This review provides an overview of diterpene synthases which were initially identified via genetic and/or biochemical means, traversing all organisms researched to date.

Four new polycyclic polyprenylated acylphloroglucinol type metabolites, hypercohones D-G(1-4), along with four known analogues(5-8), were isolated from the aerial parts of Hypericum cohaerens. The structures of these isolates were elucidated by extensive spectroscopic methods. The inhibitory activities of these isolates against five human cancer cell lines in vitro were also tested.

Age related cataract is the leading cause of blindness associated with accumulation of oxidative stress in the eye lens. The present investigation reveals the rational of the beneficial effects of the natural compound C-phycocyanin(CPC) is beneficial when administered to rat pups to protect against the secondary effects of sodium selenite induced cataractogenesis. A single subcutaneous dose of sodium selenite(19 μmol/kg body weight) on the 10th day of postpartum is adequate to induce cataract in rat pups. Serum biochemical parameters, such as the level of electrolytes, mean activities of anti-oxidant enzymes i. e. superoxide dismutase, catalase and reduced glutathione were observed to be significantly altered during selenite induced cataractogenic process. Histopathological examination revealed signs of degradation of normal cell architecture in the liver, kidney and eye lens. Interestingly, the deleterious effects of sodium selenite toxicity were restored with the simultaneous treatment with C-PC. The results suggest that an administration of 200 mg/kg body weight of C-PC has the ability to prevent/alter the secondary changes reflected in the serum biochemical and histological modifications in rats exposed to sodium selenite. These results complement the beneficial role of C-PC of cyanobacterial origin as a efficacious anti-cataractogenic agent against sodium selenite toxicity.

The perennial herbaceous plant Euphorbia jolkinii(Euphorbiaceae) is a noxious weed widely distributed in the grasslands of northwestern Yunnan and has greatly threatened the local biodiversity. Phytochemical investigation on the fresh roots of E. jolkinii afforded six new diterpenoids 1, 2, 4-6, and 8, together with fifteen known diterpenoids. Their structures were elucidated on the basis of 1D and 2D NMR and other spectroscopic methods. Casbane, lathyrane, abietane, and ent-kaurane diterpenoids were reported from this plant for the first time. Selected compounds were evaluated for their antifeedant and anti-RSV(respiratory syncytial virus) activities. Compound 2 and ingenol(3) exhibited moderate antifeedant activity against a generalist insect herbivore, Spodoptera exigua, with EC₅₀ values of 17.88 and 17.71 lg/cm² respectively. Compound 19 showed significant anti-RSV activity, with 50% inhibition(IC₅₀) value of 10.0 μM and selective index of 8.0. Compounds 1 and 2 were less active against RSV virus, both with IC₅₀ value of 25 μM, and with selective indices of 1.0 and 3.2 respectively. These findings provided new evidence for the biological functions and utilization of the diversified diterpenoid metabolites in the roots of this rich but harmful plant.

New hexalobine type alkaloid, 5-(2", 3"-epoxy-3"-methylbutyl)-3-(3'-hydroxy-3'-methyl-1'-acetyloxy-but-2'-yl) indole(1) alongside the known hexalobines 3-(2', 3'-dihydroxy-3'-methylbutyl)-5-(3"-methylcrotonoyl) indole(2), 3, 5-hexalobine C(3) and 3, 5-hexalobine D(4) were isolated from fruits of Hexalobus monopetalus. Compounds 3 and 4 exhibited antifungal activity against Candida albicans.

