosinase inhibitory and antileishmanial constituents from the rhizomes of Paris polyphylla.

The search for bioactive natural products from the rhizomes of Paris polyphylla (Trilliaceae) has resulted in the isolation of four known constituents, 1,5-dihydroxy-7-methoxy-3-methylanthraquinone (1), diosgenin-3-O-[alpha-L-rhamnopyranosyl-(1 --> 3)-beta-D-glucopyranoside] (2), diosgenin-3-O-[alpha-L-rhamnopyranosyl-(1(Rha) --> 2(Glu))-alpha-L-arabinofuranosyl-(1(Ara) --> 4(Glu))]-beta-D-glucopyranoside (3), and diosgenin-3-O-[alpha-L-rhamnopyranosyl-(1(Rha) --> 2(Glu))-alpha-L-rhamnopyranosyl-(1(Ara) --> 4(Glu))]-beta-D-glucopyranoside (4). Their structures were identified by spectral comparison with the reported data. Compound 1 was isolated for the first time from this genus. The chloroform, ethyl acetate, and butanol extracts of the plant were found to have mild to moderate inhibitory potentials against the enzyme tyrosinase. Compound 1 showed strong (IC(50) = 0.23 microM), while compounds 2-4 and hydrolyzed product 4a showed mild to moderate (IC(50) = 0.93-36.87 microM) activities against the tyrosinase. Similarly, compounds 2-4 and 4a showed mild to moderate (IC(50) = 1.59-83.72 microg mL(-1)) antileishmanial activities.

Hydroxylation of the sesterterpene leucosceptrine by the fungus Rhizopus stolonifer.

The microbial transformation of leucosceptrine (1), the first member of class leucosesterterpenes, by Rhizopus stolonifer afforded two metabolites, 1alpha-hydroxyleucosceptrine (2), and 8alpha-hydroxyleucosceptrine (3).

Bangangxanthone A and B, two xanthones from the stem bark of Garcinia polyantha Oliv.

Two xanthones, bangangxanthone A (1) [1,5,8-trihydroxy-6'-methyl-6'-(4-methylpent-3-enyl)- pyrano[2',3':3,4]xanthone] and B (2) [1,4,8-trihydroxy-2-prenylxanthone], along with two known xanthones, 1,5-dihydroxyxanthone, 2-hydroxy-1,7-dimethoxyxanthone and the pentacyclic triterpenoids, friedelin, oleanolic acid and lupeol were isolated from the chloroform extract of the stem bark of Garcinia polyantha. The structures of these compounds were assigned by spectroscopic analysis. Compounds 1-4 showed antioxidant DPPH radical scavenging activities.

Cholinesterase inhibitory pregnane-type steroidal alkaloids from Sarcococca hookeriana.

The bioassay-guided phytochemical investigation on Sarcococca hookeriana have resulted in the isolation of four new pregnane-type steriodal alkaloids: hookerianamide-D [(2'E,20S)-20-(N,N-formyl(methyl)amino)-3beta-(3',4'-dimethyl-2'-pentenamido)-5alpha-pregnane] (1), hookerianamide-E [(2'E,20S)-20-(N,N-dimethylamino)-3beta-(senecioylamino)-5alpha-pregn-14-en-2beta-O-acetate] (2), hookerianamide-F [(2'E,20S)-20-(N-methylamino)-3beta-(tigloylamino)-5alpha-pregn-2,14-dien-4-one] (3), and hookerianamide-G [(20S)-20-(N,N-dimethylamino)-3beta-(N-methylbenzamido)-5alpha-pregn-4beta-O-acetate] (4), along with five known alkaloids 5-9. Their structures were determined by spectroscopic analysis. These steroidal alkaloids and chemically derived derivatives of compound 5 have displayed varying degree of inhibitory activities against acetylcholinesterase and butyrylcholinesterase enzymes in a concentration-dependent fashion, with the IC(50) values ranging from 1.5 to 148.2 and 0.6 to 100.2 microM, respectively.

Novel sesterterpenes from Leucosceptrum canum of nepalese origin.

Two novel sesterterpenoids, leucosesterterpenone (1) and leucosesterlactone (2), with novel skeleta were isolated from the hexane extract of the medicinal plant, Leucosceptrum canum. Their structures were established by the analysis of NMR data and the single-crystal X-ray diffraction of compound 1. Compounds 1 and 2 were found to exhibit activity against prolylendopeptidase (PEP).

Leucosceptrine--a novel sesterterpene with prolylendopeptidase inhibitory activity from Leucosceptrum canum.

A novel sesterterpene, leucosceptrine, was isolated from the medicinal plant Leucosceptrum canum from Nepal. The structure was determined by single-crystal X-ray diffraction and spectroscopic techniques. The biosynthesis of leucosceptrine (1) is proposed here. Leucosceptrine (1) exhibited prolylendopeptidase inhibitory activity.