Obesity is a serious health complication in almost every corner of the world. Excessive weight gain results in the onset of several other health issues such as type II diabetes, cancer, respiratory diseases, musculoskeletal disorders (especially osteoarthritis), and cardiovascular diseases. As allopathic medications and derived pharmaceuticals are partially successful in overcoming this health complication, there is an incessant need to develop new alternative anti-obesity strategies with long term efficacy and less side effects. Plants harbor secondary metabolites such as phenolics, flavonoids, terpenoids and other specific compounds that have been shown to have effective anti-obesity properties. Nanoencapsulation of these secondary metabolites enhances the anti-obesity efficacy of these natural compounds due to their speculated property of target specificity and enhanced efficiency. These nanoencapsulated and naive secondary metabolites show anti-obesity properties mainly by inhibiting the lipid and carbohydrate metabolizing enzymes, suppression of adipogenesis and appetite, and enhancing energy metabolism. This review focuses on the plants and their secondary metabolites, along with their nanoencapsulation, that have anti-obesity effects, with their possible acting mechanisms, for better human health.

Low desiccation resistance of Drosophila ananassae reflects its rarity outside the humid tropics. However, the ability of this sensitive species to evolve under seasonally varying subtropical areas is largely unknown. D. ananassae flies are mostly lighter during the rainy season but darker and lighter flies occur in the autumn season in northern India. We tested the hypothesis whether seasonally varying alternative body color phenotypes of D. ananassae vary in their levels of environmental stress tolerances and mating behavior. Thus, we investigated D. ananassae flies collected during rainy and autumn seasons for changes in body melanization and their genetic basis, desiccation‐related traits, cold tolerance and mating propensity. On the basis of genetic crosses, we found total body color dimorphism consistent with a single gene model in both sexes of D. ananassae. A significant increase in the frequency of the dark morph was observed during the drier autumn season, and body color phenotypes showed significant deviations from Hardy‐Weinberg equilibrium, which suggests climatic selection plays a role. Resistance to desiccation as well as cold stress were two‐ to three‐fold higher in the dark body color strain as compared with the light strain. On the basis of no‐choice mating experiments, we observed significantly higher assortative matings between dark morphs under desiccation or cold stress, and between light morphs under hot or higher humidity conditions. To the best of our knowledge, this is the first report on the ecological significance of seasonally varying total body color dimorphism in a tropical species, D. ananassae.

Mating speed and copulation duration respond rapidly to laboratory selection in Drosophila melanogaster Meigen (Diptera: Drosophilidae), but there is a lack of data on the evolutionary response to natural selection in the wild. Further, it is not clear whether body melanization and mating behavior are correlated traits. Accordingly, we tested whether variation in body color impacts on mating latency, copulation duration, and fecundity in latitudinal populations of D. melanogaster. We observed geographical variation (cline) for mating propensity, i.e., mating speed as well as copulation duration increased along latitude. Phenotypic plastic responses for body melanization at 17 and 25 °C also showed significant correlations with mating latency and copulation duration. Within‐population analysis based on assorted dark and light flies of five geographical populations showed significant positive correlations of copulation duration and fecundity with body melanization. To assess the role of males and/or females on mating speed and copulation duration, we used atypical body color strains (i.e., dark and light males of D. melanogaster) for no‐choice mating tests. Our data showed a major influence of males for copulation duration and of females for mating speed. Furthermore, a difference in impact of body melanization on mating speed and copulation duration was demonstrated between species, i.e., low melanization in Drosophila ananassae Doleschall is correlated with lower mating speed and shorter copulation duration than in D. melanogaster. Geographical changes in mating propensity were significantly correlated with body melanization at three levels, i.e., within and between populations and between species. Thus, we have shown that a relationship exists between body melanization and mating success. Further, we found seasonal changes in temperature and humidity to confer selection pressures on mating‐related traits.

SUMMARYDrosophila ananassae has successfully invaded the cold and dry montane localities of the Western Himalayas in recent years. The ability of this desiccation-and cold-sensitive tropical species to evolve in response to seasonal changes in montane localities is largely unknown. Here, we investigated how this sensitive species adapt to seasonally varying environmental conditions that are lethal to its survival. We observed change in the frequency of dark and light morphs of D. ananassae in five mid-altitude localities during the last decade (2000-2010). We document invasion of D. ananassae to montane localities and increase in frequency of the dark morph. The stress tolerance of morphs (dark and light) remained unaffected of developmental acclimation. However, adult acclimation has shown significant effects on tolerance to various environmental stresses in morphs and effect of this acclimation persist for long durations. Desiccation and cold stress tolerance was increased after adult acclimation for respective stress in the dark morph; while tolerance of the light morph was not affected. Further, heat tolerance of the light morph was increased after adult heat acclimation with no influence on heat tolerance of the dark morph. Our results suggest a possible role of adult acclimation in successful invasion and adaptation of D. ananassae to montane localities. Future experiments should be carried out to determine whether the survival in adverse conditions of low versus high temperature and humidity during seasonal changes is assisted by different acclimation abilities of the two morphs of D. ananassae. Supplementary material available online at

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