Mature seeds of Helicteres isora L. were collected from seven geographical locations of Maharashtra and Goa(India) and evaluated for diosgenin(a bioactive steroidal sapogenin of prime importance) extraction and quantification. Chemotypic variations were evidenced with diosgenin quantity ranging from 33 μg g^-1 seeds(Osmanabad forests) to 138 μg g^-1(Khopoli region). Nodal and leaf explants from in vitro-raised seedlings were used for callus and Agrobacterium-mediated transformation, respectively. Compact, hard, whitish-green callus(2.65 g explant^-1) was obtained on MS+13.32 μM BAP+2.32 μM Kin after 30 days of inoculation. Various parameters including types of explant and Agrobacterium strain, culture density, duration of infection and various medium compositions were optimized for hairy root production. A. rhizogenes strain ATCC-15834 successfully induced hairy roots from leaf explants(1 cm²) with 42% efficiency. Transgenic status of the roots was confirmed by PCR using rolB and VirD specific primers. Hairy roots showed an ability to synthesize diosgenin. Diosgenin yield was increased ~8 times in hairy roots and ~5 times in callus than the seeds of wild plants. Enhanced diosgenin content was associated with proline accumulation in hairy roots. This is the first report on induction of hairy roots in H. isora.

Artemisinin, a constituent of Artemisia annua L. , is a well-known antimalarial drug. Artemisinin-type drugs also inhibit cancer growth in vitro and in vivo. Herbal extracts of A. annua inhibit the growth of cancer cell lines. Here, we report on the use of capsules containing powder of Herba Artemisiae annuae to treat pet sarcoma. The surgical tumor removal as standard treatment was supplemented by adjuvant therapy with A. annua. One cat and one dog with fibrosarcoma survived 40 and 37 months, respectively, without tumor relapse. Two other dogs suffering from fibrosarcoma and hemangioendothelial sarcoma also showed complete remission and are still alive after 39 and 26 months, respectively. A. annua was well tolerated without noticeable side effects. These four cases indicate that A. annua may be a promising herbal drug for cancer therapy.

Nine previously-unreported farnesylphenols, involving eight neogrifolin derivatives(1-8) and one grifolin analogue(9), together with three known compounds, were isolated from the fruiting bodies of the mushroom Albatrellus caeruleoporus. Their structures were elucidated as(S)-17-hydroxy-18, 20-ene-neogrifolin(1),(S)-18, 19-dihydroxyneogrifolin(2),(S)-9-hydroxy-10, 22-ene-neogrifolin(3),(9S, 10R)-6, 10-epoxy-9-hydroxyneo grifolin(4),(9S, 10R)-6, 9-epoxy-10-hydroxyneogrifolin(5),(-)-13, 14-dihydroxyneogrifolin(6), albatrelin G(7), albatrelin H(8), and one grifolin analogue,(S)-10-hydroxygrifolin(9), grifolin(10), neogrifolin(11), and albatrellin(12) by extensive spectroscopic analyses and chemical methods. Compounds 7 and 8 showed weak cytotoxic activity to cell lines HL-60, SMMC-7721, A-549, and MCF-7, in vitro.

Phytochemical investigation of Sanrafaelia ruffonammari Verd and Ophrypetalum odoratum Diels that belongs to the rare genera confined to East African coastal forests led to the isolation of enantiomeric styrylpyrone dimer,(±)-5-methoxy-7-phenyl-[4-methoxy-2-pyronyl]-1-(E)-styryl-2-oxabicyclo-[4.2.0]-octa-4-en-3-one(1) alongside(+)-6-styryl-7, 8-epoxy-4-methoxypyran-2-one(2) and the enantiomeric(+)-(3) and(-)-6-styryl-7, 8-dihydroxy-4-methoxypyran-2-ones(4). Their structures were established by means of spectroscopic methods. In this paper we reveal for the first time the occurrence of styrylpyrones in East African biodiversity.(+)-6-Styryl-7, 8-epoxy-4-methoxypyran-2-one(2) and the dihydroxystyrylpyrone enantiomer(3) showed in vitro antifungal activity against Candida albicans at a concentration of 24.4 and 26.2 lM with zones of inhibition of 17 and 9 mm, respectively. Compound 2 exhibited strong activity in the brine shrimp test with LC₅₀=1.7 μg/mL. Their high cytotoxic and antifungal activities render them candidates for further scientific attention for drug development programs against cancer and microbial infections.