Aryltetralone and arylindanone neolignans from Virola sebifera

The fruits of Virola sebifera contain several tetralone neolignans, including 2,4-dihydroxy-6,7-methylenedioxy-2,3-dimethyl-4-veratryltetralin-1-one. The 3-hydroxylated derivative of this compound may undergo a biosynthetic pinacol-pinacolone rearrangement to give 2-acetyl-3-hydroxy-2-methyl-5,6-methylenedioxy-3-veratrylindan-1-one which, together with other indanone neolignans, was also isolated.     

Non-alkaloidal constituents of Virola elongata bark

Eleven of the major non-polar constituents of the dried bark of Virola elongata were isolated. A new neolignan, virolongin, two new lignans, dihydrosesartemin and β-dihydroyangambin, as well as the neolignan, eusiderin, the lignans, epi-sesartemin, epi-yangambin and yangambin, the cis and trans isomers of 3,5,4′-trimethoxystilbene and sitosterol were identified. The structures of virolongin, dihydrosesartemin and β-dihydroyangambin were determined.     

Acylresorcinols from Virola sebifera and Virola elongata

The fruits of Virola sebifera and V. elongata (Myristicaceae) contain three ω-phenylundecanoyl-substituted compounds, a 2,6-dihydroxybenzene, a 2,6-dihydroxy-4-methoxybenzene and a 3-hydroxycyclohexan-2,6-dione. Three additional 2,6-dihydroxybenzenes are substituted by hexadecanoyl, hexadec-4Z-enoyl and 8-hydroxyoctadec-4Z-enoyl groups.     

Lignoids from the fruit of three Virola species

The fruits of Virola peruviana contain, besides i 1-phenyl-1-1-(2′,6′-dihydroxyphenyl)-undecan-1-one and the neolignan 2,3-dimethyl-1,4-diveratryl-n-butan-1-ol, 3,4-methylenedioxycinnamyl alcohol. In contrast, the fruits of V. flexuosa and V. multinervia both contain oxidative dimers of cinnamyl alcohols such as asarinin, cubebin, dihydrocubebin and sesamin. The former contains additionally fargesin and O-methylpiperitol, besides 7,4′-dimethoxyflavone, and the latter contains additionally hinokinin.     

Flavonoids from Iryanthera laevis

Trunk wood of Iryanthera laevis Markgr. (Myristicaceae) contains 2′,4′-dihydroxy- 4,6′dimethoxydihydrochalcone, three 2′-hydroxy-4′,5′-methylenedioxyflavans with differently substituted A-rings (7-OH-6,8-diMe; 7-OH-5,8-diMe; 5-OH-7-OMe-6,8-diMe) and 1-(2′-hydroxy-4′-methoxy-5′-methylphenyl)-3(2″-hydroxy-4″,5″-methylenedioxphenyl)- propane, as well as three additional known diarylpropanes.     

Horsfieldin,a lignan and other constituents from Horsfieldia iryaghedhi

A new lignan, horsfieldin [2-(3-hydroxy-4-methoxyphenyl)-6-(3,4-methylenedioxyphenyl)-3,7-dioxabicyclo(3,3,0)octane], d-asarinin, (?)-dihydrocubebin, dodecanoylphloroglucinol, myristic acid, trimyristin and sitosterol have been isolated and characterized from the hot methanol extract of Horsfieldia iryaghedhi seeds. The absolute configuration of the lignans and the chemotaxonomic significance of their occurrence is discussed.     

1,11-diarylundecan-1-one and 4-aryltetralone neolignans from Virola sebifera

The seed of Virola sebifera contains besides the polyketide 1 - (2′,6′ - dihydroxyphenyl) - 11 - henylundecan - 1 - one, four neolignans: (2S, 3S, 4R) - 4 - hydroxy - 2,3 - dimethyl - 5,6 - methylenedioxy - 4 - piperonyl - 1 - tetralone and its 2-epimer, as well as (2R, 3R, 4S) - 4 - hydroxy - 6,7 - dimethoxy - 2,3 - dimethyl 4 - piperonyl - 1 - tetralone and its (2R, 3S, 4R) - dehydroxy analogue.     

Determinants of biased sex ratios and inter-sex costs of reproduction in dioecious tropical forest trees

Estimates of the sex ratio and cost of reproduction in plant populations have implications for resource use by animals, reserve design, and mechanisms of species coexistence, but may be biased unless all potentially reproductive individuals are censused over several flowering seasons. To investigate mechanisms maintaining dioecy in tropical forest trees, we recorded the flowering activity, sexual expression, and reproductive effort of all 2209 potentially reproductive individuals within 16 species of Myristicaceae over 4 years on a large forest plot in Amazonian Ecuador. Female trees invested >10 times more biomass than males in total reproduction. Flowering sex ratios were male-biased in four species in ≥1 year, and cumulative 4-year sex ratios were male-biased in two species and for the whole family, but different mechanisms were responsible for this in different species. Annual growth rates were equivalent for both sexes, implying that females can compensate for their greater reproductive investment. There was no strict spatial segregation of the sexes, but females were more often associated with specific habitats than males. We conclude that male-biased sex ratios are not manifested uniformly even after exhaustive sampling and that the mechanisms balancing the higher cost of female reproduction are extremely variable.     

Rapid Assessment of Seed Removal and Frugivore Activity as a Tool for Monitoring the Health Status of Tropical Forests

Ecological processes in tropical forests are being affected at unprecedented rates by human activities. Yet, the continuity of ecological functions like seed dispersal is crucial for forest regeneration. It thus becomes increasingly urgent to be able to rapidly assess the health status of these processes in order to take appropriate management measures. We tested a method to rapidly evaluate seed removal rates on two animal‐dispersed tree species, Virola kwatae and V. michelii (Myristicaceae), at three sites in French Guiana with increasing levels of anthropogenic disturbance. We counted fallen fruits, fruit valves, and seeds of each focal fruiting tree in a single 1 m² quadrat, and calculated two indices: the proportion of seeds removed and the proportion of fruits opened by mammals. They both provide an indirect and rapid assessment of frugivore activity. Our results showed a significant decrease in the proportion of removed seeds (16%) and fruits opened (19%) at the most impacted site in comparison with the other two sites (79% for seeds, 60% and 35% for fruits). This testifies to an increased impoverishment of the primate and toucan communities at the disturbed sites. This standardized protocol provides fast information about the health status of the community of seed dispersers and predators and of their seed removal services. It is time‐ and cost‐effective and is not species‐specific, allowing comparisons among sites or over time. We suggest using it with the pantropical Myristicaceae and any other capsule‐producing family to rapidly assess the health status of seed removal processes across the tropics.     

Forest cover,hunting pressure,and fruit availability influence seed dispersal in a forest‐savanna mosaic in the Congo Basin

Forest fragmentation, reduced forest cover, and hunting pressure are the main threats affecting animal‐mediated seed dispersal. However, their combined effects on seed dispersal rates have been simultaneously investigated only rarely, and never in Africa. We aimed to disentangle the effects of forest cover, hunting pressure, frugivore abundance, and fruit availability at the local and landscape scales on the seed dispersal rates of Staudtia kamerunensis (Myristicaceae). To estimate the percentages of seed dispersal failure (undispersed seeds), we quantitated fruit remains below fruiting trees distributed across five contrasting sites in a semi‐natural forest‐savanna mosaic in the Democratic Republic of Congo. We used statistical analyses accounting for spatial autocorrelation and found that forest cover in the surrounding landscape, hunting level, the associated abundance of dispersers, and fruit availability all had significant effects on the percentage of seed dispersal failure. The combination of high fruit availability and reduced abundance of seed dispersers could accelerate seed disperser satiation, causing the seed dispersal system to be saturated. Our study highlights how two major factors associated with anthropogenic activities, forest cover and hunting, affect seed dispersal by animals. These findings could have far‐reaching implications for our understanding of tree‐frugivore interactions and the conservation of tropical communities.